Hybrid Hydrogen Energy Storage Michael Penev May 22, 2013 All-Energy 2013 Aberdeen, UK NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
2 Talk Overview Key Components of H 2 Storage Case Study of Islanded Hybrid-H 2 Storage Concept of Power to Gas Energy Storage
3 What is an Electrolyzer? DC Power Water Hydrogen Oxygen H 2 O + electricity H 2 + ½ O 2 Ideal energy = 39 kwh/kg H2, HHV Electrolyzers can respond instantaneously to power fluctuations, thus offering high frequency dispatchability For every cubic foot of H 2 produced, half cubic foot of O 2 is produced. H 2 and O 2 are produced at high purity
4 Electrolyzer Types Capacity (kw) Efficiency HHV Alkaline 1 2,300 72% PEM 1 130 60% Solid Oxide pilot scale only 82% Alkaline technology is commercially available. Proton Exchange Membrane (PEM) systems are available in smaller capacities, but offer long term performance and cost benefits. Solid Oxide Electrolyzers (SOEC) are in development and will offer very high efficiency and low cost. All electrolyzer costs are approximately $1000 per kw in MW-scale context. References: Alkaline: NEL-Hydrogen system specifications PEM: Proton On-Site system specifications Solid Oxide: NREL/DOE internal systems analysis and cost estimations, 2011
Alkaline Electrolyzers Largest Installations Norsk Hydro s 30,000 Nm 3 /h (~150 MW) Electrolyzer Plant (1948-1990) Connected to a hydroelectric plant, generating about 70,000 kg/day Reference: Knut Harg, Hydro Oil & Energy, Hydrogen Technologies NAS Hydrogen Resource Committee, April 19, 2007 5
6 Hydrogen Storage Types Storage Type Terrestrial compressed tank** $ 45 Deep-ocean gas storage*** $ 10 Liquid hydrogen storage ** $ 2.5 Geologic storage (porous rock formations) $ 0.50 Dry-mined salt caverns $ 0.25 Solution-mined salt caverns $ 0.05 H 2 Storage cost $/kwh* * using 20 kwh/kg H 2 (51% HHV efficiency) ** using H2A components model cost estimates *** NREL cost estimate Reference: Crotogino, F.; Huebner, S. (2008). Energy Storage in Salt Caverns: Developments and Concrete Projects for Adiabatic Compressed Air and for Hydrogen Storage. Solution Mining Research Institute Spring 2008 Technical Conference, Porto, Portugal, April 28 29, 2008. Deep ocean gas storage: NREL internal cost estimation, 2010
Power Generation Equipment Generator Type Scale MW Cost $/kw Efficiency (HHV) Combine cycle (CC) plant 50-550 $550-720 51% Oxy-combustion CC 50-550 $550-720* 62% PEM Fuel Cells 0.1-1.0 $2,500-5,000 40% SOFC Fuel Cells 0.01 - TBD $4,500 61% Only PEM Fuel Cells have been demonstrated for H 2 to power for grid support. * Oxy-combustion plant is assumed to have the same per-kw cost as CC. Oxycombustion has many simplifying aspects over air-combustion CC. References: Combine Cycle: Cost and Performance Baseline for Fossil Energy Plants, DOE/NETL, 2010 http://www.netl.doe.gov/energy-analyses/pubs/bitbase_finrep_rev2.pdf Attachment: http://www.netl.doe.gov/kmd/cds/disk50/ngcc%20plant%20case_fclass_051607.pdf Oxy-combustion reference: Masafumi Fukuda and Yoshikazu Dozono, Double Reheat Rankine Cycle for Hydrogen-Combustion Turbine Power Plants, Toshiba Corporation, Journal of Propulsion and Power, Vol. 16, No. 4, July-August 2000, Page 562 Solid Oxide: NREL/DOE internal systems analysis and cost estimations, 2011 PEM Fuel Cells: Personal communication with Kevin Bell from Ballard Power. 7
8 Talk Overview Key Components of H 2 Storage Case Study of Islanded Hybrid-H 2 Storage Concept of Power to Gas Energy Storage
DC BUS 9 100% Hybrid Renewable Storage Inverter Demand Renewable Electricity Battery Diurnal operation Electrolyzer Power Generator Hydrogen Storage Turns on when battery < ~70% state of charge
10 30,000 ft View of Storage Pros & Cons Energy storage system type Round-trip efficiency Bulk-energy storage cost (non-diurnal) Ability to be refueled? Batteries only 80% $700-$800/kWh No H 2 only 30%-50% $0.05-$45/kWh Yes H 2 & batteries (hybrid) 40%-70% $0.05-$45/kWh Yes Note: hybrid energy storage offers spill over capability for displacing transportation emissions via fuel cell vehicles
Example Island Installation (Wind & Solar Resource) 11
12 Demand Mismatch (measured data) Hourly electricity demand Hourly energy output per turbine (kw) Large gaps in wind power Note: Solar power was used as well. It was relatively constant throughout the year.
