Putting the pressure on algae to create biofuel

By Ben Coxworth
17:20 April 29, 2010

If you’ve read even a little bit about potential sources of biofuel, you’ll know that algae is one of the big ones. During photosynthesis, this unicellular aquatic plant turns sunlight and carbon dioxide into oil. It’s grown in ponds, where it’s not taking land away from food production, and yields much more oil than other biofuel crops, such as corn or soybeans. Researchers at the University of Michigan have recently come up with a method of getting algae to give up its oil more quickly and efficiently than has previously been possible - they pressure cook it.
The current method of creating algae fuel involves cultivating special oily types of algae, drying them out, then extracting their oil. UM’s method allows the use of regular, less-oily algae, which is added to water. The algae-water is heated to 149C (300F), and kept at a high enough pressure that it remains liquid instead of turning to steam. The high pressure and temperature cause the algae to react with the water and break down, plus they cause the algae’s proteins and carbohydrates to rapidly decompose. The result of both reactions, after 30 to 60 minutes, is crude bio-oil.
It’s the same basic process that created fossil fuels from prehistoric plants, only UM’s method takes minutes instead of millennia.
Presently, the oil has a tar-like consistency. The researchers looking at ways of making it flow better, along with the possible use of catalysts to increase its energy-density, and the reduction of its sulfur and nitrogen content to make it cleaner.