California Cows Start Passing Gas to the Grid

March 5, 2008 — -- Imagine a vat of liquid cow manure covering the area of five football fields and 33 feet deep. Meet California's most alternative new energy.

On a dairy farm in the Golden State's agricultural heartland, utility PG&E Corp began on Tuesday producing natural gas derived from manure, in what it hopes will be a new way to power homes with renewable, if not entirely clean, energy.

The Vintage Dairy Biogas Project, the brainchild of life- long dairyman David Albers, aims to provide the natural gas needed to power 1,200 homes a day, Albers said at the facility's inauguration ceremony.

"When most people see a pile of manure, they see a pile of manure. We saw it as an opportunity for farmers, for utilities, and for California," Albers said.

In addition to being a partner in the 5,000-head Vintage Dairy, Albers is also president of BioEnergy Solutions, the company that funded and built the facility which cost millions of dollars. PG&E is simply a customer and the companies declined to give details of project finances.

As cow manure decomposes, it produces methane, a greenhouse gas more potent than carbon dioxide. Scientists say controlling methane emissions from animals such as cows would be a major step in addressing climate change.

Enter the Vintage Dairy project. As luck would have it, methane can be captured and treated to produce renewable gas, and California regulators have directed PG&E and other utilities to make renewable energy at least 20 percent of their electricity supplies by 2010.

PG&E expects to reach 14 percent this year, thanks in small part at least to its partnership with BioEnergy Solutions.

To tap the renewable gas from cow manure, the Vintage Dairy farm first flushes manure into a large, octagonal pit, where it becomes about 99 percent water. It is then pumped into a covered lagoon, first passing through a screen that filters out large solids that eventually become the cows' bedding.

The covered lagoon, or "digester," is the size of nearly five football fields and about 33 feet deep. It is lined with plastic to protect the ground water and the cover, made of high density polyethylene, is held down at the edges by concrete. The digester's cover was sunken into the lagoon on Tuesday, but officials said it would be taut and raised in a few days as the gas collects underneath it.