\"Battery capacity is frequently used to store solar and wind energy when there is low demand, and respond in times of peak demand.\"

John, though this seems to be a popular assumption, I have yet to see evidence this is how batteries are being used. I see a lot of evidence, matched by financial incentive, to charge batteries with A) a grid mix, or B) the direct output of natural gas plants.

Building a large battery installation next to a solar farm is great for optics. It makes it look like the batteries are storing 100% clean energy, that is then being used to power the grid with 100% clean energy. But that is far from the most financially-rewarding option for the facility's developer. When the sky is cloudy or it's after sundown and his batteries aren't charged, they're useless. If he charges from the grid mix at night when prices are low, he can sell energy from his fully-charged batteries back to the grid at a profit the next day. Any time, in any weather.

If that is the case (and there's no reason to think it isn't), batteries enable an arbitrage scheme that only increases carbon emissions. They're storing imported gas- or coal-fired electricity at night (you didn't think California's energy imports were all from clean sources, did you?), wasting at least 20% of it in storage losses, then spitting it out the next day at a profit.

By usage data, batteries are seldom used to shave peak demand. They're used far more often to supply-balance intermittent renewable energy - to patch the holes left when the wind dies, or clouds move over the sun. They're used to provide ancillary services - to correct voltage / frequency instabilities introduced by solar and wind sources. In short: get rid of renewable energy and they're 100% unnecessary.

I submit fewer emissions would result by carting renewables and grid batteries off to the electronic waste dump and generating all of our electricity with efficient CCGT gas plants - meeting demand efficiently, in real-time. Proving that's not the case, before lining the pockets of venture capitalists with $billions in rate increases for electricity customers, should be Step #1. Shouldn't it?

Battery Energy Storage Projects & Developments