Californias made impressive progress transitioning to clean energy, cutting its power-sector CO2 emissions nearly in half over the past 15 years. But with rapid energy system changes have come grid management challenges, as this week's blackouts show: https://slate.com/technology/2020/08/california-blackouts-wind-solar-renewable-energy-grid.html 1/7

The proximate cause of the blackouts was an unexpected drop in wind output, limited imports from neighboring states, and outages at two gas plants. But more broadly, the amount of "ramp-up" in generation between mid-day and evening in August has doubled in the past 5 years: 2/7

This has been met in large part by increased imports from neighboring states, as well as running in-state gas plants less and keeping them on standby. But imports cannot be relied on as other states also decarbonize, and are more limited during heat waves. 3/7

A high renewable grid (and particularly a high solar grid) is one that necessarily requires a lot more firm and dispatchable generation sources, large-scale energy storage, and/or large grid interconnections over wide regions. 4/7

There is a lot of work being done on all of these, but at least today it's clear that leaders like California are seeing some new stresses on the grid from high levels of renewables integration. These are solvable problems, but they are also real ones. 5/7

Solar, wind, and battery storage technologies have gotten significantly cheaper over the last decade. They are modular and have proven much easier to deploy and build than, say, new nuclear power plants. The reasons to support the deployment of solar and wind are myriad. 6/7

But we also cannot expect the transition to be seamless and without hiccups, and we need to recognize the importance of firm clean energy, storage, and transmission to compliment a high wind and solar grid in the future. 7/7