GRA
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https://www.greencarcongress.com/2018/12/20181212-ucsd.html
. . . The researchers selected 16 of the largest utilities companies in the country and dug into their tariff structure, carrying out the first systematic analysis of how much utility companies charge residential customers to forecast the economic and environmental impact of these systems, if they were to be widely deployed across the country.
Conventional wisdom may suggest that these storage systems—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% 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, the researchers said. Utilities would need to make energy cheaper for consumers when the grid is generating low-carbon electricity, researchers said. . . .