United States
Environmental Protection
Agency
Office of Water &
Waste Management
Washington DC 20460
December 1979
vvEPA
Solid Waste
Multimaterial
Source Separation
in Marblehead and
Somerville, Massachusetts
Energy Use and Savings from
Source-Separated Materials
and Other Solid Waste
Management Alternatives
for Marblehead
Volume IV
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An environmental protection publication (SW-824) in the solid waste
management series. Mention of commercial products does not constitute
endorsement by the U.S. Government. Editing and technical content of this
report were the responsibilities of the State Programs and Resource Recovery
Division of the Office of Solid Waste.
Single copies of this publication are available from Solid Waste
Information, U.S. Environmental Protection Agency, Cincinnati, OH 45268.
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MULTIMATERIAL SOURCE SEPARATION
IN MARBLEHEAD AND SOMERVILLE, MASSACHUSETTS
Energy Use and Savings from Source-Separated Materials
and Other Solid Waste Management Alternatives for Marblehead
Volume IV
This report (SW-824) was prepared
under contract no. 68-01-3964
for the Office of Solid Waste
U.S. ENVIRONMENTAL PROTECTION AGENCY
1979
-------
MULTIMATERIAL SOURCE SEPARATION REPORT SERIES
This volume is one in a series of reports about the
demonstration of multimaterial source separation in
Marblehead and Somerville, Massachusetts. The series
presents the key results of demonstration programs
initiated and funded by the U.S. Environmental Pro-
tection Agency in 1975. Intended to provide local
governments and the interested public with useful
information for planning, implementing, and operating
their own source separation programs, the reports in
the series cover a range of issues related to source
separation. The reports are:
The Community Awareness Program in Marblehead
and Somerville, Massachusetts (SW-551)
Collection and Marketing (SW-822)
Composition of Source-Separated Materials and Refuse (SW-823)
Energy Use and Savings from Source-Separated Materials
and Other Solid Waste Management Alternatives for
Marblehead (SW-824)
i
Citizen Attitudes toward Source Separation (SW-825)
Any suggestions, comments, or questions should be
directed to the Resource Recovery Branch (WH-563),
Office of Solid Waste, U.S. Environmental Protection
Agency, Washington, B.C. 20460.
Resource Planning Associates, Inc. conducted the
studies and prepared this series under contract no.
68-01-396M.
-------
Acknowledgements
It would be extremely difficult to acknowledge the
great number of people who contributed to the success
of this complex study of source separation in Somerville
and Marblehead, Massachusetts. However, we would like
to thank the following people for their help: Mr.
Raymond Reed, Marblehead Board of Health; Mr. John
Clement, MATCON Recycling; Mr. Pat Scanlon, Northshore
Recycled Fibers, Inc.; Mr. Paul Anderson, Clark Equipment
Company; Mr. Alden Howard, Wheelbrator, Frye, Inc.; and
Ms. Penelope Hansen and Mr. Stephen E. Howard, U.S.
Environmental Protection Agency.
Henri-Claude Bailly, Project Director
Lawrence Oliva, P.E., Project Manager
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Contents
CHAPTER
PAGE TITLE
INTRODUCTION
CHAPTER 1
CHAPTER 2
ENERGY USE AND SAVINGS FROM
MARBLEHEAD'S EXISTING SOLID
WASTE MANAGEMENT PROGRAM
5 Collection
7 Preparation
11 Transportation
12 Treatment
SAVINGS FROM SOLID WASTE
MANAGEMENT ALTERNATIVES
FOR MARBLEHEAD
15 Energy-Recovery System
19 Combined Source-Separation/
Energy-Recovery System
23 Landfill Disposal
APPENDIX A
Program Background
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Introduction
Sanitary landfilling has traditionally been the method
most widely used by municipalities to dispose of their
solid waste. Over the last decade, however, increasingly
stringent environmental regulations have restricted the
number of sites available for landfilling, while
municipal solid waste streams have been growing in
volume. Consequently, many municipalities are investi-
gating other disposal systems, many of which involve
recovering and recycling some components of the waste
or burning the waste to supply energy for various uses.
In selecting a waste disposal system, municipalities
usually consider the capital costs, labor costs, land-
use requirements, and potential environmental effects of
competing systems. These are, and are likely to
remain, the decisive factors; however, as the need to
conserve energy increases, municipalities are also
comparing the energy expended in operating a system to
the energy that can be extracted from the waste.
Early in 1976, the U.S. Environmental Protection
Agency (EPA) awarded 3-year grants to the communities
of Marblehead and Somerville, Massachusetts, to demon-
strate the source separation of paper, cans, and glass
by residents. For the first 2 years of the grants, the
communities commissioned Resource Planning Associates,
Inc. (RPA), to assist them in designing and implementing
their programs. For the third grant year, EPA engaged
RPA to assess the results of the two programs and to
study the characteristics of the communities' residen-
tial waste streams.
