Energy Storage in Carbon Neutral Fuels Leon Di Marco FSK Technology Research OU Energy 3 April 2014

Why Store Renewable Energy in HydroCarbon Fuels ? High Energy Density Compatible with infrastructure etc Made from water and carbon dioxide Used for transport and power generation Can be gas - methane CH 4, or liquid - octane C 8 H 18, diesel, kerosene Potentially lots of excess wind + solar

Making Components Hydrogen from electrolysis with renewable electricity - high energy + efficiency Future PhotoElectroCatalysis direct solar Carbon Dioxide captured from air (CO 2 from fossil flue gas has high net emissions) or BECCS CO 2 air capture in early stages of development

Direct Air Capture of CO 2 Use wet (dry) alkali to chemically bond to 400ppm airflow at 2 m / s Can be KOH or NaOH but very strong bond energy for recycling alkali Alternatives - carbonate / bicarbonate cycle Na 2 CO 3 + CO 2 + H 2 O 2 NaHCO 3 Ammonia (carbonate) or amines (but not MEA) or “ionic liquids”

Synthesising Fuel Methanation a standard process - Audi using CO 2 from biogas for car e-gas Synthetic gas to liquid fuel(s) Fischer-Tropsch catalysis is well understood and used by Shell to make synthetic diesel from methane in Qatar Very low net carbon emissions using renewable components

Conversion Efficiency Air Fuel Synthesis currently 45% using intermediate CO 2 + H 2 to methanol then standard methanol to gasoline process 70% from future high efficiency process using low energy CO 2 capture and co- electrolysis of CO 2 and H 2 O at high temp Waste heat used for air capture process and CHP

Costs Mainly arise from making hydrogen More expensive than fossil fuel with low carbon price - about twice Not necessarily prohibitive compared with alternative low carbon transport solutions Power2Gas captures excess renewable power that will otherwise be lost

Power2Gas 1 IWES study shows wind power can create 390 TWhr = 2/3 of German 2010 demand Grid storage for fluctuation = 0.04 TWhr but gas network storage = 217 TWhr and X 10 greater output rate Conversion efficiency >60% and use spare heat for CHP then use stored gas to fire generators when wind power is low

Power2Gas 2 Audi e-gas project with two 3.6 MW wind turbines giving 53 GWhr / year 2,800 tonne bio CO 2 makes 1000 tonnes e-gas Fuels 1500 A3 e-gas cars for 15,000km with 150 tonnes spare ( high efficiency turbo gas engines) Spare electricity powers 1000 A1 e-tron electric cars for 10,000 km WTW emissions < 30 gmCO 2 / km but life cycle emissions of e-gas car lower than e-tron

Stored Carbon in Fuel German gas network stores 21 bn m3 = 14 Mtonne methane or 37 Mtonnes CO 2 5 Tonne CO 2 embedded per car so offsets nearly 8 M cars or 20% of German fleet Better using liquid fuel with 1000 X density so about 2 m3 to offset a car Large strategic oil reserves - Germany 11 M m3, UK 3 Mtonnes (?)

Current Activity Liquid Fuels from air + water Air Fuel Synthesis ( UK) Sunfire (Germany), CRI ( Iceland ) e-gas methane Audi/Fraunhofer (Germany) Air Capture - Coaway, Kilimanjaro, Global Thermostat, Carbon Engineering - ( US / Canada ), Carbon Cycle ( UK), Climeworks ( Swiss ) 4 kg / day CO 2 demonstrator = 1 Tonne / year

Original IEEE paper Energy Storage via Carbon-Neutral Fuels Made From CO2, Water and Renewable Energy Proc IEEE Vol 100, No2, Feb 2012 Richard Pearson, lead author, and Jamie Turner Lotus Engineering, now BP and JLR Matt Eiseman on air capture - PARC, now Brookhaven National Lab Peter Edwards Oxford Uni Chemistry team

New Work on UK Advanced Fuels For DfT Advanced Fuel Consultation 2014 Looks at integrated transport solution with energy storage for power system - P2G Estimates that 10 million advanced hybrid cars can be fuelled for 10km using a 10GW wind farm in 2030, meeting EU urban rule Fuel cost > £1 / litre but only £ 0.05 / km

Future Work Fuel component R&D - CO 2 Chem network Integrated manufacturing plant High efficiency transport development Need for techno-economic model for UK with transport and power sector © FSK Technology Research 2014

References Goeppert et al, Air as the renewable carbon source of the future, Energy Env Sci 2012, Vol 5 Graves et al, Sustainable Hydrocarbon Fuels by recycling CO 2 and H 2 O with renewable or nuclear energy, Renew Sust Energy Rev, Vol 15, 2011 Sterner M, Renewable Power Methane, Fraunhofer IWES ( PhD thesis etc) Kay et al, Powering Ahead, RAC / Ricardo 2013 Advanced Fuels : call for evidence, DfT Dec 2013

Negative Emissions ? about 2 Ttonnes of fossil CO 2 already emitted - half is now in the sea, so about 2 kgCO 2 / m2 in air = 45 mol / m2 Desert Solar power = 270 W / m2 or 8 GJ / m2 / year Enough solar energy to remove 32,000 mol CO 2 per year Remove 1Ttonne over 40 years ie 25 Gtonne / year So use 1/ (40 X 750) = 1/30,000 of earth area = 20,000km2 this is 1% of Saudi land Machine aperture size 1000 km2 - say 10m X 100km “Great Wall of Carbon” 40 X 500km oblong with 2,500 strips every 200m