WattTime, a Berkeley, Calif. nonprofit, has developed a smartphone app that will only charge an electric vehicle with energy provided by renewable energy power plants, thus reducing CO2 emissions.

WattTime’s cofounder, Gavin McCormick, said using the app can curb CO2 emissions by at least 5 percent, with some regions where nuclear or solar power are more prevalent even benefitting from a 100 percent reduction, Spectrum IEEE eports.

The power grid shifts minute-to-minute between a coal plant and say, a solar or wind farm, depending on energy demand.

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WattTime mines two datasets that enable the app to predict what power plant will be used to meet increased electricity demand at any moment in 106 markets across the U.S.


If a carbon-spewing coal plant is coming on line to meet additional demand, the app will delay charging until a clean source of energy is being used, delivering the greenest electricity possible.

A WattTime analysis of New England’s power grid suggests that chargers designed to optimize for price, rather than emissions, can actually increase carbon emissions.

WattTime is partnering with electric vehicle charging companies, plus it has partnerships with smart thermostat providers that use the app’s intelligence to time electric heating and air conditioning for minimum carbon emissions.

Spectrum IEEE