With Malta, Alphabet’s X is exploring a salt-based solution to store renewable energy

From 9to5google

Abner Li

– Jul. 31st 2017 9:10 am PT

@technacity

 

While clean energy is not a new area for Alphabet’s X, the moonshot division has previously only focused on energy creation. With a new “exploration” called Malta, Alphabet is now looking at cost-effective energy storage solutions.

Nintendo Switch

“Explorations” are X’s “early-stage attempts to investigate new moonshots.” Energy storage is increasingly falling into that category as companies like Tesla are building battery-centered solutions to capture energy from renewable resources.

X is instead “developing a thermal storage system that uses salt to store renewable energy at scale.” Malta is specifically tackling the “mismatch” between the abundance of renewable energy from wind and solar and the lack of cost-effective technologies to store it, especially during peak power usage:

If there’s more energy produced than the electric grid needs, the capacity of wind and solar farms is simply wasted.

With no clean, cost-effective technology for storing renewable energy to serve these peaks, the amount of renewable energy the grid can handle could be capped, and the growth of renewable energy over the next decade could stagnate.

Malta’s solution is to contain just captured electricity as thermal energy. The work behind it comes from Nobel prize-winning Stanford physics professor Robert Laughlin who created as “theoretical system that stores electricity as heat (in high temperature molten salt) and cold (in a low temperature liquid similar to the antifreeze you have in your car).”

For the full story go here

HT/ Resourceguy, although next time could you at least link to a story instead of making me go find it? Winking smile

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David

Research lab eh?
More like a boardroom where they will either buy and hide, or buy and sell any real developments.

Greg

:

… from wind and solar and the lack of cost-effective technologies to store it, especially during peak power usage:

No, you need to store the energy during peak power PRODUCTION not during peak demand.
The idea of converting electricity into heat and back again is a on starter thermodynamically. You degrade ordered energy into disordered movement and you will not recover more than about 35% as electricity whatever you do.
If you want thermal storage start with thermal capture like Ivan Paw which will capture far more energy to start with.
Wind turbines only capture at best 30 odd % of the kinetic energy of wind, they run at 25-30% of boiler plate rating as an annual production rate. Solar PV is at best 15% efficient.
If you then waste another 60-70% of what you managed to capture it is nonsensically in terms of physics.
I wonder what the Stanford , Nobel winner is qualified in.
There is nothing new here they are just trying to adapt molten salt storage as is already used in concentrated solar to wind and PV where it is very wasteful.
Sounds more like an attempt to capture some govt grants or tap into the billions available from the UN slush fund. Having a Nobel on board will probably help make that claim look more credible to bureaucrats.

hunter

+10.
Follow the climate hype money hunt.

Greg

oops, sorry , I messed up closing the blockquote

Greg

“theoretical system that stores electricity as heat (in high temperature molten salt)

You cannot store electricity has heat. You can only CONVERT electricity to heat. Converting it back again is very inefficient. Nobel laureate Prof Richard Laughlin has just invented a “theoretical ” means of wasting 60% of the generated electricity.

Robert of Ottawa

60%? Oh more than that. A very wasteful and uneconomic approach to a totally artifical problem created by ideology.

rocketscientist

YES! I spotted the lunacy too. They are proposing converting solar energy into heat….wait for it…to reduce global warming!!!!
Who ties these morons shoes?

Solar energy has been converted to heat ever since glass windows were installed on the south side of a building in cold climates.

You convert heat to work to electricity without combustion via Rankine cycle. It’s about 35% thermal efficiency or 65% heat loss. This Alpha X crap is idiotic. Why use a heat pump? You don’t need a refrigerator. You only need an electric stove to convert electric to heat. Still, the system is inefficient.