EPA has commissioned RPA to conduct studies and prepare a
series of reports about the two demonstration programs.
The reports concern the collection and marketing of
source-separated materials, citizen attitudes toward
source separation, the composition of the source-
separated materials and refuse, the energy use and
savings from source separation and other solid waste
management alternatives, and the community awareness
programs developed to encourage participation in the
source-separation programs.
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INTRODUCTION
This report presents our s.tudy of the energy use and
savings from Marblehead's existing solid waste program,
in which 25 percent of the waste stream is source-
separated and processed. Energy is used in the exist-
ing source-separation program in the form of electricity,
gasoline, or diesel fuel expended in handling and
disposing of wastes and recovery materials. Energy is
saved by recycling materials or generated by using [
materials in energy-recovery systems.
The report also presents our findings on energy use and
savings for three solid waste management alternatives
that Marblehead could pursue. In the first alternative,
all waste would be transported to an energy-recovery
facility near Marblehead and burned in a waterwall
combustion unit to produce steam for an industrial ,
plant. Noncombustible residual waste from the unit
would be landfilled at the incinerator site. In the
second, all solid waste would be hauled to the >
Marblehead solid waste transfer station and from there
to the regional landfill. The third alternative is a
combined system of source separation and energy recovery
at different rates of source separation: 12.5 percent
of total waste; Marblehead's current recycling rate of
25 percent; and a theoretical maximum of 40 percent.
To calculate energy use and savings, we separated the
existing and alternative systems into four independent
steps: F
• Collection, which comprises collecting waste
materials from curbside and hauling them in recycling
trucks or refuse trucks to a processing or preparation
site
• Preparation, which comprises sorting, crushing |P
shredding, baling, and compacting waste materials
to prepare them for reuse or transportation to land-
fill sites
• Transportation, which comprises hauling processed
waste from preparation sites to treatment sites in-
heavy-duty tractor-trailer trucks
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INTRODUCTION
• Treatment, which comprises reusing wastes in a
manufacturing process, burning them to recover
energy, or landfilling.
We calculated the direct energy use and savings from
each step independently by considering such factors as
energy directly consumed by machinery and lighting,
energy directly conserved by substituting recycled
materials for virgin raw materials, and energy directly
generated by using solid waste for fuel to produce
steam. For practical reasons, we did not calculate
indirect energy expenditures, such as energy consumed
in manufacturing the equipment used by the systems.
We then computed net energy use and savings per ton of
total solid waste (source-separated materials and
remaining waste). We found that:
• Marblehead's existing source-separation program
returns about 1.6 million Btu/ton of total solid
waste, which is equivalent to about 12.8 gallons
of gasoline per ton.
• Of the disposal alternatives, the combined
source-separation/energy-recovery system with a
40-percent source-separation rate had the highest
energy return of 7.7 million Btu/ton. In Marble-
head, source separation increases the total energy
savings because recycling noncombustible materials
such as glass and cans saves energy that cannot be
used by energy-recovery systems.
• Energy recovery of all wastes would return
about 6.3 million Btu/ton
• Landfill disposal of all wastes would use about
0.4 million Btu/ton.
In Chapter 1, we discuss our calculations of energy use
and_savings for each step of Marblehead's existing
solid waste management program. In Chapter 2, we
discuss the calculations we performed for each solid
waste management alternative. Appendix A provides
additional background on Marblehead's solid waste and
source-separation programs.
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Exhibit 1.a
Energy Used And Saved In Marblehead's
Existing Solid Waste Program
(103 Btu/ton)
Collection
Recovered paper, glass, and cans
Remaining waste
Subtotal
Preparation
Recovered glass and cans
Recovered paper
Remaining waste
Subtotal
Transportation
Recovered glass
Recovered cans
Recovered paper
Remaining waste
Subtotal
Treatment
Recovered glass
Recovered cans
Recovered paper
Remaining waste
Subtotal
Total
Energy
Used
96
131
227
15
70
70
162
40
47
18
116
221
-
—
—
44
44
654
Energy
Saved
—
—
—
~"~
— •
—
—
—
-
770
376
1,103
2,249
2,249
Total
(162)
(221 ) ,:
2,205
1,595
SOURCE: Resource Planning Associates, Inc.
NOTE: Parentheses indicate net energy use.
