Presentation on theme: "Flue Gas CO 2 Capture with Rapid Growth Algae to Produce Biodiesel and Other Renewable Fuels An Xcel Energy Renewable Development Fund Grant RD3-2 – Final."— Presentation transcript:
Flue Gas CO 2 Capture with Rapid Growth Algae to Produce Biodiesel and Other Renewable Fuels An Xcel Energy Renewable Development Fund Grant RD3-2 – Final Presentation 8/9/2011
Objectives of the RDF Grant (M1) Review literature on existing methodologies for algae cultures. Construct a lab-scale bioreactor. Establish optimal operating parameters for the lab-scale bioreactor. (M2) Select and collect algae samples. Establish algae cultures and cultivate algae in the laboratory. Optimize the algae growth parameters. Analyze and profile algae compositions. (M3) Scale up cultivation of algae to a large scale. Analyze algae composition and test algae cultures. Develop algae preservation process. (M4) Develop algae oil extraction process, extract algae oil and produce biodiesel from the algae oil with the optimized Mcgyan ® process. (M5) Test biodiesel and confirm that the fuel meets ASTM standards. Investigate alternative markets for the algal biomass and the residual fractions left after biodiesel production. Conduct data analysis and large-scale feasibility study of the CO 2 to algae to biodiesel process. Validate project results.
Reasons for Selecting Dunaliella tertiolecta Published literature led us to it Fast growth rate & good potential to fix large amounts of carbon dioxide Known to produce 30% - 50% total lipid Possesses favorable attributes Grows at temperatures up to 104° F Resistant to contamination from other organisms due to saline environment
Algae Growth Rate Comparison Algae SpeciesAverage Growth (g/L/day) D. tertiolecta.0790 D. parva.0446 D. salina.0375 N. oculata.0556
Algae Carbon Dioxide Capture (tons/acre/year) SpeciesBased on Harvest*Based on Growth Rate** D. tertiolecta 42.1261.77 D. parva 16.6923.49 D. salina 15.9116.23 N. oculata 26.0937.96 *Based on harvest: average grams dry matter/liter/day used in calculation. **Based on growth rate: increase in optical density used in calculation.
Dunaliella tertiolecta Composition Analysis performed by Minnesota Valley Testing Labs
Harvesting Algae Primarily harvested by centrifugation followed by dehydration and pulverizing Electrolytic flocculation tested, found effective at separating algae cells from liquid medium Time-consuming process Electrolytic flocculation faster than centrifuge
Dried & Pulverized Algae Dried in vacuum oven or food dehydrator then pulverizedin a ball mill – several techniques were tested
Lipid Extraction Process Soxhlet method used to extract neutral lipids Neutral lipid yield averaged 3.9% of dry weight Batch-to-batch yield was variable About 1/3 of total lipids are neutral lipids or free fatty acids, useful for making biodiesel Activated carbon used to remove pigment from extracted material Multi-step process
D. tertiolecta based biodiesel ASTM fuel analysis
Potential Markets for Residual Biomass Algae cake for animal feed (high protein) Cosmetic & antioxidant products Oils from pyrolysis Co-combustion with coal to produce heat Bioconversion to produce methane, etc. These uses may qualify for carbon credit Presence of heavy metals would rule out animal feed and cosmetics applications
Scale up Feasibility Raceway ponds recommended, 0.3M deep Paddlewheel mixers to run 24 hours/day Flue gas diffusion into deeper, sump area 300 days/year operation Piping & pumps needed to deliver flue gas, makeup water & heat to ponds and transport algal slurry to harvesting equipment Power plant could fulfill needs for heat
Project Benefits Significant quantities of carbon were captured (fixed) by the algae in intensive culture environment Capture of CO 2 emissions was shown to be viable Algae can produce feedstock oil for biodiesel fuel at a higher rate than traditional soybean oil productivity The Mcgyan ® process will convert all of the neutral lipids to biodiesel, including free fatty acids; traditional processes are unable to do this This process produces a valuable, renewable, universally consumed fuel while helping to reduce green house gas emissions from coal burning power plants Revenue generating products produced which can be used to offset the costs associated with the process New jobs would be created in the process of commercializing this technology This process will not compete with food crops to produce fuel
Usefulness of Project Findings Carbon emissions from a power plant can be brought full-circle and create a useful fuel in the process CO 2 emissions directed into microalgae can result in less money spent on paying taxes on carbon emissions; this may curtail rate increases to the consumers Algae have value for making biodiesel fuel or bio chemicals Algal solids can be burned to help fuel the generation of electricity Algal components, such as protein, could potentially be sold as additives for animal feed, fertilizer or other products One result could be greater diversification in the Minnesota economy and creation of new jobs
Project Lessons Learned Manipulation of the growth medium influences the algal growth rate Light penetration, circulation of the cultures and uninterrupted flow of CO 2 are essential to a thriving algae population Maintaining a pH that is neutral or somewhat acidic ensures more efficient utilization of CO2 and higher growth rates Outdoor cultures are more likely to have problems with competing organisms Harvesting at the most appropriate stage of growth helps to prevent algal self-shading and helps sustain high growth rates. There are limitations on re-using the post-harvest algae growth medium due to build up of metabolites such as glycoproteins, which inhibit algae growth
Conclusions, suggestions for further research Delivering flue gas to many ponds over a large area would require a significant amount of capital equipment. Techniques for concentrating and delivering CO 2 would be desirable; this might involve learning whether the CO 2 can be attached to a salt and pelletizing it or liquefying the CO 2. Extraction of neutral lipids from algae presented challenges. Developing techniques that are economical, fast, reliable and thorough would be highly desirable. Harvesting micro algae continues to be a time-consuming and expensive procedure. Finding more cost effective methods of harvesting would be important. Complete transfer of CO 2 into the liquid medium does not take place. Finding ways to improve mass transfer of CO 2 to the liquid would be helpful in reducing the amount that is exhausted to the atmosphere.
Acknowledgements Xcel Energy, Inc. - Renewable Development Fund Dr. Arun Goyal Dr. Mary Ann Yang Nick Blixt Robert Quigley Joel Schumacher, P.E. Cool Clean Technologies Solution Recovery Services Water 360, LLC Dr. Dan Nowlan Dr. Ben Yan Shane Wyborny Julie Jenkins Ever Cat Fuels, LLC