Integrating Variable Renewable Energy into the Grid Requires Change

variable-renewable-energy-VRE

Want more wind and solar? We’ll need to get rid of outdated grid rules.

Vox, July 23, 2015. Image credit: Ivana @ St Nicks

For the most part, wind and solar — also known as variable renewable energy (VRE) — haven’t run into those constraints yet, because their penetration remains relatively low. In 2014, wind generated just 4 percent of US electricity; solar produced less than 1 percent. But if wind and solar ever hope to supply 30 percent, 50 percent, or even 100 percent of electricity, they’ll have to address the obstacles posed by current grids.

Remember that electricity is a unique commodity in that it cannot be economically stored in large quantities. Excess generation not only goes to waste, it can destabilize a grid. Supply must always precisely match demand.

Until very recently, grid operators had a good handle on how to do that. There’s a certain minimal level of electricity demand that persists around the clock. For that “baseload” demand, grid operators run big, lumbering coal and nuclear power plants, the kind that are very slow (and expensive) to shut down and restart. These plants run all the time, basically, except when closed for maintenance or unexpected faults.

Now throw VRE into the mix. Grid operators cannot turn wind and solar plants up and down at will — these power sources are not “dispatchable.” Instead, VRE generators push energy onto the grid whenever the wind is blowing or the sun is shining and don’t when they aren’t. Grid operators can’t control wind and solar; they must accommodate them.

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