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Comment by pkulak | Hacker News Reader

This is the other end of the solar/wind puzzle. And it will work in the same way: individual consumers operating in their best self interest.

My power company just came out with a new rate plan that I jumped on: 8 cents for all but 5-9, which is 26 cents. It's pretty obvious the "duck curve" is slamming them pretty hard. I'm making it mostly work with creative home automation and timers on my car charger and water heater, but with just 6 kWh or so of batteries I could completely eliminate my peak power usage. I don't have any place to put solar panels on my property, so I'm looking forward to sodium batteries making this a viable way for me lower my electric bills.

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Texas idles a bunch of wind, but also has desperate need for immense amount of fresh water — which simply cannot be met with falling & ground supplies. The obvious solution (pitched by GW Bush?) was: wind power for gulf desalination. There's unlimited demand for fresh water, it'd have marginal impact on coastal brackishness, and means the wind could be run at nameplate full-time; peaker demand just means reducing power to desalination plants, which can be done extremely quickly. No need for batteries.

> Texas idles a bunch of wind, but also has desperate need for immense amount of fresh water

Texas needs freshwater just like California does--aka not at all.

Both states have plenty of freshwater for their citizens. The citizens simply don't soak up that much water. Yes, even with lawns, swimming pools, and golf courses there is plenty of water for citizens.

What both states don't have is plenty of water for agribusinesses--they are pumping their aquifers dry. And desalinization with renewables has zero hope of ever being cost effective enough for agriculture.

So... they both need freshwater. I agree that there is plenty for residents. and I'm annoyed at the silly stuff they ask people to do, like lather up in the shower with the water off. but agriculture is pretty important for everyone.

I suspect that, at least when pitched by GW Bush, the capital costs would have reduced or eliminated profitability. (And maybe not just capital? I wouldn’t be surprised if intermittently operated equipment fouls as or more quickly than continuously operated equipment, so opex may not scale down all the way with utilization.)

It’ll be interesting if electric cars become ubiquitous and have enough charge to stay above 50% with daily use… a simple change like Ford does with the F150 lightning can allow them to deliver power back to the house, which will be crucial during peak loads, and they can charge up again at random off-peak times. A car can basically function as a mobile power sink/source to distribute load evenly throughout the grid.

That sounds similar, though not identical to my rate plan. 7.43 cents from 9pm to 7am, then 11.9 cents until 5pm, and then 32.8 cents from 5-9. Clearly they want people to just turn off everything they can at 5pm.

> just 6 kWh or so of batteries I could completely eliminate my peak power usage

Out of curiosity I took a wild ass guess at what it would take for me.

I usually use about 7 kWh between 5-9pm, so lets say ~$2K for an even 10 kWh of LFP. Probably at least that much more to get a suitably capable 240V inverter and smart transfer switch. My low quality napkin math says at least 20 MWh to break even. I probably wouldn't make that bet. It would take a long time to go net positive and any kind of equipment failure would instantly tank the ROI. And that's also ignoring the time value of money altogether.

If the batteries were free, it would be a somewhat better deal, but still not a slam dunk.

Yeah. A lot of it, for me, would be to ride out small power outages and blips. Taking money off my bill is the kind of secondary benefit I’d need to actually give it a shot.

IMO the problem isn’t the batteries per se. Those 6kWh or so of batteries should be under $1k wholesale. The balance of the system is egregious markup, packaging, safety certification, the mess that results in no one’s batteries interoperating well with anyone else’s equipment, etc.

Cutting even 50% off the cells won’t help much.

(Hmm. Maybe Na-ion will end up with a nice discharge curve so that one can actually parallel or, better, series-connect a bunch of batteries, use an external BMS without fancy per-cell connections, and get good results. Despite the number of vendors selling two-terminal LiFePO4 batteries with internal BMSes, they really don’t work well. Lead acid, for all its faults, works fine with dumb batteries.)

duck curve: https://en.wikipedia.org/wiki/Duck_curve

The key is really getting the costs down on batteries + the necessary inverter and charger.

Any power routed through batteries is expensive - compared with power pulled directly from grid / solar panels etc.

Sodium ion batteries won't change that equation any time soon.

But they can make whatever grid storage is installed (whether in homes, electric car, or grid scale), a lot cheaper.

Some limited amount of such storage + some smarts to control when heavy users are run & when batteries are (dis)charged, can go a long way. Just 'flattening the curve' is enough.

This is very true. A good quality inverter/charger with enough capacity to run a home is $$$$. Also need some kind of transfer switch to connect/disconnect the grid, and that's $$$$. It's hard to make a good case for it on ROI alone, you need to be solving some other problem, like frequent power interruptions if you live out in the sticks or something. But in that case batteries probably won't be enough so you need a generator anyway.

True that both battery systems and, more surprisingly, automatic transfer switches are pretty expensive. But I think a lot of that still has to do with lack of demand and competition. There are literally only 2 or 3 providers that I could find that make automatic transfer switches. and it was a minimum of $800. I ended up going with a $40 AliExpress option that is supposedly able to handle 125 amps which is enough for my needs but isn't UL listed, so I think would only work for diy. I also built my own battery and inverter system for about $2500 in parts that is about the size and power of a Tesla Power wall which they sell for more than $10k last I checked. but again, inverter is not UL listed.

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