Optimization Methodology Gradient descent minimization of levelized cost of electricity (LCOE) Optimization parameters (using HOMER model): 1. Size of solar panels 2. Number of wind turbines 3. Number of batteries 4. Capacity of power electronics 5. Size of fuel cell 6. Size of electrolyzer 7. Size of hydrogen storage - $5,500 /kw, no tracking - $4,400 /kw, 1.8 MW each - $745 / kwh, Xtreme Power DPR 1500 - $609 /kw, rectifier & inverter - $4,000 /kw, 40% HHV efficiency PEM - $1,000 /kw, 70% HHV efficiency Alkaline - $700/kg, Terrestrial, steel tank Note: only off-the-shelf technologies were used for this analysis. Reference: Xtreme Power Battery: system specifications from Xtreme Power concept illustration of gradient descent from wikipedia 13
Energy Storage Content (MWh) 14 Energy Storage State of Charge 2,500 Hydrogen storage energy content (MWh) Battery energy content (MWh) Cumulative Energy to Load (MWH/year) 2,000 1,500 10 Solar Wind Battery Fuel Cell 1,000 5 500-5000 5100 5200-0 1000 2000 3000 4000 5000 6000 7000 8000 Hour of the year
Hour of Day Hour of Day Energy Storage State of Charge 24 18 12 6 0 Stored energy in batteries (MWh) Total batteries = 9 MWh, $6.8 million Battery Energy Content Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Day of Year MWh 9.6 8,800 8.8 8,000 8.0 7,200 7.2 6,400 6.4 5,600 5.6 4,800 4.8 4,000 4.0 3,200 3.2 2.4 2,400 1.6 kwh 9,600 1,600 24 18 12 6 0 Stored hydrogen (MWh) Stored Hydrogen Total H 2 stored = 150,000 kg, $105 million Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Day of Year kg 160,000 144,000 128,000 112,000 96,000 80,000 64,000 48,000 32,000 16,000 0 MWh 2,400 2,160 1,920 1,680 1,440 1,200 960 720 480 240-15
LCOE ($/kwh) LCOE Vs. Renewables Fraction $0.45 $0.40 $0.35 $0.30 $0.25 $0.20 $0.15 $0.10 $0.05 $0.00 0% 20% 40% 60% 80% 100% Renewable Fraction 100% renewable fraction solutions resulting LCOE: - 100% hydrogen = 0.51 $/kwh - Hybrid hydrogen = 0.43 $/kwh - 100% batteries = 3.56 $/kwh 16
Best-in-class: SOEC, Salt Cavern, Oxy-Combustion Salt formation Hydrogen Solution Mine Oxygen Solution Mine 17 Plant components - High pressure electrolyzer (SOEC) - Gas storage: solution mined salt dome - H 2 /O 2 turbine ~1km
SOEC, Salt Cavern, Oxy-Combustion 18 Hydrogen Production Technology Alkaline PEM SOEC Power Gen. Technology Component HHV efficiency 72% 60% 82% Air-combustion CC 51% 37% 31% 42% Oxy-combustion CC 62% 45% 37% 51% PEM 40% 29% 24% 33% SOFC 61% 44% 37% 50% Best in class for this location long-term: - Solid oxide electrolyzer (SOEC) $1,000/kW (not available) - Salt cavern storage $0.08/kWh (not available today)* - Oxy-combustion CC $720/kW (not available today) - Levelized cost of electricity = 20.2 /kwh Note: - ancillary service revenues can rival power production revenue - * Additional storage cost of O 2 increases cost from $.05 kwh to $.08 per kwh.
19 SOEC, Salt Cavern, Oxy-Combustion NPV of Equipment Cost (including O&M) Net Present Cost ($) Solar panels Wind turbines H 2 /O 2 turbine Batteries Power electronics Electrolyzer Hydrogen storage PV Lin FC DPR1500 Converter Electr. H2 Tank 0 0 20,000,000 40,000,000 60,000,000 80,000,000 Net present value (millions of $) PV 1.8MW Linearized Fuel Cell Xtreme Pow er DPR 1500 Converter Electrolyzer Hydrogen Tank 100,000,000 20 40 60 80 100 Cash Flow Summary
Key Technologies Oxy-combustion hydrogen turbines o o o Enables low-cost, high-round trip energy storage Engineering development required No scientific breakthroughs needed Solid oxide electrolyzers, high-pressure o o o o o Enables low-cost, high-round trip energy storage Solid oxide materials are ideal for high-pressure operation (low back-diffusion due to material impermeability) Science & engineering development required 1000 s of hours of operation have been demonstrated on modules High pressure operation has been demonstrated on stacks 20
21 Talk Overview Key Components of H 2 Storage Case Study of Islanded Hybrid-H 2 Storage Concept of Power to Gas Energy Storage
Hydrogen DC BUS Power to Gas Energy Storage $$$ Battery ancillary services Electrolyzer Inverter Transmission $$$ RECs Transportation Power Gen. Heating Natural Gas Pipeline Natural gas pipelines can operate with 10% H 2 (as much as 20% has been commercially demonstrated) 22
Questions? 23
BACKUP SLIDES 24
25 Hydrogen Storage (Terrestrial) 300 kg H2 storage in ISO containers, in Pearl Harbor Hickham
26 Power Generation (Fuel Cell) 1.1 MW Ballard Hydrogen Fuel Cell @ Toyota Headquarters in CA
27 Toshiba Advanced H 2 /O 2 Cycle This cycle is a hybrid between a combustion and steam turbine. Toshiba predicts 61.7% HHV or 72.8% LHV efficiency for this cycle.
