Algae Biofuel: A Review of Some Recent Developments
by Milsa Vijayadharan* (Advanced Biofuels USA) Most of the oil that we drill out of the ground was formed by algae and other sea-borne flora that piled up at the bottom of the ocean over the course of millions of years, then got compacted and heated and transformed into petroleum. So why not try to find a way to turn algae into crude oil in a faster and cost effective way? Lots of research is going on in this direction.
Algae have several advantages over conventional crops such as corn, soybeans, rapeseed, palms, etc., for biofuels production. Algae reproduce and photosynthesize fast. They have a harvesting cycle of 1-10 days thus permitting several harvests in a very short time frame, they can have high biofuel yields. Algae can be cultivated on land unsuitable for traditional agricultural such as arid land, drought stricken land and they can use water that is not usable for other crops such as sea water, brackish and wastewater. Like any plants, algae grow using sunlight and consume CO2 releasing O2. For higher productivity algae requires more CO2, which can be supplied by emissions sources such as power plants, ethanol facilities and other sources. After oil extraction, the remaining algal biomass can be dried and used as fuel that can be burned in industrial boilers and other power generation sources.
All these factors bring algae to the forefront of alternative fuels. However, a number of challenges also remain to be addressed. Among these is the most efficient way to process algae from the culture to a finished fuel product.
Solvent extraction process is most commonly used to extract the oil from algae. The algae have to be dried out by removing all the water; this process is expensive. Then solvents are used to extract hydrocarbons from the dried material.
Scientists at the Pacific Northwest National Laboratory have developed a method of converting wet algae into crude oil by pressure cooking it for 30 minutes. This process is called Hydrothermal Liquefaction. Researcher Douglas Elliott said they are duplicating the process that took place in the earth over the course of millions of years at a much, much faster rate by using high pressure and temperature like in a pressure cooker. Slurry of wet algae is pumped into a chemical reactor and in less than an hour crude oil comes out, which is in the form of green paste having the consistency of pea soup, by a continuous chemical process. All the organic matter is not converted into oil, the process also yields a stream of carbon dioxide, hydrogen and oxygen which can be converted into synthetic natural gas and burned to generate heat and electricity. Also left over is water rich in the plant nutrients (nitrogen, phosphorous and potassium) previously present in the algae. This water can be used in the algae ponds as fertilizer. A biofuels company, Utah-based Genifuel Corp., has licensed the technology and is working with an industrial partner to build a pilot plant using the technology.
Sapphire Energy, Inc., is one of the world leaders in algae-based green crude oil production, and the technology company The Linde Group in partnership with Sapphire Energy announced that they will work to commercialize a new industrial scale conversion technology needed to upgrade algae biomass into crude oil. Together, the companies will refine the hydrothermal treatment process developed and operated today by Sapphire Energy at pilot-scale. Sapphire Energy along with Linde is working to build a commercial oil upgrading process designed to increase yield and lower the cost of crude oil production. Linde is the leading CO2 supplier in the U.S. They are exclusive supplier of CO2 for Sapphire Energy’s algae-to-energy facility in Columbus, New Mexico.
Sapphire Energy is successfully converting algae into a renewable, sustainable and scalable source of energy, also known as Green Crude. First- and second-generation biofuels are not compatible with the petroleum infrastructure while green crude fits within the existing infrastructure – from refining through distribution, including the retail supply chain for cars, trucks, and airplanes.
Due to all these new technologies to convert algae into biofuel, algae-based fuels could be a long-term, sustainable source of fuels once producers comply with regulatory hurdles to authorize its use. These are important technologies to watch.
*Milsa Vijayadharan has a masters degree in Chemistry and experience working in scientific laboratories. As she keeps up with developments in advanced biofuels, she occasionally writes articles and adds posts to the Advanced Biofuels USA web site library.