ConocoPhillips, the fifth largest oil refiner in the world, has begun commercial production of renewable diesel fuel at the company's Whitegate Refinery in Cork, Ireland. The production process was developed by ConocoPhillips, and the finished product meets European Union standards for diesel fuels, according to Phil Blackburn, a company spokesman.

The refinery is producing 1,000 barrels (40,000 gallons) of renewable diesel fuel per day for sale in the Irish market. "The product is chemically similar to conventional diesel fuel and thus can be shipped by existing pipelines," Blackburn said.

The fuel is produced using existing equipment at the refinery. It has a higher cetane value than regular diesel at a lower cost, according to Blackburn. Renewable diesel only has 95 percent of the energy content of conventional diesel, yet 10 percent more energy than biodiesel. Renewable diesel is defined as a non-ester renewable fuel, while biodiesel is produced using mono-alkyl esters.

ConocoPhillips conducted a successful renewable diesel production test at Whitegate last year. Soybean oil will be the primary feedstock, although the plant can use other vegetable oils and animal fats. Renewable diesel burns cleaner than conventional diesel, has a lower sulfur content and emits less nitrous oxide, Blackburn said. A reduction in carbon dioxide emissions will contribute to Ireland's goal of meeting standards required under the Kyoto protocol.

Renewable diesel has been under some scrutiny in the United States. At the 2007 National Biodiesel Conference & Expo in San Antonio in February, National Biodiesel Board CEO Joe Jobe said some petroleum companies are pursuing a broader definition of renewable diesel so they can blend a minute amount of biomass into diesel fuel. Those companies would then collect a renewable fuels standard credit set aside in the Energy Policy Act of 2005. In that legislation, renewable diesel has an equivalency value of 1.7 gallons, compared with biodiesel's 1.5 gallons. Values are based on energy content.