With bipartisan support, the 2004 state Legislature passed a bill requiring new power plants to offset 20 percent of the carbon dioxide they send into the air through mitigation projects.

Eligible projects include energy conservation projects, forestland preservation or converting diesel-powered buses to natural gas.

Power producers can either finance the projects on their own or pay an independent third party approved by state authorities to do it for them at the rate of $1.60 per ton of carbon dioxide produced.

Energy conservation groups hailed the bill as a sign that lawmakers are taking global warming and its effect on the environment, public health and the economy, seriously.

"A year ago, this vote wouldn't have been possible," said KC Golden, of the Olympia-based Climate Solutions. Golden is the former director of energy policy for the state.

The bill sailed through the Senate with a 40-6 vote and the House on a 69-27 vote. It awaits the signature of Gov. Gary Locke, who supported the bill.

Bill LaBorde, of the Northwest Energy Coalition, a Seattle-based energy conservation group, said the bill is an improvement over a rule the state Energy Facility Site Evaluation Council was considering because it sets the carbon dioxide payment higher and it covers all power plants 25 megawatts and larger. The energy council has authority only over plants 350 megawatts and larger.

However, the carbon dioxide calculations are based on only 60 percent of a plant's operating capacity, compared with 100 percent in the proposed energy council rule, LaBorde said.

The energy council and state Department of Ecology will need to draft new rules to implement the bill, energy council project manager Allen Fiksdal noted.

Power plants are responsible for about 40 percent of the carbon dioxide emissions produced in the United States. Here in the Northwest, motor vehicles account for about 60 percent of all global warming pollution, according to the Northwest Energy Coalition.

"We supported the bill largely on the belief that it provides some certainty," said Puget Sound Energy spokesman Roger Thompson.

In recent years, the energy siting council has made greenhouse-gas mitigation a condition of project approval on a case-by-case basis.

The bill gives the energy council authority to adjust the carbon dioxide fee every two years.

The bill only applies to existing power plants if they boost their carbon dioxide emissions 15 percent or more.

Golden said some Northeast states are considering legislation to apply carbon dioxide emission fees to old and new power plants alike.

"The state legislation is a small, but very positive, first step," Golden said.

John Dodge covers energy and the environment for The Olympian. He can be reached at 360-754-5444 or jdodge@olympia.gannett.com.