Tar Peter

To Greg and to everybody who thinks that it is impossible to convert electricity to heat with more than 100% efficiency. Use heat pump, and will reach 200-300% efficiency and use the same heat pump in the opposite direction and it will give back to you 100 % of the electric energy entered in the system, at least theoretically. In practice 60-70% recovery can be achieved, IMHO.
[???? ???? .mod]

Mike Rossander

Tar commits the fallacy embraced by marketers of heat pumps everywhere (and which is hard-coded into their chosen measure of efficiency, HSPF). Specifically, Tar assumes that the energy available in the environment is “free” and infinite. In more technical terms, that T >>> delta T.
Heat pumps move heat, they don’t create it (ideally). The HSPF measure of “efficiency” is the ratio of BTUs moved over the watt-hours used to make it move. Since you’re getting your starting BTUs for “free” and ignoring the BTUs lost at the sink, it is possible for that “heating” ratio to be well above 100% without violating the law of entropy. Think of an elevator and a counter-weight. If the two masses are properly balanced, even a very small motor can move the much heavier elevator to the top of a really high building.
HSPF is the equivalent of comparing the potential energy of the elevator car now at the top of the shaft to the minor motor power used to get it there, while ignoring all the loss of potential energy from lowering the counterweight to the bottom.
So far, no problem. If you have unlimited distance to keep lowering the counterweight forever, you can continue to pile up energy at little cost. The breakdown occurs when you need to get energy back out of the system. Unless you’re willing to cut the elevator cable (creating a one-time, irreversible energy transfer), you have to lower the elevator while simultaneously raising the counterweight. That also will cost some small measure of energy.
The result – while heat pumps can move large quantities of energy back and forth very efficiently, there are process losses at ever step AND ONLY THOSE PROCESS LOSSES REALLY MATTER. For home-sized units, approximately 25% in the heating cycle and about 33% in the cooling cycle for an efficiency of the total loop of about 50%. Presumably, an industrial sized structure could do better but it will never exceed 100% of loop efficiency.

If you have to ask how much it costs…

According to X, salt-based thermal energy storage has the potential to be many times cheaper than battery storage because most of the materials necessary — steel tanks, salt and antifreeze — are inexpensive and abundant. The company says its Malta technology may be recharged thousands of times and last for up to 40 years, several times longer than today’s batteries.
Sadoway, who is also unaffiliated with X, said it’s too soon to say how Malta would compete on cost compared to other electricity storage technology because the company hasn’t provided any cost data publicly. “Thermal storage competes well with lithium-ion on service lifetime and on safety,” he said.
X declined to comment.

http://www.climatecentral.org/news/alphabet-molten-salt-clean-energy-21671

Duncan

“steel tanks” and “molten salt”, that cannot end well….I assume Nickel or Hastelloy based metal but X must dumb it down for the plebs (and the investors).

David

Iconel would work fine, even steels with a proper liner can do it.

Crispin in Waterloo but really in Beijing

Use glass. High temperature glass. Metals are so yesterday. Modern ceramics out-perform metals.

Ed Bo

I can’t imagine that the charge/discharge efficiency of this system would be better than abysmal. It’s hard to create large temperature differences with a heat pump, so the efficiency of the subsequent heat engine would be tiny.

Walter Sobchak

Hater.

The maximum theoretical energy loss in a heat engine was figured out by Carnot some years ago.
(Th – Tc)/Th * 100%
Degrees Kelvin are convenient. So let us try some numbers that are not too far fetched.
800°K – Th
250°K – Tc
(800-250)/800 * 100 = 68.75%
So ideally if those temperatures are obtainable you only lose 31.25% of the energy input. Real world results will be worse.
800°K = 980.33°F
250°K = -9.67°F

jorgekafkazar

Where do you get your heatsink Tc of minus 9.67°F?

Menicholas

Is that for each direction of the storage/reconversion?
And then there are losses due to imperfect insulation, etc.

Greg

That is just recovery. Converting elec to heat is near 100% efficient. It is converting disorder motion ( heat ) into directed energy which is inefficient.

rocketscientist

Greg, first you need to generate electricity to generate the heat. Why make the extra conversion? Take the heat directly from the solar energy and store it.
Such a system will be way more efficient than CO2 at trapping solar heat on earth.

