Small Landfills, Big Benefits

Shelley Cohen

Landfill gas-to-energy (LFGTE) projects are only viable for large landfills, right?

Wrong.

Traditionally, LFGTE project developers have overlooked small landfills because it was not apparent that economically feasible projects could be developed.

Furthermore, small landfills, or landfills with only 1 million to 3 million tons of waste in place, are not subject to the New Source Performance Standards and Emissions Guidelines (NSPS/EG) also known as the "Landfill Rule" under the Clean Air Act, which requires some landfills to collect and combust their landfill gas.

On the other hand, some landfill owners and operators are discovering that small LFGTE projects can provide big benefits to the environment and the surrounding community, and also are economically feasible if resources are leveraged properly and project plans are realistic.

In fact, of the LFTGE projects currently under construction or planned, more than half are at landfills not affected by the Landfill Rule. This is in part because many of the larger landfills already have projects, but there are other factors affecting this growth.

Many small landfills have long-term waste capacity expansion potential, so although the landfill is small, methane generation will increase throughout its life.

There also are a variety of opportunities to use landfill gas (LFG) at smaller landfills. For example, the methane gas can be used to: heat an onsite greenhouse; offset onsite energy demands; power equipment that needs minimal LFG flow, such as microturbines; or to power soil restoration equipment that can be placed on the landfill and run off of LFG. The microturbines, which are portable machines, can be a good investment at small sites because they can be disassembled quickly and moved to another area of the landfill or another site, enabling them to recapture some of their initial investment.

Smaller landfills also tend to be closer to communities, making direct use of LFG by a single customer, such as a small factory or a municipal building, ideal. Here, the LFG demand may be equal to the landfill's LFG production.

Recently closed landfills or cells are best for LFG generation, as newer municipal solid waste (MSW) typically produces the most LFG. But landfills with depths greater than 40 feet and shallow, smaller landfills that use horizontal well gas recovery also are good candidates for LFG recovery.

Small landfills are not immune from the problems that often plague communities with larger landfills, such as methane migration, odors and local air and water pollution. But collecting and converting the LFGTE mitigates many of these harmful effects and even may help to improve relations between the community and the landfill owner and operator. In other words, mutually beneficial projects create good neighbors no matter what the landfill size.

Small Landfills, Large Success The Berkeley County landfill, Martinsburg, W. Va., is a good example of a small site that has found a good use for its gas. It opened in the 1970s and stopped accepting waste in November 1991. The landfill has a 24-acre footprint, less than 1 million tons of waste in place and is unlined, except for a 1.5 acre area lined with a single high-density polyethylene (HDPE) liner. Here, recovered LFG approximately 200 cubic feet per minute (cfm) has been collected, mixed with air and natural gas and used directly as boiler fuel since 1986 by a nearby Department of Veterans Affairs medical center.

The project is operated by Manus Corp., Sewickley, Pa., a private developer, through a lease agreement with the Berkeley County Solid Waste Authority. Berkeley receives royalty payments equal to 12.5 percent of the gross receipts for LFG removed from the landfill, with a minimum annual royalty of $10,000.

Manus currently is considering converting the pipeline to natural gas and selling it, and the right-of-way, to Shenandoah Gas, Martinsburg, W. Va., to supply the medical center. If that happens, the authority may sell the LFG to a local brick manufacturing plant.

Another small landfill with a successful LFGTE project is the Intervale landfill, located on a 34-acre site within the city limits of Burlington, Vt. Spanning approximately 17 acres, the landfill has received about 850,000 tons of refuse during its operating life from 1965 until 1989.

Zahren Alternative Power Corp. (Zapco), Avon, Conn., has operated the facility since 1994, including the LFG collection system and two Caterpillar Inc., Peoria, Ill., engine/generators (gensets). Each genset, is designed to produce 350 kilowatt (kW) of power at full capacity (700 kW between the two engines).

The LFG collection system consists of 18 vertical extraction wells with four self-draining condensate traps and 4-inch to 8-inch header piping. The LFG flow rate to the gensets is approximately 320 cubic feet per minute (cfm) with an average generating capacity of 520 kW.

The project cost approximately $800,000, and Burlington Electric Department pays an average of 4.5 cents per kWh. Section 29 tax credits of just over $1 per million British thermal units (MMBtu) (approximately $60,000 per year) contributed to the project's economic feasibility. As a result, the city of Burlington, which owns the landfill, has an active LFG collection system with zero installation or operation and maintenance (O&M) costs.

In addition, the pre-existing LFG migration control system connected to the LFG collection system has no O&M costs either.

Currently under development, Project Branch Out at the Yancy/ Mitchell landfill will use methane to operate a greenhouse to serve as a learning center for high school and college students and as a research facility to re-establish rare plants and uncover income opportunities for the region.

This site also will host rehabilitation programs for emotionally and physically challenged individuals, and will serve as an "incubator" for investors interested in greenhouse-related businesses. The project has been funded completely by grants and has earned the support of local, state and federal governments.

The landfill, with approximately 1.5 million tons of waste in place, still is emitting landfill gas enough to generate 1.2 megawatts, to heat 894 homes. The project also will reduce emissions by 0.01 million metric tons of carbon equivalent (MMTCE), the equivalent to removing 21,002 cars from North Carolina's roads.

The Future of LFGTE Almost half of the new LFGTE projects brought on-line in 1998 were at small landfills not required by the U.S. Environmental Protection Agency (EPA), Washington, D.C., to install LFG collection systems. Will this type of growth continue?

With 125 LFGTE projects planned and 82 under construction in the United States, the EPA estimates that an additional 400 to 500 landfills, including many smaller sites, could make projects work economically.

For more information on the Landfill Methane Outreach Program, a voluntary assistance program started by the EPA to help communities and project partners investigate the potential for landfill gas use, contact toll-free: (888) 782-7937. Website: www.epa.gov/lmop

Using landfill gas (LFG) can be a win/win situation no matter the site's size. Landfill gas-to-energy (LFGTE) projects:

* Involve citizens in sustainable community planning;

* Create partnerships between landfills and local energy users;

* Use an existing resource that otherwise would go to waste;

* Eliminate LFG emissions;

* Reduce unpleasant odors;

* Reduce explosion threats at a landfill;

* Offset the need for non-renewable resources such as coal and oil;

* Reduce emissions of air pollutants such as sulfur;

* Help fight global climate change;

* Create economic benefits from the sale of the gas to an energy consumer; and

* Create jobs associated with the design, construction and operation of energy recovery systems.