A New Processing Scheme for Algae Biofuels
OriginOil, an algae biofuel company based in Los Angeles, has developed a simpler and more efficient way to extract oil from algae. The process combines ultrasound and an electromagnetic pulse to break the algal cell walls. Then the algae solution is force-fed carbon dioxide, which lowers its pH, separating the biomass from the oil.
“It’s low energy, there’s not a lot of machinery, and it’s a simple process,” says CEO Riggs Eckelberry. The algae and oil can be separated in a matter of minutes, he adds.
A number of companies are attempting to take advantage of the fact that algae naturally produce oil. But growing algae and extracting its oil efficiently is difficult, time consuming, and expensive. While some companies are focusing on better growing and harvesting methods, others, such as OriginOil, are focused on finding new ways to access the oil.
Each algal cell has a sturdy cell wall protecting it, making the oil hard to get at. The algae also have to be separated from the water that they are grown in and dried out before the oil can be removed. Typically, the oil is expelled from algae by using a press to physically squeeze it out. The leftover mashed-up pulp is then treated with a solvent to remove any remaining oil. While the combination removes about 95 percent of the oil, it is energy intensive. Another method does away with the press and treats the algae pulp with supercritical fluids that can remove nearly all the oil, but the process requires special machinery, adding to the expense. Other researchers are genetically engineering algae that secrete oil.
In OriginOil’s process, the algae solution is channeled through a pipe to which an electromagnetic field and ultrasound are applied, rupturing the cell walls and releasing the oil. Carbon dioxide is bubbled through, which lowers the pH. The resulting solution is then piped into another container. The lowered pH separates the biomass from the oil, and the oil floats to the top, while the biomass sinks to the bottom. The oil can be skimmed off, the biomass can be further processed, and the water is recycled. The whole process takes a matter of minutes, says Eckelberry.
Although the technology looks promising, “the whole industry has been haunted by hype,” says Leonard Wagner, an analyst at London-based Mora Associates
and author of a 2007 report on the algae biofuel industry. Wagner estimates that it will be four to five years before any company goes commercial with the technology, and a decade before anyone produces a meaningful amount of biofuel using it.
In order to be cost competitive with petroleum, the price of algae biofuel will have to be $50 a barrel, says Wagner. With today’s technology, algae biofuel could be produced for around $400 to $1,600 per barrel, says Al Darzins, group manager of bioenergy at the National Renewable Energy Laboratory, in Golden, CO. Darzins says that in order to make the economics work, companies will have to sell more than just the biofuel. For instance, algae oil could be sold as cooking oil, and the biomass, which is rich in protein, could be used as animal feed.
Another idea, says Eckelberry, is to locate algae plants next to power plants or other major emitters of carbon dioxide. Carbon dioxide could then be sequestered and fed to the algae, which need it to grow. Particularly if a price is put on carbon emissions, this could prove to be a good scheme, says Eckelberry.
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