Algal Biofuels Dr. Patrick J. P. Brown

Topics to be covered Reasons for researching algae as a source of biofuels Botryococcus braunii and its various oils Hydrogen production by algae

U.S. petroleum consumption The production of crude oil in the united states peaked around 1965 Since then domestic production has declined steadily Our imports of oil have risen from just over 4,000,000 barrels a day in 1983 to 11,000,000 barrels a day in 2008 There is therefore a real bad need for some other source of fuel if we want to keep driving trucks

Are renewable fuels the wave if the future? According to wikipedia there are only about 50 years worth of oil left There are already cars that burn E85 gas or biodiesel Ethanol can be made by fermenting sugary crops like corn, sugar cane, & beets. Its hard to grow enough corn to make all the ethanol we’d need to run everything on E85 Vegetable oils can be transesterified to produce methyl-ester fatty acids that can be burned in conventional diesel engines This so-called biodiesel has similar energy densities to conventional petro-diesel Hydrogen gas can power a fuel cell, but curent methods for extracting hydrogen from water are too costly

Pond scum in the gas tank? There are many new companies out there betting on turning pond scum (algae) into usable fuel Algae are little microscopic plants that live in ponds and oceans Algae can grow much faster than terrestrial crops and many produce more sugars than even the highest yield crops (like sugar cane) Other species produce triglycerides that can be transesterified just like vegetable oils to yield biodiesel Still other algae have fats and waxes that can be turned into gas if you run it through a hydrocracker Even other algae directly make hydrogen gas that can be captured and used for fuel cell vehicles.

Botryococcus braunii Botryococcus braunii From Wikipedia, the free encyclopedia Botryococcus braunii (Bb) is a green, pyramid shaped planktonic microalga of the order Chlorococcales (class Chlorophyceae) that is of potentially great importance in the field of biotechnology. Colonies held together by a lipid biofilm matrix can be found in temperate or tropical oligotrophic lakes and estuaries, and will bloom when in the presence of elevated levels of dissolved inorganic phosphorus. The species is notable for its ability to produce high amounts of hydrocarbons, especially oils in the form of Triterpenes, that are typically around 30-40 percent of their dry weight.[1] Compared to other green algae species it has a relatively thick cell wall that is accumulated from previous cellular divisions; making extraction of cytoplasmic components rather difficult. Fortunately, much of the useful hydrocarbon oil is outside of the cell.

Botryococcus Braunii

Biodiesel Currently soy beans are the number one crop for biodiesel production Like corn-based ethanol, the yields are rather low and it diverts a food crop into energy According to NREL there are several pond scums that produce extractable oil in amounts that could be economically feasible

Algae into biodiesel Scenedesmus dimorphus produces the highest yield of oils, but is heavy and forms bottom sludge if not agitated Dunaliella tertiolecta has a oil yield of 37% dry weight and sequesters more CO2 than any other green alga Both green algae species remove nitrate from the water and could be used to limit eutrophication Phaeodactylum cornatum (a diatom) is favored for its combination of fast growth rate and excellent yield of both oil and fermentable carbohydrates, but it requires silica as an essential nutrient

Hydrogen Production by algae One of the most difficult hurdles in fuel cell technology is getting enough hydrogen fuel to make them worthwhile Also, hydrogen is an energy carrier, not an energy source, so power must be expended to generate it (i.e. from a powerplant that could be fueled by fossil fuels) Currently 95% of hydrogen is produced by steam reforming of natural gas = nonrenewable Algal production of hydrogen would make it a much more environmentally friendly and renewable alternative

Hydrogen is produced in response to stress Many algae will switch from photosynthesis to fermentive pathways when subjected to nutrient deprivation The cyanobacterium Synechocystis responds especially well to moderate sulfur deficiency in the presence of ammonium 3 Strains of the green alga Chlorella have been shown to produce very high quantities of hydrogen gas under sulfur deprivation and microaerobic conditions

Autotrophic cultivation of Botryococcus braunii for the production of hydrocarbons and exopolysaccharides in various media C. Dayananda, R. Sarada, M. Usha Rani, T.R. Shamala, and G. A. Ravishankar Biomass and Bioenergy, 2007

BG11 is better than Chu 13 or derivataves of Bold’s Basic Medium, including one with added Si

A 16:8 light:dark regimine seems to work best for production of hydrocarbons

Unlike carbohydrates, exopolysacchraides are produced best when there is constant illumination and shaking.

Conclusions Algae are the future of the U.S. energy market Algae produce sugars that can be fermented into ethanol, lipids that can be turned into diesel, hydrogen gas for fuel cells, and hydrocarbons that can be turned directly into gasoline Botryococcus braunii grows best in BG11 medium Botryococcus braunii produces the most hydrocarbons on a 16:8 light:dark cycle Botryococcus produces the most exopolysaccharides with continuous light and shaking

References http://www.technologyreview.com/Energy/19438/ www.nrel.gov/docs/legosti/fy98/24190.pdf Ladygina, N., Dedyukhina, E.G., & M.B. Vainshtein (2006) A review of microbial synthesis of hydrocarbons. Process Biochemistry 41 (11) 1001-1014 http://en.wikipedia.org/wiki/Fuel_cell http://pubs.ext.vt.edu/442/442-886/442-886.html Dayananda, C., Sarada, R., Usha Rani, M., Shamala, T.R., & G.A. Ravishankar (2007) Autotrophic cultivation of Botryococcus braunii for the production of hydrocarbons and exopolysaccharides in various media. Biomass & Bioenergy 31: 87-93 http://www.oilgae.com/algae/oil/yield/yield.html http://en.wikipedia.org/wiki/Biodiesel http://www.eia.doe.gov/