BELFAST – The 1939 World’s Fair in New York gave visitors glimpses into their futures with displays of new technologies such as television.

The organizers of the first-ever Green Future Fair, held in Belfast on Saturday, wanted to do the same. If they are as prescient as their counterparts in 1939, the air will be a lot cleaner in the world of the future.

Blessed with a summerlike day, the organizers were successful in encouraging many visitors to bicycle to the event, held at the city’s Steamboat Landing waterfront park. Volunteers from the Bicycle Coalition of Maine offered “valet” parking of all two-wheeled transportation, rolling visitors’ bicycles to wooden racks set up on the grass.

Inside the Boat House building, two dozen organizations were represented at information tables. At one of the tables was Joel Glatz, owner of Frontier Oil Co. in South China.

Glatz sells traditional fuels, including No. 2 oil, kerosene, diesel and gasoline, but at the fair he was talking about a soybean-derived biofuel he is offering customers. A jar of the fuel, which looked like a lighter version of olive oil but smelled slightly like diesel, sat surrounded by a pile of soybeans on the table in front of Glatz. He said the biofuel’s benefits include that it is a renewable resource, is nontoxic and biodegradable, and produces fewer emissions than petroleum fuels.

The soy biofuel can be used as a supplement to No. 2 heating oil or as a replacement for diesel fuel in vehicles, Glatz said. No retrofit of a traditional oil-fired furnace is needed to convert to the biofuel, other than a different filter in the fuel line, and diesel vehicles can run on the fuel without significant modifications.

The Belfast-based Audubon Expedition Institute uses biofuel to power its fleet of buses, Glatz said.

Because the biofuel sells for $1.98 per gallon, Glatz provides customers with a blend of heating fuel that is 80 percent No. 2 oil and 20 percent biofuel, which sells for $1.39 per gallon. No. 2 alone currently sells for $1.20 per gallon.

Another reason to use a blend, Glatz said, is that when used alone, biofuel tends to degrade certain rubber seals in an oil burner.

The biofuel is produced at plants in the Midwest, in what Glatz said was a relatively low-tech process. Frontier Fuel is the only business in Maine to offer the product for sale, he said.

Asked why he was selling biofuel, Glatz said his reasons had little to do with profit.

“I want to be part of the solution,” he said.

Glatz owns a convenience store in addition to the fuel business, and has felt badly about selling alcohol and cigarettes, he said. Offering biofuel is his way of improving the environment, he said, and contributing to public health.

On the lawn of the waterfront park, four alternative fuel-powered cars were displayed by their owners. Mike and Margie Shannon of Knox recently purchased the newest generation of alternative-fuel cars, a 2003 Honda Civic Hybrid.

The car is just like the standard Civic in every way, Mike Shannon said, with such amenities as air conditioning and air bags, except it is equipped with an electric motor and batteries in addition to the gasoline-powered engine. When the gas engine is running, an alternator charges the bank of batteries under the back seat, he said, making use of kinetic energy when the driver applies the brakes, slowing the engine by engaging the alternator.

The car gets 51 miles to a gallon of gas because the engine is assisted by the electric motor, Shannon said. The electric motor engages when the car is climbing a hill or accelerating, he said, yet the Civic Hybrid can reach the speed limit just as quickly as a gas-powered car.

“We can go 650 miles on a single tank of gas,” Shannon said. The car has a 13-gallon gas tank.

In testing by the manufacturer, the Hybrid was driven across the country with just four gas refills. Also contributing to its efficiency is a feature that automatically turns the engine off if it idles for a certain period; the engine is restarted automatically as soon as the driver applies pressure to the gas pedal, Shannon said.

Asked why he and his wife chose the Hybrid, which they purchased at the Darling dealership in Bangor for $19,999, Shannon said its energy efficiency was consistent with the couple’s values.

“It’s part of our lifestyle,” he said.