Energy storage can also be accomplished (often at a lower cost) by withdrawing surplus electricity from the grid and storing it as heat or cold. As shown above, thermal storage is more common around the world (at 3.3 GW) than battery storage (at 1.9 MW).

Examples of thermal storage include: making ice or pre-cooling water for air conditioning (chillers); or heating domestic hot water tanks. Ceramic heaters can use off-peak, nighttime electricity to keep a home warm all day. There is a natural link between Ontario’s need to electrify space and water heating to reduce GHG emissions, and the potential to do so (at least in part) by using surplus off-peak electricity.

A great example of thermal storage is the Heat for Less Now initiative in the City of Summerside, Prince Edward Island (P.E.I.). It installs purchased or leased Electric Thermal Storage (ETS) systems, such as water heaters, room/space heaters and furnaces, in homes to take surplus green energy (mostly from wind power) and store it as heat. The ETS system is controlled remotely by Summerside’s utility using smart grid technologies. The utility uses cheap off-peak electricity to fully heat the ETS systems. The stored heat warms the homes or water heaters all day, so they use much less power during the more expensive peak hours. (Source: Environmental Commissioner of Ontario: 2018 Energy Conservation Progress Report, Volume One).