TECHNICAL SUPPORT DOCUMENT FOR THE IRON AND STEEL SECTOR: PROPOSED RULE FOR MANDATORY REPORTING OF GREENHOUSE GASES Office of Air and Radiation U.S. Environmental Protection Agency September 9, 2008 ------- CONTENTS INTRODUCTION 2 1. INDUSTRY DESCRIPTION 3 1.1 Integrated Iron and Steel Facilities 4 1.1.1 Blast Furnaces 4 1.1.2 Basic Oxygen Furnace (EOF) 6 1.1.3 Sintering 8 1.1.4 Miscellaneous Combustion Sources 9 1.2 Coke Production 10 1.3 Taconite Iron Ore Processing16 14 1.4 Electric Arc Furnace (EAF) Steelmaking24 16 1.6 Other Steelmaking Processes 21 1.7 Miscellaneous Emissions Sources 22 2. TOTAL EMISSIONS 23 3. REVIEW OF EXISTING PROGRAMS AND METHODOLOGIES 24 3.1 2006 IPCC Guidelines 10 24 3.2 U.S. EPA GHG Inventory 28 25 3.3 WRI/WBCSD Calculation Procedure 2925 3.4 European Union (EU) Emissions Trading Scheme 30 26 3.5 DOE Technical Guidelines 31 27 3.6 AISI Methodology 32 27 3.7 Environment Canada Guidance Manual 33 27 3.8 Current Practices for Estimating Greenhouse Gas Emissions 28 5. OPTIONS FOR REPORTING THRESHOLDS 30 6. OPTIONS FOR MONITORING METHODS 31 6.1 COi Emissions from Process Sources 31 6.2 Methane and Nitrous Oxide Emissions 33 6.3 COi Emissions from Coke Pushing Operations 33 7. OPTIONS FOR ESTIMATING MISSING DATA 34 8. QA/QC REQUIREMENTS 35 9. REFERENCES 36 APPENDIX A. DEFINITIONS AND THEIR ORIGINS 39 APPENDIX B. EXAMPLES OF COMBUSTION UNITS 41 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases INTRODUCTION The iron and steel industry in the United States is the third largest in the world (after China and Japan), accounting for about 8 percent of the world's raw iron and steel production l and supplying several industrial sectors, such as construction (building and bridge skeletons and supports), vehicle bodies, appliances, tools, and heavy equipment. Currently, there are 18 integrated iron and steel steelmaking facilities that make iron from iron ore and coke in a blast furnace (BF) and refine the molten iron (and some ferrous scrap) in a basic oxygen furnace (BOF) to make steel. In addition, there are over 90 electric arc furnace (EAF) steelmaking facilities that produce steel primarily from recycled ferrous scrap. In 2007, integrated mills produced 40 million metric tons (mt) of raw steel and minimills produced 58 million mt. 2 The iron and steel source category also includes taconite (iron ore) processing facilities, cokemaking facilities, and direct reduced ironmaking (DRI) facilities. There are eight taconite iron ore processing facilities that produced 52 million mt of pellets in 20073, primarily for use in blast furnaces to make iron. There are 18 cokemaking facilities that produced 15.8 million mt of coke in 2007, 4 also primarily for use in blast furnaces, and 7 of these coke plants are co-located with integrated iron and steel facilities. There is one operating DRI plant located at an EAF steelmaking facility that produced 0.2 million mt of iron in 2007. 5 GHG emissions from the source category are estimated at about 85 million metric tons of carbon dioxide equivalents per year (MMTCC^e/yr) or just over 1 percent of total U.S. GHG emissions. Emissions from both process units (47 million MMTCC^e/yr) and miscellaneous combustion units (38 million MMTCC^e/yr) are significant.a Small amounts of N2O and CFLi are also emitted during the combustion of different types of fuels. The primary process units that emit GHG emissions are BF stoves (24 million MMTCC^e/yr), taconite indurating furnaces, BOFs, EAFs (about 5 million MMTCC^e/yr each), coke oven battery combustion stacks (6 million MMTCC^e/yr), and sinter plants (3 million MMTCC^e/yr). Smaller amounts of GHG emissions are produced by coke pushing (160,000 MMTCC^e/yr) and DRI furnaces (140,000 MMTCO2e/yr). In addition to the blast furnace stoves and byproduct coke battery underfiring systems, the other combustion units where fuel is the only source of GHG emissions include boilers, process heaters, reheat and annealing furnaces, flares, flame suppression systems, ladle reheaters, and other miscellaneous sources. Emissions from these other combustion sources are estimated at 16.8 million MMTCO2e/yr for integrated iron and steel facilities, 18.6 million MMTCO2e/yr for EAF steelmaking facilities, and 2.7 million MMTCO2e/yr for coke facilities not located at integrated iron and steel facilities. This document describes the various processes in the iron and steel industry that generate greenhouse gas emissions and provides information on the locations and sizes of facilities that may be impacted by the proposed mandatory reporting rule. The impact of potential thresholds on the number of facilities reporting and the emissions coverage is also discussed. Options for monitoring greenhouse gases to determine the level of emissions are also presented and discussed. Other sections of this document address procedures for estimating missing data, quality assurance/quality control (QA/QC) requirements, and reporting procedures. ' These are preliminary estimates and are documented in the following sections of this Technical Support Document. ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 1. INDUSTRY DESCRIPTION This section summarizes the processes and major emission points of greenhouse gases for taconite iron ore processing, coke plants, sinter plants, blast furnaces, basic oxygen furnaces, electric arc furnaces, and plants producing iron by direct reduction. Other processes associated with steelmaking, such as ladle metallurgy, argon-oxygen decarburization, and casting are also discussed. The focus of this document is on process sources of GHG emissions because the methodologies for determining GHG emissions from combustion units are discussed in the technical support document that applies to all types of general stationary fuel combustion sources.b However, there are several types of combustion units unique to the iron and steel industry, and they are important parts of the different processes. A description of these processes is given in this section to provide background on combustion units at iron and steel facilities. In addition, the information on combustion units at iron and steel facilities needs to be presented to develop and describe preliminary estimates of total GHG emissions from all sources in the source category, including estimates of both process emissions and combustion unit emissions. The combustion units at iron and steel facilities where GHGs are formed solely from burning fuels include: Byproduct recovery coke oven battery combustion stacks, Blast furnace stoves, Boilers, Process heaters, Reheat furnaces, Flame suppression systems, Annealing furnaces, Flares, Ladle reheaters, and Other miscellaneous combustion sources. The major process units at iron and steel facilities where raw materials, usually in combination with fuel combustion, contribute to the emission of GHGs include: Taconite indurating furnaces, Nonrecovery coke oven battery combustion stacks, Coke pushing, BOFs, EAFs, DRI furnaces, and Sinter plants. b Process emissions of GHGs include emissions from processes where raw materials, usually in addition to the combustion of fuels, contribute to the formation of GHGs. Combustion units are those in which the GHGs are generated solely from the combustion of fuel. ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 1.1 Integrated Iron and Steel Facilities This section discusses the processes at integrated iron and steel facilities that are the major sources of GHG emissions: blast furnaces, BOFs, sinter plants, and miscellaneous combustion units. A few integrated facilities also have co-located coke plants. However, coke production is discussed in a separate section because there are many independent (stand-alone) coke plants, and the complex production processes are best described in a separate section. 1.1.1 Blast Furnaces There are 35 blast furnaces at 17 plant locations shown in Table 1. Table 1. Blast Furnace (BF) Locations and Capacity 6 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Plants with Blast Furnaces (BF) Mittal (formerly Ispat-Inland) US Steel Mittal (formerly ISO, Bethlehem) Mittal (formerly LTV) Severstal (formerly ISO, Bethlehem) Mittal (formerly LTV) US Steel (formerly National Steel) Mittal (formerly Weirton Steel) Severstal (formerly Rouge Steel) US Steel Edgar Thomson Works US Steel (formerly National Steel) Republic Technologies Wheeling Pittsburgh Steel AK Steel US Steel AK Steel WCI Steel Location East Chicago, IN Gary, IN Burns Harbor, IN Cleveland, OH Sparrows Point, MD East Chicago, IN Ecorse, MI Weirton, WV Dearborn, MI Braddock, PA Granite City, IL Lorain, OH Mingo Junction, OH Middletown, OH Fairfield, AL Ashland, KY Warren, OH Total Number of BFs 5 4 2 2 1 2 3 2 2 2 2 2 2 1 1 1 1 35 BF Capacity (tpy)c 6,500,000 5,560,000 5,100,000 4,100,000 3,500,000 3,100,000 2,781,000 2,700,000 2,700,000 2,500,000 2,400,000 2,300,000 2,300,000 2,200,000 2,000,000 1,900,000 1,400,000 53,041,000 tpy = short tons per year Iron Production 6'7 Iron is produced in blast furnaces by the reduction of iron-bearing materials with a hot gas. The large, refractory-lined blast furnace is charged through its top with iron ore pellets, sinter, flux (limestone and dolomite), and coke, which provides fuel and forms a reducing atmosphere in the furnace. Many modern blast furnaces also inject pulverized coal or other sources of carbon to reduce the quantity of coke required. Iron oxides, coke, coal, and fluxes react with the heated blast air injected near the bottom of the furnace to form molten reduced iron, carbon monoxide (CO), and slag (a molten liquid solution of silicates and oxides that solidifies upon cooling). The molten iron and slag collect in the hearth at the base of the furnace. The by-product gas is collected at the top of the furnace and is recovered for use as fuel. The production of one ton of iron requires approximately 1.4 tons of ore or other iron- bearing material; 0.5 to 0.65 ton of coke and coal; 0.25 ton of limestone or dolomite; and 1.8 to 2 0 Note: Throughout this document the terms "ton" and "tons per year (tpy)" refer to short tons (2,000 Ibs), which is consistent with the way the U.S. industry reports production and capacity. The abbreviation "mt" is used for metric tons (also known as "tonne" or 2,205 Ibs) and is used for emissions, which are conventionally expressed in metric units. ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases tons of air. By-products consist of 0.2 to 0.4 ton of slag and 2.5 to 3.5 tons of blast furnace gas containing up to 100 pounds of dust. The molten iron and slag are removed from the furnace periodically (this is called "tapping" or "casting"). The casting process begins with drilling a taphole into the clay-filled iron notch at the base of the hearth. During casting, molten iron flows into runners that lead to transport ladles. Slag also flows from the furnace and is directed through separate runners to a slag pit adjacent to the casthouse or into slag pots for transport to a remote slag pit. At the conclusion of the cast, the taphole is replugged with clay. The area around the base of the furnace, including all iron and slag runners, is enclosed by a casthouse. The molten iron is transferred to a refractory-lined rail car (called a "torpedo" car because of it shape) and sent to the BOF shop. The hot metal is then poured from the torpedo cars into the BOF shop ladle; this is referred to as hot metal transfer (also known as "reladling"). Hot metal transfer generally takes place under a hood to capture emissions of PM including kish (flakes of carbon), which is formed during the process. Blast Furnace Gas6'7 The blast furnace by-product gas, which is collected from the furnace top, has a low heating value (about 90 Btu/ft3) and is composed of nitrogen (about 60 percent), carbon monoxide (28 percent) and carbon dioxide (12 percent). A portion of this gas is fired in the blast furnace stoves to preheat the blast air, and the rest is used in other plant operations. There are generally three to four stoves per blast furnace. Before the blast air is delivered to the blast furnace, it is preheated by passing it through a regenerator (heat exchanger). In this way, some of the energy of the off-gas that would otherwise have been lost is returned to the process. The additional thermal energy returned to the blast furnace as heat decreases the amount of fuel that has to be burned for each unit of hot metal and improves the efficiency of the process. In many furnaces, the off-gas is enriched by the addition of a fuel with much higher calorific value, such as natural gas or coke oven gas, to obtain even higher hot blast temperatures. This decreases the fuel requirements and increases the hot metal production rate to a greater extent than is possible when burning blast furnace gas alone to heat the stoves. Desulfurization 6'7 Desulfurization of the hot metal is accomplished by adding reagents such as soda ash, lime, and