Exhibit 2.3
Energy Used and Saved in Marblehead's
Solid Waste Disposal Alternatives
(103 Btu/ton)
Source Separation/
Energy Recovery System
Collection
Preparation
Transportation
Treatment
Total
Energy
Recovery
(224)
(103)
( 52)
6,678
6,299
12.5%
Rate
(132)
(108)
7,486
7,046
25%
Rate
(161)
(144)
8,005
7,473
40%
Rate
(197)
(199)
8,323
7,669
Landfill
Disposal
(224)
(103)
( 52)
( 59)
(438)
SOURCE: Resource Planning Associates, Inc.
NOTE Parentheses indicate net energy use.
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1
ENERGY USE AND SAVINGS FROM MARBLEHEAD'S
EXISTING SOLID WASTE MANAGEMENT PROGRAM
The reuse of materials from Marblehead's source-separation
program conserves about 3.5 times as much energy as is
used by the town's entire solid waste collection and
disposal operations (see Exhibit l.a). About 2.25xl06
Btu/ton is saved by source separation, while about 0.65
Btu/ton is used by equipment for collection, preparation,
transportation, and treatment of source-separated materials
and remaining waste. The resulting net energy savings
from Marblehead's existing program are about 1.6
million Btu/ton of solid waste, or savings the equiva-
lent of 0.29 barrels of oil per ton. For Marblehead's
total solid waste stream of about 8,700 tons per year,
2,530 barrels of oil are conserved from the existing
program of source separation and landfilling of remaining
waste.
Collection and transportation equipment use more energy
than equipment used to prepare or treat source-separated
materials and remaining waste. Collection consumes
about 35 percent of the energy used, and transportation
34 percent.
COLLECTION
All of Marblehead's source-separated materials and
remaining waste are collected on different days at
curbside once per week. Source-separated materials are
taken directly to a materials processor in Salem,
Massachusetts, less than 5 miles away, while remaining
waste is delivered to a transfer station in Marblehead.
Two gasoline-powered trucks that can carry about four
tons of materials each are used to collect source-
separated materials. The trucks have separate
compartments for paper, clear glass and cans, and
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ENERGY USE AND SAVINGS
colored glass and cans. Fuel consumption for the
source-separation vehicles, as reported in town records,
is 3.09 gallons per ton of recovered materials collected,
or 386xl03 Btu/ton. During July and August 1977, 892
gallons of gasoline were used in collecting 289 tons of
source-separated materials (1 gallon of gasoline equals
125xl03 Btu).
The town has three diesel-powered standard 18-cubic-yard
compactors to collect remaining waste. Fuel consumption
for the vehicles is 1.25 gallons per ton of remaining
waste or 175xl03 Btu/ton. During July, August, and
September 1977, 2,083 gallons of fuel were used in
collecting 1,667 tons of refuse (1 gallon of diesel
fuel equals 139xl03 Btu).
Of the total solid waste stream, 25 percent is collected
by source-separation vehicles and 75 percent is collected
by refuse trucks. Therefore, the energy used for
collection per ton of solid waste may be calculated as
follows:
(386xl03 Btu/tons of source-separated materials x-,~-)
+ (174xl03 Btu/ton of remaining waste
= (96 + 131) x 103 Btu/ton
= 227xl03 Btu/ton of total solid waste.
PREPARATION
Energy is used to prepare source-separated materials,
such as paper and glass and cans, at the materials
processing plant in Salem. The energy used to prepare
remaining waste is expended at Marblehead's transfer
station.
Recyclable glass and cans are delivered to MATCON
Recycling, Inc., in Salem. Two small front-end loaders
transfer the materials from the point of delivery to
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ENERGY USE AND SAVINGS
a conveyor belt, leading to a magnetic drum where the
ferrous materials are separated.* They are then
flattened by one of the front-end loaders in preparation
for transportation to a buyer. Glass is conveyed
through a hammermill, broken into approximately 2-inch
cullet, and stored in large bins before transportation.
The front-end loaders are operated on gasoline and
propane. All other equipment, heating, and lighting
are operated by electricity.
During October 1977, MATCON prepared 932 tons of glass
and cans, using 2,700 kWh of electricity, 584 gallons
of gasoline, and 104 gallons of propane.1 The thermal
value of propane is 73,390 Btu/gallon. The energy used
per ton of glass and cans may then be calculated as
follows:
(2,700 kWh x 10,286 Btu/kWh) + (584 gal x 125xl03
Btu/gal gasoline) + (104 gal x 73,390 Btu/gal propane
•
gas 7932 tons = 116xl03 Btu/ton.
Recycled paper is delivered to Northshore Recycled
Fibers, Inc., in Salem. The paper is dumped onto the
warehouse floor and pushed into a large shredder by two
small gasoline-fueled front-end loaders. The shredded
paper is conveyed to a baling machine, baled, and
loaded on a truck by the front-end loaders. All
equipment except the loaders is powered by electricity.
