A new state law aims to give Whatcom County dairy farmers a reason to consider using cow manure as a source of fuel.

The law, signed by Gov. Chris Gregoire March 31, takes effect July 1. It offers a six-year exemption on a portion of the property and leasehold taxes paid by a farmer who purchases a digester before Dec. 31, 2012.

The tax break, which can amount to thousands of dollars a year, is meant to be an incentive for farmers to purchase digesters, which take cow manure, extract methane gas and turn that into natural gas and electricity, said Jay Gordon, executive director of the Washington State Dairy Federation.

Farmers can use that electricity and natural gas or sell it to utility companies as energy from a renewable resource, Gordon said.

Robert Smit, a dairy farmer in Lynden with 600 cows, said he is interested in getting a digester. Along with his son, Nathan, Smit runs a composting business with the manure from his cows. He wants to separate the manure into liquids and solids, and then use the digester to make natural gas from the liquid and compost out of the solid.

“I want to be marketing both sides of the cow,” Smit said. “I feel really strongly that this should be the direction we should be going. But I’m always thinking of things I don’t have the money to do.”

Interest in the technology is growing, said Mike Apol, a regional manager for Andgar Corp. in Ferndale. Andgar makes digesters and installed the first one in Washington at Darryl Vander Haak’s farm in Lynden in November 2004. Vander Haak’s farm, which has about 1,500 cows, is the only one with a digester in Whatcom County and is one of two in the state.

“I see more interest growing in them,” Apol said. “They need time to germinate, but green energy is the way everything’s going.”

Farmers have been reluctant to purchase the digesters because they can cost about $1 million, depending on the size of the farm. For some farmers already struggling with high feed and diesel prices, purchasing a digester is tough to justify, Gordon said. To offset the high price, grants are available from organizations such as the U.S. Department of Agriculture. Many farmers, though, would still have to take out loans to purchase the machines, which they don’t want to do, he said.

Aside from cost, another deterrent is the low price of electricity in Washington due to the abundance of hydropower, Gordon said. While renewable energy gets a slightly higher price per kilowatt hour, it’s not enough of a return on the money borrowed to validate purchasing a digester, he said.

“The market is not signaling that it wants us to do this,” Gordon said. “Every technology has an adoption curve, and we’re trying to learn as quickly as possible. If it made sense economically, more of us would do it.”