30 March 2010 17:49 [Source: ICIS news]
By Frank Zaworski
HOUSTON (ICIS news)--As children, early science lessons taught us that the petroleum we use for energy was formed hundreds of millions of years ago from the remains of plants and animals that were covered by sediment and subsequently subjected to the digenetic forces of heat and pressure.
During the Carboniferous Period of 354m to 290m years ago, the Earth was a warm, wet and swampy place, an ideal environment for the production of plants such as giant ferns and algae, lots of algae. Pile on a few million years of sediment in the form of limestone and sandstone, and voila, the resultant heat and pressure caused the pyrolysis that resulted in the coal and petroleum deposits found in many places around the globe.
Now scientists say a goodly portion of the petroleum found today might not have required heat and pressure over geologic time to become what we know as fossil fuel. Thanks to a lot of green algae, it may have already been 'fuel' when sediment started piling up.
A team of scientists at Texas A&M University, College Station, Texas, working with green algae to produce biofuel, said algae have been producing biofuel for hundreds of millions of years.
“Oils from the green algae Botryococcus braunii can be readily detected in petroleum and coal deposits, suggesting that B braunii has been a contributor to developing these deposits and may be the major contributor,” said Dr Timothy Devarenne, AgriLife Research scientist with the Texas A&M department of biochemistry and biophysics.
B braunii is a prime candidate for biofuel production because some races of the green algae typically accumulate hydrocarbons from 30% to 40% of their dry weight, and are capable of obtaining hydrocarbon contents up to 86% of their dry weight, Devarenne said.
According to the US Department of Energy (DOE) Joint Genome Project, B braunii is a colony-forming green microalga of the species Chlorophyceae. It is found in many environments across the globe and has been noted to be capable of growing in both freshwater and brackish environments.
During its growth cycle, the algae synthesise long-chain liquid hydrocarbon compounds and sequester them in the extracellular matrix of the colony to afford buoyancy.
The oils of B braunii, a family of isoprenoid compounds termed botryococcenes, hold the most promise as an alternative energy source, the DOE said. Botryococcenes have been converted to fuel suitable for internal combustion engines through caustic hydrolysis.
The fuels derived from B braunii hydrocarbons are chemically identical to gasoline, diesel and kerosene.
“Thus, we do not call them biodiesel or bio-gasoline - they are simply diesel and gasoline,” Devarenne said.
The ability of algae to produce usable fuels has ignited the interest of many companies and research organisations, including ExxonMobil Research and Engineering Company (EMRE), which has partnered with California’s Synthetic Genomics Institute (SGI) with a $600m (€444m) multi-year investment to develop, test and produce biofuels from photosynthetic algae.
Through aggressive and comprehensive research and development, EMRE and SGI will work together to develop solutions for the challenges of large-scale production and commercialisation of biofuels from photosynthetic algae.
These challenges include identifying or developing algal strains that can achieve high bio-oil yields at lower cost, determining the best production systems for growing algal strains - either in open (ponds) or closed (for example, tubular) photobioreactors - and determining how to supply the large amounts of carbon dioxide needed to grow algae while also providing benefits for mitigating greenhouse gas emissions.
Additionally, the collaboration will study development of the large, integrated systems required for full-scale, economic production, and the upgrading and commercialisation of biofuels.
Algae have the potential to yield greater volumes of biofuel per acre of production than other biofuel sources, ExxonMobil said. Algae could yield more than 2,000 gal of fuel per acre per year of production, compared to a mere 50 gal/year/acre from soybeans.
According to researchers at Texas A&M, using green algae to produce hydrocarbon oil for biofuel is nothing new; nature has been doing it for hundreds of millions of years.
($1 = €0.74)
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