magnesium. Injection of the reagents is accomplished pneumatically with either dry air or nitrogen. Desulfurization may take place at various locations within the iron and steel making facility; however, if the location is the BOF shop, then it is most often accomplished at the hot metal transfer (reladling) station to take advantage of the fume collection system at that location. Emissions The vast majority of GHGs (62) are emitted from the blast furnaces stove stacks where the combustion gases from the stoves are discharged. A small amount of emissions may also occur from flares, leaks in the ductwork for conveying the gas, and from blast furnace "slips." A slip occurs when the burden material hangs or bridges in the furnace rather than continuing its downward movement. When this happens, the solid material below the "hang" continues to move downward and forms a void below the hang that is filled with hot gas at very high ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases pressure. When the hang finally collapses, the sudden downward thrust of the burden material forces the hot gas upward with the force of an explosion. To prevent damage to the furnace, the pressure is relieved through bleeder stacks on top of the furnace that discharge the particle-laden gas directly to the atmosphere. Emissions of CC>2 are also generated from the combustion of natural gas using flame suppression to reduce emissions of particulate matter. Flame suppression maintains a flame over the surface of the molten metal (for example, during tapping) to consume oxygen and to inhibit the formation of metal oxides that become airborne. Emissions also occur from the flaring of blast furnace gas. The IPCC guidelines also note that a small amount of CH4 may be emitted from blast furnace stoves. The blast furnace gas, which is mostly nitrogen, carbon monoxide, and CC>2, is usually supplemented with natural gas, which is mostly CFLi, and a small amount of methane may be emitted because of incomplete combustion. Title V operating permits were reviewed to obtain data on the design energy input of blast furnace stoves and to relate the energy input to capacity. 8 The results are given in Table 2 and show an average of 2.2 million Btu per short ton of iron (0.00255 TJ/mt of iron). The IPCC guidelines provide an emission factor of 260 MMTCC^e /TJ for the combustion of blast furnace gas. 9 Based on the production of 36.1 million mt of pig iron on 2007,2 CC>2 emissions from blast furnace stoves would be about 24 million MMTCC^e/yr. Table 2. Energy Consumption by Blast Furnace Stoves 8 Capacity (million short tons per year) 5.5 4.0 2.5 1.6 2.0 3.4 2.7 1.2 1.0 1.4 1.3 1.6 0.9 Million Btu/hr 1,320 586 953 441 486 1,025 700 309.1 298.4 309.9 319.2 301.5 192.9 Average Million Btu per short ton of iron 2.10 1.28 3.34 2.41 2.13 2.64 2.27 2.31 2.68 1.97 2.12 1.68 1.88 2.22 1.1.2 Basic Oxygen Furnace (EOF) As shown in Table 3, there are 18 plants that operate 46 BOFs at 21 EOF shops. A "shop" consists of at least two furnaces (sometimes three) that may be operated alternately or together with each furnace in a different stage of the operating cycle. ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Table 3. Basic Oxygen Furnace Locations and Capacity No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Plants with BOFs Mittal (formerly Ispat-Inland) US Steel Mittal (formerly ISO, Bethlehem) Severstal (formerly ISO, Bethlehem) Mittal (formerly LTV) Mittal (formerly LTV) US Steel (formerly National Steel) Severstal (formerly Rouge Steel) Mittal (formerly Weirton Steel) US Steel Edgar Thomson Works US Steel (formerly National Steel) AK Steel Republic Technologies Wheeling Pittsburgh Steel US Steel AK Steel WCI Steel Mittal (formerly Acme Steel) Location East Chicago, IN Gary, IN Burns Harbor, IN Sparrows Point, MD Cleveland, OH East Chicago, IN Ecorse, MI Dearborn, MI Weirton, WV Braddock, PA Granite City, IL Middletown, OH Lorain, OH Mingo Junction, OH Fairfield, AL Ashland, KY Warren, OH Riverdale, IL Total Number of BOFs 4 6 3 2 4 2 2 2 2 2 2 2 2 2 3 2 2 2 46 EOF Capacity (short tons per year) 10,000,000 7,500,000 4,700,000 3,900,000 3,800,000 3,800,000 3,800,000 3,309,000 3,000,000 2,900,000 2,800,000 2,716,000 2,700,000 2,600,000 2,200,000 2,200,000 1,900,000 750,000 64,575,000 EOF Steelmaking 6,7 The BOF is a large, open-mouthed vessel lined with a basic refractory material (the term "basic" refers to the chemical characteristic of the lining) that refines iron into steel. The BOF receives a charge composed of molten iron from the blast furnace and ferrous scrap. A jet of high-purity oxygen is injected into the BOF and oxidizes carbon and silicon in the molten iron in order to remove these constituents and to provide heat for melting the scrap. After the oxygen jet is started, lime is added to the top of the bath to provide a slag of the desired basicity. Fluorspar and mill scale are also added in order to achieve the desired slag fluidity. The oxygen combines with the unwanted elements (with the exception of sulfur) to form oxides, which leave the bath as gases or enter the slag. As refining continues and the carbon content decreases, the melting point of the bath increases. Sufficient heat must be generated from the oxidation reactions to keep the bath molten. There are currently three methods that are used to supply the oxidizing gas: (1) top blown, (2) bottom blown, and (3) combination blowing. Most bottom blown furnaces use tuyeres consisting of two concentric pipes, where oxygen is blown through the center of the inner pipe and a hydrocarbon coolant (such as methane) is injected between the two pipes. The hydrocarbon decomposes at the temperature of liquid steel, absorbing heat as it exits and protecting the oxygen tuyere from overheating and burn back. The distinct operations in the BOF process are the following: Charging - the addition of molten iron and metal scrap to the furnace Oxygen blow - introducing oxygen into the furnace to refine the iron ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Turndown - tilting the vessel to obtain a sample and check temperature Reblow - introducing additional oxygen, if needed Tapping - pouring the molten steel into a ladle Deslagging - pouring residual slag out of the vessel. The basic oxygen steelmaking process is a thermochemical process; computations are made to determine the necessary percentage of molten iron, scrap, flux materials, and alloy additions. Various steelmaking fluxes are added during the refining process to reduce the sulfur and phosphorus content of the metal to the prescribed level. The oxidation of silicon, carbon, manganese, phosphorus, and iron provide the energy required to melt the scrap, form the slag, and raise the temperature of the bath to the desired temperature. Process Emissions The major emission point for CC>2 from the BOF is the furnace exhaust gas that is discharged through a stack after gas cleaning. The carbon is removed as carbon monoxide and CC>2 during the oxygen blow. Carbon may also be introduced to a much smaller extent from fluxing materials and other process additives that are charged to the furnace. Using the default values in the IPCC guidelines for iron (0.04) and steel (0.01) for the fraction of carbon 10 gives an emission factor of 0.11 MMTCO2e/mt steel for carbon removed from the iron as CC>2. Applying the emission factor to the production of 40 million mt of steel in BOFs in 2007 2 yields an estimate of 4.4 million MMTCO2e/yr. 1.1.3 Sintering Sintering is a process that recovers the raw material value of many waste materials generated at iron and steel plants that would otherwise be landfilled or stockpiled. An important function of the sinter plant is to return waste iron-bearing materials to the blast furnace to produce iron. Another function is to provide part or all of the flux material (e.g., limestone, dolomite) for the ironmaking process. As shown in Table 4, there are currently 5 plants with sintering operations, and all of the sinter plants are part of an integrated iron and steel plant.6 Table 4. Sinter Plants No. 1 2 O 4 5 Plant US Steel Severstal (formerly ISO, Bethlehem) Mittal (formerly ISO, Bethlehem) Mittal (formerly LTV) Mittal (formerly Ispat-Inland) Location Gary, IN Sparrows Point, MD Burns Harbor, IN East Chicago, IN East Chicago, IN Total Sinter Capacity (short tons per year) 4,400,000 4,000,000 2,900,000 1,900,000 1,400,000 14,600,000 Sinter Process Feed material to the sintering process includes ore fines, coke, reverts (including blast furnace dust, mill scale, and other by-products of steelmaking), recycled hot and cold fines from the sintering process, and trim materials (calcite fines, and other supplemental materials needed ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases to produce a sinter product with prescribed chemistry and tonnage). The materials are proportioned and mixed to prepare a chemically uniform feed to the sinter strand, so that the sinter will have qualities desired for satisfactory operation of the blast furnace. The chemical quality of the sinter is often assessed in terms of its basicity, which is the percent total basic oxides divided by the percent total acid oxides ((CaO+MgO)/(SiO2+Al2O3)); sinter basicity is generally 1.0 to 3.0. The relative amounts of each material are determined based on the desired basicity, the rate of consumption of material at the sinter strand, the amount of sinter fines that must be recycled, and the total carbon content needed for proper ignition of the feed material. The sintering machine accepts feed material and conveys it down the length of the moving strand. Near the feed end of the grate, the bed is ignited on the surface by gas burners and, as the mixture moves along on the traveling grate, air is pulled down through the mixture to burn the fuel by downdraft combustion; either coke oven gas or natural gas may be used for fuel to ignite the undersize coke or coal in the feed. Process Emissions The primary emission point of interest for the sinter plant is the stack that discharges the windbox exhaust gases after gas cleaning. The CC>2 is formed from the fuel combustion (natural gas or coke oven gas) and from carbon in the feed materials, including coke fines and other carbonaceous materials. Based on the IPCC emission factor of 0.2 MMTCO2e/mt of sinter 10 and the production of 13.3 million mt of sinter, 6 CC>2 emissions are estimated as 2.7 million mt/yr. However, greenhouse gas emissions from sinter plants may vary widely over time as a consequence of variations in the fuel inputs and other feedstock, especially in the types and quantities of iron-bearing materials that are recycled. Both natural gas and coke oven gas contain CH4, and when the gases are burned, a small amount of the CH4 is emitted with the exhaust gases due to incomplete combustion. Consequently, sinter plants (and any other process that burns fuels that contain CH/t) also emit a small amount of CH/t. 1.1.4 Miscellaneous Combustion Sources There are many different types of combustion processes at iron and steel facilities not directly related to the major production processes discussed in previous section. These include boilers, process heaters, flares, dryout heaters, and several types of furnaces (more detailed examples are given in Appendix B). For example, soaking pits and reheat furnaces are used to raise the temperature of the steel until it is sufficiently hot to be plastic enough for economic reduction by rolling of forging. Annealing furnaces are used to heat the steel to relieve cooling stresses induced by cold or hot working and to soften the steel to improve machinability and formability. Ladle reheating using natural gas to keep the ladle hot while waiting for molten steel. Natural gas is the most commonly used fuel; however, coke oven gas and blast furnace gas are also used in the combustion processes. Table 5 provides the results from reviewing the operating permits of 6 integrated iron and steel plants to extract information on the sizes of their combustion units. The facilities average 3.12 MM Btu/ton of steel for combustion units burning natural gas, coke oven gas, and blast furnace gas. At 90 percent utilization of combustion capacity, the average is 2.91 MM Btu/ton ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases of steel (0.00338 TJ/mt steel). Table 6 illustrates the development of an emission factor of 0.42 MMTCO2e/mt of steel for combustion units based on the energy distribution of these gases for fuel, 90 percent utilization of combustion capacity, and the IPCC emission factors for the three gases. For a production rate of steel of 40 million mt in 2007, emissions from combustion units at integrated iron and steel plants would be 16.8 million MMTCO2e. Table 5. Design Capacity of Combustion Units at Integrated Iron and Steel Facilities 8 Steel capacity (short tons per year) 3,800,000 2,800,000 2,716,000 2,700,000 2,600,000 2,200,000 MM Btu/hr 1,088 1,113 844 1,055 1,033 952 Average At 90% MM Btu/short ton 2.51 3.48 2.72 3.42 3.48 3.79 3.23 2.91 Table 6. Development of an Emission Factor for Combustion Units Fuel Natural gas Coke oven gas Blast furnace gas % of energy n 51 14 34 IPCC emission factor (mtCO2/TJ) 9 56.1 44 260 TJ/mt of steel" 0.0017 0.00047 0.0011 Total mtCCVmt of steel" 0.097 0.021 0.30 0.42 a (% of energy/100) * (0.00338 TJ/mt of steel) b(IPCC emission factor in mtCO2/TJ)*(TJ/mt of steel) 1.2 Coke Production As shown in Table 7, there are 18 coke plants in the U.S. that produce coke from coal primarily for use in blast furnaces to make iron, but also for use at iron foundries and other industrial processes. In 2007, coke plants produced 15.8 million mt of coke and coke breeze (undersize coke).4 Most coke is produced in by-product recovery coke oven batteries. However, there are three non-recovery coke oven batteries, including the two newest coke plants, and both of the newest nonrecovery plants use the waste heat from combustion to generate electricity. The recovery of waste heat to generate electricity reduces the purchase of electricity, the need to purchase additional fuel to generate electricity onsite, or when supplied to the grid, reduces the amount of electricity that must be produced from fossil fuel combustion. 