Conversion of CO 2 to fuel and back using high temperature electrochemical cells and solar/wind power

Transcription

1 Conversion of CO 2 to fuel and back using high temperature electrochemical cells and solar/wind power Christopher Graves <cgra@dtu.dk> Closing the Carbon Cycle: Fuels from Air conference at Arizona State University, Sept , Sept 2016

2 CO 2 -to-fuels: renewable transportation fuels Two sources of CO 2 point sources or the atmosphere Closed-loop C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) doi: /j.rser Sept 2016

3 Denmark s need for energy storage Storing excess renewable electricity Expected wind power supply compared with gross electricity consumption in Denmark in 2020 and The wind power supply data from 2012, obtained from energinet.dk, is simply scaled up so the total for the year comprises 50% and 100% of the total consumption. The electricity consumption is assumed constant; the consumption data from 2012 is used without re-scaling. CO 2 + H 2 O + electricity hydrocarbons Electrolysis on the Danish agenda! transportation fuel natural gas network (back to electricity) 3 29 Sept 2016

4 CO 2 /power-to-fuels via electrolytic hydrogen production Ingredients needed: Low cost electricity High efficiency system Low cost electrolysis, CO 2 capture, system capital cost 4 29 Sept 2016

5 Cost drivers for power-to-fuels OPEX Electricity cost Efficiency Here Stack efficiency System losses Theis O&M CAPEX Electrolyzer Resistance Anne Lifetime Anne, Theis, Here Capacity factor Here CO 2 capture device Yesterday Balance of system Here Latest levelized cost of installed solar PV: 2.99 /kwh (Dubai, May 16) and 2.91 /kwh (Chile, Aug 16) cleantechnica solarlove 5 29 Sept 2016

6 Electrolyzer efficiency and rates (why solid oxide cells?) C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO2 and H2O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) doi: /j.rser Sept 2016

7 Solid oxide cells: Commercialization Mainly SOFC so far for combined heat & power, and recently mobile, applications Competes with established gas turbines & engines, but higher efficiency + smaller scale vs turbines SOEC for H 2 /CO production using excess renewable electricity H 2 production competes with established alkaline electrolyzers, but with higher efficiency CO production for on-site specialty-gas supply HTAS initial niche market Small markets at the moment, huge growth expected Bloom Energy Servers (SOFC) 100s of MW installed since 2010 at Apple, AT&T, Bank of America, Coca-Cola, ebay, Google, Ikea, Kellogg, Target, Wal-Mart Nissan announced EV with SOFC rangeextender that runs on bio-ethanol (June 2016) 7 29 Sept 2016

8 Stack mass production factory economies of scale Well suited to achieving very low cost by automated mass production like in the electronics and automotive industries (and electronics-like energy technology like solar PV and batteries) D. Villareal PhD thesis, Sept 2016

9 Cost drivers for power-to-fuels OPEX Electricity cost Efficiency Here Stack efficiency System losses Theis O&M CAPEX Electrolyzer Resistance Anne Lifetime Anne, Theis, Here Capacity factor Here CO 2 capture device Yesterday Balance of system Here D. Villareal PhD thesis, Sept 2016

10 Balance of system cost and size (handling gas and heat flows) Literature studies estimate the SOC stack cost at 10-20% of the total installed CAPEX depending on system design Heat exchangers, power electronics, installation are each estimated to cost equal to double that amount D. Villareal PhD thesis, Sept 2016

11 Reconsidering large chemical plants mass produced systems Sept 2016

12 Power-to-methanol plants Currently operational Proposed, conventional chemical plant Carbon Recycling International (CRI) alkaline H2O electrolysis + CO2+H2 to methanol SOEC methanol plant design (Haldor Topsoe) J.B. Hansen, N. Christiansen, J.U. Nielsen, Production of Sustainable Fuels by Means of Solid Oxide Electrolysis, in: ECS Transactions 35(1), Montreal, QC, Canada, 2011: pp doi: / Sept 2016

13 Power-to-methanol device Proposed: integrated, self-contained, mass-produced, everything at 50 bar S.H. Jensen, X. Sun, S.D. Ebbesen, R. Knibbe, M. Mogensen, Hydrogen and synthetic fuel production using pressurized solid oxide electrolysis cells, International Journal of Hydrogen Energy. 35 (2010) doi: /j.ijhydene System scale Efficiency CAPEX Installation cost CRI operating plant Large ~50% High High HTAS plant design Large 80% High High Proposed Small 80%+ Low Low Sept 2016

14 Power-to-fuel devices Commercialized MicroCHP / micro power generation Let s aim for Micro power-to-fuel production Bloom boxes Sept 2016

15 Lowering the system cost OPEX Electricity cost Efficiency Here Stack efficiency System losses Theis O&M CAPEX Electrolyzer Resistance Anne Lifetime Anne, Theis, Here Capacity factor Here CO 2 capture device Yesterday Balance of system Here Mass production Integration Reversible operation Sept 2016

16 Reversible operation of solid oxide cells Conversion of CO 2 to fuel and back using high temperature electrochemical cells and solar/wind power (H 2 O not shown) Sept 2016

17 Reversible operation of solid oxide cells Electrolysis mode electricity fuels Fuel cell mode fuels electricity Perform almost equally well in both modes C. Graves, S.D. Ebbesen, M. Mogensen, Co-electrolysis of CO2 and H2O in solid oxide cells: Performance and durability, Solid State Ionics. 192 (2011) doi: /j.ssi current density (A/cm 2 ) Sept 2016