Duncan

Two issues with this;
1) The assumption of renewable energy as being “abundant”.
2) Inefficiencies of converting from mechanical (wind) or solar electricity source, to a heat source and then back to electricity.
Something tells me this “moonshot” is the little ‘triangle’ in the centre of the image (hope the link works).
https://lh3.googleusercontent.com/g-wl8rCelzH5TjZPVZfkm_Zvw0rSJmuOVIDInLHTf7fQ67MqbHnKiMhWXyckfa7QLyOmbxyYMfqqYINGeX8i=s880

Taylor Ponlman

A private company (SolarReserve) has been working to commercialize this in conjunction with solar towers (mirror based). Not clear about the efficiency, but in that case the solar heating is directly melting the salt and the heated fluid is used as a buffer to produce steady power. Not exactly a universal solution, but may be practical in desert areas, etc

Duncan

Taylor, what you described has been around for a while and covered here on WUWT (see link), molten salt solar collection. ‘Buffer’ is one thing, a couple days storage is a whole other due to size and complexity.
Converting electricity to heat is easy, heat to electricity much less efficient/cumbersome requiring cooling towers/water/generators, very expensive. Wind and Solar already create electricity at their point source, converting it is asinine, use it or lose it.
https://wattsupwiththat.com/2016/06/21/worlds-first-247-solar-power-plant-powers-75000-homes-for-3-hours-per-day/

Hans-Georg

Yes, the evil cost. They would rather be excluded. Technically, many things have been possible for a long time, but not economically. 700 pumped storage plants can also be built in Germany. Only then electricity could only afford the top 10,000 of the money. One could also build enormous batteries in the format of football fields, then it would be only the upper 5,000. One tries to transport the electricity into the middle and southern part of Germany with the north-south links (power lines from the offshore and onshore installations in and on the north and Baltic Sea). But also this electricity is unstated and causes enormous grid costs. How to turn and apply: There is as yet no economic solution to this problem. One can hardly compare today’s windmills with those of the Middle Ages. Today they have to generate steady electricity and do not create this, the others in the middle age convert wind directly into moving energy. This worked better than today’s model.

Duncan

Agreed Hans, “this worked better than today’s model”, wind was great for grinding grain or pumping irrigation water in a non-time sensitive economy. Today, when a couple of extra MW’s is required between 10am and 11am and tomorrow a couple of MW’s less, not so much.

jorgekafkazar

The diagram (which looks like a Venn diagram) is meaningless.

schitzree

That’s not how you use a venn diagram.
^¿^

jhborn

I’m going to vent here.
Why don’t such pieces give numbers: energy lost in the heat pump, energy lost in the heat engine? (I’ll swallow that insulation will be adequate.) And, of course, some dollar-denominated data.
The article gives us nothing from which we might infer whether the proponents have really taken the idea very far. Saying “Nobel prize-winning Stanford physics professor Robert Laughlin” is all well and good, but most of us here are probably of a certain age, and a sizable minority of us have had some significant experience dealing with technological developments. So the fact that somebody came up with something in the past doesn’t cut much ice with us. Give us real data.
Thanks for indulging the vent.

Tom Halla

Ditto. My objections too. No numbers.

David

No numbers because they haven’t ran any yet. Odds are this is just another example of vaporware that will be used as publicity whenever there is bad news about Alphabet.

Menicholas

I am going to predict that the numbers will be incredibly awful.

MarkW

They are trying to attract (sc@m) investors.

An interesting (I think) little Wikipedia blurb that I found:
https://en.wikipedia.org/wiki/Robert_B._Laughlin
Clipped from the above linked item:
View on climate change[edit]
Laughlin’s view of climate change is that it may be important, but the future is impossible to change, since any effort to slow the rate of fossil fuel usage will “leave the end result exactly the same: all the fossil fuel that used to be in the ground is now in the air, and none is left to burn”, and since the climactic/geologic recovery process “will take an eternity from the human perspective, but it will be only a brief instant of geologic time.”. He writes “The geologic record suggests that climate ought not to concern us too much when we’re gazing into the energy future, not because it’s unimportant, but because it’s beyond our power to control.”
I had never heard of him, but this indicates that he may be a rather bright guy. And, by the way, his Nobel Prize appears to have had nothing to do with climate or climate change.

jhborn

Thanks for the tip. it does seem likely that he addressed the first-order thermo questions, so I can’t dismiss the idea itself as quickly as some–although I actually didn’t take the time to review what little thermo I knew, so my opinion of how promising it is isn’t worth much.
But I think this kind of writing, which leaves out all of the most-relevant information, is awful.