10 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Table 7. U.S. Coke Plants12'14 No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Company Indiana Harbor Cokea Haverhill Cokea US Steel Jewell Coke and Coaf US Steel Mittal Steel Mountain State Carbon AK Steel EES Coke ABC Coke US Steel Mittal Steel Shenango Sloss Industries AK Steel Koppers Tonawanda Erie Coke City East Chicago Haverhill Clairton Vansant Gary Burns Harbor Follansbee Ashland Ecorse Tarrant Granite City Warren Neville Island Birmingham Middletown Monessen Tonawanda Erie State IN OH PA VA IN IN WV KY MI AL IL OH PA AL OH PA NY PA Total Number of batteries 4 4 12 6 4 2 4 2 1 O 2 1 1 3 1 2 1 2 55 Coke capacity (short tons per year) 1,300,000 1,100,000 5,573,185 649,000 2,249,860 1,877,000 1,247,000 1,000,000 1,000,000 699,967 601,862 550,000 514,779 451,948 429,901 372,581 268,964 214,951 20,099,998 12,13 a These are nonrecovery coke plants. By-product Recovery Coke Oven Batteries Coke ovens use thermal distillation to remove volatile non-carbon elements from coal to produce coke. Thermal distillation takes place in groups of ovens called batteries. A by-product coke oven battery consists of 20 to 100 adjacent ovens with common side walls made of high quality silica and other types of refractory brick. The wall separating adjacent ovens, as well as each end wall, is made up of a series of heating flues. At any one time, half of the flues in a given wall will be burning gas while the other half will be conveying waste heat from the combustion flues to a heat exchanger and then to the combustion stack. Every 20 to 30 minutes the battery "reverses," and the former waste heat flues become combustion flues while the former combustion flues become waste heat flues. This process avoids melting the battery brick work (the flame temperature is above the melting point of the brick) and provides more uniform heating of the coal mass. Process heat comes from the combustion of coke oven gas, sometimes supplemented with blast furnace gas. The flue gas is introduced from piping in the basement of the battery and combusted in flues. The gas flow to each flue is metered and controlled. Waste gases from combustion, including GHGs, exit through the battery stack. 11 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Each oven holds between 15 and 25 short tons of coal. Offtake flues remove gases evolved from the destructive distillation process. Process heat comes from the combustion of gases between or beneath the coking chambers. The operation of each oven in the battery is cyclic, but the batteries usually contain a sufficiently large number of ovens so that the yield of by-products is essentially continuous. Coking continues for 15 to 18 hours to produce blast furnace coke and 25 to 30 hours to produce foundry coke. The coking time is determined by the coal mixture, moisture content, rate of underfiring, and the desired properties of the coke. Coking temperatures generally range from 900 to 1,100°C and are kept on the higher side of the range to produce blast furnace coke. Pulverized coal is mixed and blended, and sometimes water and oil are added to control the bulk density of the mixture. The prepared coal mixture is transported to the coal storage bunkers on the coke oven battery. A specific volume of coal is discharged from the bunker into a larry cara charging vehicle that moves along the top of the battery. The larry car is positioned over an empty, hot oven; the lids on the charging ports are removed; and the coal is discharged from the hoppers of the larry car into the oven. To minimize the escape of gases from the oven during charging, steam aspiration is used to draw gases from the space above the charged coal into a collecting main. After charging, the aspiration is turned off, and the gases are directed through an offtake system into a gas collecting main. The maximum temperature attained at the center of the coke mass is usually 1100°C to 1500°C. At this temperature, almost all volatile matter from the coal mass volatilizes and leaves a high quality metallurgical coke. Air is prevented from leaking into the ovens by maintaining a positive back pressure of about 10 mm of water. The gases and hydrocarbons, including GHGs, that evolve during thermal distillation are removed through the offtake system and sent to the by- product plant for recovery. Near the end of the coking cycle, each oven is dampered off the collection main. Once an oven is dampered off, the standpipe cap is opened to relieve pressure. Volatile gases exiting through the open standpipe are ignited if they fail to self-ignite and are allowed to burn until the oven has been pushed. At the end of the coking cycle, doors at both ends of the oven are removed, and the hot coke is pushed out the coke side of the oven by a ram that is extended from a pusher machine. The coke is pushed through a coke guide into a special rail car, called a quench car, which traverses the coke side of the battery. The quench car carries the coke to a quench tower where the hot coke is deluged with water. The quenched coke is discharged onto an inclined "coke wharf to allow excess water to drain and to cool the coke to a reasonable temperature. Gates along the lower edge of the wharf control the rate that the coke falls on the conveyor belt that carries it to a crushing and screening system. Gases evolved during coking leave the coke oven through standpipes, pass into goosenecks, and travel through a damper valve to the gas collection main that directs the gases to the by-product plant. These gases account for 20 to 35 percent by weight of the initial coal charge and are composed of water vapor, tar, light oils, heavy hydrocarbons, and other chemical compounds. At the by-product recovery plant, tar and tar derivatives, ammonia, and light oil are extracted from the raw coke oven gas. After tar, ammonia, and light oil removal, the gas undergoes a final desulfurization process at most coke plants to remove hydrogen sulfide before being used as fuel. Approximately 35 to 40 percent of cleaned coke oven gas (after the removal 12 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases of economically valuable by-products) is used to heat the coke ovens, and the remainder is used in other operations related to steel production, in boilers, or is flared. Coke oven gas has a heating value of 500 to 600 Btu/ft3 and is composed of hydrogen (about 47 percent), methane (32 percent), carbon monoxide (6 percent), and CC>2 (2 percent). Nonrecovery Coke Oven Batteries12'13 As the name implies, the nonrecovery cokemaking process does not recover the numerous chemical by-products as discussed above. All of the coke oven gas is burned, and instead of recovery of chemicals, this process offers the potential for heat recovery and cogeneration of electricity. Non-recovery ovens are of a horizontal design (as opposed to the vertical slot oven used in the by-product process) with a typical range of 30 to 60 ovens per battery. The oven is generally between 9 and 14 m (30 and 45 ft) long and 1.8 to 3.7 m (6 to 12 ft) wide. The internal oven chamber is usually semicylindrical in shape with the apex of the arch 1.5 to 3.7 m (5 to 12 ft) above the oven floor. Each oven is equipped with two doors, one on each side of the horizontal oven, but there are no lids or offtakes as found on by-product ovens. The oven is charged through the oven doorway with a coal conveyor rather than from the top through charging ports. After an oven is charged with coal, carbonization begins as a result of the hot oven brick work from the previous charge. Combustion products and volatiles that evolve from the coal mass are burned in the chamber above the coal, in the gas pathway through the walls, and beneath the oven in sole flues. Each oven chamber has two to six downcomers in each oven wall, and the sole flue may be subdivided into separate flues that are supplied by the downcomers. The sole flue is designed to heat the bottom of the coal charge by conduction while radiant and convective heat flow is produced above the coal charge. Primary combustion air is introduced into the oven chamber above the coal through one of several dampered ports in the door. The dampers are adjusted to maintain the proper temperature in the oven crown. Outside air may also be introduced into the sole flues; however, additional air usually is required in the sole flue only for the first hour or two after charging. All of the ovens are maintained under a negative pressure. Consequently, the ovens do not leak under normal operating conditions as do the by-product ovens which are maintained under a positive pressure. The combustion gases are removed from the ovens and directed to the stack through a waste heat tunnel that is located on top of the battery centerline and extends the length of the battery. Emissions The primary emission point of gases is the battery's combustion stack. Test data were obtained for 53 emission tests (generally 3 runs per tests) for CO2 emissions from the combustion stacks at by-product recovery coke plants for development of an emission factor for EPA's 2008 revision to AP-42. 13 These tests averaged 0.143 MMTCO2e/mt coal ( 0.21 MMTCO2e/mt coke). Test results for a nonrecovery battery were obtained and analyzed. The average of three runs at Haverhill Coke resulted in an emission factor of 1.23 MMTCO2e/mt coke, 15 approximately six times higher than the factor for the combustion stack at by-product recovery batteries. The emission factor for nonrecovery combustion stacks is much higher because all of the coke oven gas and all of the by-products are burned. In comparison, organic liquids (such as tar and light oil) are recovered at by-product recovery coke plants, and only about one third of the gas is consumed in underfiring the ovens. Emissions from combustion 13 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases stacks based on the 2007 production rate are estimated as 3 million MMTCO2e from nonrecovery battery stacks and 2.8 MMTCC^e/mt from byproduct recovery battery stacks. A small amount of CC>2 is emitted from the pushing operation when the incandescent coke is pushed from the oven and transported to the quench tower where it is quenched with water. The 2008 revisions to EPA's AP-42 compilation of emission factors provides an emission factor of 0.008 MMTCO2e/mt coal (0.01 MMTCO2e/mt coke).13 Using the 2007 production rate for coke (15.8 million mt),4 the emissions from pushing are estimated as 158,000 MMTCO2e/yr. Fugitive emissions occur during the coking process from leaks of raw coke oven gas that contains methane. The leaks occur from doors, lids, offtakes, and collecting mains and are almost impossible to quantify because they change in location, frequency, and duration during the coking cycle, and they are not captured in a conveyance. However, the number, size, and frequency of these leaks have decreased significantly over the past 20 years as a result of stringent regulations, including national standards, consent decrees, and State regulations. Many by-product recovery coke plants also have other combustion sources, primarily boilers and flares. These units use excess coke oven gas that is not used for underfiring the battery or shipped offsite for use as fuel in other processes. The IPCC guidelines 10 provide an emission factor of 0.56 MMTCO2e/mt coke (assuming all of the coke oven gas is burned). Emissions from the combustion of coke oven gas in units other than the coke battery underfiring system are estimated as 0.35 MMTCO2e/mt coke (0.56 - 0.21 MMTCO2e/mt coke). For the production of 7.6 million mt of coke in stand alone byproduct coke plants (i.e., coke plants not located at iron and steel facilities), emissions from other combustion units would be 2.7 million MMTCO2e/yr. (Emissions from the combustion of coke oven gas from coke plants co-located with integrated iron and steel facilities are included in the estimates for integrated iron and steel facilities.) 