Electrolysis without Membranes Glen O’Neil, Oyin Talabi, David Brown, Cory Christian, Ji Qi, Jack Davis, Anna Dorfi Dan Esposito Department of Chemical Engineering Lenfest Center for Sustainable Energy Columbia University Closing the Carbon Cycle Conference Tempe, AZ, September 29th, 2016 9/29/16 D. Esposito, Closing the Carbon Cycle 1 Mission The mission of the Lenfest Center for Sustainable Energy (LCSE) is to advance science and develop innovative technologies that provide sustainable energy for all humanity while maintaining the stability of the Earth’s natural systems. Research Themes Six interconnected, topical research areas that fall under the overall theme of sustainable energy conversion and utilization pathways: I. Novel Materials/Nanotechnology for energy conversion, utilization and storage with a reduced environmental footprint. II. Novel Reaction Pathways for sustainable energy materials conversion throughout the engineered and natural elemental cycles, including innovative device development (e.g. 3-D printed reactor systems). III. Catalysis for novel reaction pathways. IV. Separations using smart, multi-functional materials for sustainable energy and materials. V. Energy Storage and Systems Integration for optimized deployment of renewable energy. VI. Earth Systems for sustainable energy extraction, conversion and waste storage (e.g. waterless or CO2-rich fracking of shale, enhanced oil recovery, geothermal heat recovery with integrated CO2 conversion, and CO2 storage). 9/29/16 D. Esposito, Closing the Carbon Cycle 2 Electrochemical Production of Fuels (+) (-) H2O Electrolysis V - Red.: + - e 2H +2e → H2 - Ox.: - + e H2O →2e 2H +0.5O2 Overall: H2O → H2 +0.5O2 O2 H+ H2 H2O Anode Cathode membrane Side-view of PEM electrolysis cell. 9/29/16 D. Esposito, Closing the Carbon Cycle 3 Electrochemical Production of Fuels (+) (-) H2O Electrolysis V - Red.: + - e 2H +2e → H2 - Ox.: - + e H2O →2e 2H +0.5O2 Overall: H2O → H2 +0.5O2 C H O O2 x y z H+ CO2 Electrolysis + - Red.: xCO2 + 2nH + 2ne →CxHyOz H O CO2 - + 2 Ox.: n(H2O →2e + 2H + 0.5O2) Overall: xCO + nH O → C H O Anode Cathode 2 2 x y z membrane Side-view of PEM electrolysis cell. CxHyOz= CO, CH4, HCOOH, CH3OH, C2H4, and more 9/29/16 D. Esposito, Closing the Carbon Cycle 4 Sometimes it may seem as if we have two choices.. “Hydrogen Renewable Economy” “Hydrocarbon Economy” H2 CxHyOz http://blog.capterra.com/wp-content/ 9/29/16 D. Esposito, Closing the Carbon Cycle 5 “Hydrogen-carbon Economy” “Hydrogen Renewable Economy” “Hydrocarbon Economy” H2 CxHyOz But it is important to remember that H2 and CHO’s are complementary http://blog.capterra.com/wp-content/ 9/29/16 D. Esposito, Closing the Carbon Cycle 6 Examples of the “Hydrogen Carbon” Economy Example 1: Fischer Tropsch Process Electrolyzer CO2 CO + O2 liquid Fischer- (-CH)n H2 Tropsch H2O Example 2: Sabatier Process Example 3: Methanol Synthesis 3a. CO + 2H2 → CH3OH CO2 + 4 H2 → CH4 + 2 H2O 3b. CO2 + 3H2 → CH3OH + H2O Ethylene, Propylene, acetic acid, and others 9/29/16 D. Esposito, Closing the Carbon Cycle 7 Economics of H2 from Low Temperature Water Electrolysis What’s it going to take?! $2-4 /kg H2 DOE Hydrogen & Fuel Cells Program target cost for production & delivery in order to compete 1. Polymer Electrolyte membrane with gasoline at the pump.