Every day I hear the hype about batteries and how they are the key to a 100% renewable energy grid. The focus has now turned to Long Duration Storage and how it will be much cheaper than lithium-ion. Well, let’s take a deeper look into this.
First, how long is “long duration storage”? There isn’t an agreed-upon definition. The Storage Industry Association labels long duration as anything between 4 and 24 hours, while the National Renewable Energy Laboratory (NREL) puts the limit at 100 hours. Maybe it’s because I am old, but 100 hours does not feel long to me. The industry and technology vendors look at the problem in the very narrow context of the day/night cycle. Let’s extend the timeframe.
Storage is supposed to take excess solar and hold it for when we need it later. However, later might be 6 months from now. The difference in average solar production in the United States between summer and winter is a factor of 2. A 100 Kwh solar production in the summer will only generate 50 Kwh during the winter. As we electrify everything with heat pumps and EVs we are flattening the load between summer and winter, so we can’t take solace in a reduction in load during the winter. To balance our generation and load we need to store electricity for 6 months.
Long duration storage is touting a capital investment of only $ 100 per kWh. To pay for the storage we must pay a premium per kWh in the winter to pay for the battery. Assuming a 20-year life, no degradation, and a required rate of return of 10%, the premium is $ 1.70 per kWh. The average cost of retail electricity in the United States is $0.163 kWh. Long-duration storage would increase winter electricity prices by a factor of at least 10 times.
I don’t think our consumers and population will tolerate this incredible blow to their budgets and standard of living. We need to get realistic. People put down nuclear because it’s too expensive compared to solar. But nuclear can deliver in the winter at less than 1/ 10 th the cost.