1.3 Taconite Iron Ore Processing16 There are eight taconite or pellet production facilities that mine taconite ore from the Mesabi Iron Ore Range with six facilties in Minnesota and two in Michigan (Table 8). Taconite ore is transported from the mine to primary crushers, and after crushing, the ore is conveyed to large storage bins at the concentrator building. In the concentrator building, water is typically added to the ore as it is conveyed into rod and ball mills, which further grind the taconite ore to the consistency of coarse beach sand. In a subsequent process step, taconite ore in the slurry is separated from the waste rock material using a magnetic separation process. The concentrated taconite slurry then enters the agglomerating process where water is removed from the taconite slurry using vacuum disk filters or similar equipment. Next, the taconite is mixed with various binding agents such as bentonite and dolomite in a balling drum that tumbles and rolls the taconite into unfired pellets. When the unfired pellets exit the balling drum, they are transferred to a metal grate that conveys them to the indurating furnace. During the indurating process, the unfired taconite pellets are hardened and oxidized in the indurating furnace at a fusion temperature between 2,290° to 2,550°F. 14 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 17 1 Table 8. Taconite or Pellet Production Facilities ' No. 1 2 O 4 5 6 7 8 Facility USS Keetac USS Mintac Empire Tilden United Taconite Hibbing Northshore Ispat-Inland City Kewatin Mountain Iron Palmer Ishpeming Forbes Hibbing Silver Bay Virginia State MN MN MI MI MN MN MN MN Totals Number of furnaces 2 O 2 1 2 2 2 2 16 Pellet capacity (tpy) 6,160,000 16,352,000 9,408,000 8,802,000 6,608,000 9,632,000 5,376,000 3,248,000 65,586,000 Coal usage (tpy) 146,000 105,833 191,067 166,589 97,100 706,589 Natural gas (MMCF/yr) 292 7,231 2,781 2,120 476 3,000 3,591 1,540 21,031 tpy = short tons per year MMCF/yr = millions of cubic feet per year Process Emissions The primary source of greenhouse gas emissions is the exhaust from the indurating furnaces. These furnaces are considered to be process sources of GHG emissions rather than exclusively combustion sources because a significant amount of the CC>2 emissions originate from carbon in the raw materials (dolomite, bentonite, iron ore). The indurating furnaces have historically been fired with natural gas; however, several plants converted to coal after natural gas prices surged over the past several years. None of the plants can burn 100 percent coal, and three of the plants are not permitted to burn coal. Data on fuel type and consumption along with pellet production rates were obtained for the 2004 to 2005 time period from personal communications with plant representatives and are shown in Table 9. The fuel consumption data were scaled up from production rates to capacity to estimate fuel consumption when operating at capacity. Test data for CC>2 were obtained from a plant burning coal as fuel and from the same plant when burning natural gas as fuel. 19'20 As shown in Table 9, the CC>2 emissions were 0.11 MMTCO2e/mt pellet when burning coal and 0.072 MMTCO2e/mt pellet when burning natural gas. The IPCC default emission factor is 0.03 MMTCO2e/mt pellet; however, this is apparently based on carbon in the fuel (natural gas) and does not include the carbon in the feed materials or the use of coal as fuel. For the CC>2 emission estimate, the emission factors from the tests were used for coal and natural gas, and coal and natural gas consumption was scaled to the 2007 production rate of 52 million mt of pellets to provide an estimate of 5.6 million MMTCC^e for 2007. Although the indurating furnace is by far the primary source of CC>2 emissions, the taconite facilities also have other combustion units. A review of operating permits indicated that most of the plants have boilers. Other combustion devices reported include space heaters and 15 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases emergency diesel generators. One company also operates a power plant at the site to supply electricity for taconite processing and to supply the electricity grid. 8 Table 9. Test Results for a Taconite Plant Tilden - natural gas as fuel (March 13, 1995)19 pellets (tph) natural gas (MCF/hr) CC>2 emissions (tph) CC>2 emissions (ton/ton pellets) CC>2 emissions (ton/MCF) 779 289.5 56.3 0.072 0.194 Tilden - coal as fuel (July 13, 2000)20 pellets (tph) coal (tph) CC>2 emissions (tph) CC>2 emissions (ton/ton pellets) CC>2 (ton/ton coal) 609 15.85 65.8 0.11 4.15 tph = short tons per hour MCF/hr = thousands of cubic feet per hour 24 1.4 Electric Arc Furnace (EAF) Steelmaking The production of steel in EAFs (minimills) has increased dramatically over the past 30 years. Minimills accounted for 10 percent of the national steel production in 1970, 30 to 40 percent in the 1980s, 40 to 50 percent in the 1990s, and 59 percent in 2007. The growth has been attributed in part to an expansion in the types and quality of steel products that minimills can produce, including heavy structurals, rail, plate, specialty bar, hot rolled, cold rolled, galvanized, and stainless flat rolled products. Most of the steel produced in EAFs is carbon steel used in the manufacture of construction materials, automobiles, appliances, and other applications. Approximately 4 percent (about 2 million tons) is specialty and stainless steel, which are high value steel products. The types of steel are defined by their composition of alloying elements. Stainless and alloy steels contain less carbon and zinc and more chromium, manganese, and nickel than carbon steels. Some stainless steel grades contain 12 to 28 percent chromium and 4 to 25 percent nickel. Table 10 lists 92 EAF minimills, their location, and capacity. Table 10. Electric Arc Furnace Locations and Capacity 22,23 No. 1 2 o 5 4 5 6 7 8 9 10 11 12 13 Company Nucor Corporation Nucor-Yamato Steel Nucor Corporation Steel Dynamics Inc. Northwestern Steel & Wire Co. Nucor Corporation TXI Chaparral Steel Nucor Corporation CMC Steel/SMI Steel. North Star Steel - Blue Scope Steel Steel Dynamics Inc. Gerdau Ameristeel (Gallatin Steel) Oregon Steel Mills City Berkeley Co. Blytheville Hickman Butler Sterling Decatur Midlothian Crawfordsville Birmingham Delta Whitley Co. Ghent Pueblo State SC AR AR IN IL AL TX IN AL OH IN KY CO Capacity (short tons per year) 3,300,000 3,277,000 2,400,000 2,200,000 2,070,000 2,000,000 2,000,000 1,900,000 1,855,000 1,800,000 1,600,000 1,500,000 1,200,000 Cumulative percent of capacity 4.6 9.1 12.4 15.4 18.3 21.0 23.8 26.4 29.0 31.5 33.7 35.7 37.4 16 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Table 10. Electric Arc Furnace Locations and Capacity 22,23 No. 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 Company TXI Chaparral Steel Nucor Corporation Nucor Corporation Ipsco Inc. Ipsco Inc. Mittal Steel CMC Steel Group/SMI Steel Republic Engineered Steels, Inc. Gerdau Ameristeel Keystone Steel & Wire Mittal Steel Nucor Corporation AK Steel Corporation Gerdau Ameristeel CMC Steel Group/SMI Steel. Gerdau Ameristeel Mittal Steel Nucor Corporation Coras Tuscaloosa Timken Co. Gerdau Ameristeel Nucor Corporation Gerdau Ameristeel North American Stainless Nucor Corporation Gerdau Ameristeel TAMCO MACSTEEL. (Quanex) Nucor Corporation Roanoke Electric Steel Corp. AK Steel Corporation Cascade Steel Rolling Mills, Inc Bayou Steel Corp Gerdau Ameristeel V&M Star Gerdau Ameristeel Gerdau Ameristeel MACSTEEL (Quanex) Gerdau Ameristeel (formerly Sheffield Steel) MACSTEEL. (Quanex) NS Group Inc./Koppel Steel Corp. Nucor Corporation City Dinwiddie Plymouth Norfolk Axis Muscatine Steelton Cayce Canton Beaumont Peoria Georgetown Cofield Butler Wilton Seguin Jackson Coatsville Darlington Tuscaloosa Canton St. Paul Seattle Perth Amboy Ghent Kankakee Sayreville Rancho Cucamonga Jackson Jewett Roanoke Mansfield McMinnville LaPlace Cartersville Youngstown Charlotte Baldwin Fort Smith Sand Springs Monroe Beaver Falls Auburn State VA UT NE AL IA PA SC OH TX IL SC NC PA IA TX TN PA SC AL OH MN WA NJ KY IL NJ CA MI TX VA OH OR LA GA OH NC FL AR OK MI PA NY Capacity (short tons per year) 1,200,000 1,111,000 1,103,000 1,100,000 1,100,000 1,100,000 1,089,000 1,050,000 1,002,000 1,000,000 1,000,000 1,000,000 960,000 917,000 900,000 892,000 880,000 872,000 870,000 870,000 843,000 840,000 800,000 800,000 800,000 750,000 750,000 725,000 725,000 710,000 700,000 700,000 683,000 658,000 650,000 622,000 607,000 607,000 600,000 600,000 550,000 550,000 Cumulative percent of capacity 39.0 40.6 42.1 43.6 45.1 46.7 48.2 49.6 51.0 52.4 53.7 55.1 56.4 57.7 59.0 60.2 61.4 62.6 63.8 65.0 66.2 67.3 68.4 69.5 70.6 71.7 72.7 73.7 74.7 75.7 76.6 77.6 78.6 79.5 80.4 81.2 82.1 82.9 83.7 84.5 85.3 86.1 17 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Table 10. Electric Arc Furnace Locations and Capacity 22,23 No. 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 Company Charter Manufacturing Gerdau Ameristeel BetaSteel Corporation Hoeganeas Corp. Mittal Steel (Ispat Inland) Nucor Corporation Nucor Corporation Wheeling-Pittsburgh Steel Oregon Steel Mills, Inc. Allegheny Technologies Inc. Carpenter Technology Ellwood Quality Steels Allegheny Technologies Inc. CitiSteel USA Inc. Marion Steel Co. Mittal Steel Erie Forge and Steel Timken Co. Lone Star Steel Inc. Border Steel Mills, Inc. Standard Steel Arkansas Steel LeTourneau Inc. Hoeganeas Corp. Universal Stainless & Alloy Products, Inc. Steel of West Virginia Electralloy Finkl, A., & Sons Kobelco Metal Powder of America Timken Co. Standard Steel National Forge Co. Crucible Materials Union Electric Steel Inmetco Haynes International Champion Steel Co. City Saukville Knoxville Portage Gallatin East Chicago Birmingham Jackson Mingo Junction Portland Brackenridge Reading New Castle Midland Claymont Marion Cleveland Erie Canton Lone Star El Paso Burnham Newport Longview Riverton Bridgeville Huntington Oil City Chicago Seymore Latrobe Latrobe Irvine Syracuse Carnegie Ellwood City Kokomo Orwell State WI TN IN TN IN AL MS OH OR PA PA PA PA DE OH OH PA OH TX TX PA AR TX NJ PA WV PA IL IN PA PA PA NY PA PA IN OH Total Capacity (short tons per year) 515,000 515,000 500,000 500,000 500,000 500,000 500,000 500,000 499,000 496,000 450,000 410,000 400,000 400,000 400,000 396,000 385,000 358,000 265,000 250,000 231,000 130,000 124,000 112,000 105,000 100,000 90,000 90,000 63,000 60,000 59,000 58,000 50,000 35,000 28,000 20,000 6,000 72,488,000 Cumulative percent of capacity 86.8 87.5 88.2 88.9 89.6 90.2 90.9 91.6 92.3 93.0 93.6 94.2 94.7 95.3 95.8 96.4 96.9 97.4 97.8 98.1 98.4 98.6 98.8 98.9 99.1 99.2 99.4 99.5 99.6 99.6 99.7 99.8 99.9 99.9 99.96 99.99 100.0 U.S. minimills are the largest recyclers of metal scrap in the world. Recycled iron and steel scrap nationwide includes approximately 25 percent "home scrap" (from current operations at the plant), 26 percent "prompt scrap" (from plants manufacturing steel products), and 49 percent post-consumer scrap. The primary source of post-consumer scrap is the automobile, and 18 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases in 2004, the steel industry recycled 14.2 million tons of iron and steel scrap from 14 million vehicles.21 EAFSteelmaking21'24 EAFs are operated as a batch process that includes charging scrap and other raw materials (loading these materials into the EAF), melting, slagging (removing slag), and tapping (pouring the molten steel into a ladle). The length of the operating cycle is referred to as the tap-to-tap time, and each batch of steel produced is known as a "heat." Tap-to-tap times range from 35 to over 200 minutes with generally higher tap-to-tap times for stainless and specialty steel. Newer EAFs are designed to achieve a tap-to-tap time of less than 60 minutes. After ferrous scrap is charged to the EAF, the melting phase begins when electrical energy is supplied to the carbon electrodes. Oxy-fuel burners and oxygen lances may also be used to supply chemical energy. Oxy-fuel burners, which burn natural gas and oxygen, use convection and flame radiation to transfer heat to the scrap metal. During oxygen lancing, oxygen is injected directly into the molten steel; exothermic reactions with the iron and other components provide additional energy to assist in the melting of the scrap and removal of excess carbon. Alloying elements may be added to achieve the desired composition. Refining of the molten steel can occur simultaneously with melting, especially in EAF operations where oxygen is introduced throughout the batch. During the refining process, substances that are incompatible with iron and steel are separated out by forming a layer of slag on top of the molten metal. After completion of the melting and refining steps, the slag door is opened, and the furnace is tipped backward so the slag pours out ("slagging"). The furnace is righted, and the tap hole is opened. The furnace is then tipped forward and the steel is poured ("tapped") into a ladle (a refractory-lined vessel designed to hold the molten steel) for transfer to the ladle metallurgy station. Bulk alloy additions are made during or after tapping based on the desired steel grade. Process Emissions CO2 emissions are generated during the melting and refining process when carbon is removed from the charge material and carbon electrodes as carbon monoxide and CC>2. These emissions are captured and sent to a baghouse for removal of particulate matter before discharge to the atmosphere. The CO2 emission estimate of 4.6 million MMTCC^e for EAFs is based on the IPCC emission factor of 0.08 MMTCO2e/mt of steel 7 and the production of 58 million mt of steel in 2007. 