Oregon's largest biodiesel plant is rehiring workers after closing down a month ago.

The Associated Press

SALEM — Oregon's largest biodiesel plant is rehiring workers after closing down a month ago.

SeQuential Pacific Biodiesel in Salem was built to produce 5.8 million gallons per year.

But owners could not run the plant at capacity because of a lack of buyers, and had to store 250,000 gallons in early spring until it could find markets. Manager Tyson Keever said that the plant has begun to run at half capacity.

"We need the market to grow before we can get at full production," Keever said.

The Statesman Journal newspaper said that, with warmer weather, customers are buying fuel blends with a higher biodiesel content — blends that can gel in cold weather.

Portland's Water Bureau fleet, for example, moved from a 20 percent biodiesel blend to a 99 percent biodiesel blend April 15.

"That helped dig our inventory down," Keever said.

In addition, Imperium Renewables, an $88 million biodiesel plant in Hoquiam, Wash., has closed.

SeQuential converts used vegetable oil it gets from restaurants into fuel, and focuses on using waste from local sources, such as the Burgerville restaurant chain, based in Vancouver, Wash. About 90 percent of waste vegetable oil collected is converted to biodiesel.

In 2008, the chain's 39 restaurants sent 69,432 gallons of used vegetable oil to SeQuential.

Users of SeQuential's biodiesel include Tri-Met in the Portland metro area, DeSantis Landscapes in Salem and Willamette Valley Vineyards.

Encore Oils, a subsidiary of SeQuential Pacific Biodiesel, runs five trucks to pick up used cooking oil from restaurants, universities, catering companies and hospitals in Oregon and western Washington.

"It is made here and then sold here," said John Miller, a SeQuential investor. "It is the perfect situation both for our Oregon economy and for the environment."