The loaders are in operation approximately 6 hours per
day, using 2.5 gallons of gasoline per hour.2
1. Personal communications from John Clement, MATCON
Recycling, Inc.
2. Personal communications from Mr. Patrick Scanlon,
Northshore Recycled Fibers, Inc., and Mr. Paul Anderson,
Clark Equipment Company, Fargo, North Dakota.
* Aluminum constitutes less than 1 percent of the
recyclable waste stream in Marblehead and is not accounted
for in our calculations.
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ENERGY USE AND SAVINGS
Approximately 11 tons of paper are processed per
hour.3 Consequently 0.22 gallons are consumed per
ton processed. The energy used by the loaders is:
0.22 gal/ton x 125xl03 Btu/gal = 28xl03 Btu/ton.
No data were available on the operation or energy
consumption of the Northshore Recycling equipment.
However, similar equipment consumes 50 kWh of electri-
city to compact and bale 1 ton of paper.4 |
The energy used for shredding and baling may then be
calculated as follows:
50
kWh/ton x 10,286 Btu/kWh = 514xl03 Btu/ton.
The total figure for paper is:
(28 + 514) x 103 Btu/ton of paper = 542xl03 Btu/ton
of paper).
All remaining waste in Marblehead's existing program
is delivered to the Marblehead transfer station,
reduced to one-seventh of its original volume in a
compactor, and loaded in a heavy-duty truck for
further transportation. All equipment at the station
is powered by electricity.
Electricity for heating, lighting, and operating of
equipment costs approximately $300 per month, repre-
senting an average of 13,300 kWh consumed per month
at local commercial rates to process 1,330 tons of
3. EPA, Demonstrating Source Separation in Somefville
and Marblehead (draft), February 1977, pp. 4-6.
4. EPA, Environmental Impacts of Production of Virgin
and Secondary Paper, Glass and Rubber Products. This
figure does not include electricity for lighting or
administrative offices.
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ENERGY USE AND SAVINGS
waste.5 The fuel-fired value of purchased electricity
is 10,286 Btu/kWh.6 The energy expenditure for
preparation of remaining waste is therefore:
13,300 kWh x 10,286 Btu/kWh = 103xl03 Btu/ton.
1,300 ton
Of the total solid waste stream, 12 percent is recovered
glass and cans, 13 percent is recovered paper, and 75
percent is remaining waste. Therefore, the energy
used to prepare all solid waste is calculated as follows
12.
(116xl03 Btu/ton of glass and cans x IOQ) +
13
542xl03 Btu/ton of paper x IOQ) + 103xl03 Btu/ton
75
of remaining waste XIQO) ~~
= (15+70+77) x 103 Btu/ton
= 162xl03 Btu/ton of total solid waste.
5. Personal communications from Mr. Charles Eris at
Service Corporation of American (SCA), operators of the
station, and Mr. Frank Stevenson, Marblehead transfer
station. Electricity rates are $1.60/kwh for the first
20 kWh; $0.67/kWh for the next 100 kWh; $0.37 kWh for
the next 590 kWh; and $0.19 kWh for all additional
kWh.
6. U.S. Federal Energy Administration, The Data Base;
The Potential for Energy Conservation in~Nine Selected
Industries, 1975, vol. 8: p. 6. This value accounts
for boiler inefficiency and transmission losses.
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ENERGY USE AND SAVINGS
10
TRANSPORTATION
In the transportation step, source-separated glass,
cans, and paper are shipped to their final markets and
remaining waste is transported from the transfer
station to the regional landfill. Source-separated
material and remaining waste are hauled in heavy-duty,
diesel-fueled trucks. To simplify calculations, we
assumed that twice as much fuel is consumed by trucks
when fully loaded as when returning empty.' We also
assumed that the trucks all consume 3.45x10J Btu/
ton-mile, even though they are used to haul different
materials.
Remaining waste is hauled from the transfer station
to the regional landfill in Amesbury, Massachusetts,
30 miles away. Therefore, energy used to transport
remaining waste is calculated as follows:
3.45xl03 Btu/ton-mile x 30 miles/trip x 1.5 trips
= 155xl03 Btu/ton.
Source-separated glass cullet is shipped from MATCON
to Dayville, Connecticut, approximately 80 miles from
Salem. The energy used to transport recycled glass is
3.45xl03 Btu/ton-mile x 80 miles/trip x 1.5 trips
= 414xl03 Btu/ton.
Prepared cans are transported to Newark, New Jersey,
for detinning and from there to Pittsburgh for reuse,
a total distance of 590 miles. We assumed that the
trucks return fully loaded. The energy used to
transport recycled cans can therefore be calculated
as follows:
3.45xl03 Btu/ton-mile x 590 miles/trip = 2,035xl03
Btu/ton.