2 Combustion Emissions EAF facilities have the same miscellaneous combustion units found at integrated iron and steel facilities: boilers, process heaters, flares, dry out heaters, soaking pits, reheat furnaces, annealing furnaces, and ladle reheating. A difference is that the EAF facilities burn natural gas exclusively in these unit, and integrated facilities burn a combination of fuels (natural gas, coke oven gas, and blast furnace gas). Operating permits were reviewed for several EAF facilities, including both small stainless and specialty steel producers as well as large carbon steel producers, to obtain 19 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases information on combustion units. As shown in Table 11, the average capacity of the combustion processes was 5,400 CF of natural gas per ton of steel. CC>2 emissions were estimated based on the processes operating at 90 percent of their rated capacity, 1,000 Btu/CF for natural gas, and an IPCC emission factor of 56.1 MT CO2/TJ. 9 The calculation is shown below and results in an emission factor of 0.32 MMTCO2e/mt steel from combustion units at EAF facilities: (5,400 CF/ton)* (0.9)*(56.1 mtCO2/TJ)*(l,000 Btu/CF)*( 1.1 ton/mt)/(947.8 E6 Btu/TJ)= 0.32 MMTCO2e/mt steel. The production of 58 million mt of steel in EAFs in 2007 results in an emission estimate of 18.6 million MMTCC^e from combustion units burning natural gas Table 11. Natural Gas Usage from EAF Operating Permits 8 EAF steel capacity (short tons per year) 105,000 385,000 410,000 500,000 607,000 960,000 3,300,000 Capacity of combustion units (MMCF/yr) 584 1,839 1,564 5,600 2,847 5,718 6,079 Average Natural gas per short ton of steel (CF/short ton) 5,562 4,777 3,815 11,200 4,690 5,956 1,842 5,406 1.5 Direct reduced iron (DRI) production As of December 2006, there were two DRI plants in the U.S., one operating and one shut down.25 Both are located at EAF steelmaking facilities. The DRI process operates below the melting point of iron; consequently, the iron from the furnace is in solid form whereas blast furnaces produce molten iron. The operating plant is owned by Steel Dynamics in Butler, IN and began operation in 1998. The process feeds iron ore and coal to a rotary hearth furnace fired by natural gas at 376 million (MM) Btu/hr. 26 The non-operating DRI plant is located at Mittal Steel's EAF shop in Georgetown, SC. It was built in 1971 with a capacity of 500,000 mt/yr and was subsequently idled.25 Emission of CC>2 are generated in the DRI furnace from the combustion of natural gas in the furnace and from the carbonaceous materials (coal, coke) used to reduce the iron ore into iron. The IPCC guidelines also note that a small amount of CFLt is emitted from the DRI process. 10 The CFLi is the primary component of the natural gas used as fuel, and for any type of process or combustion unit burning natural gas, a small amount of CH4 may be emitted because of incomplete combustion. The plant produced about 200,000 mt of iron in 2006 (less than 0.5 percent of the U.S. total), and this represents about 50 percent of the plant's capacity. Using the IPCC emission 20 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases factor of 0.7 MMTCO2e/mt iron for DRI, 10 CO2 emissions are about 140,000 MMTCO2e /yr based on actual production and about twice that operating at capacity. 1.6 Other Steelmaking Processes This section discusses miscellaneous processes at iron and steel facilities, and in general, these processes are not significant emitters of GHGs based on review of test reports that show CC>2 levels that are not distinguishable from background. An exception discussed below is argon-oxygen decarburization, which uses oxygen to remove carbon from steel to make low- carbon and specialty steels. Ladle Metallurgy The molten steel from BOFs and EAFs is transferred to a ladle metallurgy facility (LMF) for further alloy additions to achieve the desired specifications. The purpose of ladle metallurgy (also referred to as secondary steelmaking) is to produce steel that satisfies stringent requirements of surface, internal, and microcleanliness quality and mechanical properties. Ladle metallurgy is a secondary step of the steelmaking process and is performed in a ladle after the initial refining process in the primary BOF or EAF is completed. This secondary step enables plants to exercise control over many processing conditions contributing to a higher quality of steel including the following: Temperature, especially for continuous casting operations Deoxidation Decarburization (ease of producing steels to carbon levels of less than 0.03 percent) Addition of alloys to adjust chemical composition. This step also increases production rates by decreasing refining times in the furnace. Several LMF processes are commonly used, including vacuum degassing, ladle refining, and lance powder injection. Argon Oxygen Decarburization 6'24 Argon oxygen decarburization (AOD) is a process used to further refine the steel outside the EAF during the production of certain stainless and specialty steels. In the AOD process, steel from the EAF is transferred into an AOD vessel and gaseous mixtures containing argon and oxygen or nitrogen are blown into the vessel to reduce the carbon content of the steel. Argon assists the carbon removal by increasing the affinity of carbon for oxygen. The carbon is removed from the steel and emitted as CO and CO2, which makes AODs a source of GHG emissions. Casting 6 At most plants, the molten steel is transferred from ladle metallurgy to the continuous caster, which casts the steel into semi-finished shapes (slabs, blooms, billets, rounds, and other special sections). Although continuous casting is a relatively recent development, it has essentially replaced the ingot casting method because it increases process yield from 80 percent to over 95 percent, and it offers significant quality benefits. Another finishing route, which is not used as frequently as continuous casting, is ingot casting. Molten steel is poured from the ladle into an ingot mold, where it cools and begins to 21 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases solidify. The molds are stripped away, and the ingots are transported to a soaking pit or reheat furnace where they are heated to a uniform temperature. The ingots are shaped by rolling into semi-finished products, usually blooms, billets, slabs, or by forging. Ingot casting is typically used for small specialty batches and certain applications for producing steel plates. Rolling Mills 6 Steel from the continuous caster is processed in rolling mills to produce steel shapes that are classified according to general appearance, overall size, proportions of the three dimensions, and intended use. Slabs are always oblong and are mostly 2 to 9 inches thick and 24 to 60 inches wide. Blooms are square or slightly oblong and mostly in the range of 6 inches by 6 inches to 12 inches by 12 inches. Billets are mostly square and range from 2 inches by 2 inches to 5 inches by 5 inches. Rolling mills are used to produce the final steel shapes that are sold by the steel mill, including coiled strips, rails and other structural shapes, sheets, bars, etc. Other Steel Finishing Processes 6 The semi-finished products may be further processed by a number of different steps, such as annealing, hot forming, cold rolling, pickling, galvanizing, coating, or painting. Some of these steps require additional heating or reheating. The additional heating or reheating is accomplished using furnaces usually fired with natural gas. The furnaces are custom designed for the type of steel, the dimensions of the semi-finished steel pieces, and the desired temperature. 1.7 Miscellaneous Emissions Sources There are dozens of emission points and various types of fugitive emissions at integrated iron and steel facilities. These emissions from iron and steel plants have been of environmental interest primarily because of the particulate matter in the emissions. Examples include ladle metallurgy operations, desulfurization, hot metal transfer, sinter coolers, and the charging and tapping of furnaces. The information EPA has examined to date indicates that fugitive emissions contribute very little to the overall GHG emissions from the iron and steel sector (probably on the order of one percent or less). For example, fugitive emissions of blast furnace gas may be emitted during infrequent process upsets (called "slips") when gas is vented for a short period or from leaks in the ductwork that handles the gas. However, the mass of GHG emissions is expected to be small because most of the carbon in blast furnace gas is from carbon monoxide, which is not a greenhouse gas.27 Fugitive emissions and emissions from control device stacks may also occur from blast furnace tapping, the charging and tapping of BOFs and EAFs, ladle metallurgy, desulfurization, etc. However, EPA has no information that indicates CC>2 is generated from these operations, and a review of test reports from systems that capture these emissions show that CC>2 concentrations are very low (at ambient air levels). Fugitive emissions containing methane may occur from leaks of raw coke oven gas from the coke oven battery during the coking cycle. However, the mass of these emissions is expected to be small based on the small number of leaks that are now allowed under existing Federal and State standards that regulate these emissions. In addition, since these emissions are not captured in a conveyance, there is no practical way to measure them. 22 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 2. TOTAL EMISSIONS Table 12 summarizes the emission estimates developed in the previous section for each type of plant and for the major GHG emitting units. Table 12. Summary of Emission Estimates Type of facility Taconite indurating furnaces Byproduct coke stand alone: Nonrecovery coke EAF facilities Integrated plants: Byproduct coke co-located Blast furnaces BOFs Sinter plants Total integrated Total for all facilities Number of facilities 8 9 3 92 6 17 18 5 18 130 Emissions (MMTCO2e/yr)a Process units 5,600,000 1,592,640C 2,953,968C 4,780,000 1,221,024 23,934,300d 4,400,000 2,654,545 32,209,869 47,136,477 Miscellaneous combustion units (b) 2,654,400 (b) 18,560,000 16,800,000 38,014,400 Total 5,600,000 4,247,040 2,953,968 23,340,000 1,221,024 23,934,300 4,400,000 2,654,545 49,009,869 85,150,877 a Emission estimates are provided for the predominant GHG (CO2). Small amounts of methane (CH4) may also be emitted because combustion is not complete (i.e., some of the CH4 in fuel may not be combusted), and some CH4 may be emitted from leaks in the equipment that handles the fuels (compressors, valves, flanges). Small amounts of N2O may be emitted as a by-product of combustion. There is not enough data available to develop a credible estimate of the emissions of CH4 and N2O for this preliminary analysis. b No information on combustion units at these plants, but emissions are expected to be small compared to those from the production processes. 0 From the battery combustion stack. d From the blast furnace stoves. 23 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 3. REVIEW OF EXISTING PROGRAMS AND METHODOLOGIES This section presents a review and summary of methodologies for measuring or estimating greenhouse gas emissions for the iron and steel sector that have been developed by different international groups, U.S. agencies, and others. The following resources are examined and their approaches are summarized: 1. 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. Chapter 4.2 Iron & Steel and Metallurgical Coke Production. 2. U.S. Environmental Protection Agency (EPA). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006. USEPA#430-R-08-005. April 2008. http://www.epa.gov/climatechange/emissions/usinventoryreport.html. 3. World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD). Calculating Greenhouse Gas Emissions from Iron and Steel Production. January 2008. Available at: http://www.ghgprotocol.org/calculation- tools/iron-and-steel-sector. 