Technical Support Document
Coal-to-Liquids Products Industry Overview
Proposed Rule for Mandatory Reporting of
Greenhouse Gases
Office of Air and Radiation
U.S. Environmental Protection Agency
January 28, 2009
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Coal-to-Liquids Product Suppliers Technical Support Document
Table of Contents
1.0. Introduction 1
1.1. Purpose 1
1.2. Organization of this Report 1
2.0. Overview of the Coal-to-Liquids Industry 1
2.1. Three Technologies 2
2.1.1 Fischer-Tropsch (FT) 2
2.1.2 Methanol to Gasoline (MTG) 5
2.1.3 Direct Liquefaction 5
2.1.4 Products 7
3.0. Plants 8
3.1. Existing Plants 8
3.2. Planned Plants 9
4.0. Carbon Content of Products 9
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Coal-to-Liquids Product Suppliers Technical Support Document
List of Exhibits
Exhibit 1: Coal Liquefaction Technologies 3
Exhibit 2: Coal to Liquids Flow Diagram (Fischer Tropsch Synthesis) 4
Exhibit 3: Coal to Liquids Flow Diagram (Direct Liquefaction) 6
Exhibit 4: Sasol CTL Synthetic Jet Fuel 9
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Coal-to-Liquids Product Suppliers Technical Support Document
1.0. Introduction
1.1. Purpose
This document provides an overview of the status of the emerging coal-to-liquids (CTL)
industry both in the United States and elsewhere. The analysis here is part of a larger
effort to develop guidelines for mandatory reporting requirements for greenhouse gases
(GHGs). In December 2007, Congress enacted an omnibus appropriations bill that
directs EPA to develop and publish a rule requiring measurement and reporting of GHG
emissions above appropriate thresholds in all sectors of the economy. The bill
mandates that EPA publish a proposed rule within nine months and a final rule within 18
months. Understanding the information that fuel suppliers already generate and report
to federal agencies is a first step in developing mandatory GHG reporting requirements.
Since CTL is a nascent industry in which the only operational plants are overseas this
document focuses more on the status of the industry, the emerging technologies, and
identifies the operational plants and those that are planned.
Existing research and development (R&D) work indicates that the carbon content of the
products from a CLT plant, particularly a plant using Fischer Tropsch technology, have a
different and potentially lower carbon content compared to those from a conventional
petroleum refinery. However, data are difficult to identify and the current approach, until
further knowledge is available, is to use the petroleum default table in Subpart MM
Petroleum Suppliers to calculate the carbon content of CTL derived products.
1.2. Organization of this Report
To provide context for the CTL sector, section 2 provides an overview of the industry and
focuses on the two dominant technologies, the indirect Fischer Tropsch and direct
liquefaction of coal. There is too a brief discussion of Mobil's methanol-to-gasoline
(MTG) process. There is also some discussion of the type of products that come from a
CLT plant and whether or not they need further processing. Section 3 discusses the
existing plants, plants that are under construction and planned plants. Since this is a
nascent industry the discussion is not confined only to the United States. Finally,
Section 4 focuses on what is known about the carbon content of CTL products.
2.0. Overview of the Coal-to-Liquids Industry
Coal-to-Liquids technology has been known and used for a long time. The underlying
technology, coal gasification, was developed in the 19th century, the product being "town
gas" which was used for lighting and cooking. Use of town gas became widespread in
both Europe and the United States. In the 1920s the Fischer-Tropsch process was
developed to convert the main constituents of the gas, hydrogen and carbon monoxide
to liquid fuels.
At the beginning of the 20th century the direct liquefaction process was first done by
reacting coal with hydrogen and process solvent at high temperatures and pressure to
produce liquid fuels. This direct liquefaction process was used to produce high octane
aviation gasoline by Germany during World War II. The Fischer Tropsch technology
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Coal-to-Liquids Product Suppliers Technical Support Document
was also used in Germany in the war. However, given the costs of the technology and
the very low prices of petroleum its only use came towards the end of the Nazi regime in
Germany and during the period of apartheid in South Africa. Sanctions and war cut off
most petroleum to these two countries so that need rather than prices determined the
use of the technology.
Although research into CTL has continued, apart from the South African plants no other
plants were planned before the substantial increase in crude oil prices commencing after
2000. The substantial increase in crude oil prices, combined with concern over
geopolitical instability in the major producing areas, and the increasing competition for
limited resources has resulted in attention once again turning to alternative sources for
transportation fuels, whether biofuels, gas to liquids, coal gasification, or coal to liquids.
