Hog farm, utilities, state team up to explore
porker power
 |
| A group from the Governor's Office
of Energy Management and Conservation tours Colorado Pork's
anaerobic digester. Colorado Amendment 14, passed in 1998,
required large hog farms to place impermeable covers on
anaerobic manure lagoons. (photo courtesy of Southeastern
Colorado Power Association) |
Southeastern Colorado
Power Association set out to support a customer's anaerobic
digester project and wound up as a partner in a cutting-edge
renewable energy experiment that could create up to 4 MW of
biogas-based electricity generating capacity and revive the
state's hog-farming industry.
"It's our job to help our consumers," explained
SECPA Chief Operating Officer Jack
Wolfe. "In rural communities, that often means helping farms
find ways to stay afloat and comply with environmental regulations."
Odor control amendment opens
door to renewable energy production
One such farm, the 5,000-hog operation Colorado Pork, LLC, in
Lamar, Colo., meets that dual challenge by converting its animal
waste to energy. In 1999, the farm received funding from the
U.S. Department of Agriculture's AgStar
program to build an anaerobic digester system from the ground
up. With a matching grant from the Governor's
Office of Energy Management and Conservation, the owner
built a 500,000-gallon capacity, in-ground storage pit covered
by a flexible reinforced plastic collection dome.
The biogas captured from about 12,500 gallons
of daily manure initially fed a modified natural gas engine,
generating about 40 kW. Combining the system with energy efficiency
measures, Colorado Pork reduced its monthly electric bill to
about $3,500, compared to the $10,000 to $11,000 costs typically
associated with farms of that size.
Equally important, the airtight digester cut
down the manure volume and reduced odor levels to fully comply
with Colorado Amendment 14, which regulates odor emissions.
Among its requirements, the 1998 legislation mandated large
commercial hog farms to place impermeable covers on all anaerobic
lagoons. "The project took a waste management restriction and
leveraged it into a cost-cutting tool," said Wolfe.
Changes in technology, legislation,
give project unique twist
SECPA's first involvement with the project was helping the farm
interconnect the anaerobic digester to the grid. That changed
in December 2001 when Colorado Pork and OEMC added a Capstone
30-kW microturbine to the system. The farm became the first
livestock facility in the United States to generate electricity
with a microturbine fueled by methane from an anaerobic digester.
"Because of the altitude and the quality of biogas,
the Caterpillar engine only generated about one third of its
nameplate capacity," said Wolfe. "For biogas generation to move
forward, it will have to be more efficient and require less
maintenance. Microturbine technology offered way to accomplish
that."
SECPA and Tri-State
Generation and Transmission joined the demonstration project
to test the feasibility of the microturbine/anaerobic digester
combination. Capstone Turbines, the Department of Energy, Colorado
Department of Public Health and Environment, McNeil Technologies
and Southeast Land and Environment were among several other
partners in the project. In the year-long study, the microturbine
and internal combustion engine ran side by side to compare performances,
including emissions and other variables. Together, the two machines
provided about 35 percent of the farm's electricity and 50 percent
of its peak load.
The project was also the first to be net metered
under Colorado's 2002 net metering bill. Colorado Pork plans
to sell any excess power it produces to SECPA, although so far
none has been sent to the grid. When that day comes, the utility,
its power wholesaler, Tri-State, and the farm will pay Colorado
Pork the avoided cost for surplus power and allow SECPA to buy
the power off the grid. "Tri-State issued a letter of understanding
making an exception in our contract," said Wolfe. "They are
very supportive of biomass energy."
Study compares technology cost and maintenance
Tri-State's support extended well beyond the net metering agreement.
"Anything that helps our rural members, we're interested in,"
said Tri-State Senior Engineer-Member Services Mike
McCoy of the power wholesaler's participation in the pilot
project.
In mid-2004, Colorado Pork and OEMC will
install a 55-kW Stirling combustion engine to operate along
side the CAT and the Capstone. Tri-State is funding a study
by the Electric Power Research
Institute to compare all three generators at once, another
first. The goal, said McCoy, is to determine which technology
makes the most cost-efficient use of methane and to ferret out
design weaknesses that could add to maintenance.
Maintenance issues are a big part of the
learning curve in demonstration projects, and the hog farm digester
has been typical in that respect. The harsh hydrogen sulfide
gas that is a biproduct of anaerobic digestion corroded the
system's first steel pipes, so they had to be replaced with
PVC. The gas compressor for the microturbine suffered even more.
"We went through three compressors before installing a stainless
steel unit," said Wolfe. "Like anything new, it takes time to
work the bugs out."
Every banished "bug" brings Colorado Pork
a step closer to generating excess power. The farm is experimenting
with adding chemicals to the manure and grinding the waste to
boost methane extraction. Not that biogas is likely to become
a second cash crop for hog farms, McCoy pointed out. On the
other hand, "People have to maintain and operate biomass generators,
and that creates jobs in rural areas. And anaerobic digesters
help livestock operations to be better neighbors while containing
operating costs," he added.
SECPA and Tri-State do not underestimate
the value of those benefits in a region where the agriculture
industry is struggling. "There are four or five big pork producers
in the state who really want this project to work," Wolfe said.
"Its success could mean big things for hog farming and for renewable
energy in Colorado."