Crude oil reserves around the world were formed millions of years ago as ancient microorganisms, such as algae and plankton, died and sank to the sea floor. Under extreme heat and compression due to sedimentary rock formation, the ancient biomass slowly decomposed anaerobically, resulting in deposits of crude petroleum buried in the strata.
Biofuels researchers have been working to recreate this process in the lab. By using biomass, typical biofuels ought to have at least a carbon-neutral emissions factor. Basically this means the carbon emitted by combustion is equal to or less than the carbon removed from the atmosphere by the biomass.
Professor of chemical engineering at University of Michigan, Phil Savage, is trying to recreate the process using a green marine micro-alga of the genus Nannochloropsis. Over a number of experiments, Savage’s team has been able to convert, using heat and pressure, about 50% of a sample of the algae into a synthetic oil, biocrude. They had their best results at 570°F for 10 to 40 minutes.
Then they tried something different, cooking the algae for just one minute in 1,100°F sand, which should bring the sample temperature to about 550°F. In that experiment, 65% of the algae had converted to biocrude, which was their best result. “My guess is that the reactions that produce biocrude are actually must faster than previously thought,” Savage said.
Current biofuels using algae first dry the samples and extract the fats, which stands at about $20 per gallon right now. The new method, using wet algae, extracts up to 90% of the energy from the algae, as it also breaks down the proteins and carbohydrates.
Savage believes this new process is about is efficient as it can get, which means that biocrude and biofuel facilities could be built smaller and cheaper. Additionally, researchers estimate that an area of brackish water the size of New Mexico, could supply all of the algae-to-biocrude needs of the US without occupying valuable food crop areas.
