> Liu and colleagues focused on redesigning the power module
A flow battery separates the power portion (the electronics, electrodes, pumps, etc) from the energy portion (tanks, fluid). Which is not so amazing for a car or a UPS where you want tens of minutes to a few hours of charge or discharge time, but is potentially great for grid use, where a discharge time of days to months is useful.
Not sure I know the use case for a duration of that length. It's possible today with pumped hydro, but I don't think it's used in that mode.
The DoE's "long duration storage earthshot" effort is loking for 10+ hours, which makes more sense: https://www.energy.gov/eere/long-duration-storage-shot
Chemical storage could be a big win when a mountain isn't readily available. Or the land is too expensive to use for power storage.
There are other options, of course - new nuclear plants, importing renewable power from countries with better weather, huge numbers of wind turbines, and so on - but cost-effective long-term power storage would address some issues if it was available.
Better long distance transmission infrastructure is a much better solution to this.
Winds are stronger in winter time.
Depending on your risk tolerance you overbuild to reduce that. Same as with all types of energy production.
Why store winter heat as work when you could just store it as heat or chemical energy?
All you need is a hole, some plastic sheeting, an element, and some pipes to store many GWh. Alternatively one of many cheap phase change materials, thermochemical stores, or some low grade sand unsuitable for construction.
Lump those together, halve it for the magic of heat pumps but then add some back because winter will be above average use, call it 30kWh/day. Three months of winter is ~90 days, and ~30 million households, is storage of 30,000 x 90 x 30million = 81,000,000,000,000; eighty one trillion Watt-hours.
A classic (non-EV) car battery stores ~1kWh, so eighty one billion of them to store that kind of power. Thousands per household. Even to store ten percent of it is hundreds of car batteries per household which is still unfeasible, and not going to get you through winter.
Working your example - google tells me that zinc-iodine electrolyte gets you about 200 Wh per liter. Therefore you need about 400 million cubic meters of storage for the capacity you suggest. To estimate the cost of this, I looked at reservoirs. The largest drinking reservoirs in the world are in Qatar, where they have built 5 tanks of 436,000 cubic meters each. Therefore we'd need about 200 of those facilities. The cost was around 5 billion dollars, so our total cost would be around a trillion dollars.
This is obviously a lot! But not unimaginable - the government borrowed over 300 billion pounds in the 2020 fiscal year alone just to pay for Covid. In practice you'd need considerably less than 90 days of continuous power, because the wind does blow and the sun does shine even in winter. All you really need is tanks to buffer the difference in renewable capacity between winter and summer, which is certainly not 100%. And the system can be built up incrementally over a long period of time, and still yield value - we don't need to spend a trillion dollars all at once. And in the worst case - you can erode the fraction of load taken on by renewables with nuclear (doesn't look so expensive now eh?).
Obviously take all these numbers with a grain of salt, this is a back-of-the-envelope calculation built on another back-of-the-envelope calculation (in particular, I haven't included the cost of the electrolyte). The point is merely to show that it's not orders of magnitude outside our ability.
World GDP is only around a hundred trillion, and we're talking of maybe ten trillion of it to build a heating system for Western Europe, for very little financial return for any investors.
Practically, we've been struggling to build one nuclear power plant (Hinkley C) for twenty years. I think it sounds like it is orders of magnitude outside our ability.
I have no idea whether there are containment or environmental challenges that make this especially hard.
It would seemingly also allow you to carry around 50 miles of juice when you are running around town and bump up to 400 miles of juice when you are taking a road trip. This really only makes sense if the car is able to recharge the juice.
Maybe a new hybrid model (not gas electric hybrid) could emerge. The base (say 50 mile) capacity is solidish state like we have today and a flow battery range extender could be filled with fluid when the extended range is needed. This would make it so the car wouldn’t need to charge the fluid, if that helps.
motor <-> lithium <-> flow battery
the low current from the flow battery could be continuously augmenting and replenishing the lithium ion battery
or even:
supercapacitor <-> lithium <-> flow battery
And it's easy to imagine retrofitting a gas station to all of a sudden have charged electrolyte instead of gas, but I'm sure that has all sorts of additional complexities that I know nothing about... ;)
In a UPS the tanks and valves and pumps are new points of failure, as the other responder states. In a car they are many times more complicated than electric vehicles, yes, but still less complicated than ICE vehicles by far. Your heater has more moving parts. Hell, the emissions control gear is probably more complex than the entire drivetrain of the electric vehicle.
A Li-Ion battery can charge and discharge in something like an hour. If you double the number of cells in a battery or installation, you can store twice as much energy and you can draw twice as much power. (You don’t have to provision twice as much power circuitry, but you do need to purchase that extra power worth of electrodes in the cells.)
If you’re building something for which a roughly predetermined power to energy ratio (i.e. hours of use at a reasonable rate of discharge for the technology), this is fine. Similarly, if overprovisioning power or energy is not a problem for cost or weight, also fine.
But for grid use, wide differences in the duration of energy storage for different purposes can make sense. And a flow battery can separately provision power and energy. This gives a possible cost benefit to flow batteries.
It also have lower energy density so you pumping 600l of new electrolyte on the station might still give you only 200km of range
or maybe a locomotive, which is less sensitive to weight and cargo capacity?
For locomotives ? I'd imagine the simplest solution would be to have "battery wagon" ; get on the station, replace the battery wagon, and be on your merry way while it is recharging in the station waiting for next train to pick it up, at least for the long haul stuff. But capacity density still matters, if flow batteries are being close and cheaper then it makes sense, but if you need to pay slighty more per KWh but get 2x the capactity... thats 2x the range and less maintenance.
Or, you know, just electric rail. It already works fine in many places. I wonder if making some hybrid solution with electric rails also being covered by solar panels (basically so same maintenance crew can manage both) would make sense
So it all depends to what level of density it gets. If it is same capacity per kg but lower power there are still many places it can be used, if it is much lower it stops being sensible for moving stuff. And the price would need to be significantly below the normal batteries for anyone to even bother.
Trains maybe, but surely the money is better spent on overhead wire? Even if tunnels/bridges/etc. can't take it you're better with just the power-buffer battery and no flow battery.
And rail is far cheaper to operate once built per unit capacity than trucking. If you don't inflate it with endless feasibility studies and contracts that get paid regardless of output the initial building costs are about double a 4 lane highway, but it carries a lot more and maintenance is lower.