Batteries Could Worsen CO2 Emissions — Study

by Christa Marshall (E&E News) Home batteries like the Tesla Powerwall could spike greenhouse gas emissions significantly unless current policies governing the electrical grid change around the country, according to a new study.

The findings in the journal Environmental Science & Technology run counter to the conventional wisdom that energy storage is inherently a "clean" technology.

That's not always the case, and batteries on the market today could make it more difficult to address climate change in the short term, according to researchers at University of California, San Diego.

"While the increase in home batteries deployment is underway, we need to work on multiple fronts to ensure that their adoption is carbon minded," the paper states.

The reason residential batteries could worsen emissions is that people looking to reduce their electricity costs typically draw power from the grid when it's cheapest — which, in many locations, means electricity from coal and other fossil fuel sources.

Also, households that use batteries draw more power than they actually need and use energy when delivering stored power, increasing emissions, the study said.

For the dynamic to change, utilities need to alter their rate structure so that electricity is costlier for customers during the times of day when the grid is relying heavily on the dirtiest fuels, Hanna said. A carbon tax or general "tariff reform" among utilities would lower the carbon footprint of the technology, the study said.

"Storage operation that has the goal of decreasing emissions means that it is charged when the cleanest power plants in the region are producing power and discharged when the most carbon-intensive power plants are producing power," Hanna said.

With policies in place to ensure that, home storage systems could help reduce emissions by 2.2 to 6.4 percent on average, according to the study.

However, the monetary incentive that households would need to receive from utilities to become CO2-neutral currently ranges from $180 to $5,160 per metric ton of CO2, depending on the fuel mix in a given location.

In a blog post this summer, Jason Burwen, vice president of policy at the Energy Storage Association, said that creating a price signal for storage to charge with low greenhouse gas generation would minimize or avoid the problem of higher emissions.

In March, researchers at Rochester Institute of Technology found that adding 3 gigawatts of storage in the Midcontinent Independent System Operator, which operates the Midwest's transmission, could increase emissions by the equivalent of adding more than 6,000 cars to the road annually. An 8 percentage point increase in use of wind and solar in the region could reverse that (Greenwire, March 5). READ MORE