7. Portland Recycling Team, Resource Conservation Through
Citizen Involvement in Waste Management: Report to
the Metropolitan Service District, 1975.
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ENERGY USE AND SAVINGS
11
Baled waste paper is shipped from Northshore Recycled
Fibers to a papermill at Haverhill, Massachusetts, a
distance of 27 miles. The energy used to transport
recycled paper is therefore:
3.45xl03 Btu/ton-mile x 27 miles/trip x 1.5 trips
= 140xl03 Btu/ton.
Of the total solid waste stream, about 9.7 percent is
recovered glass, about 2.3 percent is recovered cans,
13 percent is recovered paper, and 75 percent is
remaining waste.
Therefore, the energy used to transport all solid waste
is computed as follows:
(414x103 Btu/ton of glass x 9.7 ) + (2,035x103 Btu/
100
ton of cans x 2.3 ) + (140 x 103 Btu/ton of paper x
100
_13_) + (155xl03 Btu/ton of remaining waste x 75 )
100
= (40 + 47 + 18 + 116) x 103 Btu/ton
- 221xl03 Btu/ton of total solid waste.
TREATMENT
Treatment of solid waste consists of converting the
recovery materials into new products and landfilling
the remaining waste. Energy is saved by reprocessing
recovered materials, which uses less energy than
mining, milling, or manufacturing products from virgin
materials.
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ENERGY USE AND SAVINGS
12
About 3,970xl03 Btu of energy is conserved by producing
1 ton of glass containers from a 50-percent mixture of
recycled glass cullet and virgin materials.0 There-
fore, each ton of recycled glass cullet used saves
7,940x103 Btu.
Manufacturing pig iron from recovered cans conserves
16f340xl03 Btu per ton of iron produced, compared to
the manufacture of pig iron from virgin materials.
This excludes the energy used during preliminary
detinning, for which data were not available, petin-
ning uses less energy than making tin from virgin
materials. However, since the amount of tin in ferrous
metal cans is small compared to the amount of iron, the
energy saved by detinning would also be small.
Recovered paper from Marblehead is converted into
corrugated containers. About 4,888xl03 Btu per ton
of manufactured corrugated containers is conserved if
recovery paper is used rather than virgin materials.^
One ton of recovered paper is used to produce 1.74 tons
8. EPA, Environmental Impacts of Production of Paper,
Glass, and Rubber Products, pp. 149-150.
9. PEA, The Data Base, 1975, pp. 342-345. No difference
in energy use was assumed among steelmaking processes or
input materials.
10 EPA, Environmental Impacts of Production of Paper,
Glass and Rubber Products, p. //. The production^
corrugated containers trom virgin materials uses 23,80Ux
103 Btu, including harvesting, transportation, and con-
version of pulpwood. No energy savings are realized from
the actual milling operations in making corrugated con-
tainers from recovered paper. Milling packaging paper-
board, printing paper, and tissue paper from recovered
paper would conserve an additional 4,000x10-3 Btu/ton,
5,000xl03 Btu/ton, and Il,000xl03 Btu/ton, respectively.
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ENERGY USE AND SAVINGS
13
of corrugated containers, so the energy conserved per
ton of waste paper may be calculated as follows:
4,888xl03 Btu/ton of corrugated containers x 1.74 ton
of corrugated containers/ton of recovered paper
= 8,486xl03 Btu/ton of recovered paper.
s remaining waste is treated simply by
landfill disposal, which uses energy in. the form of
diesel fuel to power the bulldozer that spreads and
covers waste; we estimated that 59xl03 Btu are used
per ton of remaining waste.11
The composite energy saved in treatment processes for
all solid waste is as follows:
(7,940xl03 Btu/ton of glass x 9.7 ) + 16,340 Btu/
100
ton of cans x 2.3 ) + (8,486 Btu/ton of paper x 13 )
100 -
59xl03 Btu/ton of remaining waste x 75)
To~o
= (770 + 376 + 1,103 - 44) x 103 Btu/ton
= 2,205 Btu/ton.
