Short Mountain Landfill Gas
Like spinning straw into gold, the Short Mountain Methane Power Plant
takes ozone-damaging landfill gas and turns it into valuable
electricity.
The first phase became operational in 1992. The second phase expansion
started up in 1993. The project's total cost was $2.6 million. It
generates about 15 million kilowatt hours (kWh) and approximately 2.5
megawatts (MW) annually. This is the equivalent of nearly 33,000
barrels of oil per year. It provides enough electricity to power about
1,000 homes. The project paid for itself in about seven years. Since
the Short Mountain Landfill is an operating landfill and plans to
accept refuse for many years into the future, this project will
continue to produce electricity for about another 20 years.
In 1985 Emerald approached Lane County with the concept of a
landfill-gas-to-electricity plant. Lane County subsequently put out a
request for proposals that was granted to Emerald. In November 1988,
Emerald's Resource Planning Citizens Advisory Committee,
a customer committee charged with studying EPUD's resource strategy,
recommended to the Board of Directors development of the Short Mountain
Project. After extensive study, a public hearing, and careful analysis,
Emerald's Board of Directors made the final determination to proceed
with development in March of 1991.
While this project was unique in the Northwest at the time, the
technology is now widely used. As of December 2005, there were 395
similar operating projects in the U.S. and another 600 with potential
for development. These 395 projects generate about 9 billion kWhs
annually-enough energy to power three communities the size of
Eugene-Springfield.
The Short Mountain project brings many benefits to the local community,
EPUD, and the Pacific Northwest. As a "green" or "renewable" resource,
it is consistent with the resource priorities of our customers and the
region. The project also diversifies Emerald's resource portfolio,
lowering our risk; enhances Emerald's bottom line; uses a "homegrown"
renewable resource; creates two full-time jobs; and has a positive
economic impact on the community. It uses the best available
emission-control technology, and significantly reduces methane, a
powerful greenhouse gas, which naturally escapes from the landfill.
Equally important, Short Mountain is a relatively low-cost resource
that will help keep Emerald's rates stable. Through a Billing Credits
agreement with BPA, the project will average $250,000 per year in
additional revenue for Emerald. Lane County also receives a royalty of
about $26,000 per year, and avoided having to build a $1.1 million
collection system. The project also contributes over $12,000 per year
in property taxes to schools and local and state governments.
Process Description and Environmental Benefits
EPUD is extracting naturally occurring methane from the Short Mountain
Landfill through vertical and horizontal wells in the landfill. The
wells are connected in a system of plastic pipe called the collection
system, which delivers the landfill gas to the power plant. A blower
that creates a vacuum on the collection system draws the landfill gas
from the wells. The landfill gas is then filtered and piped directly
into large Caterpillar 3516 gas-fired internal combustion engines (1150
horsepower from 16 cylinders generating 800 KW each), where the
landfill gas is burned to generate electricity. All ownership and
operation of the landfill itself is done exclusively by the Lane County
Solid Waste Management Division. EPUD owns and operates the collection
system and power plant.
The flow chart above
graphically demonstrates the process. Starting at the left, a
combination of vertical and horizontal wells extract the landfill gas.
30 vertical wells ranging between 45 and 85 feet deep, and the 65
horizontal wells buried in the landfill capture the 1,200 cubic feet
per minute of landfill gas used in the power plant. As new sections of
the landfill are filled, Emerald will install additional wells to
replace old wells. Once the landfill gas is extracted from the
individual wells, it is piped through the collection system and brought
to the power plant. The gas passes through a clean-up system that
removes the moisture and filters out particulates and other impurities.
After the gas is cleaned, it's injected into the engine carburetors for
combustion. The Caterpillar engines Emerald were specifically designed
to run on landfill gas. Combustion of the gas in the engines turns the
engine crankshafts, which turn the generators, which creates the
electricity. Through switching gear and step-up transformers, the
electricity is tapped directly into the utility distribution grid for
use by Emerald's customers in the Goshen, Creswell, and Pleasant Hill
areas.
The Environment
The project is also environmentally sensitive. Emerald is a partner
with the U.S. EPA in its Climate Challenge Initiative to combat global
warming. Landfill gas is essentially methane, which is a powerful
greenhouse gas about 22 times more harmful than carbon dioxide. In the
combustion process to create electricity, the landfill's methane is
converted to carbon dioxide, thereby significantly reducing the
greenhouse effect of the landfill.
The benefits of a typical 2-megawatt
plant like Short Mountain is the same as removing 17,000 cars and their
emissions, or planting 23,000 acres of forest, or forgoing the burning
of 430 railcars of coal! The U.S. EPA estimates that if the additional
600 landfills in the U.S. were to use this technology, we could
generate 13.7 billion kWhs of electricity - the equivalent of 10
coal-fired power plants - generating enough electricity to meet the
power needs of over a million homes. This would also reduce greenhouse
emissions equivalent to taking 14 million cars off the road. In addition,
by capturing the landfill gas, this project has nearly eliminated the
odor problems at Short Mountain.
Concern for the environment also
motivated Emerald to choose equipment that uses the best
emission-control technology available. The Caterpillar engines are
specially designed to be "low emission" engines, low enough to meet the
stringent California emission standards. The Lane Regional Air
Pollution Authority approved and permitted the project. The Short
Mountain Methane Power Plant takes an environmental problem and changes
it into a green and profitable solution. In 1996, it was awarded the
USDOE National Award for Energy Efficiency and Renewable Energy.