Photosynthesis. Harvest, dewatering, Lipid extraction, Transesterifictation/hydrotreating

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2 Algae, in one form or another, dates back ~3 billion yrs. into the Precambrian era. These eukaryotes (have a nucleus) use photosynthesis to convert the sun s light into energy. Algae biodiesel involves both solar energy and CO 2 sequestration: Photosynthesis Harvest, dewatering, Lipid extraction, Transesterifictation/hydrotreating

3 Algae grow much faster than land plants (can double biomass in one day!) and can have oil content up to 50% of the cell (dry-weight basis). 4 At 10 g biomass/m 2 d and oil content 15%: Crop Oil Yield (gal/km 2 ) Corn 4,448 Soybeans 11,861 Algae 156,412 Algae can be grown on non-arable land. Algae can grow in fresh or salt water, and even nutrientfilled wastewater. 4 Can be used to sequester carbon from flue gas. Possible issues with toxic flue gas components. Bi-prod. alcohol fermentation is 97-99% CO 2 by volume Knoshaug, Eric P., Al Darzins. Algal Biofuels: The Process. Society for Biological Engineering Supplement, Mar Rushing, Sam. Carbon Dioxide Sources and the Production of Algae. Oilgae Blog. 14 Sept Web. 5 Jun 2012.

4 Phosphorus is a key element of fertilizer, and it enables agriculture on today s scale. Must be mined; finite supply Predictions of shortages within next century Phosphorus runoff from farms is a serious issue. Depletes farmland of the mineral unnaturally quickly. Forms massive dead zones where the runoff is deposited. The Mississippi River delta is home to a 20,000 km 2 dead zone, and there are more than 400 worldwide, which cover over 245,000 km Vaccari, David A. Phosphorus Famine: The Threat to Our Food Supply. Scientific American. June 2009.

5 These dead zones are formed when the nutrients in the runoff create giant algal blooms. Blooms could be seen as a fuel source. Harvest could be used as a tool to recycle phosphorus. Trelleborg, Sweden harvests algae at effluent deposit, burns in biogas plant, uses residue as fertilizer. 1 Called struvite, sells for ~$577.45/ton 1. Alm, Anders. Using algae for phosphorus and nitrogen recycling in the Baltic Sea. Nordic Investment Bank Web. 1 Jun

6 Open Pond: Water can be channeled from nearby sources (lakes, rivers, sewage plants) Relatively inexpensive to build Uncontrolled evaporation (high water consumption) Exposure to weather can change water chemistry, allow for algal escape. High harvesting costs PBR: No evaporation loss=less water consumption Fine-tuned control over inputs and conditions of growth (light, ph, CO 2 levels, etc.) Scale up estimates vary; but assuredly more expensive than open ponds 6 Uses energy, which, if coming from fossil fuel source, will negate carbon neutrality Photosynthetic oxygen must be removed/let off 6. Scott, Stuart A., Matthew P Davey, John S Dennis, Irmtraud Horst, Christopher J Howe, David J Lea-Smith, Alison G Smith. Biodiesel from Algae: Challenges and Prospects. Current Opinion in Biotechnology, 17 Apr

7 Which to grow? Wanted: high lipid content high levels of triacylglycerides (biodiesel feedstock) Green algae species hold promise: Various Chlorella strains Botryococcus braunii (which can be up to 60% lipid by wt.) 6 Needs of the crop To produce enough algae to meet 15% of US diesel demand, we would theoretically need: 5 44,353 km 2 of land 770 million metric tons CO 2 For comparison, US currently has 1,788,710 km 2 zoned for cropland (source:usda) and the most polluting power plant in the US (Scherer in Juliet, AL) releases 25.3 million tons of CO 2 annually. (source:carma) 5. Pate, Ron, Geoff Klise, Ben Wu. Resource Demand Implications for US algae biofuels production scale up. Applied Energy, 11 May Scott, Stuart A., Matthew P Davey, John S Dennis, Irmtraud Horst, Christopher J Howe, David J Lea-Smith, Alison G Smith. Biodiesel from Algae: Challenges and Prospects. Current Opinion in Biotechnology, 17 Apr

8 After harvesting and drying, a transesterification rxn is used to convert the lipids from the biomass into biodiesel: Excess methanol is used to drive the rxn to completion. It is collected and reused. 3 Conventionally, this is a costly batch process that uses a liquid catalyst. Product purification, wastewater production 3. Demirbas, Ayhan, M. Fatih Demirbas. Importance of Algae Oil as a Source of Biodiesel. Energy Conservation and Management, 16 Jul

9 New York firm, United Environment and Energy, LLC, has developed a fixedbed reactor that allows for continuous production. Uses a solid catalyst Reactor contains a tube filled with solid catalyst; TAG solution flows over catalyst and is converted. 9 Claimed to be 40% cheaper than conventional method. 2 Photo Credit: Science Daily Head researcher James Wen (Vice President of company); work funded by NSF Planning pilot plant w/production capacity of 1million gal/yr American Chemical Society. "'First Economical Process' For Making Biodiesel Fuel From Algae." ScienceDaily, 25 Mar Web. 29 May Wen, Ben. Algae: A New Way to Make Biodiesel. LiveScience, 5 Jun Web. 29 May 2012.

