Is Powerwall good for coal and nuclear?
No one seems to have spelt this point out, but there’s an obvious potential for Powerwall to be used in ways that benefit coal, nuclear and geothermal power, as well as renewables like wind and solar. Advocates of these technologies love to cite the fact that they are “baseload” supplies, but this is a misconception. Because they are costly to turn on and off (or even up and down), these technologies produce too much power at times of little demand (late night and early morning).
If owners of home solar systems, connected to grids with an off-peak excess supply, install battery storage on a large scale, it would make sense to run two cycles per day. The systems (most sensibly oriented west) would charge up from solar panels in the early afternoon, and supply power in the evening. Then they would recharge from the grid in the early morning, and supply power to meet the morning peak associated with getting ready for work, school etc.
What’s the net effect of this. First, obviously, it makes storage a more appealing economic choice for householders. Second, although it reduces costs for any kind of electricity that is not fully dispatchable, the benefits are bigger for renewables for two reasons. First, the variability of these sources is greater. Second, pricing systems, at least those in Australia, are already set up to encourage use of off-peak grid power, whereas current feed-in tariffs discourage solar PV.
From our current starting point, effect of adding more systems with a combination of solar PV and storage will be to reduce total demand for coal-fired power (and, where it exists, nuclear power), and to enable more efficient use of existing capital stock. So, it’s likely to discourage new investment in these sources. However, unless we have a carbon price, or other measures in place, it won’t necessarily accelerate the closure of existing coal-fired plants.
Update A note on the economics: Calculations I’ve seen on the web assumed that lithium batteries have a life of 1000 recharge-discharge cycles, but it appears this number can be improved drastically. These guys are claiming 20 000. More on this soon, I hope.