With gas prices leaping and bounding and global warming heating up as a prominent political issue, it's no wonder more and more people are ditching their gas guzzlers for more fuel-efficient vehicles.

Some hail the hybrid car as a possible answer to our environmental crisis. Others, like Milwaukee's Jason Hass, remain fuel focused. Haas has been running his Volkswagen Jetta TDI (Turbocharged Direct Injection) on biodiesel for almost two years now, and he's hardly alone. Still, the idea of putting vegetable oil into a gas tank is, for most people, slightly mystifying.

"Many people have heard of biodiesel; they think it's something good, but they're not quite sure exactly what it is," says Haas.

Here's the short answer: Biodiesel is a renewable, environmentally safe energy source produced from agricultural products, rather than petroleum. It's made from soybeans, canola oil, sunflowers or fryer grease and can be used in any diesel engine.

For a more in-depth look at the alternative fuel and how some Milwaukeeans are using it, the grand opening of the Milwaukee Biodiesel Co-op this Saturday promises a bevy of information on the issue.

The co-op's president, Swee Sim, co-owns Future Green, a self-sustaining, organic living retail store at 2352 S. Kinnickinnic Ave. in Bay View. Utilizing the shop as headquarters, it is here that the seven board members -- all biodiesel users -- have met for the past year with virtually one major goal in mind: provide a local source of commercial-grade biodiesel to Milwaukeeans.

"It was not easy to procure the stuff," says Hass, a co-op board member. "It was never readily accessible in Milwaukee -- people drove to Madison to a co-op called PrairieFire BioFuels where they sell it at the pump. But that's all about to change."

Sim's idea for the co-op came after a lot of reading and some serious hands-on experience. Two years ago he started homebrewing fuel in the basement of his store by using old grease he picked up from a friend's Chinese restaurant.

"Store customers were intrigued that fuel can be derived from old grease, and they started to regularly to help me make biodiesel. After a few months we bought a diesel Benz and started to test the fuel that we made. The rest is history -- we have been running on biodiesel ever since."

The Milwaukee biodiesel Co-op does not make its own biodiesel on site -- it is shipped in from a refinery in Lake Geneva -- but, thanks to board member Marshall Nickelson, it is able to re-sell it to customers at cost. Marshall, a Milwaukee diesel mechanic, donated a 20 gallon per minute fuel pump, which Sim now runs on solar energy from panels he installed on the roof of Future Green. There is enough leftover energy to run the lights in the shop's bathroom.

Due to space limitations, customers are not able to drive their cars up to the biodiesel tank as they would at a gas station, but they are, however, welcome to fill up as many five-gallon fuel totes as they wish. This is Milwaukee's only commercial grade, ASTM (American Society for Testing and Materials) certified biodiesel pump, which achieves one-third of the co-op's mission.

"A long term goal of ours is to have a gas station, but instead of selling gasoline, we'd sell biofuel," says Haas. "Part of the licensing for gas stations requires an underground fuel tank, but the good part about biofuel is that it's non-toxic and biodegradable, so you can have it above ground and not worry about it contaminating anything. If it leaks, you wait a month and it degrades into fats."

In addition to being a biodiesel provider, the co-op wants to educate the public about biodiesel and renewable energy as well as encourage the use of biodiesel in the public and private sectors.

With negotiations in progress for the proposed Jones Island biodiesel refinery -- which would produce 24 million gallons of fuel a year and be the first of its kind in Milwaukee -- biofuel is assuming a stronger role in the plan for a greener city.

Milwaukee County Supervisor Marina Dimitrijevic recently pushed for the use of biofuel and green cars in her "green print" initiative, stating in her legislation to "direct the Director of Transportation and Public Works to purchase, when applicable, new cleaner technology fleet vehicles that use alternative fuels such as biofuels, hybrids and plug-in hybrids."

The City of Milwaukee already uses a biodiesel blend in its fleet and the co-op hopes for increased percentages as the fuel becomes more readily available.

Obsessed as we all are with fuel economy, it's no secret that diesel engines get better mileage -- about 30 percent higher -- than gasoline engines, clocking in between 40 and 50 miles per gallon. Co-op board member Kyle Capizzi has been using biodiesel in his Passat since 2004 and got similar mileage, but says that he noticed about a five percent hit when he started using B100, 100 percent biodiesel, last year.

Like anything, everyone agrees there is a flip side to using biodiesel. First, its use is restricted to diesel engines only. For a sedan in the U.S., that means buying a Volkswagen -- the Jetta, Passat, Golf and Beetle all make TDIs -- or a Mercedes Benz. Haas says General Motors has plans to introduce a diesel Saturn, Honda will have one by 2010 and that Peugeot is working on a diesel hybrid car.

Additionally, although the demand is increasing every year, it still hasn't reached the point where biodiesel prices are lower than that of petrolium gas or diesel. Currently, the Milwaukee biodiesel Co-op charges $3.20 per gallon for members, $3.68 for non-members. Haas says the non-member price includes the delivery fee and storage costs that are paid by the co-op.

"That number could go down. If we get a better deal, we all pay less."

And, like all cars, there are still emissions.

"There's no such thing as a perfect fuel," says Haas. "As great as biodiesel is, the one minor drawback is that is does have slightly higher -- about two percent -- nitrous oxide omissions, which contributes to smog. It's not that much higher than what comes from petrol diesel, but the good news is that it does not emit any soot or carcinogens into the air like other fuels. The next round of cars from Volkswagen and Mercedes Benz will have technology that traps the nitrous oxide and cleans it."

For the co-op's grand opening at Future Green this Saturday, July 28 is open to the public and features food, live music, an educational presentation by Capizzi and, of course, biofuel for the selling.