Home energy storage systems might save you money, but under current policies, they would also often increase carbon emissions. That is the conclusion reached by a team of researchers at the University of California San Diego in a study published recently in the journal Environmental Science & Technology.

Conventional wisdom may suggest that these storage systems, which are essentially household batteries such as the Tesla Powerwall, could be instrumental in weaning ourselves off greenhouse gas-emitting energy sources. But deploying them today, without making fundamental policy and regulatory reforms, risks increasing emissions instead.

If residents use these systems to reduce their electricity bills, the batteries would draw energy from the grid when it is cheapest. And because utilities don’t structure how much they charge with the goal of lowering emissions, the cheapest power more often comes from power sources that emit carbon, such as coal. In addition, batteries do not operate at 100 percent efficiency: as a result, households that use them draw more power from the electric grid than they actually need.

For the systems to actually reduce greenhouse gasses, utilities need to change their tariff structures substantially to account for emissions from different power source. They would need to make energy cheaper for consumers when the grid is generating low-carbon electricity, researchers said.

The first-of-its-kind study, conducted by a research team from UC San Diego’s School of Global Policy and Strategy and Jacobs School of Engineering, modeled how residential energy storage systems would operate in the real world. The study modeled deployment across a wide range of regions, utilities and battery operation modes.

Read more at University of California – San Diego