4. European Union (EU) Emissions Trading System. 2007/589/EC: Commission Decision of 18 July 2007 Establishing Guidelines for the Monitoring and Reporting of Greenhouse Gas Emissions Pursuant to Directive 2003/87/EC of the European Parliament and of the Council. Available at: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32007D0589:EN:NOT. July 2007. 5. U.S. Department of Energy (DOE). Technical Guidelines: Voluntary Reporting Of Greenhouse Gases (1605(B)) Program. Section I.E. 4.1.6. Iron and Steel Production. January 2007. 6. American Iron and Steel Institute (AISI) protocol presented through the Climate Vision Program. Principles for a Steel Industry Methodology for Reporting Carbon-Related Energy Sources and Raw Materials. 1. Environment Canada. Guidance Manual for Estimating Greenhouse Gas Emissions. Primary Iron and Steel Production, http ://www. ec. gc. ca/pdb/ghg/guidance_e. cfm. 2008. 3.1 2006 IPCC Guidelines 10 The IPCC Guidelines present three tiers for estimating CO2 emissions. The Tier 1 method uses production-based emission factors in which default emission factors are multiplied by the quantity of material produced (coke, iron, steel iron ore pellets). For Tier 1, the only site-specific input that is needed for the emission estimate is the production for the year of interest for coke, steel, pig iron, direct reduced iron (DRI), sinter, and iron ore pellets. 24 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases The Tier 2 approach for estimating CC>2 emissions uses a carbon balance in which carbon in the process outputs inputs is subtracted from carbon in process inputs, and the difference is assumed to be converted to CC>2. The guidelines provide typical or default values of the carbon content of process inputs and outputs (e.g., blast furnace gas, coke oven gas, limestone, dolomite, iron, ferrous scrap, steel). For Tier 2, the site-specific information is needed for the quantity of process inputs and outputs for each process for the year of interest. The carbon balances are performed around each process: the coke plant, sinter plant, iron and steel processes combined, DRI plant, and pellet production. The Tier 3 approach for CC>2 emissions uses plant-specific emissions data to estimate national emissions and describes actual site-specific emission measurements as the preference. If emission measurements are not available, the next choice is to use site-specific data in the Tier 2 approach and then sum the results across plants to determine national totals. The Guidelines provide two Tiers for estimating methane (CFLi) emissions for coke, iron, and sinter production. The Tier 1 approach uses a default emission factor, and Tier 3 is based on plant-specific emissions data. There is no Tier 2 approach for methane. 3.2 U.S. EPA GHG Inventory 28 The current U.S. Inventory methodology for iron and steel and metallurgical coke production uses a mass balance approach based on an estimate of the amount of carbon contained in the steel produced, metallurgical coke oven byproducts produced, and pig iron produced and used for non-steel purposes. This amount of carbon is deducted from the carbon introduced into the iron and steel production process from metallurgical coke produced from coking coal, metallurgical coke consumed for pig iron production, and scrap steel consumed at steel plants. In addition, the amount of carbon generated from carbon anode consumption for steel produced in an electric arc furnace is estimated. The difference between the carbon inputs to metallurgical coke and iron and steel production and carbon outputs from these processes constitutes the CC>2 emissions from these processes. The U.S. Inventory methodology does not account for certain other carbon inputs to the process including natural gas, limestone, etc. The GHG emissions from these other carbon inputs are included (but not separately identified) elsewhere in the U.S. Inventory (e.g., Energy, Lime, Limestone, and Dolomite use, etc.). The U.S. Inventory methodology also does not include consumption of raw materials for sinter, pellet, and direct reduced iron production; the GHG emissions from these other processes are included (but not separately identified) in the "Energy" section of the Inventory. Methane emissions from metallurgical coke production and pig iron production are estimated using emission factors and activity data. Emissions of CC>2 and CH4 associated with metallurgical coke production and iron and steel production are attributed to the Industrial Processes chapter of the U.S. Inventory. 3.3 WRI/WBCSD Calculation Procedure 29 The WRI/WBCSD protocol presents two procedures for estimating CC>2 emissions from the production of coke, sinter, DRI, and iron and steel, and both use a carbon balance approach. 25 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases The preferred approach is Tier 3, which uses facility-specific data for carbon content of all process inputs and outputs and the mass rate of all process inputs and outputs. In the absence of facility-specific data, Tier 1 default factors for carbon contents of inputs and outputs are provided. CC>2 emissions from flaring are based on the volume of gas flared, the carbon content of the gas, and a combustion efficiency of 98 percent. CIHLt emissions from flaring are estimated by assuming 2 percent of the CR4 in the gas is not burned. The WRI/WBCSD provides equations for estimating CR4 emissions from the production of coke, sinter, pig iron, and DRI; CR4 emissions from steelmaking are assumed to be negligible. In the absence of facility-specific data that would allow the derivation of Tier 3 emission factors, equations and default emission factors (Tier 1) are provided for CR4 emissions for all of these processes except for pig iron production. 3.4 European Union (EU) Emissions Trading System 30 Source streams are defined as: (1) "de-minimus" sources that collectively contribute less than 1,000 MT CO2/yr or that contribute less than 2% of total emissions up to 20,000 MT/yr); (2) "minor" sources that collectively contribute less than 5,000 MT CCVyr or that contribute less than 10% of total emissions up to 100,000 MT/yr); and (3) "major" sources that include all other streams. The highest tier must be used for major source streams unless it is not technically feasible. Tier 1 can be used for minor source streams, and a facility may use their own no-tier method for de-minimius streams. Annex V addresses sinter and iron ore pellets plants, and Annex VI addresses pig iron and steel manufacture, including continuous casting. If the process is part of a larger integrated iron and steel plant, the operator is given the choice of a carbon balance approach around either the entire plant or around each process. The tiers relate to the quality of the input data: Tier 1 2 3 4 Uncertainty in mass flow of inputs and outputs must be less than ±7.5% ±5.0% ±2.5% ±1.5% Carbon content Default (typical) values Country-specific values Analysis of representative samples This approach is similar to the IPCC Tier 2/3 methods. 26 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 3.5 DOE Technical Guidelines 31 The DOE guidelines provide 3 general approaches for the production of iron and steel that are given a rating of A, B, or C. A rating of "A" is for approaches that use a carbon balance around the process with site-specific data for process inputs, outputs, and carbon content. Default values are given for carbon content, and if the default values are used, the approach is given a rating of "B". The "C" rating is assigned when emissions are simply estimated as 1.75 MT CO2/ton of steel. The approach focuses on the streams that contain the most carbon: limestone, dolomite, coke/coal, iron, steel, and graphite electrodes. The approach does not consider slag or air pollution control residues (dusts and sludges) that are not likely to contain much carbon. 3.6 AISI Methodology 32 The AISI methodology is based on a net carbon balance within the fence line of the facility. Their approach states that: ...if all of the carbon in metallurgical coal is accounted for by the total quantity of coal entering a plant, it is not necessary to determine if that carbon is ultimately emitted as CO 2 emissions from coke battery stacks, blastfurnace stoves, flares, boilers, EOF off-gas, or other sources of byproduct fuel combustion. It is only important to make adjustments for carbon that may leave the plant boundary in a form other than CO2 (e.g., sold or transferred coke, tar, byproducts, or byproduct fuels such as blastfurnace gas or coke oven gas). Adjustments can also be made for carbon contained in steel products if deemed to be significant. The carbon balance focuses on the streams contributing the most carbon and do not include minor contributors, such as iron ore, scrap, semi-finished steel, or ferroalloys. However, raw materials with intrinsic carbon content (e.g., iron carbide, carbon electrodes, charge carbon, limestone) should be reported if they are significant. In addition, adjustment (subtraction) should be made for offsite transfer of process gases, slag, scrap, or coke by-products if they are significant. They suggest emissions less than 1% of the facility's total should be considered de minimus. The methodology includes a simple reporting form that requests the quantity of all fuels by type, all carbon-containing materials consumed onsite, and the amount of steel produced by BOFs and by EAFs. The form also requests information on the amount of electricity and steam that was purchased. The methodology also provides factors that convert fuel and raw material quantities to CO2 emissions (e.g., 5,540 Ib CO2/ton of coking coal). 3.7 Environment Canada Guidance Manual 33 The guidance for mandatory reporting in Canada primarily references the IPCC guidelines. However, the guidance also contains a section on developing a site-specific emission factor rather than using default emissions factors with these observations: 27 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases A facility-specific emission factor is preferred over general or industry-averaged factors because they provide a better representation of emissions from a facility's specific operations. It may be necessary to update facility-specific emission factors on a periodic basis to account for changes in facility conditions. Obtaining emissions data by continuous emissions monitoring system (CEMS) is the preferred method when data on emissions are needed over an extended period. There are various types of monitoring systems available for installation, which use different instrumentation equipment. It is necessary for the facility to ensure the proper operation and calibration of the monitoring equipment used. Stack sampling and analysis can be used to obtain direct data on emissions over a short period (during the period of the test). Details on the sampling method and lab techniques used should be provided if you choose to collect facility data through this method. Standardized sampling and lab analysis protocols should be used when available. 3.8 Current Practices for Estimating Greenhouse Gas Emissions The current practice of many U.S. iron and steel companies as well as international iron and steel facilities is to voluntarily report GHG emission intensity (e.g., in terms of MMTCO2e/mt steel produced). Many of these facilities are using the methodologies described in the WRI/WBCSD protocol. 