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

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

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 3

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

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 –CO 2 –Energy Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 5

System Specifications Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 6  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

Results Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 7 GWP g CO 2 e/galEnergy MJ/gal Capital Impacts Operating Impacts Total Impacts Diesel Fuel Output/Input

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

Sensitivity Studies Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 9 Scenario NameProductivityLipid %Allocation MethodN Recycle %P Recycle % Baseline3050Energy (methane)5075 No Recycle3050Energy (methane)00 Displacement3050Displacement (electricity)50 Electricity Co-Product3050Energy (electricity)50 Double Productivity6050Energy (methane)5075 Half Productivity1550Energy (methane)5075 Half Lipids3025Energy (methane)5075 Achievable EA1525Energy (methane)5075 Achievable DA1525Displacement (electricity)5075 Achievable NR1525Energy (methane)00

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

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 12 SourceC%N%P% shastri 2005 (Synechocystis) Grobbelaar 2004 (microalgae) Powell 2008 (Scenedesmus spp.) 0.4 to 3.2

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

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 14

Carbon Mass Transfer  In absence of point sources, growth likely to be mass transfer limited  At current atmospheric CO 2 concentration and 30% lipids content, CO 2 from 1,100,000 m 3 of air must be extracted to produce 1 barrel of algae oil Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 15 Algae Lipid ConcentrationVolume of Air at STP Required to Supply Carbon to Produce One Gallon of Fuel (m 3 ) 15%52,000 30%26,000 50%16,000 70%11,000

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

Nitrogen Analysis  Nitrogen probably a soft limit as fertilizer production can be scaled up reasonably easily using Haber-Bosch process –H 2 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 17

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

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 years  Like N, competes with agriculture for nutrient supply Environmental Science Division, IPEC 17th International Petroleum & Biofuels Environmental Conference 19

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 20

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 21

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