11. Portland Recycling Team, Resource Conservation
Through Citizen Involvement, p. 128. ~~
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Exhibit 2.b
Energy Used and Saved in Combined Source
Separation and Energy Recovery System
(103 Btu/ton)
Source Separation Rates
Collection
Recovered paper, glass and cans
Remaining waste
Subtotal
Preparation
Recovered glass and cans
Recovered paper
Remaining waste
Subtotal
Transportation
Recovered glass
Recovered can's
Recovered paper
Remaining waste
Subtotal
Treatment
Recovered glass
Recovered cans
Recovered paper
Remaining waste
Subtotal
Total
12.5%
( 48)
(152)
(200)
( 7)
( 35)
( 90)
(132)
( 20)
( 34)
( 9)
( 45)
(108)
385
270
552
6,279
7,486
7,046
25%
( 96)
(131)
(227)
( 14)
( 70)
( 77)
(161)
( 40)
( 47)
( 18)
( 39)
(144)
770
376
1,103
5,756
8,005
7,473
40%
(154)
(104)
(258)
( 22)
(113)
( 62)
(197)
( 64)
( 75)
( 29)
( 31)
(199)
1,231
605
1,765
4,722
8,323
7,669
SOURCE: Resource Planning Associates, Inc.
NOTE: Parentheses indicate net energy use.
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2
SAVINGS FROM SOLID WASTE MANAGEMENT
ALTERNATIVES FOR MARBLEHEAD
Using Marblehead as a base case, we examined the energy
used and savings from three solid waste disposal
alternatives: recovering energy through a mixed-waste
processing system; a combination of source separation
and energy recovery from remaining waste; and landfill
disposal of all solid wastes. We examined the combined
system at source-separation rates of 12.5, 25, and 40
percent of total wastes.
The combined system with a source-separation rate of
12.5 percent would have a net energy savings of 7.0
million Btu/ton, which is higher than the energy-
recovery alternative which would save 6.3 million
Btu/ton. The combined system with a 40-percent source-
separation rate would have the highest energy savings
of all the alternatives: 7.7 million Btu/ton. The
combined system with 25-percent source separation would
yield an energy savings of 7.5 million Btu/ton. In
contrast, landfill disposal of all waste would use 0.4
million Btu/ton, which is equivalent to using about 2.3
gallons of gasoline per ton (see Exhibit 2.a).
ENERGY RECOVERY SYSTEM
To calculate the amount of energy that would be saved
using an energy-recovery system, we assumed that waste
is collected at curbside and delivered to the transfer
station in Marblehead. Before the source-separation
program began in Marblehead, all solid waste was
collected by five compactor vehicles twice per week.
Records on energy consumption for that period were not
available. However, we assumed that twice-per-week
collection uses 29 percent per ton more energy than
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SAVINGS FROM MARBLEHEAD
16
Marblehead's current once-per-week collection.i
Therefore, energy consumption for twice-per-week
collection is computed as follows:
174xl03 Btu/ton of solid waste x 1.29
= 224xl03 Btu/ton of solid waste.
The waste would then be prepared at the transfer .
station using the same amount of energy as Marblehead s
existing system: 103xl03 Btu per ton of waste.
Prepared waste would be transported from the Marblehead
transfer station to an energy-recovery plant in Saugus,
Massachusetts, 10 miles away. The energy used in
transporting waste to the plan may therefore be cal-
culated as follows:
3.45xl03 Btu/ton-mile x 10 miles/trip x 1.5 trips
= 52xl03 Btu/ton.
In the energy-recovery system, all prepared waste would
be delivered to the Saugus facility, dumped into_a
large storage pit, and fed into a large waterwall
combustion chamber where it would be burned to produce
steam at a temperature of 875°F and a pressure of 690
psig.2 We assumed a boiler efficiency, less steam
transmission losses, for waterwall incineration of t>7
percent.3 Noncombustible residue would be landfilled
at the site. The thermal value of refuse in Marblehead
1. Kenneth A. Shuster, "Fuel Conservation in Solid
Waste Management," Virginia Town and City, December 1974.
2 U.S. Department of Energy, Overcoming Institutional
Barriers to Solid Waste Utilization as an Energy Source,
November 1977, p. 28.
3 Oak Ridge National Laboratory, Solid Waste Utiliza-
tion Incineration with Heat Recovery, April 1978, p. 9.
Boiler efficiency is 69 percent, transmission losses are
2 percent.
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SAVINGS FROM MARBLEHEAD
17
is 4,340 Btu/lb.4 At the specified boiler efficiency
and steam temperature and pressure, the thermal value
of the steam would be:
4,340 Btu/lb x 2,000 Ib/ton x 67 = 5,816xl03 Btu/ton.
100
Steam would be delivered to an industrial plant, one-
third of a mile from the facility. If the same quantity
of steam at the same temperature and pressure were
raised on-site in an oil-fired boiler with an efficiency
of 82 percent, the energy saved would be:
5,816xl03 Btu/ton x 82 = 7,093xl03 Btu/ton.