28 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 4. TYPES OF INFORMATION TO BE REPORTED Based on the review of existing programs and the emission sources at iron and steel facilities, the major GHG (by far) to be reported is CC>2. However, CIHLt is emitted due to incomplete combustion, and N2O is emitted as a byproduct of combustion. These are the three major GHGs to be reported for the iron and steel industry. The type of information to be reported will depend in large part on the option chosen for determining GHG emissions. However, in order to check the reported GHG emissions for reasonableness and for other data quality considerations, certain types of typical information about the emission sources is needed. The following items are recommended for reporting to assist in checks for reasonableness and for other data quality considerations: 1. Annual emission estimates for CC>2 presented by calendar quarters for coke oven battery combustion stacks, coke pushing, blast furnace stoves, taconite indurating furnaces, BOFs, EAFs, DRI furnaces, and sinter plants; 2. Annual emission estimates for CH4 and N2O presented by calendar quarters for each type of fuel that is burned; 3. Total for all process inputs and outputs when the carbon balance is used for specific processes by calendar quarters; 4. Site-specific emission factor for all processes for which the site-specific emission factor approach is used; 5. Annual production quantity for taconite pellets, coke, sinter, iron, raw steel by calendar quarters (in metric tons); 6. Annual production capacity for taconite pellets, coke, sinter, iron, raw steel; and 7. Annual operating hours for taconite furnaces, coke oven batteries, sinter production, blast furnaces, DRI furnaces, EAFs, and BOFs. 29 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 5. OPTIONS FOR REPORTING THRESHOLDS In evaluating potential thresholds for iron and steel production, EPA considered emissions-based thresholds of 1,000 MMTCO2e, 10,000 MMTCO2e, 25,000 MMTCO2e, and 100,000 MMTCO2e. Table 14 summarizes the emission estimates developed in the previous sections and shows that the average emission level for each type of plant is well above the thresholds. However, there are several small EAF facilities that would fall below some of the thresholds. Table 15 illustrates the various thresholds and their estimated effect on the amount of emissions that would be covered (reported). All integrated iron and steel facilities and taconite facilities exceed the highest emissions threshold considered. Most EAF facilities (with the possible exception of about 11 facilities) are estimated to exceed the 25,000 MMTCO2e emissions threshold. Table 15 also provides an estimate of the production level that corresponds to the emission thresholds. The production thresholds are estimated from the emission factors developed earlier for EAF processes (0.08 MMTCO2e/mt steel) and combustion sources (0.32 MMTCO2e/mt steel). Table 14. Summary of Emission Estimates Facility Taconite Byproduct coke stand alone Nonrecovery coke Integrated plants EAF Total facilities Number of plants 8 9 3 18 92 130 Production (mt/yr) 52,000,000 7,056,000 2,234,400 40,000,000 58,000,000 159,290,400 Type of production pellets coke coke steel steel products Total emissions (mt of CO2e) 5,600,000 4,247,040 2,953,968 49,009,869 23,340,000 85,150,877 Average per plant (MMTCO2e) 700,000 471,893 984,656 2,722,771 253,696 655,007 Table 15. Reporting Thresholds Threshold level MMTCO2e all in 1,000 10,000 25,000 100,000 Production threshold (mt/yr) 0 2,500 25,000 62,500 250,000 Total national emissions (MMTCO2e) 85,150,877 85,150,877 85,150,877 85,150,877 85,150,877 Total number of U.S. facilities 130 130 130 130 130 Emissions covered MMTCO2e/yr 85,150,877 85,150,877 85,141,423 85,013,059 84,468,696 Percent 100.0 100.0 99.99 99.8 99.2 Facilities covered Number 130 130 128 121 111 Percent 100 100 98 93 85 30 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 6. OPTIONS FOR MONITORING METHODS 6.1 COi Emissions from Process Sources The monitoring methods for the iron and steel sector include emissions from stationary combustion sources and from process sources. The methods for combustion sources, where the only source of CC>2 emissions is the carbon in the fuel, are addressed separately for stationary combustion sources in general. (See the technical support document for general stationary fuel combustion sources for more details EPA-HQ-OAR-2008-0508-004.) This section summarizes the monitoring methods for process sources, which are defined as sources in which the process feed materials, usually in addition to the fuel, contribute the carbon for CO2 emissions. The affected processes are each indurating furnace, BOF, nonrecovery coke oven battery, coke pushing operation, sinter plant, direct reduction furnace, and EAF. The approach to develop the monitoring options was to consider accuracy, uncertainty, completeness, and comparability in the estimates; whether they were technically feasible, reasonably easy to implement, and cost effective; and if they provided adequate flexibility to the owner or operator. The five options that were developed from the review of existing methods for monitoring CC>2 emissions from the process sources are described below: 1. Option 1: Apply a default emission factor based on the type of process and an annual activity rate (e.g. quantity of raw steel, sinter, or direct reduced iron produced). This option is the same as the IPCC Tier 1 approach. 2. Option 2: Perform a carbon balance of all inputs and outputs using default or typical values for the carbon content of inputs and outputs. Use facility production and other records to determine the annual quantity of process inputs and outputs. Calculate CO2 emissions from the difference of carbon-in minus carbon-out assuming all is converted to CO2. This option is the same as the IPCC Tier 2 approach, the WRI default approach, and the DOE 1605(b) approach that is rated "B." It is similar to the approach recommended by AISI except that the carbon balance for Option 2 is based on the individual processes rather than the entire plant. 3. Option 3: Perform a monthly carbon balance of all inputs and outputs using measurements of the carbon content of specific process inputs and process outputs and measure the mass rate of process inputs and process outputs. Calculate CO2 emissions from the difference of carbon-in minus carbon-out assuming all is converted to CO2. This is the IPCC Tier 3 approach (if direct measurements are not available), the WRI preferred approach, the approach used in the EU Emissions Trading Scheme, and the DOE 1605(b) approach that is rated "A." 4. Option 4: Develop a site-specific emission factor based on simultaneous and accurate measurements of CO2 emissions and production rate or process input rate during representative operating conditions. Multiply the site-specific factor by the annual production rate or appropriate periodic production rate (or process input rate, as 31 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases appropriate). This approach is included in Environment Canada's methodologies and might be considered a form of direct measurement as in the IPCC's Tier 3 approach. 5. Option 5: Direct and continuous measurement of CC>2 emissions using a continuous emission monitoring system (CEMS) for CC>2 concentration and stack gas volumetric flow rate based on the requirements in 40 CFR part 75. This is the IPCC Tier 3 approach (direct measurement). Two characteristics of Options 1 and 2 are the use of default values and lack of direct measurements, which results in a very high level of uncertainty in the emission estimates. These default approaches will not provide site-specific estimates of emissions that will reflect differences in feedstocks, operating conditions, fuel combustion efficiency, variability in fuels and other differences among facilities. Methodologies based on default values have commonly been used more for sector wide or national total estimates from aggregated activity data than for determining emissions from a specific facility. Options 3, 4, and 5 use approaches that provide good site-specific estimates of emissions that reflect differences in feedstocks, operating conditions, fuel combustion efficiency, and other differences among plants. These three options span the range of types of methodologies currently used that do not apply default or typical values. The options also provide flexibility. For example, a CO2 CEM may be the most accurate measurement method: however, it may expensive except for the largest emission sources, it would certainly be expensive for sources with multiple stacks, and it is not feasible for certain sources, such as flares and other emission points where emissions are not captured in a conveyance (e.g., a stack). In those cases, one of the other two options would be more appropriate. Several iron and steel companies in the U.S. and abroad have recommended and are using a carbon balance approach similar to or a variation of the one described in Option 3. Many of the measurements required for that approach, such as the amount of specific feedstocks consumed, production rates from each process, process gas (coke oven gas, blast furnace gas) production and consumption, and purchased fuel consumption, are already routinely measured and used for accounting purposes (e.g., determining the cost of production), process control, and yield calculations. In addition, most plants monitor the composition of blast furnace gas and coke oven gas for process control and to ensure gas quality for combustion, and the carbon content of steel is routinely determined because it is a quality specification. Consequently, Option 3 offers an advantage in that it would use a significant amount of information that is already readily available. According to the IPCC's 2006 guidelines, the uncertainty associated with default emission factors for Options 1 and 2 is ±25 percent, and the uncertainty in the production data used with the default emission factor is ±10 percent,10 which results in a combined overall uncertainty greater than ±25 percent. If process-specific carbon contents and actual mass rate data for the process inputs and outputs are used (i.e., Option 3) or if direct measurements are used (i.e., Options 4 and 5), the guidelines state that the uncertainty associated with the emission 32 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases estimates would be reduced. Options 3, 4, and 5 meet the requirements of the IPCC's highest tier methodology (Tier 3).10 6.2 Methane and Nitrous Oxide Emissions A small amount of CH4 is emitted when any fuel that contains CH4 is burned, in either process units or combustion units, because combustion is not complete (i.e., a small amount of methane escapes unburned). A small amount of N2O is produced as a combustion byproduct when fuel is burned. For coke oven gas and blast furnace gas that are used as fuels, the recommended approach for estimating emissions of CFLt and N2O is to use the same methodology as that used for combustion units and to apply the default emission factor presented for natural gas, which is the procedure used in the IPCC Guidelines for coke oven gas and blast furnace gas,9 and the measured high heating value. 6.3 COi Emissions from Coke Pushing Operations Emissions may also occur when the incandescent coke is pushed from the coke oven and transported to the quench tower where it is cooled (quenched) with water. A small portion of the coke burns during this process prior to quenching. EPA updated the coke oven section of the AP-42 compilation of emission factors in May 2008, and the update included an emission factor for CC>2 emissions developed from 26 tests for particulate matter from pushing operations.13 The emissions factor (0.008 MMTCO2e per metric ton of coal charged) was derived to account for emissions from the pushing emission control device and those escaping the capture system. The recommended approach is for coke facilities to use the AP-42 emission factor to estimate CC>2 emissions from coke pushing operations. 33 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 7. OPTIONS FOR ESTIMATING MISSING DATA For process sources that use Option 3 (carbon balance) or Option 4 (site-specific emission factor), no missing data procedures are appropriate because 100 percent data availability would be required. (There are no valid reasons for missing data for these options because re-testing for the site-specific emission factor can be performed at any time, and for the carbon balance, only a weekly sample would be necessary). For process sources that use Option 5 (direct measurement by CEMS), the missing data procedures that are appropriate are the same as for units using Tier 4 in the general stationary fuel combustion source category. 34 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 8. QA/QC REQUIREMENTS For the carbon balance approach, the following QA/QC procedures would better ensure the quality of the reported emissions: For each process input and output other than fuels, the carbon content could be analyzed by a third-party certified laboratory using the test methods (and their QA/QC procedures) in the General Provisions (subpart A) of the proposed rule. Facilities could keep records that include a detailed explanation of how company records of measurements are used to estimate all sources of carbon input and output. The owner or operator also could document the procedures used to ensure the accuracy of the measurements of fuel usage including, but not limited to, calibration of weighing equipment, fuel flow meters, and other measurement devices. The estimated accuracy of measurements made with these devices could also be recorded, and the technical basis for these estimates provided. The procedures and equations used to convert the fuel feed rates to units of mass also could be documented. Records could be made available for verification of the records and measurements upon request. For the site-specific emission factor approach, the following QA/QC elements were identified: The QA/QC procedures in the EPA reference test methods could be followed. The results of a performance test could include the analysis of samples, determination of emissions, and raw data. The performance test report could contain all information and data used to derive the emission factor. For each of the options, all QA/QC data from each facility in the iron and steel production source category should be available for inspection upon request. 