It doesn't have to be batteries, hydrogen gas can be generated from solar at 80% efficiency, and storing hydrogen is way cheaper than batteries. Certainly way cheaper than nuclear.
Not really. For long term storage, the cost of a unit of energy storage capacity becomes more important than the round trip efficiency. This is all the more the case when the cost of the input energy declines.
For seasonal storage, hydrogen is vastly better than batteries, even with a RTE of 40%. That's because the cost of an underground hydrogen storage cavern can be as little as $1 per kWh of storage capacity.
You misrepresent what I wrote. I didn't say hydrogen was cheap. I said the PER ENERGY CAPACITY part of hydrogen storage was cheap. And it is! It's like 200x times cheaper than the same aspect of battery storage. So if we get into a situation where the per-energy capacity costs are really import (such as, long term storage), hydrogen beats batteries.
There are, of course, OTHER parts of a hydrogen storage system, whose costs scale with the input and output power, not the stored energy. And these other parts (and the lower efficiency) make hydrogen uncompetitive for diurnal load leveling.
But hydrogen is superior to batteries if the goal is to store the energy for considerably longer periods. It is TOTALLY about short vs. long term.
As for whether hydrogen is "incredibly expensive": for the things it is suitable for, it is cheaper than the alternatives. Try to optimize a CO2-free power system using just wind, solar, and batteries in Europe, vs. one that also includes hydrogen storage. The latter is cheaper! It's also cheaper than a system that includes new nuclear power plants
> In what world is $800 to $1,400 per kilowatt hour per year, "so damn cheap"?
Your units there don't even make sense. BTW, I hope you aren't taking ratio of energy capacity to power-related costs suitable for diurnal storage and applying that to a seasonal storage system. The latter charges up and discharges over months, so the ratio is very different.
The key point about hydrogen is that the cost of storage capacity (to be distinguished from costs related to charging and discharging rates) is extremely low. So if you need a system to cover very rare extended outages, or to store energy from summer for use in winter, hydrogen is much better than batteries.
Hydrogen I think has a few good advantages over batteries. Storage is cheaper and faster. Quick charging would be good for buses, trucks and trains. The cheap storage is good for things like ships. Also long term storage for the winter - you could use sunny & windy seasons to build up gas supplies for winter months.
It's much easier to make the economics work than it would be to make the economics of batteries work for seasonal storage or rare event backup.
If you look at cost optimized solutions to providing steady electrical output from solar + wind in high latitudes, hydrogen is strongly featured. It becomes much more expensive to use just short term storage like batteries.
Hydrogen is often useless, but it's sometimes essential. Hydrogen critics bleat about efficiency without understanding the limits of that argument.
My reply was refuting your claim that hydrogen storage was cheap. Now you're going off on a tangent about short term vs. long term storage and ignoring the central point of my previous comment: the cost estimates for hydrogen storage are nowhere near cheap.
> Yes, the cost to store hydrogen for LONG TERM STORAGE is higher than the cost to store electricity in batteries for SHORT TERM STORAGE. But the cost to store hydrogen for long term storage is LOWER than the cost to store electricity in batteries for the long term.
> If you are comparing batteries short term with hydrogen long term, you are comparing apples and oranges.
I'm not comparing anything. I'm providing a source on the cost of hydrogen storage, to refute your unsubstantiated claim that hydrogen storage is cheap.
And as it turns out this cost is extremely expensive, regardless of whether it's used for short term or long term storage.
> Your study does NOT say batteries are cheaper than hydrogen for long term storage. They could not possibly be cheaper for that, since there are too few charge/discharge cycles to amortize the batteries' very high cost per kWh of capacity.
Correct, this study is about the cost of hydrogen not a comparison versus batteries. And for the second time, nowhere did I compare hydrogen against batteries. My reply doesn't even mention batteries once.
All I used this study for was tho find an estimate for the cost of hydrogen storage. And that cost is $1,400 per kilowatt hour per year for normal estimates and $800 per kilowatt hour per year for optimistic estimates. This is incredibly expensive, contrary to your claim that the cost of hydrogen storage is "so damn low".
> You seem to be saying "just use short term storage!". But that's not a legitimate approach, since there are long term variations in supply and demand. Short term storage only applies to short term variations.
The point is that it's extremely expensive, and not a viable solution for any type of storage. Short term or long term. The cost per kilowatt hour of storage is just way too high to be viable. $800 per kilowatt hour per year for the optimistic estimates, and $1,400 for realistic estimates is insanely expensive. And again this is assuming that the electricity provided to convert water to hydrogen is free.
In what world is $800 to $1,400 per kilowatt hour per year, "so damn cheap"? For hydrogen to achieve even just 1 day's worth of energy storage for the USA (11.5 TWh daily usage) at a cost of $800 per kilowatt hour per year would cost $9 trillion dollars per year. And remember, that's the optimistic estimate and assuming that the energy used to produce hydrogen is free.
