Storage is a major factor in renewable electrical energy production. Without more and better storage in the future, energy production by sun and wind will be constrained.

I learned about these things at a recent renewable energy confab, during a talk by a sharp guy from Sandia National Labs, John Boyes, who spoke last week at the UNC conference, “Solar Fuels and Energy Storage: The Unmet Needs.”

Here’s the reason why (in a somewhat simplified way). During the day, the input of energy to the power grid must equal the utilization of that energy (or else, where would all those electrons go?). Power companies have different sorts of power plants: some provide constant baseload, others ramp up to meet peak loads during the day, and some, driven by gas turbines,  fine-tune the energy fed to the grid on a minute-by-minute basis, so that output to the grid equals demand.

Now, wind and solar energy production is subject to the vagaries of weather, obviously. Right now, their contribution to the grid is quite small, so their variation in solar and wind output to the grid can be accommodated all right, using the gas turbine approach. So, on a sunny day, the gas turbines can be trimmed back, for example; while on a cloudy day, they would have to put out more power to meet peak demand.

The problem is that this approach won’t work should solar and wind become a large part of our energy production. As an example, if solar were planned to meet 50% of demand in an area, there’s no way to justify the expense of having a huge number of gas turbines sitting around on sunny days, ready to turn on when it’s cloudy. The problem is similar for wind.

Enter storage as a way to harness the energy produced by solar and wind, so it can be fed to the grid as necessary. Put another way, in the publication “Solar Energy Grid Integration Systems Energy Storage,”

it will be necessary to integrate energy storage with PV [photo-voltaic] systems as PV-generated energy becomes more prevalent on the nation’s utility grid

The question becomes, do we have the means to supply this storage? My understanding is that we do not. We have ways to store small amounts of energy in batteries and such, but we don’t have the technology at present to store large amounts of energy to properly accommodate large solar and wind projects.