alternative fuels from landfills
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Alternative Fuelsrom Landflls
Landfll Gas, Canola and Biodiesel:Working Towards a Sustainable System
| Terrill Chang, P.E. and Deanna Carveth |
SnohomiSh County in weStern waShington
State began converting its vehicle eet to a blend o
biodiesel in 2005. As prices or biodiesel rose due
to increased demand or this cleaner-burning uel,
Snohomish County looked to its armers to grow this
uel locally. Suitable oil seed crops or biodiesel eedstock
include canola, mustard and camelina. The residue, or
meal, has high value as an animal eed. County armers
began with 52 acres o canola and mustard crops in 2006,
increasing to 300 acres and 700 tons in 2009.
The team consisted o Snohomish County Public
Works, engineering frms (URS Corporation and
Parametrix), Washington State University Extension,
Wolkill Feed and Fertilizer (local ertilizer company)
and various equipment suppliers, It was necessary
to develop local inrastructure or the canola project
because canola is not a traditional crop in Snohomish
County. To reduce the projects cost and environmental
ootprint, the County tapped the methane content in
landfll gas rom the closed Cathcart Landfll south o
the City o Snohomish and about 35 miles north o
Seattle as the energy source or the seed dryer, in lieu
o propane or natural gas. The canola processing acility
is located at the landfll site, adjacent to the existing
landfll gas blowers and ares. Project benefts include:
Revitalization of the local agricultural
community, increasing the Countys economic
diversity, a key goal o County government
Addition of an excellent rotational, low tillage
crop that can also convert pasture into row crops
County ownership of a commercial facility
suitable or drying other grains and crushing
other seeds or oil production
A central location of the dryer and crusher that
reduces transportation to processing and to therefnery that converts the canola oil into biodiesel
A benecial use of a declining landll gas stream
that still contributes to reaching sustainability in
vehicle uel
This article discusses the challenges o the design
and equipment procurement process, permitting,
construction and startup, operational results and
lessons learned.
Project GoalsThe goals o this project are to:
Support the use of biodiesel in Snohomish
Countys vehicle eet
Support local agriculture
Benecially use landll gas, an energy source
previously wasted through aring
Create community resiliency by reducing depend-
ence on petroleum-based uels and shortening
supply lines
With SnohomishCountys commitment tothe use of biodiesel,an ongoing project
has helped to
lessen dependency
on imported
petroleum as well
as added to the
economic diversity
of the county by
creating new crops
and jobs.
36 WasteAdvantage Magazine February 2010
The distributor at the top o the elevator directs product to the dryer, storage or the crusher.Photo courtesy o Deanna Carveth, Snohomish County Public Works.
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37 WasteAdvantage Magazine February 2010
In 2005, the Countys Fleet Management group committed
to using a cleaner uel in the Countys diesel trucks and began
converting its eet to use a 20 percent biodiesel blend (B-
20). In 2009, the County increased the blend to 40 percent
(B-40); local farmers grew 30 percent of that amount,
supporting the Countys Focus on Farming initiative (local
armers interested in growing an economically viable crop
with a local market were identifed).
A supply o unused methane gas was available as
landfll gas (LFG) currently being ared at the Cathcart
Landfll. The landfll closed in 1992, with about 1.97
million tons o waste in place. Current gas ows are about700 cm with a methane content o about 30 percent.
By growing and locally processing fuel for Snohomish
Countys diesel eet, the County has eliminated the risk
o supply line disruptions. Further, by strengthening its
local agricultural community, the County has preserved
armland or ood production.
Project Chronology2006
In January o 2006, a group o Snohomish County
armers approached the County Executive seeking a crop
to support the Countys new biodiesel initiative. Working
with Washington State University (WSU) Extension ofces,
growers planted small feld trials (52 acres) o two mustard
variants and two canola variants to determine which o
these Brassica family members would grow best in the wet,
overcast climate of the Snohomish River valley. Brassicas
were chosen because they avor moist, cooler growing
seasons and because the uel they produce can reach 28Fbeore gelling making it preerable or our cooler winters. In
contrast, soybeans preer a hotter growing climate and their
biodiesel has a cloud (gel) point o 36F.
Both crops grew better than expected. Canola had a
higher yield (pounds per acre) than mustard and more
viable markets or both the oil (35 percent o total crop
weight) and the letover meal (65 percent o total crop
weight), a sought-ater animal eed.
The County provided a grant to SnoSky Agricultural
Alliance, a growers non-proft organization, to manage
the feld trials, pay WSU sta, and otherwise promote the
project in both 2006 and 2007. The Alliance determined
that a combine was needed to eectively harvest the crop
and used grant unds to procure one.
The growers attempted to feld-dry the harvested
canola, but western Washington proved to be too rainy
and the seed germinated, rendering it useless or oil
extraction. Growers decided a crop dryer was essential
to successully harvest and market this crop. SnohomishCounty and its partners began design work or ull-scale
inrastructure.