This isn't about short term vs long term storage. Hydrogen storage is incredibly expensive, it's not "so damn cheap".
Yes, the cost to store hydrogen for LONG TERM STORAGE is higher than the cost to store electricity in batteries for SHORT TERM STORAGE. But the cost to store hydrogen for long term storage is LOWER than the cost to store electricity in batteries for the long term.
If you are comparing batteries short term with hydrogen long term, you are comparing apples and oranges.
Your study does NOT say batteries are cheaper than hydrogen for long term storage. They could not possibly be cheaper for that, since there are too few charge/discharge cycles to amortize the batteries' very high cost per kWh of capacity.
You seem to be saying "just use short term storage!". But that's not a legitimate approach, since there are long term variations in supply and demand. Short term storage only applies to short term variations.
You repeat some of the anti-hydrogen memes. Hydrogen is actually quite storable, certainly much more easily stored than energy in batteries. The cost of underground storage caverns for hydrogen is two orders of magnitude cheaper than the cost of batteries storing the same energy.
> batteries are better for storage of energy in most cases
That's not true. There are two main storage cases: from day to night and from summer to winter. Because there are 365 days and nights in a year and only one summer and one winter, a battery for seasonal storage needs to be 365 times cheaper than one for daily storage to break even after the same number of years. Of course, there are no batteries that are 365 times cheaper than lithium-ion batteries. Nothing comes close.
People are thinking that chemical energy storage could work for the case of seasonal storage. It doesn't quite work right now, but it's not off by 2 orders of magnitude, it's off by maybe a factor of 5. It is much more likely that we'll succeed in making green hydrogen production, transportation and storage economical than that we could make batteries cheaper by a factor of 100.
Separately, there is a fairly good chance that we'll be able to extract hydrogen from underground deposits (google "white hydrogen", e.g. [1]).
Third, hydrogen storage economics enjoys the square-cube law: larger pressurized tanks can hold a lot of hydrogen for not a much larger cost than smaller tanks. So hydrogen could make sense for applications where very large tanks are needed, and one such application is railways. A typical train oil car has a volume of about 130 m3. At 700 bar (typical storage tank pressure), one m3 of hydrogen weighs about 42 kg, so this is about 5.5 tons. Hydrogen has about 3 times the energy density of diesel, so that would be the equivalent of about 16 tons of diesel. Train have an efficiency of at least 400 ton-miles per gallon, which is more than 125 ton-miles per kg, or 2 million ton-miles for 16 tons. In other words, such a tanker car could be enough to propel a ten thousand ton freight train for 200 miles. It would be much easier to convert diesel locomotives to burn hydrogen than to electrify thousands of miles of railways, so there's a fairly good chance that rail could be hydrogen's killer app.
Compared to the cost of large-scale hydrogen storage batteries will always be expensive. This is why grids will use hydrogen for long-duration energy storage instead of batteries.
Hydrogen can be stored underground (and is), just like natural gas. This is much cheaper per unit energy storage capacity than storing energy in batteries.
I don't know why you are saying that. Batteries are expensive. To recoup the capital expense you need to charge and discharge them daily (so you can buy the electricity cheap and sell it expensive and you get a profit). If you want to use them for long term storage, then you buy cheap electricity in the summer, sell it for a profit in the winter, do the same each year, and find out in a few years that you are broke.
With hydrogen, the storage is cheap. We already store natural gas in tanks. We can switch to hydrogen. Maybe hydrogen will leak more, but 1. hydrogen is not a greenhouse gas and 2. the square-cube law tells you that for large tanks you don't really care about leakage.
I don't think we will find an alternative to hydrogen for long term storage of electricity.
Hydrogen will probably fill a niche for seasonal grid energy storage. In general pumped storage > batteries > hydrogen for cost/efficiency, but hydrogen has the advantage that it's cheap to store for weeks or months at a time while pumped storage/batteries are suited only to smoothing out daily or weekly variations in solar and wind output.
It's more useful for getting from 90%/95% to 100% green energy than from 0% - 90% though, and it's more expensive than natural gas performing the same function so we likely won't see it used in anger for a while.
Hydrogen is even better for longer-term storage (e.g. seasonal). Produce hydrogen via electrolysis from solar in the summer, then power things when it's cloudy + low sun angle in the winter. There are quite a few major hydrogen storage projects in progress that do exactly that, FWIW. E.g. https://www.energy.gov/lpo/advanced-clean-energy-storage (Disclaimer: My wife works on that project)
Batteries don't compete for long term storage. Losses are too high. Hydrogen is an excellent solution for longer term (weeks to months to years) storage.
Efficiency only matters in so far as it affects cost per MWh. It is plausible (from what I heard at least) that hydrogen is cheaper at the required scale than batteries. After all we will likely have incredible oversupply during long summer days where electricity is essentially free. Scaling battery manufacturing to store enough power for a whole winter is difficult.
In any case I think storage is something where „let the market figure it out“ is a reasonable strategy.
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