Guest essay by Eric Worrall
Yet another renewable energy storage idea…
To Store Renewable Energy, Try Freezing Air
Such energy storage technology could help relieve congested transmission lines in places like Vermont
By John Fialka, E&E News on January 2, 2020
The system that supplies clean electricity to Vermont is not exactly a model of Yankee ingenuity.
In 2011, the state adopted a plan to get 90% of its power from renewable sources by 2050. That led to a surge of wind-generated power from the northeastern part of the state and an expansion of solar.
But transmission lines in this sparsely populated part of Vermont have such low capacity that much of the renewable energy is often unavailable because the lines are too congested. The state was deprived of another form of emission-free power in 2014 when an aging nuclear power plant called Vermont Yankee was permanently shut down.
So what can Vermont do?
A British company called Highview Power proposes a novel solution: a storage system that uses renewable electricity from solar or wind to freeze air into a liquid state where it can be kept in insulated storage tanks for hours or even weeks.
The frozen air is allowed to warm and turn itself back into a gas. It expands so quickly that its power can spin a turbine for an electric generator. The resulting electricity is fed into transmission lines when they are not congested.
“Vermont has transmission issues,” explained Salvatore Minopoli, vice president of Highview’s USA affiliate. “It’s a situation that many places in the U.S. are dealing with where renewable energy is being deployed more and more. It’s power that’s intermittent. They need something to balance their system out.”
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Read more: https://www.scientificamerican.com/article/to-store-renewable-energy-try-freezing-air/
Now we understand what happens when you put a humanities graduate in charge of rebuilding a power grid, what about this great new energy storage idea?
Liquid-air energy storage: The latest new “battery” on the UK grid
New energy-storage solution solves some problems but creates others.
MEGAN GEUSS – 6/13/2018, 10:00 PM
A first-of-its-kind energy-storage system has been added to the grid in the UK. The 5MW/15MWh system stores energy in an unusual way: it uses excess electricity to cool ambient air down to -196°C (-320°F), where the gases in the air become liquid. That liquid is stored in an insulated, low-pressure container.
When there’s a need for more electricity on the grid, the liquid is pumped back to high pressure where it becomes gaseous again and warmed up via a heat exchanger. The hot gas can then be used to drive a turbine and produce electricity.
Tesla’s new battery in Belgium shows value is in dispatch speed The system is called Liquid Air Energy Storage (LAES, for short), and if you’re thinking it sounds remarkably like Compressed Air Energy Storage (CAES), you’re right. LAES takes filtered ambient air and stores it so it can be used to create electricity later, just like CAES. But LAES liquifies the air rather than compressing it, which creates an advantage in storage. Compressed-air storage usually requires a massive underground cavern, but LAES just needs some low-pressure storage tanks, so it’s more adaptable to areas that don’t have the right geology.
LAES has also been compared to pumped hydro, where excess electricity is used to pump water up to a reservoir above a hydroelectric turbine. Pumped hydro and LAES both can be designed to provide power for hundreds of thousands of homes. But unlike pumped hydro, LAES doesn’t require a water system or elevation differences to operate.
On the other hand, an LAES system is only 60- to 75-percent efficient, compared to the 75- to 85-percent efficiency of lithium-ion batteries. Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn’t as quick.
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Read more: https://arstechnica.com/science/2018/06/liquid-air-energy-storage-the-latest-new-battery-on-the-uk-grid/
This energy storage idea in one form or another has been kicking around the UK for several years. The original incarnation of this idea was a compressed air storage system, but liquified air has advantages of compressed air. Liquid air containers don’t have to withstand extreme pressures, and a large volume of air can be condensed into a small volume of liquid.
The manufacturers claim the system is 60-76% efficient, which with other costs likely at least doubles the cost of renewable energy stabilised via this system. Probably cheaper than a battery, but likely still hugely uneconomical compared to fossil fuel.
There are also potential problems with reheating the liquified air in adverse weather conditions. Things could get very icy around the cold end of the reheater circuit. Highview claims to have a proprietary solution to the “waste cold” problem.
60- 76% efficient is more likely 50- 60% . Then if it’s estimated cost is double then double that again. Time to go back to the drawing board.
We still have not heard from 3 experts.
This makes no sense, why not use the electricity from the windmills to make hydrogen from water? Burn the hydrogen to make electricity as required.