When do they announce that the process works much better when the salt is kept hot using natural gas?

and the cold liquid refrigerated using liquid nitrogen. Didn’t McDonalds solve this in the past?
http://www.seriouseats.com/2011/02/blast-from-the-past-the-mcdlt-mcdonalds-1980s-jason-alexander.html

Those heat pump’s and heat engine’s they refer to are not 100% efficient, except maybe in their computers. I just wonder how much of the energy put into this process actually comes out the other end.

TonyL

I just wonder how much of the energy put into this process actually comes out

Wonder no more!
The Carnot Cycle gives the maximum theoretical efficiency for a thermodynamic heat engine.
Efficiency = (Ti – To)/Ti
Or
Efficiency = 1 – (To/Ti)
where To is the cold side, or exhaust temp. (in Kelvin)
and Ti is the hot side, or inlet temp. (in Kelvin)
Wherever you have a thermodynamic heat engine, you must wrestle with the demons of energy loss.
This is why batteries and windmills are attractive. They are not heat engines, so the losses are relatively minor, from friction and electrical causes.
Here, they propose thermodynamic heat engines coming and going, an efficiency disaster in the making. The guy making the proposal must surely know this, so is probably just looking for some attention.

D. J. Hawkins

The efficiency of a heat engine is directly related to the temperature difference between the source and sink. A CCGT plant runs at about 1,400°C to 650°C in the first stage and then the steam stage is ouput at about 500°C or so with a final temperature of maybe 20°C, depending. I notice a distinct lack of numbers concerning this “solution”.

Gary Pearse

Need a Nobel or otherwise engineer to inject practicality into ‘thinking’ physicists. Unless the salt is very hot indeed, low quality heat recovery is dismal. This is even an indication of the limitations of heat recovery from hot systems. They didn’t give balllpark costs. Storing heat all day to use to generate electricity at night comes with high construction costs to minimize losses and conversion efficiencies, latent heat ‘costs’ and freezing up of the salt if the wind stops blowing…. People already pay a kings ransom for renewables and adding on costs and energy losses won’t make things cheaper.
Letting go is going to be hard, but the sunk costs are not an incentive to spend on patches to save just a bad idea.

jorgekafkazar

Alinsky rules prohibit inclusion of cost data. People would see through the scheme in seconds. The MSM would take longer.

When will the greenies ever figure out that energy storage is not going to make unreliable power generators reliable?

Curious George

It would. With an enough storage capacity. Not a day; not even a week.

Menicholas

It is also a question of efficiency.
This entire process would be doing very well to recover 25% of the electrons in wire that they began with.
And how much molten salt will they need to power on average sized state for even a day?
Every hour the salt gets colder and the cold part gets warmer.
Heat pumps are regarded as a waste of money if the cold side is lower than 40F.
They should be working on storing the energy chemically.
It is the only way to get sufficient density, and chemical energy is at least stable over time.

Menicholas

Maybe something like chlorophyll that works with thermal band photons.
Either way…good luck wit’ dat!

Rick C PE

CG: The problem is that to recharge your week’s worth of storage using your unreliable source requires massively over sizing the generating capacity. Roughly 10 to 20 times the average demand in wind or solar nameplate capacity. And once the storage is ‘charged’ when wind or sun conditions are favorable, there’s no place to store the excess. Can’t just pump it into the grid either without destabilizing.
Anyone who thinks that wind/solar can be a sole source if we just had a big enough storage capacity is dreaming in color IMHO.

Now: What if? The surplus energy could be used to produce and then to be stored as a flammable liquid or solid? Various carbohydrate compounds, maybe? Something that resembles petroleum or coal? Heck, extract the carbon for producing the compounds from the atmosphere in much the manner that plants extract it.
That would have the added benefit of reducing the anxieties of those who are worried about atmospheric CO2, CH4, etc. That would still leave the most important greenhouse gas: H2O able to do its thing to keep the planet warm enough to support life.

Latitude

How do they propose getting all this stored elec all over the country?

