# Presentation: 164731

## Overview of Wind-H2 Configuration & Control Model (WindSTORM)

- September 9, 2003
- Lee Jay Fingersh
- National Renewable Energy Laboratory

**Overview of Wind-H****2**** Configuration & Control Model**** (WindSTORM)**

## 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

## Classical wind-hydrogen storage system

- Power Grid

- Variable-speed drive

- Rectifier

- Electrolyzer

- Compressor

- Storage

- Fuel-cell

- Inverter

- Wind turbine

- Storage system efficiency: 25% to 35%

- Fuel

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- H2

- H2

- H2

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- H2

## Storage system with shared power converter

- Power Grid

- Variable-speed drive

- Electrolyzer

- Compressor

- Storage

- Fuel-cell

- Wind turbine

- Storage system efficiency: 30% to 40%

- Fuel

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- H2

- H2

- H2

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- H2

## “H2 only” system

- Storage system efficiency: 30% to 40%

- Fuel

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- H2

- H2

- H2

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- H2

## “Battery and H2” system

- Power Grid

- Variable-speed drive

- Electrolyzer

- In-tower low-pressure Storage

- Fuel-cell

- Wind turbine

- Nickel-hydrogen battery

- Storage system efficiency: 80% to 85%

- Fuel

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- e-

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- H2

- H2

- H2

- e-

- e-

- H2

## “Battery only” system

- Power Grid

- Variable-speed drive

- In-tower low-pressure Storage

- Wind turbine

- Nickel-hydrogen battery

- Storage system efficiency: 85% to 90%

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- H2

## 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

## Effect of forecasting

## “Battery and H2” and “H2 only” systems

## 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

## 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