Scale up of Algae Biofuels: Challenges and Opportunities

1. Scale up of Algae Biofuels: Challenges and Opportunities Christopher Harto Argonne National Laboratory

2. Purpose • Take a very wide perspective look at algae biofuel systems • Identify major challenges to scale up • propose potential pathways for overcoming them (DOE) (DOE) Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

3. Outline • Economic Input-Output LCA • Nutrient mass balance (C, N, P) • Challenges and future research areas Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

4. Algae Growth Requirements • Land/solar energy • Water • Energy • Carbon • Nitrogen • Phosphorus Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

5. Economic Input-Output LCA • Analysis based upon 1996 technoeconomic analysis by NREL at the conclusion of aquatic species program (Benemann and Oswalt 1996) • Uses 1997 US model in EIOLCA.net • Co-Products allocated based on energy content • Impacts Considered • CO2 • Energy Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

6. System Specifications • 400 ha, unlined, open pond • Paddle wheel mixing • Harvest through flocculation and settling along with 3 phase centrifuge • Extraction through hot oil emulsion in centrifugation step • Non-lipid biomass converted to methane through anaerobic digestion • Energy output 25% methane, 75% lipids • N recycle 50%, P recycle 75% • Productivity 30 g/m2/day and 50% lipids content Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

7. Results Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

8. Results Breakdown Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

9. Sensitivity Studies Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

10. Sensitivity Studies Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

11. Sensitivity Studies Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

12. Nutrient Mass Balances • Look at impact of scale up on flows and availability of C, N and P • Use simple mass balance approach • Assumptions: • 100% utilization efficiency Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

13. Carbon Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

14. Carbon Analysis • Due to day/night cycle and fraction point sources likely only 20-30% of total emissions viable for feedstock • Global carbon agreements may reduce total by as much as 80% of current flows • Only 4-6% of current carbon emissions likely available for long run algae fuels production • Realistic long term US algae fuel production ~ 1,000,000 barrels per day (5% of current liquid fuels consumption) Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

15. Carbon Mass Transfer • In absence of point sources, growth likely to be mass transfer limited • At current atmospheric CO2 concentration and 30% lipids content, CO2 from 1,100,000 m3 of air must be extracted to produce 1 barrel of algae oil Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

16. Nitrogen Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

17. Nitrogen Analysis • Nitrogen probably a soft limit as fertilizer production can be scaled up reasonably easily using Haber-Bosch process • H2 for process from methane produced by biomass or solar electrolysis • Alternative N sources from NOx in flue gas, wastewater or nitrogen fixing organisms • Increasing demand will probably spill over and affect agricultural markets through fertilizer price increases Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

18. Phosphorus Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

19. Phosphorus Analysis • P uptake can vary by order of magnitude depending on conditions • Typically must be supplied in excess due to tendency to complex with metal ions and become unavailable to organisms • P is mined with limited supplies in very few places – 50% global reserves in Morocco • Total P reserves maybe 50-100 years • Like N, competes with agriculture for nutrient supply Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

20. Key Research Areas • Nutrient utilization efficiency and recycling processes • Use of organisms that excrete product • Organisms with low N and P demands • Better understand potential for atmospheric carbon mass transfer • Improve understanding and management of global P cycle • Seek synergies and ways to close loops, use waste streams as nutrient sources Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

21. Agricultural Run Off and Ocean Dead Zones? • Opportunities? • Rivers concentrate agricultural runoff w/ high N and P concentration • Can they act as a water AND nutrient source? • Massive Algal blooms occur which subsequently die • Can they be harvested? • Dead organisms sink to bottom and decompose using up O2 supply creating anoxic conditions • If nutrients or organisms removed before death, is there still harm to the ecosystem? Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference

22. Thank You! Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference