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Turning Trash into Treasure: UNH and MSC to Power Campuses with Methane
Smelly landfills and cow pies hardly look like fuel. Yet these odiferous offenders hide a secret within their stink. Schools such as the University of New Hampshire and Morrisville State College are taking the lead on transforming waste–or what we call waste, anyway–into energy-saving gold mines.
Methane: The Useful Gas with the Bad Reputation
Methane is a naturally occurring gas that is emitted when organic materials are broken down by bacteria, in anaerobic, or oxygen free, conditions. The Environmental Protection Agency reports that methane is 20 times more effective in trapping heat than carbon dioxide (CO2) in a 100-year period. The high potency as a greenhouse gas, coupled with a relatively short atmospheric lifetime of 15 years, gives methane its “bad boy” reputation and makes its capture integral to efforts to slow emissions.
There are innocuous sources of methane that have nothing to do with human activity –wetlands, permafrost, freshwater bodies, the ocean and wildfires all emit methane through entirely natural processes. The EPA suspects, however, that 60% of the global methane emitted now comes from human activity, citing that the gas is more abundant now than it was 400,000 years ago. Methane from natural sources averages to 190 TgCO2 (or carbon dioxide equivalents) per year whereas human-produced methane sources average 562.4 TgCO2 per year. Methane levels have more than doubled since the pre-industrial period: whereas in 1750 methane was measured at 700 ppbv (parts per billion per volume), today that number exceeds 1,745 ppbv.
In 2003, landfills were the number one culprit of methane emissions, comprising 34% of all human emitted methane. Other perpetrators were ruminant digestion, manure management, the production, processing, storage, transmission and distribution of natural gas and oil, and coal mining.
But there’s good news: this seemingly “bad gas” is also the primary component of natural gas–90 % in fact–and can therefore be used in the same way to generate electricity and heat.
Landfills: Harmful excess into helpful energy
When the University of New Hampshire (UNH) began evaluating how to achieve carbon neutrality on their campus by 2100, and to help fulfill the requirements of the American College and University Presidents Climate Commitment, it looked at the methane emissions of the nearby Turnkey Landfill in Rochester, New Hampshire for a solution.
The gases landfills emit are 50% methane, produced from the anaerobic decomposition process of waste materials within the landfill. The other 50% is predominately carbon dioxide, with a mixing of other materials such as hydrogen sulfide and siloxanes. These landfill gases are often flared, or burned, to reduce their impact when released into the atmosphere.
The five-million square foot campus consumes 1.2 billion cubic feet of natural gas each year, and their energy costs have been growing as the school expands. The aging boilers at the central heating plant of the university were thermally constrained, and in bad need of repair. UNH made the decision to invest in a cogeneration, or cogen, plant which retains the heat normally lost in the production of electricity, and uses it to heat campus buildings.
With cogen’s ability to burn either oil or natural gas, and UNH looking for a new energy efficient project, the university teamed up with Waste Management to reroute the methane gas being burned off from the regional landfill to fuel the plant and provide heat and electricity to the campus.
A large landfill with the capacity to hold 2.5 million metric tons of waste, must destroy 98% of all of its gas emissions if not used in another fashion. Since the 1990’s, the EPA has dictated that landfill technology include a series of wells to be built as deposits are made. The wells capture excess gases, which are routed through the system of wells to a central point where, in the case of energy use, they are treated and processed, or in the case of surplus, they are burned off.
“Landfills are no longer open dumps,” clarifies Alan Davis, senior district manager of Waste Management New Hampshire, Inc. “They are now carefully planned. It’s different than it was 30 years ago.”
The University’s Department of Energy and Campus Development, led by Assistant Vice President Paul Chamberlin, worked with the board of trustees to find out if using this “waste gas” was feasible for the institution. Landfill gases (LFG) used for energy are often treated to remove excess moisture, particulates and other impurities. What this process is exactly depends not only on the specific characteristics of the LFG, but additionally on the type of system it will power. Gases are dehumidified, the particulates filtrated and siloxanes removed through adsorption beds. The first step for UNH, therefore, was ensuring that the methane could be cleared of the accompanying siloxanes and hydrogen sulfide that would coat and damage the existing turbines of their particular cogen plant.
Once the team determined the gas purification was possible, the second task was to evaluate the achievability of building a pipeline that would transport the gas from the landfill to the campus. A team of UNH representatives and planners went to conservation meetings and town council meetings of the townships of Dover, Rochester, Madbury and Durham. The project, as well as the need to run a pipe through the various townships, received positive support from the communities.
“People understood the ecological benefit,” says Larry Van Dessel, executive director of Facilities, Design and Construction at the university. “If it was only economic it would have been more difficult.”