[1] (PEM) electrolyzer http://www.hydrogenics.com (+) (- ) Where are we today? O2 H2 Gas collection [1] $4-5 /kg H2 30% KOH or NaOH (Production Cost Only) Separation Diaphragm Note: Production of H2 from CH4- [2] 2. Alkaline electrolyzer (unipolar) reforming is ≈$2/kg H2. (2012) Harrison, Levine, “Electrolysis of Water” (2007) [1.] 2012 DOE‐FCTP MYRD&D cost status and targets for Hydrogen Production. [2] S.9/29/16 Dillich , et D. al., Esposito, “Hydrogen Closing Production the CostCarbon Using Cycle Low-Cost Natural Gas”, DOE report, (2012), available online. 8 Economics of H2 from Low Temperature Water Electrolysis Breakdown of H2 production costs by water electrolysis. Data from [1] Soft Costs^ Capital 1. Polymer Electrolyte membrane (PEM) electrolyzer Costs http://www.hydrogenics.com Electricity (+) (- ) O2 H2 [1] Study by Strategic Analysis based on $0.07/kWh Gas collection electricity & PEM electrolyzer system(≈$100/kW) with 97% availability factor. 30% KOH or NaOH ^Includes indirect, O&M, and replacement Separation The cost of H2 produced by electrolysis is Diaphragm usually dominated by the cost of electricity. 2. Alkaline electrolyzer (unipolar) Harrison, Levine, “Electrolysis of Water” (2007) [1.]9/29/16 W. Colella D., et Esposito, al., “Techno Closing-economic the Analysis Carbon of PEMCycle Electrolysis for Hydrogen Production”, (2014) available online.9 Considerations for H2 Production from PV/Wind-Electrolysis: 1. The price of electricity from renewables is decreasing………. 2.4 cents/kWh http://www.pv-magazine.com/news/details/beitrag/breaking--world-record-low-price-entered-for- solar-plant-in-abu-dhabi_100026145/#axzz4LYZnCkaP 9/29/16 D. Esposito, Closing the Carbon Cycle 10 Considerations for H2 Production from PV/Wind-Electrolysis: 1. The price of electricity from renewables is decreasing………. Beyond DOE target (Upper limit) Influence of cost of electricity on cost of H2. Analysis based on electrolyzer efficiency of 75% (HHV). Note: DOE target is upper limit for production and delivery. Beyond Sunshot: http://energy.gov/eere/sunshot/photovoltaics-research-and-development 9/29/16 D. Esposito, Closing the Carbon Cycle 11 Considerations for H2 Production from PV/Wind-Electrolysis: 2. BUT often only for 25-40% of the time………. Time of use pricing Average capacity factor for utility- scale PV power generators in the U.S. (2015): [1] Time of use(TOU) pricing scheme in CF= 28.6%. Ontario Canada (Summer, Weekdays)[2] Low PV/Wind capacity factor and time of use pricing mean that electrolyzers would likely sit idle most of the time. [1.] U.S. EIA, Electric Power Monthly, (2015) https://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_6_07_b [2.]9/29/16 “Time of UseD. Esposito,Pricing in Ontario” Closing https ://www.keyframe5.com/smartthe Carbon Cycle -meters-time-of-use-tou-in-ontario/ 12 Cost Considerations for H2 Production from PV/Wind-Electrolysis: Capacity factor for PV/Wind Electrolysis or time-of-use pricing Key Assumptions Electrolyzer • 4 ₵/kWh electricity • Electrolyzer efficiency of 75% (HHV) • System lifetime=10 yrs • non-discounted analysis • Installation=12% CapEx Electrolyzer capacity factor Relationships between capital cost and capacity factor at fixed cost of electricity. Capital costs become much more important at low capacity factors. 