Overview of Wind-H2 Configuration & Control Model (WindSTORM) September 9, 2003 Lee Jay Fingersh National Renewable Energy Laboratory Introduction Wind is intermittent Hydrogen production, storage and fuel cells can be used to store electricity Batteries can also store electricity Hydrogen can also be produced from wind to be used as a fuel What is the best approach to combine hydrogen systems with wind? Wind-hydrogen interface optimization Wind turbine power converter Generator Interface DC Bus Grid Interface Multi-Pole Switch or
Switches Electrolyzer Fuel Cell or Combustion Device Battery Classical wind-hydrogen storage system Storage system efficiency: 25% to 35% e- Variablespeed drive e- Wind turbine e- Rectifier Power Grid
ee- Inverter e- eElectrolyzer H2 Compressor H2 H2 Storage Fuel-cell H2 Fuel Storage system with shared power convert Storage system efficiency: 30% to 40% e- Variablespeed drive
e- Power Grid Wind turbine e- ee- e- eElectrolyzer H2 Compressor H2 H2 Storage Fuel-cell H2 Fuel H2 only system Storage system
efficiency: 30% to 40% e- Variablespeed drive e- Power Grid Wind turbine e- ee- In-tower lowpressure Storage e- eElectrolyzer H2 H2
H2 Fuel-cell H2 Fuel Battery and H2 system Storage system efficiency: 80% to 85% e- Variablespeed drive e- Power Grid Wind turbine e- ee- e- In-tower
lowpressure Storage e- eElectrolyzer H2 Nickelhydrogen battery H2 H2 Fuel-cell H2 Fuel Battery only system Storage system efficiency: 85% to 90% e- Variablespeed drive
e- Wind turbine e- In-tower lowpressure Storage e- eNickelhydrogen battery H2 Power Grid Battery technology discussion Batteries for grid interconnect will be subjected to an enormous number of cycles in a 20 year lifetime One of the only battery chemistries that can withstand repeated daily cycles for 20 years is Nickel-Hydrogen Used in space applications for the same reason Uses the same reaction as nickel-metal-hydride Uses separate hydrogen storage rather than storing hydrogen in the electrode
Cycle life reported to be 10,000 to 500,000 cycles 2 cycles per day for 20 years is 15,000 cycles Analysis Approach (WindSTORM) Analysis is needed to answer What is the best approach to combine hydrogen systems with wind? Simulate calendar year 2002 California ISO load data Windfarm data from Lake Benton, MN Requirement: Power must balance hourly Seek to reduce necessary traditional generation capacity (windpower capacity credit) Determine optimal control methodology Calculate system size and cost Analysis parameter assumptions Wind has 50% capacity credit 100 MW wind farm reduces peak requirements on traditional generation by 50 MW Equivalent to 50 MW firm power from 100 MW windfarm
Wind has 12% energy penetration Wind has 20% capacity penetration No net hydrogen production Battery charge efficiency 95% Battery discharge efficiency 90% Electrolyzer efficiency 75% Fuel cell efficiency 50% Cost assumptions Cost of Wind: $1,000/kW Cost of battery: $70/kWh Cost of electrolyzer: $600/kW (2010) Cost of fuel cell: $600/kW (2010) Cost of H2 storage (in-tower): $3/kWh ($100/kg) FCR: 11.58% O&M: fixed at $0.008/kWh Example of system performance "Battery and H2" system load balanace 600,000
Battery Traditional generation Wind power Energy stored Load Electrolyzer Fuel Cell 25,000 400,000 20,000 300,000 15,000 200,000 10,000 100,000 5,000 -100,000 22
18 20 14 16 10 12 8 6 4 2 0 22 18 20 14 16 10 12
8 6 4 2 0 22 18 20 14 16 10 12 8 6 4 0 2
0 0 -5,000 Hour of day Power (kW) (Hydrogen systems) Power (kW) (Non-hydrogen systems) 500,000 30,000 Effect of forecasting "Battery only" storage system 0.06 3.5 3 2.5 COE ($/kWh) 2
1.5 0.04 1 0.5 0.03 0 Battery only system With CAISO load forecasting COE (system) COE (wind only) With perfect wind forecasting and CAISO load forecasting Battery size Battery Size (hours) 0.05 Battery and H2 and H2 only systems 0.09
Systems with H2 storage included 0.07 0.06 2 Same battery size and COE as "Battery Only" system with forecasting because optimizer optimized H2 system to zero size 1.5 1 0.05 0.5 0.04 0 Battery and H2 system COE (system) H2 only system COE (wind only)
Battery size Battery Size (hours) COE ($/kWh) 0.08 2.5 Important notes The battery hours of storage required and cost of energy can vary dramatically with changes in the system: Windfarm location Windfarm size Control methodology Forecasting method Alternate approach produce hydrogen Utilize slightly larger electrolyzer and more aggressive control strategy to produce some net hydrogen All other requirements remain in effect Electricity price: $0.04/kWh Hydrogen price: $0.10/kWh
Capacity credit: $18/kW/year System designed for hydrogen production Costs and revenue with and without hydrogen production 30 0.09 0.08 25 20 0.06 0.05 15 0.04 10 0.03 0.02 5 0.01 0 0 Battery and H2 system No hydrogen production
Battery and H2 system with hydrogen production Electricity Hydrogen Capacity H2 only system with hydrogen production only - no electricity COE COE ($/kWh) Revenue (M$/year) 0.07 Analysis of hydrogen production scenarios Battery and H2 system with hydrogen production 5% of windfarm output turned into hydrogen
Enough to support about 2,250 vehicles 10.7% of windfarm revenue from hydrogen 5.8% of windfarm revenue from capacity credit Cost of H2 production: $0.072/kWh ($2.40/kg) Cost of H2 production is low because electrolyzer capacity factor is greater than 58%. Cost drops to $0.062/kWh ($2.06/kg) if electrolyzer cost drops to $300/kW H2 only system no electricity Cost of H2 production: $0.081/kWh ($2.70/kg) Cost of H2 production is higher because of lower electrolyzer capacity factor (38%) Conclusions It is possible to firm up wind power for a roughly 10% increase in COE. Using batteries is cost effective Using hydrogen systems alone is not cost effective because the closed-cycle efficiency is too low Hydrogen production can be simultaneously accomplished and is cost effective Hydrogen production alone Is less cost effective Control strategy and proper system sizing are very important With further investigation, it may be possible to do much better
