New research by economic and public policy consulting group M.Cubed finds a proliferation of back-up generators across California, with nearly 90 percent being diesel-fueled, posing significant obstacles to achieving greenhouse gas reduction targets and driving nearly $136 million in annual health costs.

Over the last year, the diesel generator population jumped by 22 percent in the South Coast Air Quality Management District (SCAQMD), while the generator population in the Bay Area Air Quality Management District (BAAQMD) saw 34 percent growth in less than three years. In 2021, the two districts were collectively home to 23,507 diesel generators with a capacity of 12.2 gigawatts (GW), about 15 percent of California’s entire electricity grid.