Oil prices, driven by burgeoning global demand have reached a high enough level that
these alternative sources, despite the unprecedented increase in capital and operating
costs, can be deemed economic as well as technically feasible. CTL is the subject of
increasing attention as coal resources are widespread and voluminous.
Although there has been limited application of these alternative fuel sources, the front
end technology of gasification has advanced considerably. Between 2000 and 2007, 27
new coal gasification facilities became operational around the world.1 Three of these
plants produce electrical power using a combination of steam and gas, and the others
are used to produce synthesis gas for the manufacture of chemicals, particularly
ammonia and methanol. Consequently, there have been significant advances in coal
gasification.
2.1. Three Technologies
There are currently three established technologies for CTL plants: the indirect
method in which coal is first gasified and then converted to liquid fuels through
the process of Fischer Tropsch synthesis; the MTG process, which is a subset of
the indirect method; and the direct method in which coal is directly converted to
liquid fuels with the help of hydrogen and heavy oils. Exhibit 1 lists all the current
component technologies for CTL.
2.1.1. Fischer-Tropsch (FT)
Exhibit 2 presents a flow diagram of the Sasol CTL process. Sasol has
developed two technologies based on the Fischer Tropsch process: 1) the High
Temperature Fischer Tropsch process which can be used to produce a slate of
light products as well as the building blocks of high value added chemicals, and
2) the Low Temperature Fischer Tropsch process that is used for producing
diesel from coal.
Exhibit 2 represents the Low Temperature process. As the exhibit shows coal is
fed to gasifiers to produce raw gas which is then purified into the synthesis gas (a
mixture of hydrogen and carbon monoxide) which is then fed into the Fischer
1 The Rand Corporation, Producing Liquid Fuels from Coal, 2008
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Coal-to-Liquids Product Suppliers Technical Support Document
Tropsch synthesis and converted to heavy hydrocarbons in the presence of a
catalyst.
One of the advantages of the FT process is that the synthesis gas can be made
from a variety of feedstocks other than coal. Commercial development over the
past 20 years has centered around using various deposits of stranded gas. The
resulting various Gas-to-Liquids plants all use a variation of the FT process.
Considerable work has also been done examing adding biomass to the coal
feedstock as a means of reducing stationary source greenhouse gas emissions.
The products can be upgraded by hydrocracking, chemical workup or by refining
through a conventional petroleum refinery depending on the product slate
required.
Exhibit 1: Coal Liquefaction Technologies
Mild Pyrolysis
- Liquids from
Coal (LFC)
Process -
Encoal
- Coal
Technology
Corporation
- Univ. of North
Dakota Energy
and
Environmental
Center
(EERC)/AMAX
R&D Process
- Institute of
Gas
Technology
- Char, Oil
Energy
Development
(COED)
Single-Stage
Direct Liquefaction
Solvent Refined
Coal Processes
SRC-I and SRC-II)
-Gulf Oil
Exxon Donor
Solvent (EDS)
Process
H-Coal Process -
HRI
Imhausen High-
Pressure Process
Conoco Zinc
Chloride Process
Kohleoel Process
- Ruhrkohle
NEDO Process
Two-Stage Direct
Liquefaction
Consol Synthetic Fuel
(CSF) Process
Lummus ITSL Process
Chevron Coal
Liquefaction Process
(CCLP)
Kerr-McGee ITSL Work
Mitsubishi Solvolysis
Process
Pyrosol Process -
Saarbergwerke
Catalytic Two-Stage
Liquefaction Process -
DOE and HRI
Liquid Solvent
Extraction (LSE) Process
- British Coal
Brown Coal Liquefaction
(BCL) Process - NEDO
Amoco CC-TSL Process
Supercritical Gas
Extraction (SGE) Process
- British Coal
Co-Processing and Dry
Hydrogenation
MITI Mark I and Mark II
Co-Processing
Cherry P Process -
Osaka Gas Co.
Solvolysis Co-
Processing - Mitsubishi
Mobil Co-Processing
Pyrosol Co-Processing
- Saabergwerke
Chevron Co-Processing
Lummus Crest Co-
Processing
Alberta Research
Council Co-Processing
CAN MET Co-
Processing
Rheinbraun Co-
Processing
TUC Co-Processing
UOP Slurry-Catalysed
Co-Processing
HTI Co-Processing
ndirect
Liquefaction
Sasol
Rentech
Syntroleum
Mobil
Methanol-to-
Gasoline
(MTG) Process
Mobil
Methanol-to-
Olefins (MTO)
Process
Shell Middle
Distillate
Synthesis
(SMOS)
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Coal-to-Liquids Product Suppliers Technical Support Document
Exhibit 2: Coal to Liquids Flow Diagram
Fischer Tropsch Synthesis
Sasol CTL Process
T»vn gas
Tail Gas Lit zaton*"
Alternatives ~
Reform ,ng
Tail gas
'wQ3l - ^
Fsohe'Troc-scn
Anmon a or Mef-aro
Powsr General
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Coal-to-Liquids Product Suppliers Technical Support Document
2.1.2 Methanol to Gasoline (MTG)
The front end of a MTG plant encompassing coal gasification would be identical
to that of a CTL plant. However, the coal gasification has to produce a synthesis
gas with a hydrogen-to-carbon monoxide ratio suitable for methanol synthesis.
