"In less than 15 years, battery costs have fallen by more than 90%," according to a new report from the International Energy Agency, "one of the fastest declines ever seen in clean energy technologies." And it's expected to get even cheaper, reports Reuters: An expected sharp fall in battery costs for energy storage in coming years will accelerate the shift to renewable energy from fossil fuels, the International Energy Agency (IEA) said on Thursday... The total capital costs of battery storage are due to tumble by up to 40% by 2030, the Paris-based watchdog said in its Batteries and Secure Energy Transitions report. "The combination of solar PV (photovoltaic) and batteries is today competitive with new coal plants in India," said IEA Executive Director Fatih Birol. "And just in the next few years, it will be cheaper than new coal in China and gas-fired power in the United States. Batteries are changing the game before our eyes." [...] The global market for energy storage doubled last year to over 90 gigawatt-hours (GWh), the report said... The slide in battery costs will also help provide electricity to millions of people without access, cutting by nearly half the average electricity costs of mini-grids with solar PV coupled with batteries by 2030, the IEA said. The Los Angeles Times notes one place adopting the tech is California: Standing in the middle of a solar farm in Yolo County, [California governor] Newsom announced the state now had battery storage systems with the capacity of more than 10,000 megawatts — about 20% of the 52,000 megawatts the state says is needed to meet its climate goals. Although Newsom acknowledged it isn't yet enough to eliminate blackouts...