California readies to prevent blackouts, but threats remain

California’s top energy regulators said the state is better prepared to avoid last summer’s rotating blackouts, but they cautioned the power grid of the nation’s most populous state is still vulnerable to extreme heat waves that could force more outages later this year.

State officials say they have acquired an additional 3,500 megawatts of capacity ahead of a likely scorching summer that threatens to increase demand beyond what the grid can handle. That includes an additional 2,000 megawatts of batteries designed to store energy generated from renewable sources — like solar — that stop workin...