Development of Hydrogen Production and Power Storage Systems using Solid Oxide Electrolysis Cell

Development of Hydrogen Production and Power Storage Systems using Solid Oxide Electrolysis Cell 2015 Fuel Cell Seminar Los Angeles, CA November 19, 2015 Riko Inuzuka, Tsuneji Kameda, Hisao Watanabe and Masahiko Yamada Toshiba Corporation Power Systems Company 2015 Toshiba Corporation

Contents 1. Target SOEC hydrogen production system SOEC/SOFC power storage system 2. EC performance evaluation singular-stack multiple-stack module 3. Summary

Electrical power storage for renewable energy Output power fluctuation from climate condition Storage of surplus Absorption of fluctuation Maintenance of quality Electrical power grid PV Wind Electrical power storage system Night-time power Renewable energy Factory School

Utilization of hydrogen from renewable electricity Hydrogen power storage system PV Wind Renewable electricity Electricity (fluctuate) Hydrogen Oxygen Water electrolysis Hydrogen production unit Hydrogen storage Oxygen storage Gas storage Fuel cell Power generation unit Electricity(stable) Heat Hydrogen Oxygen

Utilization of hydrogen from renewable electricity Hydrogen power storage system Hydrogen production system PV Wind Renewable electricity Electricity (fluctuate) Hydrogen Oxygen Water electrolysis Hydrogen production unit Hydrogen storage Oxygen storage Gas storage Fuel cell Power generation unit Electricity(stable) Heat Hydrogen Oxygen

SOEC/SOFC hydrogen power storage system Electrolysis Fuel cell Hydrogen Heat Electricity /hydrogen 発電 ( FC ) 電解 ( EC ) conversion device High temperature heat storage Solid oxide electrochemical cell Electricity 空気 Air Water

SOEC/SOFC hydrogen power storage system Electrolysis Fuel cell Hydrogen Heat Electricity /hydrogen 発電 ( FC ) 電解 ( EC ) conversion device High temperature heat storage Solid oxide electrochemical cell Electricity 空気 Air Water Efficient electricity/hydrogen conversion is expected through heat management.

SOEC/SOFC hydrogen power storage system Electrolysis Heat High temperature heat storage Solid oxide cell (SOEC/SOFC) Fuel cell Hydrogen Electricity /hydrogen 発電 ( FC ) 電解 ( EC ) conversion device Electricity 空気 Air Water Key technology: SOEC/SOFC stack First step: Evaluation of SOEC performance

Evaluation of singular stack (1/5) flat-tube type cells stack Test condition(for SOEC) initial I-V property temperature : 700~800 feed gas hydrogen electrode : H 2 O/H 2 = 70/30 80/20 90/10 vol% oxygen electrode : Air current density : 0 ~ 1 A/cm 2 Evaluation items I-V properties steam utilization durability

Evaluation of singular stack (2/5) Equipment for evaluation of SOEC stack More than 90% concentration of water vapor can be supplied by this equipment

Evaluation of singular stack (3/5) Steam concentration dependence of I-V Furnace temperature : 750 H 2 O/H 2 =70/30 vol% H 2 O/H 2 =80/20 vol% H 2 O/H 2 =90/10 vol% 0.8 A/cm 2 ΔV/ΔA was almost same within the range of steam concentration 70 % - 90 %. Current density 0.8 A/cm 2 (theoretical thermal neutral point) was attained at 1.2 ~ 1.3 V.

Evaluation of singular stack (3/5) Steam concentration dependence of I-V Temperature change during the I-V measurement Furnace temperature : 750 H 2 O/H 2 = 70/30 vol% H 2 O/H 2 = 80/20 vol% H 2 O/H 2 = 90/10 vol% 0.8 A/cm 2 0.8 A/cm 2 Theoretical thermal neutral points (0.8 A/cm 2 ) corresponded to experimental thermal neutral points.

Evaluation of singular stack (4/5) Gas flow rate dependence of I-V U f = 97.5 % 97.5 97.5 97.5 U f : fuel utilization H 2 O/H 2 = 90/10 vol% 750 flow rate per effective area 1.9 ml/(min cm 2 ) 3.8 ml/(min cm 2 ) 5.7 ml/(min cm 2 ) 7.6 ml/(min cm 2 ) U f = consumption of water vapor (calculated from current) water vapor input U f = 97.5 % achieved at flow rate 3.8 ~ 7.6 ml/(min cm 2 ). ΔV/ΔA was slightly higher in smaller flow rate.

Evaluation of singular stack (5/5) durability Initial degradation rate 7.5 %/kh Temperature:750 Current Density:0.42A /cm 2 H 2 O/H 2 = 90/10 vol% U f = 85 % Initial degradation rate was 7.5 %/kh

Evaluation of singular stack (4/4) durability Furnace temperature:750 Current Density:0.42 A/cm 2 H 2 O/H 2 = 90/10 vol% U f = 85 % Similar tendency was observed between the time dependence of voltage and temperature.

Evaluation of multiple-stack module (1/4) Equipment for evaluation of multiple-stack module

Evaluation of multiple-stack module (2/4) I-V properties Influence of feed gas flow rate to hydrogen electrode U f = 73.1 % 61.7 60.9 H 2 O/H 2 =90/10vol% 750 flow rate per effective area 3.8 ml/(min cm 2 ) 5.7 ml/(min cm 2 ) 7.6 ml/(min cm 2 ) Larger U f was attained with lower flow rate.

Evaluation of multiple-stack module (3/4) Comparison of I-V between multiple-stack module and singular stack multiple U f = 60.9 % 97.5 singular flow rate = 7.6 ml/(min cm 2 ) H 2 O/H 2 = 90/10 vol% 750 Lower U f was attained with multiple-stack. Voltage increase of multiple-stack was larger than singular stack.

