cheap flow battery for off-the-grid energy storage

https://techxplore.com/news/2017-02-long-lasting-battery-decade-minimum-upkeep.html

I had assumed that the most cost effective way of dealing with the intermittent renewable power was the supergrid and assumed doing it with just batteries would be much more expensive but now it looks like it is possible to make cheap long-lasting flow batteries for off-the-grid energy storage which have only cheap non-toxic non-corrosive recyclable chemicals in them thus making it at least one cost effective solution to intermittent power without a supergrid. Perhaps the most cost effective way is to combine this with a supergrid?

With the advent of electric cars, I foresee car batteries as providing the bulk of the storage. And this doesn't necessarily mean drawing power from the car batteries although that is ideal. It just means being smart about when to charge them. Similarly smart geysers and air-conditioning is known to be able to make grids much more efficient.

It is good news though. When I investigated getting a larger UPS I discovered that the batteries which are really not much different from standard car lead acid batteries, are remarkably expensive.

Originally posted by humy
https://techxplore.com/news/2017-02-long-lasting-battery-decade-minimum-upkeep.html

I had assumed that the most cost effective way of dealing with the intermittent renewable power was the supergrid and assumed doing it with just batteries would be much more expensive but now it looks like it is possible to make cheap long-lasting flow batteries for off-the-g ...[text shortened]... er without a supergrid. Perhaps the most cost effective way is to combine this with a supergrid?

What they don't say is how much energy these things can store. I'm intrigued by this sentence: "The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour...", mains electricity costs about 15 pence per kilowatt hour, so I wonder about that $100 figure, is that meant to be the unit price of the battery? For comparison a lead acid (i.e. car) battery has an energy density of the order of a tenth of a kilowatt hour per litre and cost around £50. The Bosch S4 007 battery [1] has a total volume of about 7.5 litres, weighs 17 Kg and has a capacity of 72 Amp hours at 12 volts, giving us 0.864 kW hours of storage and an energy density of 116 Watt hours per litre and I saw a price of £70 (~$85) here [2]. So they are asking for something with about 8x the storage per dollar of a car battery. That was a relatively high end battery as well, you can get cheaper ones. So I'm left wondering why this goal wasn't achieved 50 years ago.

[1] http://www.racshop.co.uk/SiteData/Root/file/Battery-Documents/0092S40070_TDS.pdf
[2] https://www.tayna.co.uk/S4-007-Bosch-Car-Battery-Type-100-S4007-P9789.html

Originally posted by DeepThought
What they don't say is how much energy these things can store. I'm intrigued by this sentence: "The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour...", mains electricity costs about 15 pence per kilowatt hour, so I wonder about that $100 figure, is that meant to be the unit pric ...[text shortened]... 92S40070_TDS.pdf
[2] https://www.tayna.co.uk/S4-007-Bosch-Car-Battery-Type-100-S4007-P9789.html

I was wondering about that $100 figure as well.
As it is written in the link, I think it is extremely unclear what that means.

Originally posted by DeepThought
What they don't say is how much energy these things can store. I'm intrigued by this sentence: "The Department of Energy (DOE) has set a goal of building a battery that can store energy for less than $100 per kilowatt-hour...", mains electricity costs about 15 pence per kilowatt hour,

I don't think the price of mains electricity is relevant at all. We are talking about the cost to store - repeatedly - a given amount of electricity.

So they are asking for something with about 8x the storage per dollar of a car battery. That was a relatively high end battery as well, you can get cheaper ones. So I'm left wondering why this goal wasn't achieved 50 years ago
It would appear that making cheap batteries is a remarkably difficult task, just is making small lightweight batteries. Both of these factors is the reason electric cars are still not yet mainstream.
However, Tesla is changing that and battery costs are dropping dramatically.

I have a UPS that can run my computer for about 45 minutes. I am told a car battery and inverted would keep it going for several hours. Not sure how that all translates into kilowatt hours but if we looked up a UPS advert we could probably find out the current cost per kilowatt hour of a typical small UPS.

Originally posted by twhitehead
I don't think the price of mains electricity is relevant at all. We are talking about the cost to store - repeatedly - a given amount of electricity.

[b]So they are asking for something with about 8x the storage per dollar of a car battery. That was a relatively high end battery as well, you can get cheaper ones. So I'm left wondering why this goal w ...[text shortened]... UPS advert we could probably find out the current cost per kilowatt hour of a typical small UPS.

Here is one: https://www.googleadservices.com/pagead/aclk?sa=L&ai=DChcSEwjklZDvsY3SAhXXSg0KHeAaAD0YABAW&ohost=www.google.com&cid=CAESIeD2IZmWS8rHeLIvoMa3gQhKC0iDFpEcFNKC7TjixfeWQw&sig=AOD64_3BVylYIa7QQ4WAFpMrFTLdlJuysA&ctype=5&q=&ved=0ahUKEwiJvIjvsY3SAhXMRSYKHQYyAhAQuxcIqAE&adurl=

Sorry for long URL.

The gist is, 1500VA and we'll use your figure of 3/4 hour. Cost $409 US. Just quick round off, say one hour, 1kw. So it does one KwHr for 400 bucks. Not exactly overwhelming, eh. That would be about 3 watt hours for one buck. 33cents per watt hour.

Originally posted by sonhouse
Just quick round off, say one hour, 1kw.

I suspect my pc uses closer to about 200W

I believe the largest battery in a Tesla is 100KWH. I believe that works out cheaper than your $400 per kwh. Of course UPS's don't need to be so compact, so its batteries are cheaper, but at the same time, buying small usually costs more per unit, and the cost of the batteries in that UPS is probably less than half the overall cost.

It must be said that most energy grids waste an awful lot of energy (about 30% at a guess) which could be saved with batteries. So cheap batteries would have an enormous impact on energy usage worldwide.