Maintaining Grid Reliability with Renewables

The sun doesn’t always shine, the wind doesn’t always blow. Can we really rely on renewable energy? There are four basic ways to maintain reliable energy supply using renewables:

1. Limit the amount of variable renewables to the amount of conventional supply that can be turned on or off to compensate for the variability of solar and wind resources. Very few areas in the world are close to this limit.
2. Add fast-response supply resources, like gas turbines or slightly slower gas combined-cycle plants that can keep up with the variability of the renewables. Over time, the combination of renewables and gas can completely displace the slower-response coal and nuclear plants.
3. Add storage capacity, in the form of batteries, compressed air, flywheels, pumped hydro, or some other clever contraption.
4. Get energy users to adapt their energy usage to the availability of energy.

The first two are what has been happening in most of the developed world so far. California has mandated a significant investment in storage capacity over the next six years. The fourth is Demand Response, and is already starting to happen among large industrial and commercial energy users who stand to save significantly by adjusting their usage.