Denso Corp. announced June 19 it is testing industrial heat pump air conditioners that run on biodiesel fuel at the company’s headquarters in Japan.

The tests have the units running on fuel made from refined cooking grease taken from company cafeterias.

Denso officials said they believe units using biodiesel could cut carbon-dioxide emissions by up to 90 percent over conventional kerosene equipment.

“Denso expects to significantly reduce carbon-dioxide emissions from industrial heat pump air conditioners by using biodiesel fuel,” said Kenji Ohya, senior managing director in charge of the company’s sales group. “We aim to introduce biodiesel engine heat pump air conditioners for industrial use by 2010.”

Officials point out that any emissions put out by biodiesel air-conditioning equipment could be offset by the carbon dioxide absorbed by plants, making the equipment carbon neutral and reducing environmental impact.