When Hawaii shut down its last coal plant on September 1, 2022, eliminating 180 megawatts of fossil-fueled baseload power from the grid on Oahu, it installed 'the most advanced battery energy storage facility on the planet'. Kapolei alone constitutes about 17% of Oahu's peak capacity, taking on more responsibility than batteries elsewhere have ever had to. It works with the island's bustling solar sector to allow surplus clean electricity that would otherwise be wasted to get onto the grid and, in case a disaster knocks out the grid, it can jump-start other plants. When renewables growth and fossil-plant retirements pass a certain threshold, the clean technologies have to start maintaining the grid, not just feeding it. That's why this project matters to the clean energy shift everywhere: It's one of the first real-life examples of how to shift critical grid functions from fossil-fueled plants to clean energy plants.