China could use an expected boom in electric vehicles to stabilize a grid that depends heavily on wind and solar energy, officials from an influential Chinese government planning agency said Monday in Washington D.C.

“In the future we think the electricity vehicle could be the big contribution for power systems’ stability, reliability,” said Wang Zhongying, director of the China National Renewable Energy Center and deputy director general of the Energy Research Institute at China’s National Development and Reform Commission.

The Chinese do not see the cost of renewable energy as a significant obstacle to its widespread adoption, Wang told a lunchtime gathering at Resources for the Future, a non-partisan environmental research organization in the Capitol.

“The biggest challenge for renewable energy development is not economic issues, it is technical issues. Variability. Variability is the biggest issue for us,” said Wang, who explained variability like so: “When we have wind we have electricity; when we have sun we have electricity. No wind and no sun, no electricity.”

But if the Chinese deploy enough electric vehicles—which could mean up to five million new electric vehicles in Beijing alone—the array of distributed batteries could collect energy when the sun is shining or the wind is blowing and feed it back to the grid when the skies are dark and the air is still.

Wang directed a study released this week, the “China 2050 High Renewable Energy Penetration Scenario and Roadmap Study,” which plots a route for China to drastically reduce reliance on coal, derive 85 percent of electricity from renewables, and cut greenhouse gas emissions 60 percent by mid-century .

The study gets there by relying on what has become known as Vehicle-to-Grid technology, which has emerged as almost a surprise side effect of inexpensive solar panels and clean-energy policies in places like California and Germany.