An Army Humvee at Fort Shafter Flats has started tooling around with a faint smell of french fries and tempura coming from its exhaust.

The 8th Theater Sustainment Command vehicle was fueled up Wednesday with a blend of 80 percent petroleum diesel and 20 percent biodiesel from Oahu restaurant cooking oil as part of an ongoing Defense Department test of biofuel blends in tactical vehicles.

The evaluation — which includes a loader and Humvee at Marine Corps Base Hawaii running on what is known as "B20" — also is being conducted at Port Hueneme, Calif; the Marine Corps Air and Ground Combat Center at Twentynine Palms, Calif.; Fort Leonard Wood, Mo.; Moody Air Force Base, Ga.; and the Naval Surface Warfare Center in Crane, Ind., officials said.

"One thing we like about the biodiesel is yesterday it cooked your lunch, and today it takes you to lunch," Lt. Col. Matthew Garner said Thursday at a presentation on the Humvee test.

The Pentagon wants to reduce its dependence on foreign oil, and the biodiesel blend also reduces emissions and utilizes an alternative source of fuel — used cooking oil — obtained in Hawaii.

The National Defense Center for Energy and Environment said the military is the largest U.S. consumer of fuel and one of the largest consumers of biodiesel.

But while biodiesel is approved for use in nontactical military vehicles, it is not yet approved for use in tactical vehicles, including tanks, amphibious vehicles and Humvees, because of performance concerns, according to the center.

"Biodiesel offers environmental benefits but has technical limitations," according to the defense energy center. "It can gel at low temperatures, cannot be stored as long as petroleum diesel, has an affinity for water that can encourage microbial growth, and may be incompatible with certain materials used in engine components."

The Army biodiesel-blend Humvee will run alongside a "control vehicle" using regular fuel for the next four months, said David Chavez, an environmental engineer with the Naval Facilities Engineering Command in California.

"One of the things that we wanted to do was have (the test) in different climate areas — hot, cold, dry," Chavez said. The Navy was the first proponent of using B20, Chavez said, and the project started with Navy funding.

Every day, the Navy said, it consumes about 80,000 barrels of oil afloat and 20,000 megawatts hours of electricity ashore — rates that represent "strategic and operational vulnerabilities."

Chavez said the early results are positive for tests with B20 in tactical vehicles, which have been ongoing for more than a year on the mainland.

"So far we have not seen any issues as far as vehicle operations," he said.

About 320 gallons of biodiesel blend are being provided for the Army to test, Chavez said.

Mid Pac Petroleum gets refined cooking oil from Pacific Biodiesel and blends it with petroleum diesel, officials said.

Jenna Long, who works in fuel sales for Pacific Biodiesel, said the company collects used cooking oil from about 600 to 700 restaurants on Oahu.