3.2 MW of electricity can be generated from landfill gas recapturing plants like the one at Twin Bridges, Ind., which is enough to power approximately 3,500 homes of average size and electricity usage. (Photos provided)

More than one billion tons of post-recycling municipal solid waste continue to be disposed of in landfills worldwide each year — including more than 130 million tons in the U.S. alone.

The country faces mounting waste management challenges, including the declining capacity of existing landfills, growing opposition to new disposal sites, high per-capita waste generation rates, low recycling rates, and air and water pollution concerns.

Because U.S. landfills receive more than 50 percent of one billion tons of post-recycling waste a year, and recover energy from only 13 percent of that, the EPRI believes we’re one of many countries where waste-to-energy technologies have significant deployment potential.

Decomposing garbage produces methane and carbon dioxide gases. According to the Electric Power Research Institute, landfills remain the second largest human source of methane.

Twenty times more powerful at warming the atmosphere than carbon dioxide, by weight, methane has a relatively short, 12-year lifespan that makes capturing and re-using it as crucial to slowing global warming in the short term as the curbing of carbon dioxide emissions is in the long term.

Capturing the power of municipal solid waste and turning it into energy is a piece of the sustainable living puzzle whose utility was first recognized during the mid-1960s. According to the EPA, once landfill gas was determined to have value as a fuel, attempts to recover the gas for commercial purposes quickly followed.

Congress passed the Solid Waste Disposal Act in 1965, engendering subsequent federal, state and local regulations. It’s notable that prior to the SWDA, U.S. landfills had been designed and operated essentially as dump sites that were sometimes so poorly designed that modern-day attempts to recover landfill gas from them is an onerous process.

Landfills have to meet certain conditions to create a favorable environment for landfill gas generation — including depth of waste, type of wastes disposed and landfill design and operation. Landfill gases are produced at atmospheric pressure, are typically saturated with water and contain impurities. Pressurization processes and treatment procedures are required before they can be converted into electricity.

Rapid growth of landfill gas energy projects started in the mid-1980s due to an emerging industry that had the expertise to design, build, operate and finance energy projects and that recognized that producing energy from landfill gas could be economically attractive. The first-known U.S. landfill gas energy project went online in 1975 at the Palos Verdes Landfill in Rolling Hills, Calif. The landfill gas was collected and cleaned, and the resulting pipeline-quality gas went to Southern California Gas Company.

The EPA itself became a major force in advancing landfill gas recovery and utilization by forming the Landfill Methane Outreach Program in 1994. The program’s intent was to encourage productive use of landfill gas as a renewable energy resource, a goal that conformed to the country’s commitment to reduce greenhouse gas emissions under the United Nations Framework Convention on Climate Change.

The LMOP formed and continues to enter into partnerships and agreements with communities, landfill owners, utilities, power marketers, states, the landfill gas industry, tribes, nonprofit organizations and trade associations to overcome barriers to the development of landfill gas policies that include methane. The program helps partners assess project feasibility, find financing and market the benefits of project development to the community, lending direct technical and outreach assistance to those sites that need it the most.

“Attractive economics,” including renewable energy incentives and a market for the power produced, motivated the rapid geographic expansion of the trashto- cash model, according to the EPA. By October 2010 the U.S. hosted more than 500 operational projects with a total capacity of 1.6 GW, and a similar number of additional landfills currently offer energy recovery potential.

At three gas-to-energy plants at the Twin Bridges landfill in Danville, Ind., landfill gas is collected, compressed, burned and then spun through internal gas turbines like this one to create electricity. A fourth plant is scheduled to go online at the facility in June. (Photo provided)

Reflecting the high rate of private landfill ownership, half of those projects are located on publicly-owned landfills and half are on privately-owned property. In 1995, most were in California and the Northeastern U.S. Today 46 states have projects in the LMOP database with California, Pennsylvania Michigan, Illinois and Virginia tallying the highest participation by state.

Start-up costs for gas collection systems and landfill gas energy projects vary, but include capital costs and annual operation and maintenance. The size of the project, the type of energy technology selected, whether or not the landfill is already required to collect and combust landfill gas, and the distance between the energy end-user and the landfill influence each site’s price tag.

Considerations such as job growth, revenue, the offsetting of fossil fuels, a reduction in local air pollution and landfill odors can balance the initial capital outlay. Residents tend to value the increased environmental protection, better waste management and more responsible community planning, said an EPA spokesperson. Opportunities for educational outreach about green energy and positive public relations also present themselves.

Municipalities can investigate the possibility of forming part of the Landfill Methane Outreach Program by visiting www.epa.gov/lmop/ and clicking on the “Partners” tab. Partners receive technical and informational publications, software tools that calculate environmental and energy benefits of the project, an evaluation of the initial economic feasibility of 10 different energy recovery technologies, access to the U.S. Landfill and Landfill Gas Energy Project database and a network of more than 1,000 Partners, and more.