Not sure which forum this goes in; will take a guess at this one. It doesn’t seem to me to be exactly Factual Questions, but it might be; but putting it here should give more possible range to the discussion.
(No, discourse, this is not even remotely similar to any of the topics you’re suggesting!)
Aside from the argument about where they’re being made, this seems to me to be a major game changer if it works as described and can be manufactured in quantity at anything resembling an affordable price. I’m sure there are people on here who know more about battery technology than I do – anybody want to weigh in?
While continuously tweaked in the labs to offer ever better performance, vanadium flow battery technology has aimed for mass-commercialization for over 20 years. However, it has never reached volumes of scale. The installed capacities have grown steadily in recent years though, from double digits to hundreds of megawatt-hours, with major projects announced in China, Australia, and Canada.
Unlike lithium-ion batteries, vanadium flow batteries store energy in a non-flammable, liquid electrolyte and do not degrade with cycling. They hold the promise of 10-hour duration storage, tens of thousands of cycles, and even up to 25 years of service life. However, to function, these batteries require pumps and aqueous electrolytes that suffer from comparatively low energy densities.
The wikipedia article has a list of pros and cons. I would no more gamble on this being a game changer for grid storage than I would on any of the other newish battery technologies and improvements. Doesn’t mean it won’t come out on top of course.
Thanks, both of you. That’s the sort of information I was looking for.
So: not a gamechanger at this point, but significant potential for at least some uses, and multiple people working both on improvements and on possible commercialization, though more likely for large scale uses than for powering individual homes? Is that a fair summary?
Speaking of battery breakthroughs, i just heard about these things …
Sand Batteries !
(I just need to work out how much sand i’ll need to heat my 2 bedroom house this winter !)
It’s not very efficient. They use resistive heating to heat the sand, but then just use the heat directly (to keep buildings, etc. warm). But a heat pump with a geothermal system might achieve 3x the heating rate of the input energy.
That’s not to say there’s no merit to the idea. Wind farms for instance occasionally produce more energy than the grid can take, leading to negative energy prices. In this case, heating up a giant pile of sand for later use might be a decent idea. But it’s not a general-purpose replacement for electrical batteries.
And what is even better is water and a height differential, but that’s not always cheaply available in places like Florida, so some other type of energy storage might be better.
Yeah, pumped hydroelectric can be arbitrarily efficient, though in practice it’s usually around 80%.
There are some proposals for using large blocks of concrete or train cars full of gravel for areas where that isn’t possible, but they still need some kind of height differential. And it’s underappreciated that while rock is denser is water, the advantage of water is that it’s easy to store and move giant quantities of it.
Another possibility is compressed air, but that has other downsides (gets hot when you compress it, acts as a giant bomb without special measures, etc.).
The topic there wasn’t gravitational storage, but thermal storage. Which makes water better than sand because water has a much higher specific heat, and also because it’s a lot easier to exchange heat with a fluid. In some parts of the world, sand might still be cheaper than water (even though the water for this purpose can be saltwater), but I suspect that in most such parts of the world, you don’t want more heating.
In that case, I disagree. Water does have a higher specific heat, but not by as much as you think due to the difference in density (somewhere around 2.5x). But worse, you can’t heat water past 100 C without a pressurized container. Whereas the sand here can be heated to 500 C or more, so it contains a lot more energy per cubic meter.
True, it’s easier to get the energy in and out with water, but that may not be a limiting factor. These guys seem to be running air through their sand pile.
Normally I’d say that a 100% limit is assumed–which can only be achieved asymptotically–but given that heat pumps are regularly said to achieve 300% efficiency, perhaps that is not a safe assumption for this topic.
Does anybody knowledgeable ever say that? Reliable dealers do say that heat pumps have a 300% Coefficient of Performance, but that’s not at all the same thing. Any good air conditioner can make that statement.
I’m sure some people on the internet make that claim, but people on the internet say all sorts of things.
When not speaking precisely? Sure, all the time. It’s not even wrong, exactly, because efficiency is always relative to some baseline. If the baseline is resistive heating, and we call that 100% efficient, then we don’t have much choice but to call a heat pump 300% efficient.
We could say that our resistive heater is less than 100% efficient, but then we have to state that relative to the temperature difference and cold reservoir temperature. Which might end up being even more misleading if we are not interested in comparing to the Carnot limit.
Sure, speaking accurately, you’d always use CoP since that’s not ambiguous. When just bullshitting on the internet… eh, I’ve probably used the colloquial term myself a bunch of times.
I’d say as to heating & cooling, the efficiency that matters is economic, not physical.
All the various “geothermal” (another semi-misnomer) systems, and to a lesser degree air exchange heat pumps, are simply harnessing economically free energy that’s present in the great bulk of the Earth’s landmass and atmosphere. A rigorous physics-based accounting would include the energy extracted from or deposited to the environment and would give a much lower efficiency figure.
By my logic you can take the installed price of a solar panel vs the total lifetime electricity it can create over a 20-30 year (?) lifespan, and compute a cost per KWH, compare that to, e.g. a coal-fired plant, and decide it has an efficiency of 80 bazillion percent. FTW!
Actually, I wonder that that number is? I WAG it’s big, but not bazillions big. Anyone know?
Unfortunately, all too many of the more respectable YouTube general tech channels get suckered into “battery breakthrough” stuff. Many of these not involving actual, you know, batteries but other storage methods. Basically plugs for companies with very iffy business models.
One recent one was a sort of phase-change liquid thing. Nowhere in the entire video is energy density mentioned, cost per kilowatt hour, etc. Sets off all sorts of red flags.
Another was a large thing with pumped liquid sulfur storage. Um, between the losses of converting electricity to heat, loss of heat during storage and losses converting back to electricity this isn’t going to fly. Never mind the scale needed, the maintenance, etc. Just go with a gravity-based storage system.
The signal-to-noise ratio over all these posts is sadly too high. It seems that out of a hundred such videos, maybe 1-2 are actually significant and worthy of attention, investment, etc. There are breakthroughs, but calling every stupid idea a “breakthrough” isn’t helping. And the loss of investment capital wasted on all those junk schemes is sad.
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