9/29/16 D. Esposito, Closing the Carbon Cycle 13 Capital Costs for a PEM Electrolyzer System PEM Electrolyzer System Capital Cost Breakdown [1] (+) (-) V e- e- O2 + balance H H of 2 system Stacks^ H2O Anode Cathode membrane Side-view of PEM electrolysis cell. ^ ≈ 60% of stack cost is from MEA (membrane + electrodes) •Balance of system (BOS) components are important •Electrolyzer stack is the most expensive single component [1.] W. Colella, B. James, et al., “Techno-economic Analysis of PEM Electrolysis for Hydrogen Production”, (2014) available at: http://9/29/16energy.gov/sites/prod/files/2014/08/f18/fcto_2014_electrolytic_h2_wkshp_colella1.pdf D. Esposito, Closing the Carbon Cycle 14 PEM Electrolyzer Stack Single cell PEM Stack (6 cells). [1] PEM electrolyzer http://www.hydrogenics.com •60% of stack cost is from MEA[2] •An MEA design requires many parts and assembly steps[1] [1.] V. Mehta, J. Power Sources, 114 (2003). [2] W9/29/16. Colella ,D. et Esposito,al., “Techno Closing-economic the Analysis Carbon of PEM Cycle Electrolysis for Hydrogen Production”, (2014) available online.15 PEM Electrolyzer Stack Key components in PEM Stack • End plates • Flow field plates • Gaskets/seals • Fasteners • Membrane • Gas diffusion layer • Anode catalyst • Cathode catalyst PEM electrolyzer Membrane electrode assembly (MEA) http://www.hydrogenics.com •60% of stack cost is from MEA[2] •An MEA design requires many parts and assembly steps[1] [1.] W. Colella, B. James, et al., “Techno-economic Analysis of PEM Electrolysis for Hydrogen Production”, (2014) available at: http://9/29/16energy.gov/sites/prod/files/2014/08/f18/fcto_2014_electrolytic_h2_wkshp_colella1.pdf D. Esposito, Closing the Carbon Cycle 16 PEM Electrolyzer Stack Key components in PEM Stack • End plates Question: At the most • Flow field plates • Gaskets/seals basic level, how many • Fasteners parts are really needed? • Membrane • Gas diffusion layer • Anode catalyst • Cathode catalyst • Device body •60% of stack cost is from MEA[2] •An MEA design requires many parts and assembly steps[1] [1.] W. Colella, B. James, et al., “Techno-economic Analysis of PEM Electrolysis for Hydrogen Production”, (2014) available at: http://9/29/16energy.gov/sites/prod/files/2014/08/f18/fcto_2014_electrolytic_h2_wkshp_colella1.pdf D. Esposito, Closing the Carbon Cycle 17 Membraneless Laminar Flow Cells based on “Flow-by” Electrodes H2O membraneless microfluidic device Co-laminar membraneless fuel cells,[6,8] and flow batteries[7,8] Membraneless electrolyzer with separation based on the Segre-Silberberg effect.[9] Advantages of a Membraneless Cells: • Decreased capital costs Membraneless Laminar flow Cells: • Electrolyte-agnostic • Utilize “flow-by” electrodes with • No membrane degradation and fouling inherent limitations in scalability[8] • Simple: new manufacturing possibilities [6.] E. Choban, P. Kenis, et al., J. Power Sources 128 (2004) [8.] E. Kjeang, et al., J. Power Sources, 260 (2014) [9.] S. Hashemi, D. Psaltis, et al., Energy Env. Sci., (2015). [7.] Braff,9/29/16 Bazant D., etEsposito, al., Nat. Comm. Closing (2013). the Carbon Cycle 18 Membraneless Electrolyzer w/ Flow-Through Electrodes[1],[2] Low fluid flow rate Zoomed-in View H2O H2O O2 H2 O2 H2 High fluid flow rate Mesh Mesh Anode Cathode O2 H2 H O H2O 2 Membraneless electrolyzer based on Illustration of “void fracture” caused circular mesh electrodes in a face-to- by gas accumulation in the absence face configuration.[1] of insufficient fluid flow.[1] [1.] M.I.