Garbage Fumes Fuel LNG Transit Buses

Washington-based Prometheus Energy and Bowerman Landfill in Orange County, Calif., are turning landfill gas (LFG) into liquefied natural gas (LNG) that will soon be used power local transit buses and garbage trucks.

Completed in December 2006, the new plant--the first of its kind--is currently producing about 1,000 gallons of LNG per day and expects to increase daily production to 5,000 gallons during its first phase. At this production level, the plant will reduce carbon dioxide output by the equivalent of 10,000 tons per year.

As landfill materials decompose, methane is generated. If allowed to escape, methane is 23 times as potent a greenhouse gas as carbon dioxide. Therefore, air quality regulations require landfills to flare the methane if not put to use. Flaring options include burning methane to generate electricity or purifying it to add to natural gas pipelines. However, if landfills are in areas where electricity is inexpensive or far from electric transmission lines and gas pipelines, landfill gas can economically be converted to liquid transportation fuel.

Such is the case for Bowerman Landfill, which is located just five miles from the Orange County Transit Authority (OCTA). The two organizations formed a partnership--Bowerman will produce the fuel and OCTA, which is already running its buses on LNG, will use it.

All told, OCTA now uses about 13,000 gallons of LNG per day. It will soon use all the LNG produced at the Bowerman plant. The rest of OCTA's LNG will continue to be supplied by other manufacturers.

Although Bowerman currently produces only 1,000 gallons of LNG per day, it generates enough LFG to make about 50,000 gallons of LNG per day. Prometheus is actively seeking grants to eventually increase production to 40,000 gallons per day in subsequent phases (it is already permitted to do so). The company hopes to take on other fuel customers as the project continues.

Prometheus is approved to proceed with another LFG-to-LNG project in Sacramento. In this case, the fuel produced will be used in garbage trucks hauling waste to the landfill and by other municipal and private fleets. The project is being made possible by a $549,000 Clean Cities grant. Prometheus is an active member of the Puget Sound coalition and a member of its steering committee.

Source: Clean Cities Now, Vol. 11, No. 3 - June 2007.