Curious George

These are not huge factories. Small is beautiful.

Michael S. Kelly

This is very, very old hat. Get a copy of “The Whole Earth Catalog” from the 1970s. You’ll find lots of stuff like this.

jorgekafkazar

Is that the Whole Earth Catalog with the “Toe-Foo” article?

Curious George

Converting electricity to heat, you can achieve a 100% efficiency – even more than 100% if you use a heat pump. The problem is a thermodynamic limit (Carnot efficiency) when converting back:
the limit is (T[high]-T[low])/T[high]. Usually, the low temperature is an ambient temperature – about 300K. To get a 75% efficiency, the T[high] should be 1200K = 900C – a serious engineering challenge.
Undoubtedly Stanford Professor Robert Laughlin knows all of that. I only hope that he is not following in steps of a Stanford Professor Paul Ehrlich.

Hans-Georg

And the best thing is, that Alphabet (X) is seeking dumbos to share the risk and the cost of a prototype project: “Malta is part of X’s Foundry, which explores early-stage projects. It’s not an “official” project like Project Wing (drone delivery) or Project Loon (high-altitude balloons that beam the internet to the surface). X is announcing Malta now because it wants to build a prototype plant for testing how storing renewable energy can feed a power grid. It’s accepting applications for potential partners on its website.” The ever lasting guideline of pseudo-greens: Never take in hand your own money, but seek any dumbos to give the money.

jorgekafkazar

They’ll probably build a computer model plant,. The model will perform admirably and the investment dollars of the gullible will pour in. The field test will fail abysmally. There will be the search for the guilty, the punishment of the innocent, and distinction for the uninvolved.

Menicholas

Nah, they will just get a guaranteed loan from Unca Sam then ask for the loan to be forgiven.

Crispin in Waterloo but really in Beijing

Don’t forget the apportionment of blame. That too is an essential step in the process of declaring victory before going home.

F Ross

Sounds like the PITS to me (Pie In The Sky)

Phil

Why would this be better than pumped water storage?
Answer: Pumper water storage has effectively been outlawed.

Menicholas

Because you do not need a mountain and a river?

Crispin in Waterloo but really in Beijing

Something about as good as pumped water storage is compressed air, ideal for a small place like Malta. The wind turbines can compress air mechanically and pipe it into a distribution grid, which itself is a storage system. It can also incorporate underground caverns and inflatable bladders 500m under the sea.
The air should be used to run cars powered by the French invention that decompresses the air in three stages. It is quite efficient. A great number of mechanical things can be powered by air: witness any underground mine.
Air powered devices are notoriously inefficient but that is a technology problem. The Frenchman really took things forward – a former Formula 1 mechanic, he is.
A renewable energy system doesn’t have to be efficient if it is cheap and long lasting. There is much more to a technology than a system efficiency.
There are only a few things that require electricity, computers for example. Air conditioners don’t. Cars and trucks don’t. Chicago had air powered trams that ran on free “100% renewables” until the mid-thirties when the city Fathers were bought off by the electricity companies. The air was compressed by trompes (Taylor hydraulic air compressors). Google ‘Ragged Chute’.

MarkW

You are going to lose at least half the energy you put into compressed air from thermal losses.

Griff

Really? Is that just locally to you?
The UK has a large pumped storage unit, has just approved a small new unit and there are plans for another new large unit in Scotland being kicked around…
Norway is considering it for its hydro…
Germany has built hilltop wind turbines with pumped storage reservoirs at their base…

Gavin

“The UK has a large pumped storage unit…”
No numbers Griff? How large in comparison to the >30gW demand on the UK grid?
No numbers for the size of the reservoir? Acres, hectares, football pitches or Waleses will do.
Thanks.

Gavin,
From memory but the largest (of four?) pumped storage facilities in the UK is roughly the same size as one large modern power station (1,600MW). I think this is c. 6% of UK demand but only for eight hours. So if used it *has* to be recharged overnight.
Again from memory the new one that Griff is talking about is a fraction of this, maybe 100MW. Big for your house, trivial in national terms.

