SBIR-STTR Award

Landfill gas (contaminated methane and CO2) is a plentiful resource largely wasted by venting or flaring. Landfill gas could provide CO2 and energy to grow hothouse crops year-round in landfill-based greenhouse as well as methane gas for fuel cells. However, a major technical/economic barrier to the wide commercial use of landfill CO2 and methane is contaminant removal. This project will use separation technology to convert landfill gas to clean mixtures of CO2 and methane. Phase I will develop experimental thermodynamic data and integrated landfill gas process design(s) for greenhouse quality CO2 and fuel cell grade methane. In particular, the removal of ethylene, a common landfill gas contaminant which is not welcome in greenhouses, will be addressed. In Phase II, one ton CO2 will be produced for greenhouse consumption and enough methane will be produced to power a 200 kW fuel cell.

Commercial Applications and Other Benefits as described by the awardee:
The technology should lead to economic gas utilization at landfill sites with reduced greenhouse gas emissions. Alternative landfill gas products include medium Btu gas; compressed or liquefied methane for pipeline gas, high pressure turbine fuel for cogeneration, or heavy vehicle fuel; methane-CO2 feedstocks for methanol and di-methyl ether; and merchant liquid CO2.

Landfill gas, composed chiefly of methane and CO2, is a plentiful energy and chemical resource that is largely wasted in its disposal through venting or flaring. However, the major technical and economic barriers to its wide commercial use hinge on contaminate removal as well as on the necessary separation of methane and CO2. This project will use an existing liquid CO2 separation technology to remove contaminants from landfill gas to produce clean methane and high purity liquid CO2. In Phase I, experimentally-derived thermodynamic data verified the capability of a process design for the production CO2 suitable for greenhouse use, particularly in terms of the removal of ethylene removal, a common but unwanted contaminate. The methane produced by this separation technology exceeded fuel cell purity requirements by at least a factor of 2 to 3. Preliminary results have verified the technical and economic merits of liquid CO2 wash to control landfill gas contaminants. Phase II will demonstrate the production of clean methane (50 million Btu/day) and liquid CO2 (1/2 ton/day) from landfill gas, permitting the extensive analytical product testing and industry evaluation necessary for Phase III commercialization.

Commercial Applications and Other Benefits as described by the awardee:
The resultant CO2 could be used in greenhouses to enhance plant growth, replacing that currently derived from the vaporization of liquid CO2 or from the burning fossil fuels. Landfill methane could be used directly as an energy source for the generation of heat or electricity. Both products should have wide use as feed stocks in the chemical industry.