ROSEBURG (AP) — Douglas County commissioners have approved a preliminary agreement with the Massachusetts company that wants to make electricity from methane produced from rotting garbage at the county landfill.

The document calls for further talks between the county and Ameresco on a 20-year contract with renewal options.

It frees the county from paying for the planning, construction or operation of the 1 megawatt generating plant or the gas collection system.

Ameresco would get the right to buy all the methane from the landfill and to all tax credits and benefits from projects that lower emissions.

Ameresco would pay the county 7 percent of what it makes from sale of electricity from the generating plant, which would be located at the landfill.

The county would take less if contaminants in the methane increase to a level that impairs the operation.

Commissioners also considered a suggestion by Roseburg resident Brad Hisey that the county consider a high Btu facility for removing impurities and converting landfill methane into pipeline quality gas.

Hisey said the county would make more that way than through the project proposed by Ameresco.

James Kennelly, a Long Beach, Calif., consultant hired by the county to oversee the methane project, told commissioners via e-mail that such a plant is viable, but only for large landfills producing tremendous amounts of methane.

He said it would require a large investment as it is essentially a chemical processing plant with a high electrical load.

Kennelly said he is working with an East Coast developer who has been looking at the two options at a large landfill in Southern California that burns off several thousand cubic feet per minute of methane, compared with about 100 cubic feet for the Douglas County Landfill.

But the county inserted a clause in the preliminary agreement giving the county the option of buying out Ameresco at the landfill if the county wants to develop a high Btu plant.