Cow manure – the latest way to produce energy, in California at least. Earlier this week, PG&E Corp began producing natural gas derived from manure and they are hoping that the small project will become a new way to power homes in a renewable, clean way.

The Vintage Dairy Biogas Project is the creation of dairyman David Albers, whose aim is to produce enough power from the manure plant to power 1,200 homes. Albers is a partner in the Vintage Dairy as well as being he president of BioEnergy Solutions, a company that funded and built the new cow manure power plant at a cost of several million dollars, with PG&E being a customer.

Methane is produced when cow manure decomposes. Methane is a greenhouse gas which is more potent than carbon dioxide and some scientists have claimed that if methane emissions from animals such as cows could be controlled, it would make a big difference in the fight against climate change.

To actually get the methane from the manure, the manure is mixed with water in a large pit. This fluid is then pumped through a filter which removes all the large solids before being pumped into a covered lagoon. The large solids are not wasted either – they become bedding for the cows.

The lagoon is about 33 feet deep and covers an area the size of five football fields. It is lined with a high density polyethylene plastic which ensures that the ground is protected from the waste. The plastic gradually expands upwards as the gas collects underneath it. Small channels on top of the plastic then route the methane gas to a purifying unit where hydrogen sulphide and carbon dioxide is removed. The result is nearly 99% pure methane gas and it is this product that gets injected into PG&E’s pipeline before eventually being routed to a power plant.

With nearly 2 million cows in America, the potential for the technology is huge. California regulators are looking to have at least 20% of their energy requirements coming from renewable sources by 2010 so projects like this are incredibly important. There is another up-side for the farmers too – the get paid for all the energy they produce therefore giving them extra revenues on the side.

In practice, not all dairy farms will be able to participate in a scheme like this if they wanted to as many dairy farms are too far away from power plants to make the scheme feasible. Despite this, there has already been a lot of interest generated in dairy farming community with several other dairy farms around California looking to get on-board.

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