BLACKOUTS IN EXTREME WEATHER DRIVE DEMAND FOR CLEANER BACKUP POWER

Software engineer Kenna Ofoegbu in Houston, Texas tries hard to keep his three kids cool during the summer and that means air conditioning.

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Yet their house has lost power three times in just the past two and a half months. One of those outages lasted three days.

That time, Ofoegbu and his wife decided to pay for two nights at a hotel, both for the air conditioning and the connectivity.

"I could not afford to go multiple days without having internet connection," the 42-year-old said. "Having power and internet access is critical to my daily work."

When that ordeal was over, the couple did what many do if they can afford it: They bought a generator. It cost $1,500 plus some $800 for an electrician to do some wiring, and burns either propane or gasoline to keep the house running.

But burning those fuels can make the air foul to breathe and also worsens climate change, prompting Ofoegbu and many others to seek cleaner ways to maintain electricity in an emergency.

So far, the options are mostly expensive but they are improving. Here's the current state of play:

Many people are now installing arrays of batteries at their homes. As of April, more than half of rooftop solar buyers in California chose to install batteries with their solar systems so that when the grid goes down, the house doesn't. Nationally, sales of these solar-plus-battery systems jumped in the U.S. last year, according to Wood Mackenzie, a consulting firm.