Once the methanol is produced it is dehydrated to produce dimethyl ether. The
latter is then converted to a mix of hydrocarbons in the presence of special
catalysts. The hydrocarbon mix that results from this is very similar to that found
in raw gasoline. Products from the MTG process are about 90 percent gasoline
with the rest being LPG. Both products can be sold directly into the market.
Methanol is one of the major chemicals necessary for an industrialized economy.
Commercial methanol is largely produced by natural gas-derived synthesis gas.
There is, however, one commercial plant in the United States where methanol is
produced from coal derived synthesis gas2. In these cases the product desired is
methanol, but a commercial scale MTG plant operated in New Zealand from
1985 to 1995 and produced 14,500 barrels per day of gasoline.
2.1.3 Direct Liquefaction
Exhibit 3 presents a flow diagram of the CTL direct liquefaction process. Under
this approach coal reacts with a catalyst under high pressure and temperature in
the presence of hydrogen. The products are liquid hydrocarbons and a char-like
residue. This process works best using fine low-ash coal.
Compared to Fischer Tropsch synthesis direct liquefaction requires harsh
process conditions (3500psi/230bar+ and 750F/400C compared to 375psi/25 bar
and 400-630F/200-340C) and expensive feedstocks. In addition, more advances
have been made to the Fischer Tropsch process technology and catalysts than
to direct liquefaction.
2 This plant is classified as a gasification plant.
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Coal-to-Liquids Product Suppliers Technical Support Document
Exhibit 3: Coal to Liquids Flow Diagram
Direct Liquefaction
Make-Up H2
Coal + Catalyst
Recycle hb
i
A
, ,, , , * L
i L
Coal HTU Refining 1 > Gasoline
iquefaction > | ^ Djese| Fue|
H-Donor L
S
Slurry
DAO
urry i ,
Fractionation
1
Solvent
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Coal-to-Liquids Product Suppliers Technical Support Document
2.1.4. Products
FT Products
CTL plants produce a wide range of products from gasoline to waxes. The Sasol
Low Temperature process maximizes diesel fuel, while the High Temperature
process maximizes gasoline. Generally speaking the focus has been to produce
transportation fuels and chemical feedstocks, but naphthas and waxes are
always produced irrespective of the process. Considerable work has been done
in South Africa and in the United States on jet fuels for both commercial and
military aircraft.
Since 1999 Sasol has supplied a mixture of CTL components and conventional
kerosene to international airlines operating out of Johannesburg Airport. In April
of 2008 international aviation authorities approved Sasol's fully synthetic CTL jet
fuel as Jet A-1 for commercial use in all turbine aircraft. Currently ASTM is
working to incorporate the synthetic jet fuel in ASTM D1655-08a Standard
Specifications for Aviation Turbine Fuels. A blend of conventional JP8 and FT jet
fuel has recently (2006) been certified for use by the U.S. Air Forces.
The synthetic jet fuel is ultra low sulphur (<5ppm) with 8% to 25% aromatics. It is
fully fungible with petroleum-based jet fuel. Testing on FT jet fuel has revealed
significantly reduced particulate emissions compared to conventional and military
jet fuels.3 Exhibit 4 shows the flow diagram for the manufacturing process in the
High Temperature Fischer Tropsch process.
In the United States the Department of Defense has been working with Rentech
to produce a new Fischer Tropsch fuel that will meet all of the agency's needs
and that will be fungible with petroleum based products and thus able to use the
existing infrastructure.
FT diesel fuel is very high quality. Sulfur constitutes less than 1 ppm. FT diesel
has less than 1 percent aromatics and thus has a high cetane value, generally
from 70 to 80. In general high cetane-number fuels reduce hydrocarbon and
soot emissions from cold starts and reduce nitrogen oxide and particulate
emissions from a warm engine. FT diesel can be sold as a premium product or
can be blended with conventional diesel fuel to improve its qualities. Currently,
there is no approved ASTM test for FT diesel, but apparently ASTM is working on
a test that it is not yet ready to publish.4
Somewhere between 20 to 40 percent of FT products, depending on the
configuration and the catalysts used, will be naphtha. FT naphtha would have to
be upgraded either on site before being sent to a petrochemical plant or at a
refinery.
