Flare Gas Recovery for Algal Protein Production

Transcription

1 Phoenix, Az Flare Gas Recovery for Algal Protein Production C. M. Beal 1, F.T. Davidson 2, M. E. Webber 2, J. C. Quinn 3 1 B&D Engineering and Consulting LLC, 7419 State Hwy 789, Lander, WY 2 The University of Texas at Austin, 1 University Station, Austin, TX 3 Colorado State University, 1 Isotope drive, Fort Collins, CO 1

2 Acknowledgements Financial support provided by U.S. Department of Energy (DE-EP ) Alfred P. Sloan Foundation, and the Cynthia and George Mitchell Foundation Colorado State University Special thanks to: Danna Quinn Barb and Fred 2

3 Outline Flare Gas & Algae General Overview of Methods Energy Return on Investment Life Cycle Assessment Modeled Scenarios Results Potential Comparison to literature Future Direction 3

4 Algae Challenges Energy intensive Growth Harvest Drying High Nutrient Demand Nitrogen Phosphorus Carbon Dioxide Economic Viability 4

5 Flare Gas Volume of flared natural gas:140 billion cubic meters per year 10x the Colorado River in GCNP 1% of US annual production 5

6 Global Challenges Need for Alternative Protein Production Algae is promising: no land or freshwater requirements, efficient nutrient use 6 OECD-FAO Agricultural Outlook

7 Flare Gas + Algae Synergy Coupling flare gas and algae can: 1) Generate second-generation biofuels 2) Produce protein for a growing population 3) Increase omega-3 production 4) Eliminate environmental damage of flaring Production requires no arable land, freshwater, external N, or external CO 2. 7

8 Outline Flare Gas & Algae General Overview of Methods Energy Return on Investment Life Cycle Assessment Modeled Scenarios Results Potential Comparison to literature Future Direction 8

9 Methods Sustainability Modeling EROI LCA Multi-Pathway Assessment System Modeling Multiple Scales Technology Integration 9

10 System Model: Simplified System Boundary Flare Gas CHP Algae Harvest Product Recovery Ammonia Production Protein & Biocrude

11 System Model

12 Foundational Inputs Abbreviated Inputs Amount Unit Flare Gas Recovery Volumetric Flow Rate of Flare Gas 3,000 m 3 /d Combined Heat and Power Electricity Production Efficiency 44% - (Net) Heat Recovery Efficiency 38% - Overall Plant Efficiency 82% - Ammonia Production Electricity Input 0.70 MJ/kg ammonia Heat Input 12.6 MJ/kg ammonia Water Consumption 1.20 kg/kg ammonia Algae Cultivation Algae Facility Size 40.0 ha Mixing Energy Demand 100 kwh/ha-d Productivity 25.0 g AFDW/m2-d Lipid Fraction 0.25 kg lipid/kg AFDW Protein Fraction 0.40 kg protein/kg AFDW Algae Harvesting Overall Harvesting Efficiency DAF Electricity 431 kj/kg algae Centrifuge Electricity 0.11 kj/kg algae Bioproduct Separations Drying Heat 7.23 MJ/kg algae Electricity Consumption 79.9 kj/kg algae Extraction Heat Consumption 864 kj/kg algae Solvent Consumption 1.26 g/kg algae Biocrude Recovery 0.24 kg biocrude/kg algae Lipid-extracted Biomass Recovery 0.75 kg LEA/kg algae CHP: 82% overall efficiency (heat & electricity) Productivity: 25 g m-2 d-1, 25% lipid Harvesting: DAF & Centrifuge Product separation: Dry solvent extraction 12

13 Methods Sustainability Modeling EROI LCA Multi-Pathway Assessment System Modeling Multiple Scales Technology Integration 13

14 Energy Return on Investment Includes all embodied energy in materials Includes upstream energy impacts (embodied energy) EROI > 1 is desirable Displacement method applied to co-products EROI = E out E in 14

15 Energy Intensity of Protein Includes upstream energy for materials and energy consumed onsite Total energy input is divided by product yield EI = E in M out 15

16 Life Cycle Assessment Metric: IPCC 100 year global warming potential CO 2, CH 4, and N 2 O emissions Co-product allocation: Displacement and Energy Life Cycle Inventory Data 16

17 Scenarios: Accounting Methods Case I: baseline (flare gas is waste stream from Oil & Gas), excess electricity delivered Case II: Excludes excess electricity Case III: Includes energetic cost of methane Case IV: Excludes excess electricity and includes energetic cost of methane Case I is most promising, Case IV is lease promising 17

18 Outline Flare Gas & Algae General Overview of Methods Energy Return on Investment Life Cycle Assessment Modeled Scenarios Results Potential Comparison to literature Future Direction 18

19 EROI Results Output Input Case I Case II Case III Case IV Biocrude 19,899 19,899 19,899 19,899 Animal Feed 30,597 30,597 30,597 30,597 Net Electricity Yield 95, ,463 0 Flare Gas , ,500 Ammonia Production Cultivation Separations Total EROI Baseline (Case I) Inputs minimized through CHP, electricity sold to grid, flare gas assumed as waste Case II Assumes electricity cannot be sold to grid Case III Includes energetic costs of flare gas (effectively a gas-powered algae plant) Case IV Worst case scenario (combination of Case III & IV) 19

20 Beal 2011 HPC Case IV EROI Results Soy Biodiesel Quinn 2014 Batan 2010 Case III Other Algae Studies, EROI ~ 1 Beal T Corn Ethanol Refined Diesel Nuclear Solar Oil and Gas at Well Cases I & II, EROI > 60 Wind Power Case II Coal Case I EROI 20

21 Energy Intensity: Food Products Case I Case II Corn Soy Meal Wheat Apples Milk Oranges Cooked Pasta Fishmeal Eggs Chicken Pork Beal T French Fries Case III Beef Case IV Cases I & II, Negligible Energy Input for Food/Feed Production Cases III & IV, If flare gas is not a waste product, energy intensity increases drastically Energy Input (MJ/kg-product) 21

22 Case I Case II Corn Soy Meal Wheat Apples Milk Oranges Cooked Pasta Fishmeal Eggs Chicken Pork Beal T French Fries Case III Beef Case IV Energy Intensity: Protein Cases I & II, Energy Intensity < Soy, Meat Energy Input (MJ/kg-protein) 22

23 Life Cycle Results Grid Electricity 167 Refined Diesel Conventional Gasoline Solar Cases I, II, & III, Huge GHG Savings Case IV Corn Ethanol Soy Biodiesel Case II -398 Case III -523 Case I GHG Emissions (g CO2eq/MJ) 23

24 800 Life Cycle Results GHG Emissions (g-co 2-eq MJ -1 )

25 Sensitivity Analysis Algae Meal Ren. vs Total Energy Impact⁴ Flare Gas HHV Electricity Generation Efficiency Biomass Productivity Biomass Recovery³ Biocrude Recovery² Compression Energy (Flare and CO₂) Lipid Content C:N:P Uptake Rates¹ Circulation Energy Harvesting Energy Water Supply Energy Recycling and Discharge Water Energy Separations Electricity Heat Recovery Efficiency Percent Change in EROI for Cases I Case I Favorable Case I Unfavorable Importance of accounting methods -20% -15% -10% -5% 0% 5% 10% 15% 20% 25

26 Conclusion Flare gas and algae are energetically and environmentally synergetic. These technologies yield: Protein Biofuel Omega 3 Fatty Acids GHG reductions Without: Arable Land Fresh Water Additional N or CO 2

27 Future Work Development of a full TEA GIS sit identification Potential for global deployment Address energy and protein demands