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."
