by Jeff St. John

July 26, 2019 July 26, 2019

Hawaiian Electric, Hawaii’s main investor-owned utility, has been facing the challenge of incorporating renewable energy into its island grids for years now, from the weather-induced shifts in utility-scale wind and solar farms, to the backflows from rooftop solar on its distribution circuits.

But that’s nothing compared to the 100 percent renewable grids it will have to operate someday. That’s because those grids will have to operate without the stability of synchronous generators — the spinning steel turbines, wrapped in wire and magnets, and mostly powered by fossil fuels, that serve as the anchors of almost all large-scale power grids today.

Last week, HECO filed a plan with state regulators that represents its first steps toward a future grid that doesn’t rely on these massive spinning generators.

By 2024, it hopes to replace two set-to-close power plants — the 203-megawatt AES Hawaii coal-fired power plant on Oahu, and the 37.6-megawatt Kahului oil-fired power plant on Maui — with a mix of energy storage, grid services, and “Renewable Dispatchable Generation power purchase agreements."

In another bold move driven by state policy, almost all of this mix of replacements — about 240 megawatts of stand-alone storage, 200 megawatts of grid services such as frequency regulation and demand-side capacity, and up to 900 megawatts of renewables-plus-storage projects — will be built and owned not by the utility, but by third parties through an open RFP process.