100
In June 1977, the Saugus plant consumed 1,210 MWh
of electricity per month for lighting, heating, and
operation of electric power equipment, and 1,497
gallons of diesel fuel and 34 gallons of gasoline for
mobile equipment.5 The energy expenditure may
therefore be calculated as follows:
(I,210xl03 kWh/month x 10,286 Btu/kWh) + (1,497
gal of diesel fuel/month x 139xl03 Btu/gal of
diesel fuel) + (34 gal of gasoline/month x 125xl03
•
Btu/gal of gasoline) 7 30,517 ton of waste/
month = 415xl03 Btu/ton.
4- EPAf Multimaterial Source Separation in Marblehead
and Somerville, Massachusetts; Composition of Source
Separated Materials and Refuse, November 1978, p. 28.
5. Personal communications with the general manager of
the operating contractor of the Saugus facility.
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SAVINGS FROM MARBLEHEAD
18
The net energy savings for treatment in the energy-
recovery system are therefore:
7,093xl03 Btu/ton - 415xl03 Btu/ton = 6,678xl03
Btu per ton.
COMBINED SOURCE-SEPARATION/ENERGY-RECOVERY SYSTEM
The highest energy savings would be achieved by
combining source separation and energy recovery. For
this alternative, we assumed that the source-separation
system is the same as the one currently used. However,
we assumed three different rates of recovery: 12.5
percent of the total waste stream; the present rate of
25 percent; and the theoretical maximum rate of 40
percent. We assumed that energy would be recovered at
a rate similar to the one already calculated in our
energy-recovery alternative.
Source-separated materials and remaining waste would be
collected once per week. To estimate the amount of
fuel used in collection, we assumed that fuel consumption
rates per ton would be the same for different rates of
source separation. In reality, however, fuel consump-
tion rates would probably be slightly lower for higher
rates of source separation. We used the same fuel
consumption rates for source-separated materials and
remaining waste as for the existing program. Therefore,
fuel consumption for the 12.5-percent source-separation
rate is calculated as follows:
386xl03 Btu/ton of source-separated materials x 12_iJL
+ 174xl03 Btu/ton of remaining waste x 87.5
= (48 + 152) x 103 !
= 200xl03 Btu/ton of total solid waste.
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SAVINGS FROM MARBLEHEAD
19
Similarly computed for 25-percent and 40-percent
source-separation rates, fuel consumption rates for
collection are 227xlOJ Btu/ton and 258xl03 Btu/ton,
respectively.
We calculated the energy used to prepare and transport
source-separated materials and the energy saved by
treating the materials on the basis of our calculations
for Marblehead's existing program. Energy used and
recovered from materials at a 25-percent rate of source
separation was the same as for the existing program;
for a 12.5-percent rate, energy used and savings were
half of those for the existing program; and for a 40-
percent rate, energy used and savings were computed to
be 1.6 times the results from the existing program.
To compute the energy used to prepare and transport
remaining waste for different levels of source separa-
tion, we again used the energy use per ton of remaining
waste from the existing program and multiplied that
unit rate by the percent of remaining waste, 87.5, 75,
or 60 percent, in the total solid waste stream for that
option (see Exhibit 2.b).
The thermal value of Marblehead's remaining waste after
25 percent of the waste is source-separated is 4,950xl03
Btu/lb.0 The thermal value of remaining waste without
source separation is 4,340 Btu/lb. Assuming a linear
relationship between thermal values and source-
separation rates, we calculated the thermal value of
remaining waste for 12.5-percent and 40-percent
source-separation rates to be 4,645 Btu/lb and 5,070
Btu/lb, respectively.
Using an estimated efficiency for the steam boiler and
transmission losses of 67 percent and an oil-fired
6- EPA, Multimaterial Source Separation in Marblehead
and Somerville, Massachusetts; Composition of Source
Separated Materials and Refuse, November 1978. p. 28.
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SAVINGS FROM MARBLEHEAD
20
boiler efficiency of 82 percent, the energy saved by
treating the remaining waste at a 12.5-percent rate of
source separation is computed as follows:
4,645xl03 Btu/lb x 2,000 Ib/ton x 67 x 100
100 82
x
87.5 = 6,642xl03 Btu/ton of total solid waste.
T00~
Similarly, the energy savings for 25-percent and 40-
percent source-separation rates were computed to be ;
6,067xl03 Btu/ton and 4,971xlOJ Btu/ton, respectively.
We assumed that energy use in the energy-recovery plant
operations would be the same per ton of remaining waste
as for the energy-recovery alternative: 415x10J Btu/ton,
Therefore, the net energy savings per ton of total solid
waste in the energy recovery operations are as follows:
6,642xl03 Btu/ton -
6,279xl03 Btu/ton
12.5-percent
source separation;
87 .5 x 415xl03 Btu/ton
100
6,067xl03 Btu/ton
5,756xl03 Btu/ton
25-percent
source separation;
- 75 x 415xl03 Btu/ton =
100
4,971xl03 Btu/ton
4,722xl03 Btu/ton
40-percent
source separation.