18 Reversible operation yields longer cell lifetime Constant electrolysis vs charge-discharge cycles Highly enhanced stability! C. Graves, S.D. Ebbesen, S.H. Jensen, S.B. Simonsen, M.B. Mogensen, Eliminating degradation in solid oxide electrochemical cells by reversible operation, Nature Materials. 14 (2015) doi: /nmat Sept 2016

19 Two scenarios for reversible operation Controlled directly by time-series data: 1. Electricity supply/demand energy balancing driven 100% wind for a Danish island Power-to-methanol(-to-power) 2. Spot market prices of electricity and natural gas price driven Power-to-methane (buy electricity, sell gas) Natural gas-to-power (buy gas, sell electricity) Capacity factor increase by market expansion Sept 2016

20 100% wind power for a Danish island Existing wind power supply scaled up to meet total energy demand (electricity + fuel) (and heat demand met as byproduct because all energy conversion losses are in the form of heat) diesel transport, 6.95 gasoline transport, 1.85 electricity, 2.3 electric heat, 1.6 Minus ~4 MW avg diesel for ferries (shown here but not included in C. Graves, J.V.T Høgh, M. Chen, balancing) et al (in preparation) oil heat, solar heat, biomass heat, Sept 2016 heat (district), 4.9

21 Long-term load-balancing stack test 8-cell stack 800 C Energy balancing simulation C. Graves, J.V.T Høgh, M. Chen, et al (in preparation) Actual stack data Sept 2016

22 Wind Solar C. Graves, J.V.T Høgh, M. Chen, et al (in preparation) Sept 2016

23 Fuel cell mode Anode recycling 1 2 O 2 CH 3 OH Methanator CH4 O 2 O C SOC stack >0.8V, <0.5 A/cm 2 HX fluid H 2 O(g) +CO 2 (+H 2 +CO) HX fluid H 2 O(l) 3 4 H 2 O CO 2 (+H 2 +CO) In SOC stack: CH H 2 O+0.5CO 2 +Q 3.5H CO 2 H 2 +CO 2 +Q shift H 2 O+CO H 2 +½O 2 H 2 O+E+Q The reforming composition for the first reaction is just an example and not the real one. System runs independently. DME synth. Methanol synth. electricity heat Recycle heat Air capture System runs independently. Electrolysis mode Co-electrolysis In SOC stack: 1 2 O 2 CH 3 OH Methanator CH4 O 2 O C SOC stack <1.4V, <1 A/cm 2 H 2 O(g) +CO 2 (+H 2 +CO) H 2 O(l) 3 4 H 2 O CO 2 (+H 2 +CO) CO 2 +2H 2 O+E CO+2H 2 (+1.5O 2 ) H 2 +CO 2 H 2 O+CO (4H 2 +CO 2 CH 4 +2H 2 O+Q at suitable T and P) System runs independently. DME synth. Methanol synth. heat electricity Recycle Air capture System runs independently Sept 2016 C. Graves, J.V.T Høgh, M. Chen, et al (in preparation)

24 Electricity price driven Energikoncept 2035 scenario, energinet.dk Peaking generation (SOFC) From Norway Storage (SOEC) Spot market prices, 2008, energinet.dk Operate fuelcell mode Reversible operation in the Danish scenario Operate electrolysis mode Sept 2016

25 Reversible operation controlled by electricity & gas spot prices Electrolysis mode switch D. Villareal PhD thesis, Sept 2016

26 Electrolysis mode growing each year as wind supply grows Mode of operation per year Profits from each mode per year Near term: price volatility due growing variable wind is good for reversible systems (short periods of electrolysis high profits) With predicted 2050 time-seies data (100% wind electricity supply), profits by playing this game are much higher, even though the reversible system may erode the volatility and make per hour profit from electrolysis lower D. Villareal PhD thesis, Sept 2016

27 Overall fuel production cost (after mass production scale-up) 100% capacity factor 20% capacity factor If we will turn around and convert it right back to electricity, need not be convenient, portable, high energy density and plug into existing infrastructure need not be liquid hydrocarbon storage. C. Graves, S.D. Ebbesen, M. Mogensen, K.S. Lackner, Sustainable hydrocarbon fuels by recycling CO 2 and H 2 O with renewable or nuclear energy, Renewable and Sustainable Energy Reviews. 15 (2011) Sept 2016

28 Conclusions High temperature electrochemical cells offer a higher efficiency CO 2 /power-to-fuels system Lower cost expected by mass produced integrated device Lower cost by reversible operation: longer lifetime Increased capacity factor (dual markets) with only minimal system cost increase to add fuel-cell mode Low cost solar/wind power has arrived Grid surplus in spot markets Standalone solar PV < 3 /kwh Now we need to get the power-to-fuel technology ready! Sept 2016

29 Acknowledgements Diego Villarreal PhD project with Klaus Lackner Ming Chen Jón S.G. Mýrdal Peter V. Hendriksen Jens Høgh Karsten Agersted and other colleagues at DTU Energy Funding: projects: Solid Oxide Electrolysis for Grid Balancing ( ) Towards Solid Oxide Electrolysis Plants in 2020 ( ) Solid Oxide Fuel Cells for the Renew-able Energy Transition ( ) Sept 2016