28 Ongoing Efforts in Oxy-Combustion Siemens installation of oxygen-blown combustion turbine. They experience efficiency gain of 10% on LHV basis over conventional systems. This system is developed for CO2 sequestration.
Ongoing Efforts in O 2 Turbines 29
Combine Cycle (CC) Turbine Diagram as seen on: http://www.victorvilletwo.com/ Combine cycle plants are commonly designed for peaking power. Their fuel is more expensive than baseload coal plants. Plant efficiency 55-58% LHV 30
31 CC Major Differences With H 2 /O 2 H 2 O 2 Exhaust NO X clean-up would be obsolete. Exhaust would be liquid H 2 O Bottoming Steam Cycle is Integrated Pre-cooler & compressor not present with H 2 /O 2 No NO X formation. Need steam recycle Efficiency of a combine cycle is greatly impeded by atmospheric N 2 - Compression shaft energy is used to compress N2 - N2 strips heat from the process, without providing power - N2 produces NOX in the combustor - NO X reduction strategies reduce burner efficiency
32 Alkaline Electrolyzers NEL-Hydrogen Electrolyzers 2.3 MW per unit http://www.nel-hydrogen.com/
33 Proton Exchange Membrane (PEM) Electrolyzers 60 kg/day electrolyzer from Proton OnSite: Electrolyzer Unit Power Electronics http://www.protononsite.com/
34 Solid Oxide Electrolyzers (SOEC) Electricity, DC Hydrogen 800 C Steam Oxygen 650 C SOEC has very high efficiency due to thermal weakening of H-O bonds. http://www.versa-power.com/
SOEC, Deep Water Storage, Oxy-Combustion 35 Hydrogen Production Technology Alkaline PEM SOEC Power Gen. Technology Component HHV efficiency 72% 60% 82% Air-combustion CC 51% 37% 31% 42% Oxy-combustion CC 62% 45% 37% 51% PEM 40% 29% 24% 33% SOFC 61% 44% 37% 50% Best in class for this location long-term: - Solid oxide electrolyzer (SOEC) $1,000/kW (not available) - Deep water storage, $15/kWh (not available today)* - Oxy-combustion CC $720/kW (not available today) - LCOE hybrid = 32 /kwh * Additional storage cost of O2 increases cost from $10 kwh to $15 per kwh.
Net Present Cost ($) 36 SOEC, Deep Water Storage, Oxy-Combustion NPV of Equipment Cost 100,000,000 80,000,000 60,000,000 Cash Flow Summary PV 1.8MW Linearized Fuel Cell Xtreme Pow er DPR 1500 Converter Electrolyzer Hydrogen Tank 40,000,000 20,000,000 0 PV Lin FC DPR1500 Converter Electr. H2 Tank
Alkaline, Salt Cavern, Oxy-Combustion 37 Hydrogen Production Technology Alkaline PEM SOEC Power Gen. Technology Component HHV efficiency 72% 60% 82% Air-combustion CC 51% 37% 31% 42% Oxy-combustion CC 62% 45% 37% 51% PEM 40% 29% 24% 33% SOFC 61% 44% 37% 50% Best in class for this location long-term: - Alkaline electrolyzer $1,000/kW - Salt cavern storage $0.08/kWh (not available today)* - Oxy-combustion CC $720/kW (not available today) - LCOE hybrid = 21.3 /kwh * Additional storage cost of O 2 increases cost from $.05 kwh to $.08 per kwh.
Net Present Cost ($) 38 Alkaline, Salt Cavern, Oxy-Combustion NPV of Equipment Cost 120,000,000 90,000,000 Cash Flow Summary PV 1.8MW Linearized Fuel Cell Xtreme Pow er DPR 1500 Converter Electrolyzer Hydrogen Tank 60,000,000 30,000,000 0 PV Lin FC DPR1500 Converter Electr. H2 Tank