Two years ago, An Inconvenient Truth was surprisingly well-received at the Sundance Film Festival. This year another environmental doc, Fields of Fuel, turned out to be a huge hit with audiences, winning the audience award last night for documentary. Directed by environmental activist Josh Tickell, Fields of Fuel is a film about biodiesel -- fuel made from organic products. It can be made from corn or soybeans, but can also be made from agricultural product less impactful on the environment, like switch grass and algae.

Tickell lays out the case for biodiesel as the fastest and most sustainable means to reduce our country's dependence on oil: Henry Ford and Rudolf Diesel both designed their engines to operate on vegetable oil, but the increasing dominance of the oil barons, in particular John D. Rockefeller, says Tickell, killed biodiesel before it had a chance to get off the ground, laying the framework for the oil dependence that drives everything from home heating to how we get around. Fields of Fuel is a timely and relevant documentary, going beyond merely proselytizing biodiesel as a fuel alternative to informing audiences of the facts about biodiesel that most folks simply aren't aware of. Specifically, Tickell demonstrates that biodiesel fuel works in regular diesel engines without the need for any conversion kits -- just buy any diesel-engine car, and you can fill it with biodiesel at both a substantial savings and a decreased impact on the environment. And while some critics have called the film "granola crunching," it's clearly making its point with audiences.

Tickell himself is an engaging presence in the film. He talks about growing up in Australia until the age of nine, when he and his brother moved to Louisiana with their mother. Transitioning from the more pristine environment of his home in Australia to the oil-polluted environment of Louisiana had a tremendous impact on Tickell, spurring an early interest in environmental issues that culminated in Fields of Fuel.

Tickell shows various aspects of converting to biodiesel throughout the film, talking to average consumers in Europe, where biodiesel is more widely used, and a biodiesel activist here in the States who started a biodiesel co-op in order to get it available in her community. He also profiles Willy Nelson, who worked with a friend who owns a large truck stop to get truckers coming through his station to fuel up with biodiesel instead of regular diesel.

Tickell also has a conversation with the transportation supervisor of a Las Vegas school district, who converted the entire fleet of school buses to biodiesel. In addition to saving the school district substantial money, the switch is preventing children from being exposed to the fumes from regular diesel fuel. When you think about just how many school buses, city buses, taxis and semis operate on American roads on a daily basis, the reduced dependence on foreign oil, cost savings, and reduced impact on the environment make it difficult to argue with Tickell's stance that just converting trucks and buses to biodiesel would make a huge difference.

Tickell's obvious passion for his cause and the timeliness of his message with presidential elections looming overcome what minor flaws the film may have from a pure filmmaking standpoint. Fields of Fuel isn't one of your artsy documentaries, but the clear, concise way in which Tickell presents the information and its relevance given the situation with the oil supply, the war in Iraq, and prices at the gas pump, seem to resonate with audiences. If the crowd response to the film at Sundance is any indicator, Fields of Fuel could well end up being one of those rare documentaries that goes beyond just playing well to film fest audiences to actually generating real change.