In the article by David Roberts of Vox, Roberts discusses the secret behind energy storage in the US. "The way it’s typically used in the US today, it enables more fossil-fueled energy and higher carbon emissions. Emissions are higher today than they would have been if no storage had ever been deployed in the US." In his article, he references a paper written by Eric S. Hittinger and Inês Azevedo, published in Environmental Science Technology back in 2015, titled "Bulk Energy Storage Increases United States Electricity Systems Emissions". You can read the full paper here and the article by Roberts here.