This is the extruder. The oil has gone through therst virgin oil crush and is now being heated andextruded to burst the oil cell walls allowing or greater
oil extraction. Ater the rst crush, the meal is passedthrough steam locks in an extruder to prepare the meal
or nal oil extraction. Photo courtesy o Matthew Goad,Snohomish County Public Works.
WasteAdvantage Magazine February 2010 37
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2007
The previous years crop trials avored Hyola canola, so three 50-acre plots
were planted. Wolkill Feed and Fertilizer ound and transported a used 8-ton
batch dryer rom Lipton, Saskatchewan, Canada to the Cathcart Landfll.
County sta connected it to the LFG system and dried the canola. The LFG-
fred dryer was deemed a successul proo-o-concept. Seed samples taken beore
and ater drying showed no changes to seed chemistry due to exposure to LFG.
It became clear that the combine and batch dryer were insufcient
inrastructure on which to base a viable enterprise. Also, lack o local processing
meant trucking the seed 300 miles east across the Cascade Mountains toSunnyside, WA, eliminating profts in 2007.
2008
2008 was the critical year. The County received a $344,400 earmark via the
Department o Energy and a $500,000 Energy Freedom Fund Grant rom the
Washington State Community Trade and Economic Development Department.
Along with unds authorized in the solid waste budget, procurement and
installation began.
The frst purchase was a 15-ton continuous ow commercial seed dryer
with centriugal ans, a 475-bushel holding capacity, screens sized or canola
(0.050 inches), natural gas burners, oversized piping for low-BTU LFG, and
digital temperature/moisture monitoring to control burners and ans. URS
Corporation and the County had hoped to recover heat rom an existing LFG
are by re-routing hot exhaust gas through an air-to-air heat exchanger toproduce clean, hot air to dry the seed. However, the are manuacturer declined
to place a fn-tube heat exchanger cross-wise in the 8-oot diameter are, citing
concerns about corrosion and restricting the vertical ow o exhaust gas.
Ductwork to capture exhaust gas at the top o the are was also considered, but
there was no precedent or such a design. Finally, quotes or a heat exchange
system approached $750,000, exceeding the available budget
The next purchase was seed storage silos (356 ton capacity) and handling
equipment. Trucks unload on a concrete pad, where the in-ground auger
conveys the seed through a seed cleaner and into the bucket elevator. The
elevator lits the seed to the top o the silos, where an 8-way distributor directs
the seed to the appropriate silo. Bottom U-trough augers and pipe augers move
Ldfll gs, Cl, d Bdsl: wk tds Ssbl Ss
38 WasteAdvantage Magazine February 2010
Co-locating the crusher and dryer at the fare acility makes gas supply convenient and remindsvisitors o the environmental benets o the project.
Completed acility looking east to the closed landll rom which the gas is supplied.
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WasteAdvantage Magazine February 2010 39
the seed to the dryer or the elevator. The auger and elevator system provided a
continuous eed o canola to the new dryer, which dried 286 tons o canola and
414 tons o mustard in 2008.Engineering work by URS Corporation and Parametrix included the design
o concrete slabs, roadways, drainage, power supply, agricultural equipment
specifcations and the air permit application. To reduce costs, Public Works
crews amiliar with the landfll site built the concrete pads and roads, placed the
dryer, and connected the LFG piping and electrical power supply. The project
used Department o Energy unds to pay or the access road and consulting
services, and Energy Freedom Funds or the crusher system.
Solid Waste Division and Specialty Laboratories o Texas determined that using a
gas chromatograph/mass spectrometer (GC/MS) analysis showed the most potentialcontaminants or the least cost. This type o screening would also prevent missing a
key constituent o concern by looking or all constituents rather than a ew named
isomers. Testing in 2007, 2008 and 2009 showed that wet or green seed has exactly
the same fngerprint as the dried seed, except that volatile organic compounds
that naturally occur in the green seed are signifcantly lower in the dried seed. The
landfll gas did not adhere or absorb any contaminants onto the seed.
2009
In spring 2009, a seed cleaner, crusher and extruder were installed. About
12 tons o canola rom the 2008 all harvest was used to test the crusher and
extruder, producing about 1,000 gallons o oil and eight super sacks o meal
used or animal eed. The meal contained about 7 to 9 percent oil, which means
that the incoming seed had about 42 percent oil, much higher than expected.
A second grain elevator was installed to improve unctionality. Overall, 330
tons o material was dried including 214 tons o mustard, 85 tons o canola
Canola seed is tested or moisture content ater exiting the dryer to ensure it is stable orstorage. Photos courtesy o Deanna Carveth, Snohomish County Public Works.
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and 31 tons of barley; more crops were eld dried this year due to an unusually
dry summer.
Results and FindingsTwo crops per year o canola can be grown successully in western
Washingtons cool and rainy climate. The spring harvest o the winter croptakes place around late June. The seed must be dried and the oil extracted
beore the all harvest (about mid-September) o the spring-planted crop.