That makes even less sense, in addition to the problems of storing the hydrogen, the electricity you get out by burning the hydrogen is a small fraction of the energy you put in to decompose the water.
Water is a more effective greenhouse gas than carbon dioxide…..
Interestingly both Highview’s plans to improve efficiency involve fossil fuels.
To make liquefying air more efficient they plan to use waste cold from LNG regasification.
To make regasifying the air more efficient they plan to use waste heat from fossil fuel power plants.
The latter sort of makes sense as the fossil fuel power plants will be working hard when the power from the liquid air is needed.
The former is less sensible as there is likely to be an inverse relationship between demand for gas and the need to store electricity.
The problem for them us that the South Hook and Dragon LNG terminals are on the North shore of Milford Haven, while Pembroke CCGT power station is on the South shore, next to the remaining local refinery owned by Valero.
Reenewable energy is like socialism. If it doesn’t work, its because you haven’t spent enough money on it yet.
Leo,
May I help you?
Renewable energy is like socialism.
If it doesn’t work, its because you haven’t spent enough of other people’s money on it yet.
Now – that looks better – no?
Auto
Just a few observations:
This is all perfectly doable, it’s the cost that is the concern.
Variations on the Linde process has been used for a century to liquify air. All proven and off the shelf.
The choice of low-pressure tanks is a cost consideration at this scale.
First, the critical point for air (temperature and pressure limit of having any liquid) is -140C and 549 psig! To store liquid air without boil-off would require both a pressure vessel with a 600 psig rating (providing 10% margin) and you’ll still have to refrigerate to prevent boil-off.
Sure, one could use pressure vessels and minimize the boil-off from fugitive heat through the insulation, but we’re talking multi-million gallon volumes here for a grid-scale facility. That would be colossally expensive. A million-gallon Horton Sphere would be ~260 feet in diameter. It is highly likely that it is more cost effective to use atmospheric tanks, slather them in insulation and capture/recompress the boil-off.
Looking at the Baker Hughes information, it seems that this technology is aimed at peaker plants (where one is competing with gas turbine gen sets that can be lit-off quickly unlike CCGT units) or load-leveling at a steel mill where there is already the liquid air plant (oxygen for steel making) and waste heat so the revaporization heat exchangers wouldn’t cover acres.
If one takes the production cost of renewable MWh’s, add the cost (and losses) for wheeling that power to where its needed, add this storage cost and the cost of frequency control (unless the liquid air plants can provide sufficient spinning mass for inertia….), then we’re looking at some handsomely expensive power.
We’ll all be slipping-on our Designer Davis hair-shirts. : )
For my sins, I ended up as being something of an expert in safely treating and abandoning coal mine shafts in the UK.
At least one of my bosses imagined that this was a very simple task. How difficult could it be to drop a load of crap down a deep hole?
Well, actually not so simple, bearing in mind the potential for coal mine methane explosions. (And many, many other issues.)
But one problem was a seemingly never-ending string of spittle-flecked loons who thought that abandoned mines and mine shafts would be just the thing for energy storage.
I always tried to be polite with these guys, but it was a challenge when (as was often the case) they had a very scant appreciation of the basic laws of physics. Perpetual motion solutions abounded. None had even the foggiest idea of how to deal with methane, or even that there could be a problem.
Occasionally, one would propose something that might actually work, if the problem could be categorised as (a) occasionally produce a bit of electricity and (b) waste as much money as possible whilst doing so.
But the unmentioned elephant in the room was the fact that many of these crackpots were in receipt of substantial wads of taxpayers’ money, liberally handed over by various “innovation funds” (almost invariably our beloved government).
This is what motivated them to get out of bed in the morning. Not saving the planet. These guys with their fancy liquid air notions will be cut from precisely the same cloth.
The more I’ve thought about this, the more I think that it’s a ruse.
1) An “entrepreneur” sells an idea to a friend in govt. The idea beed not be good, just good enough to convince a few lobbyists and politicians that it could work.
2) The friend pulls some strings, makes some calls, and soon gets “development funding” for this revolutionary idea.
3) Once the funding arrives, spend the money! Give some back to politicos, stash the rest!
4) Declare bankruptcy. See Solyndra. The idea still exists, some still believe it could work, some other entrepreneur can “try again”. Wash, rinse, repeat.
