Algae offer a ubiquitous, renewable source of oil for fuels and various chemical products ( CE, September 2008, pp. 22–25), but the extraction of oil from the algae cells is an energy-intensive process that involves dewatering and drying the biomass, followed by solvent extraction. Now, a one-step method that breaks the algae cells and liberates the oil without the need for dewatering or solvents has been developed by OriginOil, Inc. (Los Angeles; www.originoil.com). Riggs Eckelberry, the company president, says the process promises to cut energy costs by 90%, plus "substantial savings" in capital costs for solvent extraction.
In the new method, algae ready for harvesting are pumped into an extraction tank through a static mixer, which induces cavitation in the water. Simultaneously, a low-power, pulsed electromagnetic field is applied to the algae-laden stream, and CO2 is introduced to lower the pH. The combination of these measures ruptures the cell walls and releases the oil, which rises to the surface in the tank while the biomass sinks. The final separation is achieved in a clarification tank.
OriginOil devised the separation method as part of its process to produce biofuels from algae, which is still under development. However, the company is in early discussions to market the separation process through a partnership with Desmet Ballestra (Zaventum, Belgium), which installs process systems for algae producers and other oil and fat processors.
... and a gasification process that gets methane from algae
Genifuel Corp. (Salt Lake City, Utah; www.genifuel.com) has taken a different route to producing fuel from algae (see previous item). The company has licensed a "catalytic hydrothermal gasification" process from DOE’s Pacific Northwest National Laboratory (PNNL, Richland Wash.; www.pnl.gov) and is using it to convert algae to natural gas.
An aqueous slurry containing about 20% algae is pumped continuously into the bottom of a vertical stainless-steel reactor and converted to natural gas at about 350°C and 3,000 psi, using a ruthenium catalyst. The conversion is better than 99%, says Genifuel president Jim Oyler, and the product gas consists of about 97% methane, plus ethane, propane and hydrogen. The product gas exits the top of the reactor along with steam, which is used to preheat the feed, then condensed and recycled to the algae ponds.
PNNL has tested the process with terrestrial plants, kelp and water hyacinths, as well as algae, but Oyler says algae is an ideal feed because it is easy to convert to slurry form, so preprocessing is relatively inexpensive. Also, essentially all the heat in the steam is recovered. He adds that the process operates at about half the temperature of other gasification methods that don’t use a catalyst. The present reactor produces about 100 ft3/d of natural gas, but Oyler plans to work next with a reactor that is about four times larger. He says the process can be readily scaled up.
An energy-autonomous process for capturing air humidity for drinking water has been developed by scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB; Stuttgart; www.fraunhofer.de) and Logos-Innovationen GmbH (Bodnegg, both Germany; www.logos-innovationen.com). The concept is suitable for supplying water to single households or hotels in regions where there is no electricity infrastructure.