Cliff Hilton

My question would be; what is the actual lost opportunity? How much of the wind and solar energy is neglected due to a lack of energy storage? 1%? 100%? Neither. Somewhere in between. One would only store potential lost energy. That is going to be very expensive electricity. Like others here, I’m interested in what it cost, including the 40 years of maintenance.

markl

Salt is good media for storing and buffering solar energy. Highly corrosive but relatively benign when leaked. It would alleviate the major shortcoming of Ivanpah …. cold start …. and make it more reliable and cost effective per $kwh after installation. Unfortunately it’s an eyesore and ecological nightmare. It does appear other worldly when you drive by it though.

schitzree

Ivanpah is why I find this idea so ridiculous. They already decided that it wasn’t going to be economical in the one place where it would have worked the best, a Solar Thermal Power Station.
Think about it. At Ivanpah they knew exactly how long they’d need the molten salt to need to store energy for (over night), they already had the impute energy as thermal, and they already needed a means to convert the thermal energy to electricity. All they would have needed to do was make the energy collection about double what they could run through generation and add storeage for the excess for later that night.
But they didn’t. It wasn’t worth it.
~¿~

D. J. Hawkins

You should keep up. Ivanpah does have salt storage. It doesn’t work. They have to fire up gas steam boilers to keep the salt warm enough overnight that they can actually operate when the sun comes up.

D. J. Hawkins

Sorry mistake there, that’s Crescent Dunes, not Ivanpah.

I have no problem with Alphabet wasting ill gotten Google gains on X stupidity. My son interned there between HBS years, and came away amazed at how much money they waste. Is their money.
I have a great problem seeing this recent article on something that is bound to fail on fundamental physics. Last time I saw something this stuoid, it was the ‘hot rocks’/cold rocks’ Isentropic Energy UK proposal from 2011. Mine £20 million grant/ subsidy, yup. Produce anything useful 6 years later, nope. And so it goes.

Ric Haldane

Rud, Perhaps Timothy Leary is still alive.

He is just outside looking in.

Tom in Florida

In penny stocks this process it is called “pump and dump”.

GREG in Houston

My boss told me in 1983: “Might be the best idea in the world, but if it doesn’t make money, it ain’t gonna get funded.” (Of course, he wasn’t considering project funding for money losers by the gov’t.)

JBom

Looks like a case of patent infringement, Savannah River Site, and the real Nobel Prize work that went on there and NOT at Mountain View, CA.

Rick C PE

Over the years I’ve read many articles on concepts for grid scale energy storage. Pumped hydro, various types of batteries, hydrogen, ammonia, fly wheels, compressed air, water/ice thermal, super conducting magnets, gravity lifts, and, yes, molten salts. This has been an issue considered by traditional fossil fuel utilities for load leveling for many decades. But so far not many actual economically viable installations. It seems it is hard to beat, a dammed river, giant pile of coal, large oil tank, or connection to a natural gas pile line as an energy storage media.
Trying to make wind or solar viable as a grid scale electrical energy source seems even crazier as you would have to build a huge over capacity (beyond normal peak output) to charge any storage system that would be sufficient to meet demand even for a few hours, much less a week of calm cloudy weather.

“But so far not many actual economically viable installations.”

https://en.wikipedia.org/wiki/List_of_energy_storage_projects

commieBob

Where the geography permits, pumped hydro is viable and has been used for years. There aren’t many places where it makes sense.
I’ve been following ammonia as fuel for a couple of years. It’s easy and cheap to store large amounts of ammonia so it’s possible to consider week long energy reserves. Almost no other storage technology comes close.
This paper talks about a system that uses the same cell for electrolyzing water to make the hydrogen to make the NH3 and as the fuel cell to create electricity. It claims a round trip efficiency of 72%.
I’ve followed a few technologies that made it from the lab to the pilot plant and eventually failed when they attempted to scale to full production. They always look like they could transform the world. I’m never able to predict the thing that will wreck them. If I could get even odds betting against such potentially world changing technologies, I’d be rich.

David A

Yes , even of you could do it efficiently you are still compounding the variability issue and effectively decreasing the efficiency of existing steady production fossil fuels; the hidden subsidy the Griff’s of the world ignore.

