There is great national interest in replacing imported oil with "biofuels" produced from indiginous plants and materials. However, there are many hurdles to making such biofuels competitive with petroleum-based fuels, including choosing the appropriate feedstock.
Many candidates are being considered. An acre of rapeseed, for example, can produce around 130 gallons of biodiesel per year. Problematically, replacing all of the transporation fuel currently consumed in this country with rapeseed-based biodiesel would require nearly 1.4 billion acres of rapeseed fields-- more than half the total U.S. land area.
There is, however, a "crop" that is widely recognized as having the potential to meet the demands of a biodiesel-based transportation fleet without devastating the natural landscape: algae. Some varieties of these single-celled plants can contain 50 percent or more oil. And they grow much more rapidly than ordinary cultivars with doubling times that can be as short as several hours.The U.S. Department of Energy funded considerable research on biofuel production using algae after the oil shocks of the 1970s, an effort known as the Aquatic Species Program (follow link to the right). Although this DOE program was terminated in the mid-1990s, much valuable experience was gained through research and various demonstration projects. The results suggested that algae can be grown in sufficient density to provide for the production of several thousand gallons of biodiesel per acre per year—nearly a full order of magnitude better than can be expected using palm oil and almost 50 times better than rapeseed (see the Algae Productivity section for more comparisons).
DOE's research concentrated on large open ponds (open bioreactors), which had inherent problems with wide temperature fluctuations and takeovers by invasive species of native algae. Because of this, many researchers are now concentrating on closed bioreactors which make it easier to control the algae growth. (Algae are grown in glass or plastic tubes or even plastic bags.) However, closed bioreactors are capital intensive and it is debatable whether they can ever be economically scaled up to commercial size. It is worth noting that the Japanese spent hundreds of millions of dollars attempting to develop commercially viable photobioreactors and were never successful. More recently, the widely touted GreenFuel Technologies failed when they were unable to successfully run their system at scale.
Bebout and Associates believes that the open bioreactor concept remains the most promising technology for the commercial production of biofuels from algae. We are in the process of demonstrating that the problems encountered by the DOE researchers can be overcome in in a reasonable and cost-effective manner by utilizing existing industrial infrastructure as well as renewable resources such as solar, wind and geothermal energy.
