In a world of peak oil, growing population and even faster growing demand for energy, it seems self-evident to me that we will cast in increasingly wide net in the search for new sources of energy. If that is indeed the case, we'll see much more variety in our future fuel sources, with many niche technologies and materials emerging in the years to come.
Not too long ago I cam across a small company that epitomizes this shift to me. Originally called Philadelphia Fry-o-Diesel, the company recently changed its name to BlackGold Biofuels, although, they remain in the same business - converting grease to biodiesel. And not just any grease, BlackGold specializes in converting restaurant trap grease. By their own admission, trap grease is "gross, it smells terrible ... an undesireable material".
Captured in traps in commercial kitchens, the grease must be regularly pumped out for disposal before it can escape into sewer lines and clog them. BlackGold appears to have started out with an interest in manufacturing biodeisel and has evolved to supplying its self-developed technogy to others across the U.S. who want to be in the business of converting a polluting waste into a useful energy product.
Sustainability doesn't get much better than this.
BlackGold appears to be a co-op based company and they are actively trying to license their technology but they do have some competition. CNET ran a story in February about a venture sponsored by the City of San Francisco. I've also been told that there is a company manufacturing biodiesel from trap grease here in Vancouver (Canada). However, I haven't been able to find any information on that.