60 x 415xl03 Btu/ton =
TOO"
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SAVINGS FROM MARBLEHEAD
21
Total net energy savings increase as the percentage
rate of source separation increases, as shown in
Exhibit 2.c. As more materials are source-separated,
the energy savings attributed to energy recovery
decrease since fewer materials are processed in the
energy-recovery facility.
LANDFILL DISPOSAL
Energy used to collect and prepare total solid waste
for landfill disposal is the same as for the energy-
recovery alternative: 224xl03 Btu/ton for collection
and 103xlOJ Btu/ton for preparation. All solid waste
would then be transported to the landfill in Amesbury,
30 miles away. The energy use per ton of waste is
therefore the same as for Marblehead's existing
program: 52xlOJ Btu/ton of refuse. Energy used in
treatment is also the same for this alternative as
for Marblehead's existing program: 59xl03 Btu per
ton of refuse. The total energy used for landfill
disposal of solid waste is therefore 438xl03 Btu/ton.
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Exhibit 2.c
Energy Savings for Combined Source Separation
and Energy-Recovery System
8,000
7,000
6,000
Energy Savings
(103 Btu/ton)
5,000
4,000
10 20 30
Source-Separation Rate (percent)
SOURCE: Resource Planning Associates, Inc.
Energy Savings from Source Separation
Energy Savings from Energy Recovery System
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Appendix A
23
PROGRAM BACKGROUND
As part of its evaluation of different types of resource-
recovery programs, EPA selected Somerville and Marblehead,
Massachusetts, for demonstration studies of source
separation. This appendix provides demographic infor-
mation about Marblehead and summarizes how its source-
separation program operates.
DEMOGRAPHIC INFORMATION
Marblehead is an affluent suburban community in the
Boston metropolitan area with a population of 23,000
and a density of 5,200 persons per square mile.
Seventy percent of the families live in single-family
homes. Fifteen percent of the families rent their
homes or apartments, and 85 percent own their residences
The U.S. Bureau of the Census listed the 1970 median
income for Marblehead as $12,600 per year, and the
median education level as 13.2 years.
For the source-separation program in Marblehead,
residents place three bundles — flat paper, clear
glass and cans, and colored glass and cans — at the
curb for collection on source-separation days, which
are different than regular trash collection days. As
in Somerville, no other preparation is necessary.
Special crews with three-compartment trucks pick up the
materials. In addition to the weekly collection of
source-separation materials, Marblehead has open bins
at the site of the former town landfill for residents
who wish to bring their materials. The success of
Recycle Plus helped the town to reduce the frequency of
the remaining mixed household refuse collection from
twice per week to once per week. The town also was
able to reduce its mixed-refuse equipment and labor
needs.
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PROGRAM BACKGROUND
24
Salient features of Marblehead's program can be summa-
rized as follows:
Program name
Materials collected
Recyclables collection
frequency
Refuse collection
frequency
Recycling crews
Refuse crews
Collection vehicles
Disposal cost
per ton
"Recycle Plus"
Flat paper
Cans and clear
glass
Cans and colored
glass
Weekly
Weekly
I
Two 3-man crews
Four 3-man crews
Compartmentalized
trucks with rear-
loading hydraulic
buckets; 3 compart-
ments
$18.95
pal 382.3
'SW-824
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EPA REGIONS
U.S. EPA, Region 1
Solid Waste Program
John F. Kennedy Bldg.
Boston, MA 02203
617-223-5775
U.S. EPA, Region 2
Solid Waste Section
26 Federal Plaza
New York, NY 10007
212-264-0503
U.S. EPA, Region 3
Solid Waste Program
6th and Walnut Sts.
Philadelphia, PA 19106
215-597-9377
U.S. EPA, Region 4
Solid Waste Program
345 Courtland St., N.E.
Altanta, GA 30308
404-881-3016
U.S. EPA, Region 5
Solid Waste Program
230 South Dearborn St.
Chicago, IL 60604
312-353-2197
U.S. EPA, Region 6
Solid Waste Section
1201 Elm St.
Dallas, TX 75270
214-767-2734
U.S. EPA, Region 7
Solid Waste Section
1735 Baltimore Ave.
Kansas City, MO 64108
816-374-3307
U.S. EPA, Region 8
Solid Waste Section
1860 Lincoln St.
Denver, CO 80295
303-837-2221
U.S. EPA, Region 9
Solid Waste Program
215 Fremont St.
San Francisco, CA 94105
415-556-4606
U.S. EPA, Region 10
Solid Waste Program
1200 6th Ave.
Seattle, WA 98101
206-442-1260
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