Sounds accurate.
This is beyond stupid,almost as stupid as “flying cars” – which would result in smoking cremation ‘sites’ littering the urban and suburban landscape.
Too bad fossil fuels haven’t already concentrated the diffuse energy of the sun. It would be so handy to have it ready-made, relatively easy to manage, and abundant without having to go through all these extra steps.
Scientific American is right up there with Twitter and the New York Times.
Doug
Yes, I quit reading SA many years ago.
It’s very sad to witness the decline of a once great publication. It used to be available in my youth here in the UK IFIR for well under £1 a copy, in the days when that sum would have purchased a month’s supply of confectionery. I actually had a go at several of the “amateur projects” then to be found at the back of the magazine with varying degrees of success. Yes, my teenage impressions of the USA were formed mainly by SciAm and Mad Magazine. Can’t say they’ve changed a lot since!
Is that comment in our favor?
Rather than using this idea to prop up poorly paired wind and solar, perhaps it could be used to keep nuclear plants running flat out. There should be no trouble piping in hot water to solve the frost problem.
So engineers are proposing cryogenic refrigeration to liquify air for energy storage. Meanwhile, there are giant refrigerators running powerfully as needed to deliver heat high into the atmosphere where it more easily escapes to space. It’s called convective weather. Thunderstorms. So the same engineers, if only they would think more clearly about it, ought to be able to explain why heat cannot, in fact, be accumulated to dangerous effect on the surface of a planet which is flooded with natural refrigerant (water) and possesses an atmosphere so ready to initiate the heat engine when conditions require it. The entire problem statement – harmful warming due to greenhouse gas emissions and rising concentration – goes away when you watch a thunderstorm and see it as a refrigeration machine.
The multinational M.U.F.P.C. (Magical Unicorn Fart Power Corporation) would surely capture liquid air in their invisible storage tanks at no additional charge, if the government mandates, won’t they? Although with M.U.F.P. do we really need liquid air? Shouldn’t we be using maximum capacity of invisible magical unicorn fart storage for the real deal, for the proven technology of magical unicorn farts?
Stepping back from it all, it is simple. Fossil fuels/nuclear come with high density storage built in. Renewables don’t. The cost of energy storage is very high, whatever technology is used. A simple matter of thermodynamic law.
Hence moving from fossil/nuclear to renewables as a prime source of energy will inevitably be very expensive.
It’s not merely a cost issue, it is an energy impossibility. The energy consumed to design, manufacture, install, maintain and administer renewables exceeds the energy they produce in their lifetime. The energy consumed to provide necessary energy storage/backup makes it worse.
Without the energy provided by other sources, renewables cannot exist.
I grew up in Vermont and one pride the people had back then was to maintain the environment in as pristine fashion as possible. The phone companies were frustrated because cell towers were a no=no. The companies designed replacements that looked like crosses on the rural churches, even pine trees. Then a massive influx of people from New York came, bought up the dairy farms that were just hanging in there so they could be Gentlemen Farmers, took over the whole political system, and decided that wind power was the way to go, even though there was sufficient energy being transmitted down from Canada. My college roommate, John Dynan Candon, who became an executive at Vt Yankee nuclear power plant, had convinced me of the efficacy of nuclear. Nooo, the answer was to dynamite the top off a beautiful mountain, promoted by the Governor, and install wind turbines in an essentially ecologically pristine location. He was not re-elected but got a job as spokesman for the wind energy company. Meanwhile the whole system, which had worked well, was messed up as this article suggests. All for fraudulent reasons and purposes. This whole fraud must be stopped.
Would be perfect “fuel” for running a ship, instead of diesel . Covert diesel engine to run on high pressure air from liquid air .Easy to heat liquid with huge heatsink available (ocean) , cool ocean at same time (joke) .
Wouldn’t it be great if we could take the electricity and convert it into an energy-dense stable solid that could be safely stored on or in the ground? The solid could then be used to transform the stored energy into heat and then electricity.
Even better if we didn’t even have to manufacture that energy-dense solid because it was naturally occurring.
Exactly! Carbon stabilization has worked great naturally for gases and liquids too, and all this fuss about renewables is misdirected until depletion becomes a serious constraint.
I’d be very surprised if this system was even 20% efficient due to problems with waste heat and icing.