While solar and wind power are rapidly becoming cost-competitive with fossil fuels in areas with lots of sun and wind, they still can’t provide the 24/7 power we’ve become used to. At present, that’s not big a problem because the grid still features plenty of fossil fuel plants that can provide constant baseload or ramp up to meet surges in demand.

But there’s broad agreement that we need to dramatically decarbonize our energy supplies if we’re going to avoid irreversible damage to the climate. That will mean getting rid of the bulk of on-demand, carbon-intensive power plants we currently rely on to manage our grid.

Alternatives include expanding transmission infrastructure to shuttle power from areas where the wind is blowing to areas where it isn’t, or managing demand using financial incentive to get people to use less energy during peak hours. But most promising is pairing renewable energy with energy storage to build up reserves for when the sun stops shining.

The approach is less complicated than trying to redesign the grid, say the authors of a new paper in <emJoule, but also makes it possible to shift much more power around than demand management. A key question that hasn’t been comprehensively dealt with, though, is how cheap energy storage needs to get to make this feasible.

Studies have looked at storage costs to make renewable energy arbitrage (using renewables to charge storage when electricity prices are low and then reselling it when demand and prices are higher) competitive in today’s grid. But none have looked at how cheap it needs to get to maintain a grid powered predominantly by renewables.

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