The sights and sounds will be the same, but next summer’s big Rim of the Pacific naval exercises off Hawaii will have a different smell — one that’s closer to the kitchen than a diesel truck stop.

The Pentagon recently announced the largest government purchase of biofuel in history — 450,000 gallons for $12 million — to fuel RIMPAC ships and aircraft in a large-scale test of the cleaner-burning alternative to petroleum products.

RIMPAC is held every two years in Hawaii waters. In 2010 about 25 Navy ships and submarines were involved in the world’s largest multinational maritime exercise, including the carrier Ronald Reagan, amphibious ship Bonhomme Richard and littoral combat ship Freedom. Fourteen nations participated, with 20,000 personnel, 32 ships, five submarines and more than 170 aircraft.

Navy Secretary Ray Mabus said during a news conference this week that the biodiesel will be used during next summer’s RIMPAC for what’s been dubbed the "Great Green Fleet" strike group.

"We’re going to have the entire strike group, aircraft and ships, sailing on a 50-50 blend of biofuel and diesel for the ships, biofuel and (aviation) gas for the aircraft," Mabus said. "We think this represents a major step in energy independence for the United States" and in making the Navy a "better war-fighting operation."

Aircraft carriers and submarines are nuclear-powered and won’t be part of the test. Mabus said the longer-term goal is to deploy in 2016 a carrier strike group on a normal multimonth deployment using 50 percent biofuels for the surface ships and aircraft.

Dynamic Fuels LLC, a joint venture between Tyson Foods Inc. and Syntroleum Corp., was awarded the contract to supply the Navy with the renewable fuel for RIMPAC.

Solazyme Inc. will help Dynamic Fuels fulfill the contract. Its biofuel is algae-based. Dynamic Fuels’ plant in Geismar, La., will manufacture the fuel from used restaurant cooking oil, as well as Solazyme’s algal oil, and deliver the fuel in May.

Mabus said the biofuel purchase "furthers President Obama’s goal to achieve more energy security by finding ways to lessen our dependence on foreign oil and fossil fuels."

The military and airlines have begun testing biofuel blends using cooking oil and algae, prompting odor comparisons to french fries and deep-fat-fried foods.

Beth Mathias, director of sales and marketing for Pacific Biodiesel in Hawaii, said the smell is different with cooking oil biofuels, but Pearl Harbor is unlikely to smell like french fries during RIMPAC.

The type of biofuel used by the military is filtered to such a degree that there is very little leftover debris in it, she said.

"In the old days, people used to pour used cooking oil into their engines, and that’s when they really smelled like french fries," she said. "Now there is an odor to it, but it’s like a sweet odor and it doesn’t really smell like french fries."

She added, "It’s a lot better than diesel fumes."

Pacific Biodiesel’s plants on Oahu and Maui produce about 2 million gallons of biofuel a year, she said. Among the fuel users are the Navy launches that ferry people to and from the USS Arizona Memorial, Mathias said. They use a biofuel blend.

The U.S. Department of Agriculture, which partnered with the Navy in announcing the RIMPAC fuel test, said the Navy fleet uses more than 1.26 billion gallons of fuel each year. The biofuel purchase is significant "because it accelerates the development and demonstration of a home-grown fuel source."

Mabus acknowledged the price of the biofuel is about $26 per gallon, and about $15 a gallon blended with petroleum for the RIMPAC demonstration.

Mabus was asked whether he was satisfied the Navy is paying the right price for the fuel. He said it was a "research and development purchase."

"It’s half of what we were paying last year," he said, "and it shows that as the market develops, you’re going to see costs come down."