Pacific Biodiesel has closed its central Maui production plant, company officials said Friday.

The Maui plant had been the longest continually running commercial biodiesel refinery in the nation, the company said.

The used cooking oil from Maui restaurants that went to the Puunene facility will be shipped to Hawaii island where it will be processed at Pacific Biodiesel’s new biodiesel refinery in Keaau, which opened a year ago.

The Maui plant, built in 1996, was widely recognized as a pioneer in the United States’ biodiesel industry, said Bob King, Pacific Biodiesel president and founder.

Singer Willie Nelson is a supporter of Pacific Biodiesel, and in 2012 the company named the fuel at its retail pump in Kahului "BioWillie Biodiesel."

King said the company decided to close the Maui facility after being notified in December by the Maui County Department of Environmental Management that continuing operations there would require multiple permits and extensive upgrades to comply with new county requirements.

"With just over two years left on our contract, we couldn’t justify the costly site improvements that were required to meet the county’s demands," King said.

The company will continue its full range of pumping and collection services on Maui and Lanai.

Other operations on Oahu and Hawaii island will not be affected, King said, adding that distribution of the company’s biodiesel will continue statewide.

"Needless to say it was difficult to shut down the plant after all these years but we found ourselves with little recourse given the extent of the requirements to continue operations," King said.

"We are committed to our community-based model and hope to return to Maui with our industry-leading technology in the near future," he said.

To date, Kahului-based Pacific Biodiesel has diverted more than 22 million gallons of waste oil and grease from Maui’s landfill, King said. Recycling the oils and grease also has reduced the frequency of waste-water spills caused by grease-clogged pipes, and reduced the costs restaurants previously paid to dispose of the waste products, King said.