Griff

Well, we are at the point where prototypes are going mainstream on storage…
wind projects are now getting routinely built with storage batteries…
and remember, the first best use for storage is to replace ‘peaker’ plants and manage frequency response.
In this generation we’re not at the point of providing power for more than to meet sudden demand, manage ramp down of wind/solar as predicted, black start, etc.

D. J. Hawkins

@Griff;

wind projects are now getting routinely built with storage batteries…

We are used to your stupid, but please stop with the lies. Enumerate all the wind projects currently under construction and detail those with storage batteries. If it isn’t over at least 50% it isn’t “routine”. And anyone who tried to bankroll a wind project with a storage system capable of providing, say, 8 hours of nameplate output wouldn’t find any money for the project.

MarkW

In Griff’s world, adding a couple of ‘D’ cells is sufficient to label it as having battery backup.

Those giant heat pumps are going to be very expensive, they are going to last at most 15 years before they need replacement, and they’re going to leak refrigerant, which might well cause more global warming than the CO2 emissions which climate activists hope will prevented by the energy recovered by these storage systems.

Alan Watt, Climate Denialist Level 7

What’s the best possible round-trip efficiency of such a storage system? 25% ?

Keith J

Using electricity to melt salt to store energy? I knew legalization of cannabis could cause such daft thinking but assumed it would be in lower wage circles.
Availability. Engineering dictates turning thermal or radiant energy into electrical assumes huge losses, mostly due to Carnot efficiency along with real process limitation. These same limits apply converting thermal to electrical. In each step, available energy is lost.
Molten salt. Crazy idea because heat transfer in solids is abysmally poor. Especially salts. Sure, it is better than iron but that solid is eventually going to stop the flow of molten salt.
This is why power plants use working fluids between liquid and gas states.

Tsk Tsk

Presumably they keep the salt molten at all times. And the Brayton cycle is preferred over Rankine. Water phase change is more of a bug than a feature.

Keith J

Using just specific heat of the molten salt is yet another killer. Variable temperature.
Brayton cycle has higher back work ratio. Fine for airplanes and CCGT but stinks for non combustion heat transfer cycles. Rankine works because liquid fluid is quite easy to pressurize so back work is tiny. Water is the most common fluid but its critical point is just below maximum design temps of super alloys so it lowers Carnot efficiency.

Tsk Tsk

I don’t see what the specific heat of salt has to do with it. Your only concern would be the maximum temp you could tolerate before the salt starts doing something weird, e.g. the constituents start to change phase themselves.
Brayton cycles are the preferred mode for non-combustion as well. High temp MSR or HTGR would much rather use a helium or CO2 loop than deal with the nonsense of a Rankine cycle. Who wants to run a system with a condenser and mixed phases along with the higher pressures needed to maintain supercriticality (or sacrifice efficiency)?
And water’s critical point is far below that of superalloys since those same alloys are used in much higher temp environments in fully open cycle turbines, i.e. turobojet engines.

Irrational D

The diagram of the proposed energy storage system brings back thermodynamic induced nightmares I had in grad school and looks suspiciously like a Coyote solution to capture the Roadrunner. Never worked out well for the Coyote.

jorgekafkazar

I’ll expect a large ACME sign next to the field test unit.

Tsk Tsk

And this is different from solar thermal how? Because they also waste energy pumping the heat out of the cold sink? I begin to see why we haven’t designed an aircraft that can outperform the SR-71 introduced 50 years ago. We’ve become morons.

David A

Funded morons, so perhaps con-artists instead of morons.

Crispin in Waterloo but really in Beijing

Tsk Tsk
If I told you about all the aircraft that outperform the SR-71 I’d have to kill you. You know how it goes…

Crispin in Waterloo but really in Beijing

If they are going to store heat, why create electricity as an intermediary? Just turn the wind energy into heat. Far more efficient.

jorgekafkazar

A successful full installation of this system will be cotemporaneous with porcine aerobatics.

Instead of a heat ‘engine’ how about a thermoelectric back end to get electricity out of this system?
Have been in use in space for decades.
Not sure of cost and efficiencies.
But with millions of thermocouples mass produced, economies of scale may help.

