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From Farmland Waste to Alternative Fuel

by Worldchanging Seattle local blogger, Serena Batten:

Prometheus Energy, with main offices in Bellevue and Tukwila, WA, is helping lead the wave of alternative fuel producers. The company, one of’s Green 50, was founded about four years ago. By capturing methane gas from sources such as stranded gas wells and dairy farms, Prometheus is able to produce and distribute a clean, affordable liquid natural gas (LNG) alternative fuel.

This is how they do it:

Turning Waste into a Resource
Methane is present in many locations, including in coal mines, landfills and wastewater treatment plants. Many facilities deal with this by-product gas by burning it or venting it into the atmosphere, wasting a valuable resource mostly due to the fact that there hasn't been an economical way to capture it. Prometheus has created a viable LNG production method using specialized equipment to capture and convert inexpensive feedstock into a useful fuel. As more conventional sources of natural gas become harder to find, turning to previously untapped sources becomes more necessary. Approximately 60 percent of the U.S.'s natural gas supply is located in stranded wells, which have historically been economically or physically unfeasible for production.

The methane gas that enters the atmosphere is a greenhouse gas 21 times more potent than carbon dioxide. This gas can be converted to LNG, which can be used in vehicles in place of petroleum diesel and Propane. Since the methane feedstock has gone through a purification and liquefaction process that removes oxygen, carbon dioxide, sulfur, and water that results in almost pure methane, it is a cleaner fuel option. Using the sources already identified, it is possible to generate enough LNG to replace 20% of the diesel fuel currently used in transportation in the U.S.

Managing the Entire Supply Chain
To create the most scalable and efficient production and distribution of LNG, Prometheus manages the entire supply chain. The company locates methane feedstock, then builds, installs, and operates the equipment used to capture and convert methane gas to LNG. The equipment is powered by a small portion of the methane gas it captures, and can be transferred to another site for reuse when feedstock is no longer available at the initial site. Prometheus uses cryogenic technology that CTO Dr. John Barclay, a cryogenics engineering expert, has been developing for 30 years. The LNG produced is transported in Prometheus' fleet of converted trucks and tanks to refueling stations also owned by the company.

Prometheus is creating a distributed fuel network, where fuel is produced as close as possible to where it will be consumed. Currently in the Western U.S., there are only five refineries producing liquid natural gas used as vehicle fuel. Transporting this fuel over long distances via land and pipelines can add up to 35 cents to the cost of every gallon. A distributed fuel network virtually eliminates this added cost. In addition, the liquefaction process reduces the gas to about 1/600th the volume of natural gas at the stove burner tip, further reducing the cost to transport LNG.

Fueling the End User Market
LNG can be the cleanest and most economical fuel for many types of vehicles, primarily taxis, buses, airport shuttles, construction vehicles, garbage trucks, delivery vehicles, and public works vehicles. These types of vehicles are called tethered fleets because they originate and return to a central location for parking and refueling. Current federal tax subsidies and grants of up to 80% of the cost of conversion make converting a fleet to LNG fuel very attractive. Conversion includes switching the engine to a LNG engine and the tank to a cryogenic tank that keeps the fuel in liquid form. Other potential markets include remote communities and developing regions that have little or no access to natural gas or other power sources.

This January, Prometheus Energy began producing LNG from the world's first landfill gas-to-LNG facility at the Frank R. Bowerman Landfill in Orange County, CA. This plant has the ability to produce 5,000 gallons of LNG per day, which has the environmental benefit of taking 150,000 cars off the road per year.

For further reading: - The Landfill Gas Energy Benefits Calculator to calculate the environmental benefits of capturing methane from landfills. - Tons of facts and details about natural gas as well as links to additional information.

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Serena, thanks for this great article on introducing Prometheus Energy's work here. I just learnt for the first time about stranded wells, and the that methane, as a greenhouse gas, is 21 times more potent than CO2.

So it is a triple benefit to work on methane conversion - eliminating a ton of methane will eliminate 21 equivalent tons of CO2, then will further eliminate CO emmisions from vehicles which in turn will (hopefully) stop Greenland's shore line from receeding - last count is 30 miles in the last 14 months or so.

Here is a pie in the sky thought exercise - Tethered blimps high up in the sky streaming pure methane to the ground feeding the "tethered" vehicles mentioned in the article. The blimps are of course carrying Prometheus Energy's purification and liquefication equipment and harvesting the previously released methane from the atmosphere.

Great Sunday reading together with the Verdant Energy post.

Posted by: Subbarao Seethamsetty on 1 Apr 07

Prometheus Energy looks like it is doing good in general but I would like to make two points.
1) Although methane may be 21 times more potent a greenhouse gas it has a lifetime of 1/5 to 1/20 of CO2 (6~10 years compared to 50~200 years) so the long term effect is 1~4 times that of CO2 not 21.
2)The LNG produced from stranded wells may be of an economic benifit it is still carbon being pumped out from underground and burned so there is no befit in using these wells as opposed to other wells from an eviromental point of view.

I do applaud the capturing and burning of methane from sources that would othewise be flared or directly released in to the the atmosphere. I would like to know what percentage of the LNG produced by Prometheus Energy is from such sources.


Posted by: Grant Morgan on 2 Apr 07

Need fresh idea on Energy Conservation

Posted by: Narayan Mishra on 3 Apr 07



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