Roofing shingles taken to the the Alpha Ridge Landfill are used to make asphalt. Used cooking oil becomes soap. And, food scraps become fertilizer.
Soon, another byproduct at the facility – methane gas – will also be converted to something useful: electricity to power some operations on site. The balance will be sold back to the grid for a profit, and that could pay for the project within a decade.
“It’s such a good project, it would make sense to do even if we just broke even,” said Evelyn Tomlin, chief of the Howard County Bureau of Environmental Services.
Methane is a greenhouse gas that holds more than 20 times as much heat as carbon dioxide, and using it to create electricity keeps it out of the atmosphere.
The Alpha Ridge Landfill sits on a 590-acre lot off Marriottsville Road in Marriottsville. In all, 190 acres of that land is permitted to be developed for use as an actual landfill. Right now, 110 acres have been developed, leaving 80 acres available for future use.
The majority of the trash that comes into Alpha Ridge is not buried in the landfill but taken to a transfer station where it is shipped to the King George Landfill in Virginia.
Activities at Alpha Ridge go beyond burying and transferring trash. At the facility’s entrance, for example, a working rain garden captures rain to prevent polluted runoff from entering storm drains and local rivers.
Nearby sit compost piles and rain barrels. Master gardeners give on-site demonstrations to teach residents how their food scraps and rain water can fertilize and irrigate for less money and with less environmental impact than a bag of fertilizer.
Soon, methane will also find a second life at Alpha Ridge.
The chemical and microbial breakdown of trash in the landfill creates “landfill gas,” which is about 50 percent methane, 40 percent carbon dioxide and the rest, oxygen and nitrogen, Tomlin said.
Since a large portion of the landfill is capped, or sealed, the gas needs to be removed as it is created, or it could rupture the cap, potentially contaminating the soil or nearby groundwater.
Right now, landfill gas is collected using a series of pipes and vacuums. It’s ultimately sent to a flaring station and burned, destroying the methane, a greenhouse gas that, if released into the atmosphere, traps 21 to 23 times more heat than carbon dioxide over a 100-year period. The carbon dioxide, oxygen and nitrogen are released into the atmosphere.
A methane conversion facility would do more than destroy the methane, it will put it to use powering a one-megawatt generator, creating electricity that would power the operations at the landfill. The surplus would be sold to BGE for a profit that would, depending on electricity rates, pay for the $4 million project in five to 15 years, according to Tomlin.
Generating power from landfill gas is not a new concept. It’s done at landfills across the state, including in Frederick, Baltimore and Worcester counties. Montgomery County has been turning its gas into electricity on and off since 1985. Its Gude and Oaks landfills are both home to methane conversion facilities but both landfills are now closed to trash collection, according to Peter Karasik, chief of the Division of Solid Waste Services in Montgomery County
When electricity prices are high, “it’s easy to get them built,” Karasik said of methane conversion facilities. “When electricity prices drop, it’s harder to make the economics work to build this type of facility.”
Although the price of oil is up, electricity prices have been dropping. According to the U.S. Energy Information Administration, the average retail price for electricity dropped from 14.25 cents per kilowatt-hour in 2009 to 13.29 cents in 2010.
Because of low electricity rates, Karasik said, Montgomery County decided to finance and build the methane conversion facility at the Oaks Landfill on its own dime.
“We had several false starts at the Oaks [landfill]. We couldn’t get the economics to work” Karasik said. “The county decided to build it ourselves, as a capital improvement project.”
Howard County has also chosen to pay for the research and construction of the facility on its own. The Bureau of Environmental Services has also been working with the EPA’s Landfill Methane Outreach Program, which matches municipalities with technical assistance, networking opportunities and other resources.
“It’s being financed through the landfill’s capital budget,” Tomlin said. “If a developer took all of the risk, they’d have a stake in the revenues, too.”
Tomlin said if all goes well, the facility could be online by 2012.
The waste in the capped landfill will continue decomposing and creating landfill gas for about 30 more years, Tomlin said. "For the new landfill gas to energy generator, we estimate 15 years of gas sufficient to power the engine with no additional waste buried at the landfill," she said.
For Howard County residents who are interested in recycling, electronics are taken to in Elkridge, roofing shingles are taken to a facility in Mt. Airy and used to make asphalt, and discarded cooking oil is used to make a variety of products, including poultry feed, industrial fuel, soap and cosmetics, according to the Department of Environmental Management.
Click here for a complete list of recycling options offered at the landfill.