Alphabet’s X may safely be ignored from now on, as may Abner Li’s Technacity. No energy pro or engineer would participate in horse puckey such as this. Goodness…

Tom in Florida

They are not looking for engineers or energy pros. They are looking for morons with money to burn.

Griff
MarkW

Natural gas caverns?
Bogus from the title on down.

Curious George

There is a real natural gas cavern in Turkmenistan, but it is still active.

michael hart

It feels a bit like watching another slow motion train wreck. As with the running-everything-with-renewables-electricity brainstorm, Google is spending a lot of money to slowly rediscover what sensible people already knew, and said, about energy storage. Oh well….it is their money. And if they announce the inevitable as honestly as they finally did with the renewables project, then it will put another nail in the coffin of impracticable green fantasies.
And the Stanford Physics Professor… He must feel a little bit sick to have to be drawing high-schoo/undergrad level science cartoons for schemes he knows won’t fly, when presumably he has some real physics projects he would love to be working on. O.K., I’m sure the money they pay him must help, but he probably feels he has sunk way below the dreams he once had for his career.

Ed Zuiderwijk

Thermodynamically this makes little sense. Electricity to heat goes with 100% efficiency, the other way around with at most 40%. You directly lose 60%.

Curious George

The “in” electricity is an extra power from wind turbines. Today it is 100% lost. Recovering 40% of it would be a success.

jhborn

Thermo isn’t my thing, but the “efficiency” at the front end may be greater than 100%; people who I think know this stuff have told me it takes less than a BTU of energy to drive a BTU from (say) antifreeze to salt.
Am I misinformed?

Curious George

No. With a heat pump you can “pump” one kilowatt-hour of heat from a colder medium to the medium being heated, let’s say you use a kilowatt-hour of electricity to do it – this is also converted to heat. You have achieved an “efficiency” of 200%.

Peter Morris

I can’t take this seriously.
That diagram actually says “store the cold,” as if “cold” was a thing that can be separated from heat.

Menicholas

Yeah, the elusive “coolth”.
Hard to find as them dang magnetic monopoles.

tadchem

Not considered is the expense of long-term maintenance of a molten salt system. Unless *expensive* measures are taken to scrupulously eliminate oxygen and water from the system, a molten salt system will corrode any ferrous metal components – yes, even ‘stainless’ steel. Non-ferrous alloys such as Monel that will withstand sustained molten salt temperatures are not cheap to produce or fabricate, either.

Norman Blanton

Reminds me of Project Plowshare, where they proposed using nuclear bombs to heat up an underground salt dome (that might be redundant) and pumping water down to generate steam…

Sheri

I can’t believe that didn’t work out.

Kaiser Derden

seems to me a water storage system would be the cheapest, safest and most efficient storage system for electricity …

Sheri

Perpetual motion, alchemy and the Holy Grail live on.

dp

The purpose of this is to eliminate off-peak price reductions by removing off-peak energy. The demand on the grid will approach a flat line as off-peak hours are spent heating the ground and the atmosphere. Given the energy losses in this system and similarly for pumped storage (which is just like pumping water back over the dam it just came through), it is a net consumer of electricity and that is artificial demand that competes with consumers.

MarkW

“to store it, especially during peak power usage:”
Why the heck would you want to be storing power during times of peak usage.
I thought the idea was to store when demand was low, then release when demand was high.

Shoki Kaneda

How does one store cold? I understand excluding heat from a volume but since “cold” does not exist except as the absence of heat, how is it “stored”?

Not much to it. You either chill something, or you find something which is already cold, and you insulate it:
http://www.motherearthnews.com/-/media/Images/MEN/Editorial/Articles/Magazine-Articles/1972/09-01/How-to-Build-an-Ice-House/017-020-01a.gif
It can be a lot of work, though.

Menicholas

My great grandfather was run over and killed by his own ice truck when his horse bolted when one of them newfangled auto-mobiles backfired.
1906, 13th and Race, Philly.
BTW, him and his partner were boatmen, transporting goods on the Schuylkill river. In Winter they carved out blocks of ice from the river and stored them to sell in in Spring and Summer.
That river never freezes over reliably anymore. One year in five maybe. Or less.