Depths of imagination

WIND farms and solar-energy plants have the advantage that their fuel is free, but the disadvantage that the availability of that fuel may change from minute to minute. If they are to become the large-scale contributors to power generation that their boosters suggest, then cheap and reliable means of smoothing their output, by storing surpluses for use during times of scarcity, need to be developed.

At the moment, there is only one good way of saving surplus grid electricity, regardless of how it is generated. This is pumped storage. It requires two reservoirs at different elevations, linked by tunnels and pumps in order to create a head of water whose pressure, when released, can drive the pumps backward, to act as generating turbines.

Pumped storage is cheap to run, but needs convenient geography to build in the first place. Or, rather, it did. For a pair of alternatives to the two-reservoir model, both of which still exploit the power-generating potential of a head of water by pumping fluids around, are now being investigated. One is a year old this month. The other is about to start trials.

The one-year-old project is in Toronto, Canada—or, rather, just offshore, at the bottom of Lake Ontario. It was designed and built by Hydrostor, a company founded by Cameron Lewis, who developed the technology after working in the oil industry. The plant is…Continue reading
Source: Economist