A joint venture between Linde North America and Waste Management will build the world’s largest facility to convert landfill gas (LFG) into liquefied natural gas (LNG). The facility, located at the Altamont Landfill near Livermore, California, will begin operation in 2009, and will produce up to 13,000 gallons per day of LNG—sufficient to fuel 300 refuse trucks.
Linde will use a multi-step purification system to remove CO2, N2, H2S and trace contaminants and then use a cryogenic process to cool the purified gas into LNG at a temperature of -260° F.
The $15.5 million Waste Management-Linde project will receive grant assistance from the California Integrated Waste Management Board, the California Air Resources Board, and the South Coast Air Quality Management District.
Waste Management is currently operating 10 full-scale bioreactor waste treatment landfill projects in the US and Canada to evaluating the economic and environmental impacts as well as to develop the operational knowledge needed for implementation.
A bioreactor landfill operates to rapidly transform and degrade organic waste through the addition of liquid and air to enhance microbial processes. These bioreactors can be used for the production of landfill gas. There are three different general types of bioreactor landfill configurations, according to the EPA:
Aerobic. In an aerobic bioreactor landfill, leachate is removed from the bottom layer, piped to liquids storage tanks, and re-circulated into the landfill in a controlled manner. Air is injected into the waste mass, using vertical or horizontal wells, to promote aerobic activity and accelerate waste stabilization.
Anaerobic. In an anaerobic bioreactor landfill, moisture is added to the waste mass in the form of re-circulated leachate and other sources to obtain optimal moisture levels. Biodegradation occurs in the absence of oxygen (anaerobically) and produces landfill gas. Landfill gas, primarily methane, can be captured to minimize greenhouse gas emissions and for energy projects.
Hybrid (Aerobic-Anaerobic). The hybrid bioreactor landfill accelerates waste degradation by employing a sequential aerobic-anaerobic treatment to rapidly degrade organics in the upper sections of the landfill and collect gas from lower sections. Operation as a hybrid results in the earlier onset of methanogenesis compared to aerobic landfills.
Waste Management currently is working with anaerobic and hybrid bioreactor technologies.