3 Ibidem, p.22
4 Conversation with Staff Manager for ASTM on January 28, 2009. See internal ICF Memo.
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Coal-to-Liquids Product Suppliers Technical Support Document
MTG products
MTG gasoline would be free of all sulfur. From what is known, MTG gasoline
would be equal or superior to conventional gasoline and would have positive
effects on air quality relative to benzene and Reid vapour pressure.
About 10 to 12 percent of the plant output would be LPG, mostly butane and
propane. This LPG could either be sold directly into the market or to the
petrochemical industry, or could be used at the plant itself to generate electricity.
Direct liquefaction products
The principal products from a coal-based direct liquefaction plant would be
naphthas and middle distillates. There is considerable variation in the properties
of these products, depending of course on the configuration of the plant, but
unlike the products of either FT plants or MTG plants, these products cannot be
sold directly in to the market place. In general direct liquefaction products
contain more aromatics and cyclic hydrocarbons and they may have an overall
lower hydrogen content. These products would either have to be upgraded at
the plant or sent to a refinery for further upgrading.
3.0. Plants
3.1. Existing Plants
Currently the only operational CTL plants are in South Africa. Sasol One, now
Sasol Chemical Industries became operational in the late 1950s. Sasol Two and
Three at Secunda were built in 1974 and 1978. The two plants, now combined
into one, produce approximately 160,000 b/d of mostly transportation products.
Both plants use the Fischer Tropsch indirect CTL technology.
Expected to come into operation in the near future is a major CTL complex at
Erdos, Inner Mongolia that will be run by the Shenhua Group, China's largest
coal miner. This plant, developed in conjunction with the University of West
Virginia, uses direct liquefaction technology. It is expected to convert 3.5 million
tonnes of coal per year into 1 million tonnes of oil products when operational,
predominantly diesel for transportation.
In addition, Shenhua is working with Sasol to conduct a feasibility study to build
two Fischer Tropsch CTL plants in the provinces of Shaanxi and Ningxia. Two
smaller CTL plants are also under construction in China as is one in Indonesia.
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Coal-to-Liquids Product Suppliers Technical Support Document
Exhibit 4: Sasol CTL Synthetic Jet Fuel
Iso-Paraffinic
Kerosene
to C40HC Liquid
Heavy
Naphtha
Light
Distillate #1
,r
Sasol Synthetic
Jet Fuel
3.2. Planned Plants
Currently there are fourteen CTL plants under consideration in the United States.
Three are at the design stage with the others still being studied for feasibility.
While most are CTL plants a number of the Rentech proposed plants will be
more complex with feedstock varying from waste to biomass to petroleum coke
as well as coal. Whether any will come to fruition remains to be seen.
4.0. Carbon Content of Products
There is very little hard data on the carbon content of the products of CTL plants.
The literature does seem to imply that the Fischer Tropsch products will have
lower C02 emissions when combusted. FT products contain very little aromatics
which would indicate that the carbon content of FT products may be lower than
that of conventional petroleum products. In testimony before the Subcommittee
on Energy and Environment of the U.S. House of Representatives the following
statement was made by a senior scientist from Rentech:
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Coal-to-Liquids Product Suppliers Technical Support Document
F-T fuels offer numerous benefits to aviation users. The first is an
immediate reduction in particulate emissions. F-T jet fuel has been shown
in laboratory combusters and engines to reduce PM emissions by 96% at
idle and 78% under cruise operation. Validation of the reduction in other
turbine engine emissions is still under way. Concurrent to the PM
reductions is an immediate reduction in C02 emissions from F-T fuel. F-T
fuels inherently reduce C02 emissions because they have higher energy
content per carbon content of the fuel, and the fuel is less dense than
conventional jet fuel allowing aircraft to fly further on the same load of fuel.
Given that there is a dearth of hard data and that there is, as yet, no operational
CTL plant in the United States, EPA is proposing that, until more data becomes
available, reporters from future CTL plants use the default table in Subpart MM -
Suppliers of Petroleum Products of the rule.
A number of CTL products may be sent to refineries for further upgrading,
especially those products from direct liquefaction plants. Given that petroleum
refineries are required under the rule to keep track of all non-crude feedstocks
that enter the refinery there should not be any double counting. If CTL products
are imported either they will go straight to the market place or to a refinery for
upgrading. In either case there will be little possibility of double counting.
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