Landfills are physical facilities used for the disposal of residual solid wastes in the surface soils of the earth. Historically, landfills have been the most economical and environmentally acceptable method for the disposal of solid wastes, both in the United States and throughout the world. Even with the implementation of waste reduction, recycling, and transformation technologies, nearly all of the residual solid waste in the United States today is deposited in landfills. Further­more, landfills are not going to disappear, rather they will continue to be an important component of solid waste management strategy far into the twenty- first century.

Landfills produce a large amount of gas. Anaerobic decomposition of the biodegradable portion of the municipal solid waste produces methane and carbon dioxide in roughly equal amounts. These two principal components, together with atmospheric nitrogen and oxygen and trace organic compounds, comprise landfill gas, LFG. According to the Environmental Protection Agency (EPA) Landfill

Methanol Outreach Program (LMOP) statistics, each pound of organic waste biodegrades into 10 to 12 standard cubic feet of gas during its landfill residence of approximately 25 years. Modest size landfills produce one to five million standard cubic feet of landfill gas daily. By way of example, one of the largest landfills in the United States, Fresh Kills, Staten Island, NY, produces more than 30 million cubic feet of landfill gas daily. Landfill gas generation increases while the landfill is active and decays three to five percent annually beginning several years after the landfill is closed. Significant landfill gas is generated for up to 25 years after closure of the landfill.

The 1986 Clean Air Act (CAA) requires that landfills containing over 2.5 million tons of municipal solid waste be required to collect and flare the landfill gas in order to prevent methane migration and control the odor associated with the landfill. This requirement helps prevent methane migration, which contributes to local smog and global climate change. Methane will try and escape into the atmosphere from the landfill either through fissures in the lining of the landfill or through the surface cover. Landfills are the largest human-related source of methane in the United States, accounting for about 34% of all methane emissions. The amount of methane created depends on the quantity and moisture content of the waste and the design and management and environmental practices of the landfill.

In order to comply with the CAA, LFG is extracted from the landfill by an engineered system of liners, pipes, wells, wellhead monitors, and a vacuum system to move the collected gas to a metering device and then to the constant temperature flare. Significant amounts of landfill gas that are now flared could be utilized for economically viable projects. The EPA estimates that there are between 800 and 1000 domestic landfills that are currently flaring landfill gas that could be converted to energy and energy-related projects, thereby reducing dependence on fossil energy. Methane vented or flared from existing U. S. landfills was estimated by the LMOP in 2001 to equal about 5% of domestic natural gas consumption or about 1% of domestic total energy needs.

Landfill gas is similar to low-quality natural gas in that it requires the removal of the volatile organic contaminants and the CO2 to realize substantial commercial value. Landfill gas contaminants challenge separation technology because the potential contaminants can number in the hundreds of chemical compounds and various toxic species such as vinyl chloride and hydrogen sulfide. Additionally, no two landfills have the same contaminants and these contaminants are constantly changing over the gas production life of the landfill as the decomposition occurs.

The conventional uses of landfill gas to energy include electricity generation using internal combustion engines, turbines, micro turbines and fuel cells; direct use, which would include boiler, dryer, kiln, greenhouse, wastewater treatment; cogeneration, also known as combined heat, and power that enjoys the efficiency of capturing the thermal energy in addition to electricity generation; and alterna­tive fuels that include pipeline quality gas, compressed natural gas, liquefied natural gas, methanol, and hydrogen.

Landfill ownership is either public or private. Solid waste disposal firms generally own and operate the majority of the private landfills. Privately owned landfills tend to promote their gas resource and solicit buyers or users of the gas more aggressively than their public counterparts. The process of obtaining and acquiring landfill gas rights is essentially the same for either case. Such a process usually consists of the following: a review of the proposal by the owner or appropriate public officials, the negotiation of the business plan and definition of responsibilities and liabilities, and an execution of a contractual agreement gov­erning the gas rights, responsibilities of the parties, term of the agreement, price for the gas, and other details of mutual concern.

Establishing a price for landfill gas and other project considerations requires the examination and negotiation of many factors, including but not limited to the following:

• Amount of landfill gas available and the projections of future gas generation rates.

• Gas composition or gas quality.

• Environmental regulations and permits required.

• Ownership of gas collection system and responsibility for its mainte­nance.

• Competing prices for natural gas and electric in the area.

• IRS Section 29 tax credit availability.

• Building permits and access to landfill.

• Local air quality conditions and regulations.

The IRS Section 29 tax credits were an attempt to provide a financial incentive for the utilization of the landfill gas for energy projects. The IRS Code provided for a $1.05 per million BTU tax credit to a landfill gas developer if such an energy project were started prior to June 30, 1998. These tax credits will expire on December 31, 2007, and no longer provide financial incentive to promote tradi­tional landfill gas to energy projects.