I think if you install 28 trillion dollars worth of batteries you're going to have a waste problem that will dwarf storing the waste from fission plants.

No, just a recycling problem.

On that scale you might have both. In the case of the Fukushima tsunami, how much environmental damage was caused by e.g. the (lead) batteries in the cars which were trashed? Sure, lithium isn’t lead, but that (along with arson and crashes) are important to plan for at this scale, not just the ideal product end-of-life.

Your concern seems entirely baseless to me.

Probably no damage was done by lead electrodes in Fukushima. Lots was probably done by dry-cleaning establishments, hardware stores, machine shops, pesticide inventories (in factories, stores, and farms), paint factories and stores, etc., but metallic lead? Lead is so stable that even bullets inside people's bodies, where they're constantly exposed to hot, salty, corrosive bodily fluids, usually don't cause any toxicity. Even lead sulfate (the mineral anglesite) is somewhat challenging to get a toxic dose of.

Lithium is a relatively abundant element in Earth's crust, about the same abundance as nitrogen, and more abundant than boron, tin, tungsten, or iodine. It's fairly nontoxic: the lethal dose of lithium salts for a person is measured in tens of grams, and it doesn't bioaccumulate. There are a few lithium minerals that can form (lepidolite is a lithium phyllosilicate, spodumene is a lithium aluminum silicate) but probably most lithium ions released would remain soluble, spreading into the environment. But it would take an enormous lithium release to cause problems: there's 230 billion tonnes of it in the sea without causing any toxicity. In the USA, the EPA hasn't established any limit on lithium in drinking water. The usual therapeutic dose of lithium is about a gram a day, a few times lower than the usual intake of sodium or potassium. 7-Up used to be full of lithium.

I don't think you need to worry about arson in China.

There are a lot of ways for me to be wrong given I’m not a chemist; the point, to misuse a famous quote, is that safety requires me to be wrong about every concern and danger only needs you to be wrong once. So far we’ve not got enough stuff for any hazards in any of the components to rise to the level of significance, and indeed they may just be fine even at the level we need to use them; but in the 1930s I think I could say the same of CFCs?

Scale matters, and while I’m optimistic about batteries etc., I want us to solve problems rather than ignore them — we can only do that by being open about them, and I’ve seen enough occasions where others have claimed risks “don’t exist at all” to be more comfortable with a claim of “1% risk” than of “0% risk”.

> I don't think you need to worry about arson in China.

I’m more concerned with the effect than the cause, the cause was a mere suggestion: https://www.youtube.com/watch?v=g7FXeaahRsg

I agree.

> This assumes massive advances in battery tech to support seasonal and week-to-week weather changes.

This is bad engineering. One would not use batteries for that sort of long timescale storage, one would use something like hydrogen. The round trip efficiency is much lower, but with the much smaller number of charge/discharge cycles that doesn't matter. The effect of efficiency on the cost of storage scales inversely with the average storage time; it's important for diurnal storage, not important for seasonal storage. The energy capacity cost of hydrogen storage could be maybe $1/kWh of capacity.

For a timescale of a week, thermal storage is an option, with sand heated to 1200 C. Round trip efficiency would be 53%.

28 trillion? A 3000 km long by 1m^2 cross section solid aluminium conductor would only cost 22-ish billion, and that lets you put the PV in Gobi desert with minimal losses.

But overproduction and diversity of the type of renewable is probably even cheaper.

Things get cheaper if you order for a trillion.

This logic only works if the production capacity is available.

If you have to rebuild your entire supply chain to handle that kind of demand you're prices will start to go back up again.

For China (and quite a lot of other places, including the UK) the alternative to building a battery supply chain is to build a supply chain for something else, not to keep the existing and increasingly pointless coal-based supply chains.

(That “something else” can be nuclear).