PJM has "Regulation D" signals for sub-second response from energy storage resources (which are mostly batteries in practice): https://www.pjm.com/~/media/comm

PJM has "Regulation D" signals for sub-second response from energy storage resources (which are mostly batteries in practice): https://www.pjm.com/~/media/committees-groups/task-forces/rmistf/postings/regulation-market-whitepaper.ashx https://www.pjm.com/~/media/committees-groups/task-forces/rm... An energy storage regulating resource, such as a battery or flywheel, cannot burn fuels to produce electricity, but instead charge and discharge energy from the bulk electric system itself through a power inverter. Energy storage devices can match a desired output within 200 milliseconds of receiving the regulating signal; therefore these resources do not need to model any dynamics, ramp limitations, or dead-bands. Australia is also using batteries in a similar way: "South Australian Battery Responded in Just 140 Milliseconds After A Coal-Fired Power Plant Failed" https://www.sciencealert.com/elon-musk-s-south-australian-battery-responded-in-just-140-milliseconds-after-a-coal-fired-power-plant-failed https://www.sciencealert.com/elon-musk-s-south-australian-ba...