35 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 9. REFERENCES 1. International Iron and Steel Institute. World Steel in Figures 2007. Available at http://www.worldsteel.org/?action=programs&id=52. 2. Fenton, Michael. USGS Mineral Commodity Summary 2008. Iron and Steel. Available at http://minerals.usgs.gov/minerals/pubs/mcs/2008/mcs2008.pdf. January 2008. 3. Jorgeson, John. USGS Mineral Commodity Summary 2008. Iron Ore. Available at http://minerals.usgs.gov/minerals/pubs/mcs/2008/mcs2008.pdf. January 2008. 4. 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Compiled from operating permits posted on state agency websites, including http://www.dep.state.wv.us/item.cfm?ssid=8; http://www.air.ky.gov/permitting/: http ://www. epa. gov/ARD-R5/permits/epermits. htm: http://www.in.gov/idem/permits/air/pending.html: http://www.epa.gov/ARD- R5/permits/epermits.htm: http://www.deq.state.mi.us/aps/: http://www.epa.gov/ARD- R5/permits/epermits.htm: http://www.epa.state.oh.us/dapc/title_v/permits/tvpermit.html. 9. 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. Volume 2: Energy, Chapter 2 Stationary Combustion. Available at: http://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html. 10. 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. Volume 3: Industrial Processes and Product Use, Chapter 4.2 Iron & Steel and Metallurgical Coke Production. Available at: http://www.ipcc-nggip.iges.or.jp/public/2006gl/vol3.html. 11. American Iron and Steel Institute (AISI). Annual Statistics 2005. Consumption of Fuels. 2006. 36 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 12. U.S. EPA. National Emission Standards for Hazardous Air Pollutants (NESHAP) for Coke Ovens: Pushing, Quenching, and Battery Stacks Background Information for Proposed Standards. EPA-453/R-01-006. February 2001. 13. U.S. Environmental Protection Agency. AP-42 Section 12.2: Coke Production. Available at http://www.epa.gov/ttn/chief/ap42/ch 12/fmal/c 12s02_may08.pdf May 2008. 14. Memorandum with attachments, S. Burns, RTI, to the docket, enclosing data compiled from EPA Section 114 survey responses of coke plants, July 1998. Docket Item II-I-45 in Docket Number A-2000-34. 15. URS Corporation. Compliance Test Report for Haverhill Coke Company, Franklin Furnace, Ohio. March 2006. 16. Federal Register (67 FR 77565). 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Preamble for National Emission Standards for Hazardous Air Pollutants for Electric Arc Furnace Steelmaking Facilities; Proposed Rule. September 20, 2007. 22. U.S. Environmental Protection Agency. Summary of EAF Survey Responses from Section 114 Questionnaire for 27 EAF Steelmaking Facilities. May 2004. Available in EPA Docket No. EPA-HQ-OAR-2004-0083. 23. Iron & Steel Society. Iron and Steelmaker Electric Arc Furnace Roundup. May 2003. pp. 38-49. 37 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases 24. U.S. Environmental Protection Agency. Electric Arc Furnaces andArgon- Decarburization Vessels in the Steel Industry-Background Information for Proposed Revisions to the Standard. EPA-450/3-82-020a. July 1983. 25. Midrex Technologies, Inc. 2006 World Direct Reduction Statistics. Available at http://www.midrex.com. 2007. 26. Title V Operating Permit issues to Iron Dynamics, Inc., Butler, Indiana by the Indiana Department Of Environmental Management. October 4, 2006. 27. Branscome, M., and S. Burns. 2006. Evaluation of PM2.5 Emissions and Controls at Two Michigan Steel Mills and a Coke Oven Battery. Prepared for the Air Quality Strategies and Standards Division, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. Available at http://epa.gov/air/caaac/aqm/detroit_steel_report_final_20060207.pdf 28. U.S. Environmental Protection Agency (EPA). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006. USEPA#430-R-08-005. April 2008. http://www.epa.gov/climatechange/emissions/usinventoryreport.html. 29. World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD). Calculating Greenhouse Gas Emissions from Iron and Steel Production. January 2008. Available at: http://www.ghgprotocol.org/calculation- tools/iron-and-steel-sector. 30. European Union (EU) Emissions Trading Scheme. 2007/589/EC: Commission Decision of 18 July 2007 Establishing Guidelines for the Monitoring and Reporting of Greenhouse Gas Emissions Pursuant to Directive 2003/87/EC of the European Parliament and of the Council. Available at: http://eurex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32007D0589:EN:NOT. July 2007. 31. U.S. Department of Energy (DOE). Technical Guidelines: Voluntary Reporting Of Greenhouse Gases (1605(B)) Program. Section I.E. 4.1.6. Iron and Steel Production. January 2007. 32. American Iron and Steel Institute (AISI) protocol presented through the Climate Vision Program. Principles for a Steel Industry Methodology for Reporting Carbon-Related Energy Sources and Raw Materials. 33. Environment Canada. Guidance Manual for Estimating Greenhouse Gas Emissions. Primary Iron and Steel Production, http ://www. ec. gc. ca/pdb/ghg/guidance_e. cfm. 2008. 38 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases APPENDIX A. DEFINITIONS AND THEIR ORIGINS Argon-oxygen decarburization vessel means any closed-bottom, refractory-lined converter vessel with submerged tuyeres through which gaseous mixtures containing argon and oxygen or nitrogen may be blown into molten steel for further refining to reduce the carbon content of the steel.a Basic oxygen furnace means any refractory-lined vessel in which high-purity oxygen is blown under pressure through a bath of molten iron, scrap metal, and fluxes to produce steel.b Blast furnace means a furnace that is located at an integrated iron and steel facility and is used for the production of molten iron from iron ore pellets and other iron bearing materials.13 By-product coke oven battery means a group of ovens connected by common walls, where coal undergoes destructive distillation under positive pressure to produce coke and coke oven gas from which by-products are recovered.0 Cokemaking facility means a facility that produces coke from coal in either a by-product coke oven battery or a non-recovery coke oven battery.0 Direct reduction furnace means a high temperature furnace typically fired with natural gas to produce solid iron from iron ore or iron ore pellets and coke, coal, or other carbonaceous material s.d Electric arc furnace (EAF) means a furnace that produces molten steel and heats the charge materials with electric arcs from carbon electrodes. The charge materials in the electric arc furnace is primarily recycled ferrous scrap but also may include direct reduced iron or molten iron from the blast furnace.a Electric arc furnace (EAF) steelmaking facility means a facility that produces carbon, alloy, or specialty steels using an EAF. This definition excludes EAFs at steel foundries and EAFs used to produce nonferrous metals.a Indurating furnace means a furnace where unfired taconite pellets, called green balls, are hardened at high temperatures to produce fired pellets for use in a blast furnace. Types of indurating furnaces include straight gate and grate kiln furnaces.6 Integrated iron and steel manufacturing facility means a facility engaged in the production of steel from iron ore or iron ore pellets. At a minimum, an integrated iron and steel facility has a basic oxygen furnace for refining molten iron into steel.b'f Non-recovery coke oven battery means a group of ovens connected by common walls and operated as a unit, where coal undergoes destructive distillation under negative pressure to produce coke, and which is designed for the combustion of the coke oven gas from which by- products are not recovered.0 39 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Pushing means the process of removing the coke from the coke oven at the end of the coking cycle. Pushing begins when coke first begins to fall from the oven into the quench car and ends when the quench car enters the quench tower.0 Sinter process means a process that produces a fused aggregate of fine iron-bearing materials suited for use in a blast furnace. The sinter machine is composed of a continuous traveling grate that conveys a bed of ore fines and other finely divided iron-bearing material and fuel (typically coke breeze), a burner at the feed end of the grate for ignition, and a series of downdraft windboxes along the length of the strand to support downdraft combustion and heat sufficient to produce a fused sinter product.b Taconite iron ore processing facility means a facility that separates and concentrates iron ore from taconite, a low grade iron ore, and heats the taconite in an indurating furnace to produce taconite pellets that are used as the primary feed material for the production of iron in blast furnaces at integrated iron and steel facilities.6 Origins: a40 CFR Part 63, Subpart YYYYY. National Emission Standards for Hazardous Air Pollutants for Area Sources: Electric Arc Furnace Steelmaking Facilities. b40 CFR Part 63, Subpart FFFFF. National Emission Standards for Integrated Iron and Steel Manufacturing. C40 CFR Part 63, Subpart CCCCC. National Emission Standards for Hazardous Air Pollutants for Coke Ovens: Pushing, Quenching, and Battery Stacks. d The definition of "direct reduction furnace" was developed from the process description in The Making, Shaping, and Treating of Steel (Reference 7) because there is no definition codified in 40 CFR. e40 CFR Part 63, Subpart RRRRR. National Emission Standards for Taconite Iron Ore Processing. f This definition in 40 CFR was modified by adding "and iron ore pellets" because most integrated plants use pellets in the blast furnace rather than iron ore. Also added "At a minimum, an integrated iron and steel facility has a basic oxygen furnace for refining molten iron into steel" because one integrated plant recently shut down the onsite blast furnace, but continues to operate the BOFs with molten iron supplied by a nearby plant. 40 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases APPENDIX B. EXAMPLES OF COMBUSTION UNITS Table B-l. Examples of Combustion Unit at Minimills' Plant Name Universal Stainless and Alloy Products Erie Forge and Steel Ellwood Quality Steels Company AK Steel Corporation Electroalloy Nucor Steel City Bridgeville Erie New Castle Butler Oil City Blytheville State PA PA PA PA PA AR CO2 source Ladle Reheat Furnace Vessel Reheat Furnace Electro-Slag Remelt Holding Furnace Annealing Furnaces Plate Warming Furnace Miscellaneous space heating units (75) North American Steam Boiler Ladle preheaters Ladle refining furnace Heat treat furnaces Hood furnace Boilers (4) Oxy-fuel burner (for EAF) Anneal furnaces Scrap torching Ladle preheaters EAF pre-heater Boilers Spaceheaters > 2.5 MMBtu/hr Electric furnace Slab heating furnaces Decarb furnace Silicon drying furnace AOD reactor Continuous caster Vacuum degas Anneal furnaces Drying furnace Carlite line dry furnace Ladle preheaters Miscellaneous NG (<2.5 MMBtu/hr) Anneal furnaces Granular metal process Ladle preheaters for melt shop Pickle line boilers Galvanizing line Alkali wash burners Chromate spray dryer Annealing furnaces Tunnel furnace Ladle preheaters Ladle dryouts Vertical holding stations Tundish preheaters Tundish dryers 41 ------- Technical Support Document for the Iron and Steel Sector: Proposed Rule for Mandatory Reporting of Greenhouse Gases Table B-l. Examples of Combustion Unit at Minimills' Plant Name Oregon Steel Mills Rivergate Plant Quanex Corporation - MacSteel Division City Portland Fort Smith State OR AR CO2 source Oxide reformer furnace Vacuum Degasser Boiler Degasser stack flare Other natural gas sources Glass frit rotary dryer Low NOX natural gas sources Heat treat facility Natural gas-fired boiler Tundish preheaters Three ladle preheaters One ladle dryout, six refractory dryers Reheat furnace Boiler Heat treating furnaces Car bottom furnace Table B-2. Reported Fuel Usage at U.S. Steel's Integrated Plant in Michigan (2004) 28 Source No. 2 Boilerhouse D blast furnace stove B blast furnace stove Blast furnace flares No. 1 Boilerhouse Mill furnace heaters Mill furnace heaters No. 2 Boilerhouse No. 1 Boilerhouse No. 1 Boiler Heaters Dryout Heaters Heaters Process Heaters Boiler Annealing Heaters No. 2 Boilerhouse No. 1 Boiler B blast furnace stove Annealing Heaters BOF operation No. 3 Boilerhouse Fuel Blast furnace gas Blast furnace gas Blast furnace gas Blast furnace gas Blast furnace gas Coke oven gas Natural Gas Coke oven gas Coke oven gas Coke oven gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas Natural Gas MMCF/yr 30,711 30,397 28,145 28,059 21,290 4,647 3,163 2,773 1,917 987 590 580 428 393 268 228 208 135 126 122 121 107 42 ------- |