UNH worked hard to use pre-existing corridors, such as a conveniently located railroad line, and a federal right-of-way along Route 16. Drilling under three rivers, eight streams and a wetland, they were able to minimize their impacts on the land throughout the 12.7 mile pipeline’s length.
The third step in the process was to evaluate the fiscal impacts of the project. The project would cost UNH $49 million, which the committee for the project decided to fund internally by borrowing the money with a payback of ten years. The school also determined to sell renewable energy certificates to help finance the capital costs of the project. The credits would additionally fund the ability to invest in future energy efficiency projects.
Named EcolineTM, the project has begun and will provide up to 85% of the energy used by the campus. UNH will thus recover its costs while simultaneously gaining the boasting rights of being the first campus in the country to use landfill gas as its primary fuel source.
Cow Manure: Waste-Full Energy
Energy efficiency was a factor in Morrisville State College’s (MSC) decision to look into methane capture — but so was smell. Running a 600-acre dairy farm that produces cheese, ice cream and yogurt, MSC, a small agricultural college in a town of the same name, uses the manure as a fertilizer on neighboring crops. But that is only in the summer, when agriculture is thriving. According to the Livestock Facilities Handbook, published by the Midwest Plan Service, a 1400 pound milk cow produces 115 pounds of manure per day. At MSC in the winter, there was no place to store the manure, but there were still massive daily deposits from the 250 cows.
In the natural decomposition process of manure, fumes are emitted, biogases that are 60% composed of methane. Dr. Walid Shayya, professor of Natural Resources Engineering in the School of Agriculture and Natural Resources, who has assisted with the Anaerobic Methane Digester Project since the beginning, reports that one cow can produce about 600 cubic feet of biogas a week, or 3,100 cubic feet of biogas in a year. The small herd of 250 dairy cows creates a total of 8,500,000 cubic feet of biogas, with an equivalent energy value of 1,286,300 kWh annually.
The valuable fuel was going to waste. So, the small agricultural school contracted David Palmer of Cow Power, Inc. to design a hard top-plug flow digester to turn feces into fuel.
Now, manure is scraped from the main barn to a central channel where it flows into a collection pit, capable of holding up to three days of manure. A long-term storage tank is also available at the site with a three-month storage capacity. From the collection pit, the manure is mixed and then pumped into the digester automatically every hour, accommodating up to 10,000 gallons of manure per day. The biogas that results from bacteria decomposing the manure under anaerobic conditions is 60% methane, which is captured and runs a 50-kW internal combustion engine and generator. Hot water from the engine is used to maintain the digester temperature at an optimum 98 degrees F. It also heats a nearby system conducting research on growing algae for biodiesel production. The entire process takes approximately 25 days under optimal conditions.
Treating the manure of 250 milking cows, the system generated 330,000 kilowatt hours of electricity annually in the first 21 months of operation. Each cow is able to produce the equivalent of 3.3 kilowatts of energy every day, and the whole herd can generate as much as 900 kilowatts of electrical power in a day.
After the manure is scraped, run through the digester, and the methane captured, it is still loaded with nutrients that are available as compost for agricultural crops.
The project cost MSC a total of $1,182,587 with monetary assistance from the New York State Energy Research and Development Authority, the New York State Department of Agriculture and Markets, and the United States Department of Energy. Morrisville State College wasn’t happy just with its projected annual savings of about $33,000 per year, however.
“We also wanted a system that allowed for conducting applied research while addressing environmental issues and providing energy savings and economic benefits,” states Shayya.
As such, the college is using the facility for community demonstration classes as well as formal classes for enrolled students. A Renewable Energy Training Center was established in fall 2008 to educate agricultural workers in the community. Additionally, MSC is planning to offer a new Renewable Energy Systems two-year degree program in the fall of 2009.
The biogases the University of New Hampshire and Morrison State College are capturing would go otherwise unused from their accompanying landfills and dairy farms. Their projects that harness the power of biogases generated from decomposing landfill materials and manure not only address, at least in part, future fuel concerns and stride towards energy efficiency, but also reduce the very amount of discarded matter put into landfills in the first place.
Natural gas drilling lies at the center of controversy. And yet, an alternative to drilling exists. Sources of methane, natural gas’ counterpart for energy use, are literally lying on the ground and in landfills waiting for collection. By partnering with private entities to achieve their energy efficiency goals, these institutions are addressing this incongruence and putting a new meaning into the old adage, “waste not, want not.” Coupled with the close range payback of the initial investment, indicating no financial losses on the part of the institution, it’s the kind of story that demands the question, “Why isn’t everyone doing this?”