10 Economically: In order for algae diesel to be competitive with petrodiesel, it must cost ~$0.48/L to produce. Assuming 30% oil by weight, production costs in a scaled-up process (10,000 ton biomass/yr capacity) would be: 3 $1.40 (photobioreactors) $1.81 (open pond) Main cost contributions are harvesting and cultivation. Improvements in these areas, genetic engineering, producing other high value products (such as struvite) could all drive cost down. 3. Demirbas, Ayhan, M. Fatih Demirbas. Importance of Algae Oil as a Source of Biodiesel. Energy Conservation and Management, 16 Jul

11 To generate 1 kg biodiesel from algae: 10 Method Water Needs (kg) N Needs (kg) No water recycling Ph Needs (kg) Water recycle Sea/wastewater * Thermal dewatering of algae consumes large amounts of energy (3556 kj/kg of water) and is the most energy intensive part of the entire process (69% of energy input). 7 Possibilities for solar drying exist, but are too slow for large-scale application. Enzyme use holds promise for energy reduction. 7. Sander, Kyle, Ganti S Murthy. Life Cycle Analysis of Algae Biodiesel. Int J Life Cycle Assess, 19 Jun Yang, Jia, Ming Xu, Xuezi Zhang, Qiang Hu, Milton Sommerfield, Yongsheng Chen. Life Cycle Analysis on biodiesel production from microalgae: Water footprint and nutrients balance. Bioresource Technology, * Assuming no Ph already in water

12 Still many technological challenges to overcome. Primary: making harvest less energy-intensive. Possibilities algae biodiesel holds are too great to not make the necessary investment. Quantitatively: Theoretical oil yield of 13X that of soybeans, 35X that of corn Fast growth: can double biomass in one day 1.5 to 3 pounds CO 2 sequestered/pound algae 12 Qualitatively: Wastewater treatment Phosphorus recycling no food vs. fuel dilemma 12. Rushing, Sam. Carbon Dioxide Sources and the Production of Algae. Oilgae Blog. 14 Sept Web. 5 Jun 2012.

13 There is no single solution to the task of moving humankind off of fossil fuels. Many intermediate steps. Evaluation before implementation. Some biofuels may be short-term tools for the present (sugarcane, corn). Others may represent more long-term future solutions (algae, genetically-engineered bacteria). Biofuels are important, but not the only answer.

14 1. Alm, Anders. Using algae for phosphorus and nitrogen recycling in the Baltic Sea. Nordic Investment Bank Web. 1 Jun American Chemical Society. "'First Economical Process' For Making Biodiesel Fuel From Algae." ScienceDaily, 25 Mar Web. 29 May Demirbas, Ayhan, M. Fatih Demirbas. Importance of Algae Oil as a Source of Biodiesel. Energy Conservation and Management, 16 Jul Knoshaug, Eric P., Al Darzins. Algal Biofuels: The Process. Society for Biological Engineering Supplement, Mar Pate, Ron, Geoff Klise, Ben Wu. Resource Demand Implications for US algae biofuels production scale up. Applied Energy, 11 May Scott, Stuart A., Matthew P Davey, John S Dennis, Irmtraud Horst, Christopher J Howe, David J Lea- Smith, Alison G Smith. Biodiesel from Algae: Challenges and Prospects. Current Opinion in Biotechnology, 17 Apr Sander, Kyle, Ganti S Murthy. Life Cycle Analysis of Algae Biodiesel. Int J Life Cycle Assess, 19 Jun Vaccari, David A. Phosphorus Famine: The Threat to Our Food Supply. Scientific American. June Wen, Ben. Algae: A New Way to Make Biodiesel. LiveScience, 5 Jun Web. 29 May Yang, Jia, Ming Xu, Xuezi Zhang, Qiang Hu, Milton Sommerfield, Yongsheng Chen. Life Cycle Analysis on biodiesel production from microalgae: Water footprint and nutrients balance. Bioresource Technology, recovery.tudarmstadt.de/index.php?option=com_content&task=view&id=58&itemid=1 12.Rushing, Sam. Carbon Dioxide Sources and the Production of Algae. Oilgae Blog. 14 Sept Web. 5 Jun 2012.

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