Which transportation technology cuts total emissions at the lowest cost, batteries or fuel cells? And could hydrogen technology also provide clean energy for heating and lighting buildings, as research suggests?

Scientists at Stanford University and the Technical University of Munich sought to answer these questions by comparing cars that run on batteries versus hydrogen fuel cells in a future where the cost of electric vehicles is more affordable.

All-electric battery vehicles may offer a more affordable way to reduce carbon dioxide emissions than hydrogen-powered cars.The researchers say that neither energy source is entirely emissions free. Charging battery electric cars by plugging into the power grid delivers electricity generated largely from carbon-emitting fossil fuels.

And most hydrogen fuel is derived from natural gas through an industrial process that emits carbon dioxide as a byproduct. While electrolyzers, use solar-generated electricity to split water into clean hydrogen and oxygen, the technique can be energy intensive and expensive.

Future scenarios focused on Los Altos Hills, a California town with one of the highest shares of electric vehicles in the state. The projections looked 10-20 years in the future, when battery and fuel cell vehicles are expected to be in much wider use, and when solar power and electrolyzers are cost-competitive with the electric grid.

One scenario for 2035 assumed that electric vehicles would constitute 38% of the town’s vehicle fleet. It also assumed that fuel cell vehicles would be powered by locally produced hydrogen made with the least expensive available electricity, be it solar generated or obtained from the grid.

Carbon dioxide emissions were calculated to compare each scenario’s costs to its climate benefits. The emissions winner was battery electric vehicles. The higher price of fuel cell vehicles was found to undermine their cost-competitiveness compared with the battery option. The amount of solar hydrogen storage harnessed for heating and lighting buildings is not expected to make an appreciable economic or environmental impact by 2035.