As more of our electricity is sourced from wind and solar, we know there will be times when the output from these sources will not meet our demand for electricity. This will happen during periods of overcast skies, low wind, or times of very high demand such as will occur in winter during cold snaps when most buildings are electrified.
During these times, there needs to be a source of clean electricity to fill in the gaps. Storage is seen as the prime candidate to fulfill this role. But how much storage will be needed? How much will it cost? What are the tradeoffs and what storage technology is suitable?