Evaluation of multiple-stack module (4/4) Coulomb efficiency flow rate = 7.6 ml/(min cm 2 ) H 2 O/H 2 =90/10 vol% 750 theoretical (calculated from current value) experimental (measured by flow meter) Coulomb efficiency was almost 100 %.

Summary Current density 0.8 A/cm 2 (theoretical thermal neutral point) was attained at 1.2 ~ 1.3 V with singular stack. Theoretical thermal neutral points (0.8 A/cm 2 ) corresponded to experimental thermal neutral points. The performance of multiple-stack module was lower than singular stack. Acknowledgement A part of this presentation is based on results obtained from a project commissioned by the Ministry of Economy, Trade and Industry (METI) and the New Energy and Industrial Technology Development Organization (NEDO) in fiscal 2012 to 2015. We express our appreciation.

TOSHIBA Hydrogen Energy R&D Center Opened on Apr. 6, 2015 in Fuchu Complex H 2 Fuel Cell 8.4 kw H 2 Storage Tank 150 m 3 / 0.9 MPa PEM Electrolyser 10 Nm 3 /h SOEC Electrolyser 0.5 Nm 3 /h Roof-Top PV 96 kw Demonstration of power to gas is being conducted in this R&D center. 2015 Toshiba Corporation

Comparison of Electrolysis Technology Technology Characteristics Shortage Alkaline Temperature range: 40 90 Commercial available Plant; 1-760 Nm³/h, 5 kw - 3.4 MW Low cost PEM Temperature range: 20 100 Commercial available Plant; 0.01-30 Nm³/h, 0.5-160 kw In 3-5 years: ~ 250 Nm³/h, 1.0 MW High current density Quick response SOEC Temperature range: 700 1000 R&D stage Test equipment; 5.6 Nm³/h, 17.5 kw High efficiency Heat utilization (endothermic reaction) Relatively high current density Potentially quick response Low current density Limited efficiency Corrosion by electrolysis solution Durability of membrane Slow responsibility Cost (noble metal catalyst) Limited efficiency Scale up Under development Cell material Cell and stack design, manufacturing System test, evaluation Cost Scale up

Heat 2015 Toshiba Corporation SOEC/SOFC hydrogen power storage system Thermal neutral point Current density There exists a thermal neutral point in balance of the endothermic reaction and the IR heat.

Water electrolysis technology Hydrogen power storage system Hydrogen production system PV Wind Renewable electricity Electricity (fluctuate) Water electrolysis Hydrogen Oxygen Hydrogen storage Oxygen storage Fuel cell Hydrogen production unit Gas storage Power generation unit Alkaline electrolysis <Present> PEM electrolysis <Present> Solid oxide cell electrolysis <2015~100kW class>

Comparison of power storage systems System Hydrogen Alkaline+PEFC SOEC+SOFC Nas battery Li-ion battery Pumped hydro CAES *) Alkaline electrolyzer SOEC Nas battery Li-ion battery Water reservoir Air reservoir Main device PEFC SOFC Heat retention Power generation Power generation Hydrogen storage Hydrogen storage Pump Air compressor Heat storage Pipe arrangement Pipe arrangement Output/Input 0.4 0.80 0.90 0.96 0.7 0.7 actual use for each actual use for small actual use actual use actual use actual use Development status device FC test for combined under development system for others Econom leveling for short-period ( for variable) ical leveling for day/night view storage for long-period ~ (heating) ~ (cost) (location) (location) Low O/I Scale up Heat retention Cost Restricted location Restricted location Weak point Durability for Hazardous Construction Construction fluctuation materials leading time leading time Good point Low cost Low cost High efficiency High efficiency Practial Improve GT Large scale High efficiency accomplishment efficiency *) Compressed Air Energy Storage SOEC/SOFC power storage system will provide more cost-effectiveness than batteries and less-restricted plant location than pumped hydro

Economical evaluation For long charging time, the hydrogen storage systems were evaluated cost effective.

Efficiency of Alkaline and PEM Electrolysers Manufacturer's data No standardised data Differernt pressure and H2 purity Specifications for steady state operation Ref.; Tom Smolinka, SYMPOSIUM - Water electrolysis and hydrogen as part of the future Renewable Energy System Copenhagen/Denmark, May 10, 2012

Power storage time 2015 Toshiba Corporation Map of the electrical power storage technologies Residential PV Middle-scale Single- Large-scale PV middle wind wind, PV Nighttime power 100H 10H Hydrogen power storage NaS battery Pumped hydro 1H Lithium ion battery 1kW SMES 10kW 100kW 1MW 10MW 100MW 1GW Charge-discharge electrical power capacity Hydrogen power storage Suitable for large capacity and long time power storage Less-restricted plant location

エネルギー Energy (kj/mol) (kj/m ol) 2015 Toshiba Corporation SOEC/SOFC hydrogen power storage system -100 Required 電解に必要なエネルギーの温度による違い energy for electrolysis 0 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600-50 ΔG ΔG( ギブスエネルギ差 ) G (Gibbs energy) -150-200 -250 ΔH T S TΔS( エントロピー (Entropy) ) -300-350 ΔH ( 電解エネルキ )=ΔG +T ΔS H (Energy for electrolysis) = G + T S Temperature 温度 (K) (K) A certain portion of required energy for electrolysis can be covered by thermal energy at high temperatures.

System design and potential evaluation SOEC hydrogen production system Low cost was expected comparing conventional methods. Especially the extra-heat using case is worth noting.