Energy Storage: Uncomfortable Numbers

Electrochemical and thermal storage will be the pillars of decarbonization in the energy sector. There are some challenges with these technologies that are important to be aware of and addressed before it is perhaps too late. Electrochemical batteries (ECB’s), while indispensable components in modern society, need special attention: their energy densities are 40 times lower than fossil fuels, they have embedded 50-300 kg CO2,eq/kWh, costs range from $100-1000/kWh depending on the scale, and available Lithium (~14 million tons) will be depleted within the next century with the current mining rates, unless the ocean water Lithium become sustainably extractable, or revolutionary new technologies that no longer require critical materials arise. Thermal energy storage (TES), while they can be nearly twice as cheap and are more environmentally friendly, also have challenges: 2-3 times less energy dense than ECB’s, do not always offer energy savings and have more limited applications. While TES may have a relatively high value-proposition for hot water equipment in buildings, it can be challenging when integrating it with heat pumps; the additional space and weight required, coupled with a limited return on investment, become a hard sell to end-users when the benefits are not always tangible on a local level.