Even using low-BTU LFG (~30 percent methane), the dryer functioned
properly and met air emissions requirements. A maniold tank was installed
between the LFG compressor and the dryer to accumulate enough gas at
pressure to start the ignition sequence.
The County Public Works system was not geared to agricultural projectsthe
atypical equipment and the urgent timing of the crops were a challenge. Because
the project was designed and constructed over several years by multiple parties,
using new and reurbished equipment rom various vendors, unded by grants
as well as County unds, the County was orced to act as the system integrator.
Farmers and other members o the local agricultural community worked
collaboratively with the County. Their support and continued interest in growing
oil seed crops is critical to the long-term success o the Countys biodiesel initiative.
A matter o great interest was whether burning LFG in the dryer would produce
compounds such as dioxins that adhered to the seed. The GC/MS methodology
allowed comparison o the chemical fngerprints o wet and dry seeds. Complex
market economics also aect the long-term viability o the biodiesel system.
One measure o success is the increase in the acres o canola grown orbiodiesel. Canola is a great rotational crop and it is anticipated that acreage
will grow to about 1,000 acres in production each season.
Future OpportunitiesAvailable unding provided the window o biodiesel opportunity in
Snohomish County. The Solid Waste Division had looked at using landfll
gas to generate electricity previously. The Pacifc Northwest power market
has a very high percentage of hydropower; electricity has historically been
inexpensive, making alternative technologies difcult to justiy fnancially. In2013, the Bonneville Dam bonds will be paid off, allowing the Bonneville
Power Administration greater ability to ship green power out o the Pacifc
Northwest. This will increase opportunities or newer technologies to compete
in the Puget Sound region as local utilities work to meet green power mandates.
The County is currently looking at Department o Energy ARRA grant
dollars to use combined landfll gas and methane rom a near by dairy arm
or energy. This same grant incentivizes the capture o waste heat which the
Division can potentially use to run the dryer, run a boiler to make steam or the
de-gummer system and potentially pre-heat the wash water in the nearby truckwash. Local production o uel promotes local jobs and economy, preserves acres
or arming not houses and ensures we have uel when we need it should supply
lines be disrupted.
ConclusionsThis project continues to be important on several levels. First, it showed that
landfll gas, even rom a landfll closed 18 years earlier, can be a viable energy
source or an industrial process, the drying o crops. Second, groups interested
in promoting local agriculture and the use o alternative, non-petroleum uels
worked together cooperatively to grow a non-traditional (or this geographicarea) crop and extract two useul products (oil and animal eed meal) that have
Ldfll gs, Cl, d Bdsl: wk tds Ssbl Ss
40 WasteAdvantage Magazine February 2010
Mustard seed is unloaded into the dryer system moments ater construction is completed September 18, 2008.
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WasteAdvantage Magazine February 2010 41
local markets. Third, it showed that the technology and
equipment or a crop-to-uel system could be assembled
and operated at a County solid waste acility. Fourth,because the County oers tours to interested parties,
there is an educational and public outreach component
that helps inorm students and County residents about
sustainability, alternative energy and waste management.
Fith, with the Countys commitment to the use o
biodiesel, this project helps to lessen dependency on
imported petroleum. And last but certainly not least,
it has added to the economic diversity o the County by
creating new crops and jobs. | WATerrill Chang, P.E., is a Senior Solid Waste Engineer
or URS Corporation in Seattle, WA. Hehas 35 years o
environmental and mechanical engineering experience, and
has been involved in easibility studies, planning, design,
permitting and environmental impact assessment or landflls,
incinerators, transer stations, recycling and compost acilities
or government and private sector clients. Current projects
include several county solid waste management plans and
the design o two transer stations. Terrill holds degrees
in Mechanical Engineering rom MIT and Oregon StateUniversity and is a licensed engineer in Washington, Oregon
and Idaho. He can be reached at (206) 438-2596 or e-mail
terrill_chang@urscorp.com.
Deanna Carveth is a Project Specialist IV or
Snohomish County Public Works (Everett, WA). She is a
21-year solid waste proessional, starting her career in San
Francisco packing small business and household hazardous
waste. Currently a project specialist, she manages the
Canola to Biodiesel project or Snohomish County, writes and maintains the FEMA approved Disaster Debris
Management Plan, assures compliance with NPDES
permits, is starting the Greenhouse Gas reporting program
and manages the groundwater modeling program or the
Countys closed landflls. Deanna can be reached at (425)
388-7607 or e-maildeanna.carveth@snoco.org.
AcknowledgementsThis material is based on work supported by the
Department o Energy under award number DE-FG36-08GO88177. Standard disclaimer applies.The authors also grateully acknowledge the support
o Washington State Department o Commerces EnergyFreedom Fund and our private partners including WolkillFeed and Fertilizer, Whole Energy, and Snohomish Farmsincluding Sno-Valley Farms and Reiner Farms.
This paper was originally presented by Terrill Chang, URSCorporation, during WASTECON 2009 in Long Beach, CA.Excerpts and inormation rom that presentation are reproducedwith the permission o the Solid Waste Associate o North America(SWANA).
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