
Alphabet spinoff Malta raises $26M for technology to store power in molten salt - lawrenceyan
https://www.bloomberg.com/news/articles/2018-12-19/gates-bezos-among-billionaires-backing-alphabet-energy-spinoff
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iainmerrick
Similar technology already in production in the UK:
[https://www.sunamp.com](https://www.sunamp.com)

They make a molten salt heat battery for homes and businesses. You store
excess heat or electricity in the battery, and use it for central heating and
hot water. Since you’re not trying to convert it back to electricity it’s very
efficient. It basically replaces a large expensive water cylinder with a
smallish box.

PS: I have no connection with or investment in Sunamp, I just think it’s a
terrific idea. I am a potential customer, though!

~~~
ogrisel
Are you sure sunamp is molten salt? To me, molten salt is to store energy at a
very high temperature in insulated containers.

I thought sunamp is some kind of room temperature phase change material that
does not require heavy insulation.

~~~
dangravell
Was going to mention Sunamp.

It does use a PCM, and that is described as a salt so maybe it's where the
confusion comes from.

It also has far better insulation than equivalent devices (hot water
cylinders). Typically VIPs, although I've read a few reports about the casing
being compromised recently and that wouldn't play nicely with the panel.

~~~
iainmerrick
Yes, I glommed onto the use of “salt” in both cases and figured they were
similar.

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digitalmango
Most of the Concentrated Solar Power plants uses molten salt to store energy.
First was installed in 1995 (Solar ttwo) in Spain.
[https://en.wikipedia.org/wiki/The_Solar_Project#Solar_Two](https://en.wikipedia.org/wiki/The_Solar_Project#Solar_Two)

~~~
iagovar
Torresol and other spanish companies have some experience with it.

[https://en.wikipedia.org/wiki/Torresol_Energy](https://en.wikipedia.org/wiki/Torresol_Energy)

Related:
[https://en.wikipedia.org/wiki/List_of_solar_thermal_power_st...](https://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations)

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ramblerman
The neat little graph showing the rise in global yearly investments up to 2040
is amusing. Nassim Taleb has made me very wary of these things.

what's even the calculation behind a projection like that, it even has a
little spike in 2035!

~~~
nradov
I'm guessing it's because the scheduled restrictions on sales and use of ICE
vehicles will really kick in around that time. So there will be a
corresponding higher demand on the electric grid caused by a growing fleet of
electric vehicles.

But obviously it's somewhat speculative.

~~~
hinkley
Don’t phaseout dates set in the future create a spike in demand near the
deadline?

Either people will be bored of ICEs for other reasons long before and make
this a non event. Or, everyone will try to buy a new ICE in the year or two
before they stop selling them. Automakers will use this as a justification for
trying to move the deadline out. If that happens then the spike in electric
drive will come at the next tradein time, not the deadline.

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Retric
The rather extreme losses associated with electricity > heat > heat engine >
electricity seem like an absolute deal killer. Assuming they are at an extreme
50% round trip efficiency you need to be extremely cheap to have a hope of
breaking even. Worse heat has fairly low energy density and cools over time so
they can’t really scale the up or down that much.

It might be possible if they where starting with heat, but feeding this from
wind and solar just seems unlikely.

~~~
empath75
If energy is free or nearly free and it’s being wasted currently, then how
much does the efficiency really matter?

~~~
Retric
First if you can’t charge every day then your capital costs are effectively
much higher.

It’s only ‘free’ before you have a battery in place that can use it. With this
buying at 3c/kWh and selling at 6c/kWh is losing money. If anything else can
profit and scale by buying at 3.01c/kWh and selling at 6c/kWh then that’s
going to win.

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Bombthecat
Just a question: why does a sub from Google need to raise money?

I would question the confidence if a super big company starts something and is
like: uh you know. We collect money from someone else.

~~~
nopinsight
For partnerships in an industry with powerful entrenched interests? An
analogous example is the Amazon/Buffett/JP Morgan partnership in healthcare.

~~~
cityzen
So just rich people being rich?

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lainga
Oh lord, can't you pick less conflicting names? Why don't I just name my
company Jeff Bezos LLC?

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tantalor
What are you referring to?

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pizza
It's got the same name as a whole country..

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lumberjack
Yeah, I'm wondering. Isn't this trademark infringement? EDIT: Definitely
trademarked: EU001566702

~~~
ars
Trademarked in what industry? Trademarks are not universal, they are only in
particular industries.

~~~
QuercusMax
Exactly.
[https://en.wikipedia.org/wiki/Malta_(soft_drink)](https://en.wikipedia.org/wiki/Malta_\(soft_drink\))

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partingshots
Blog post from the Malta team on their graduation from X with their molten
salt battery grid energy storage play.

[https://blog.x.company/introducing-
malta-81bceb559061](https://blog.x.company/introducing-malta-81bceb559061)

~~~
bch
From the blog post:

> Malta’s solution is to store electricity as heat in high temperature molten
> salt and cold in a low temperature liquid for days, or even weeks, until
> it’s needed. The key insight behind Malta is that electricity can be stored
> as heat in high temperature molten salt and cold in a low temperature liquid
> for days, or even weeks, until it’s needed.

The key insight is an oft forgotten energy storage fundamental called
‘tautology’.

~~~
ams6110
How can energy be stored as cold? Cold is by definition the absence of energy.

~~~
antidesitter
Temperature _differences_ are what drive heat engines, i.e. you need a hot and
a cold(er) reservoir. A nice demonstration of this is a handheld Stirling
engine, which you can power by placing ice at the bottom (since it’s colder
than the surrounding environment).

~~~
ams6110
Okay, but technically you're storing the energy in the environment, not in the
cold reservoir. Maybe a distinction not worth making.

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macawfish
This is extremely exciting technology! Any energy science aficionado worth
their salt knows that molten salt can have _very_ high energy density.

~~~
londons_explore
The paper says that at around 600C, nearly all materials have the same energy
density.

Molten salt was chosen because it is a liquid, cheap, safe, and stable.

The paper also considers using rocks, but they're tricky to pump...

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FiatLuxDave
Does anyone have any information about what kind of heat pump they are using
(e.g. multi-stage hydrocarbon, supercritical CO2, etc)? Making a heat pump
which can handle a difference of 175+ C and a high side of 200+ C may be
straightforward in theory, but it is a non-trivial engineering challenge. I am
unaware of any commercial off-the-shelf device which can meet these specs. I'm
guessing this is what they need based upon the description. I happen to be in
the market for a heat pump like this for my own research, so I am highly
interested if anyone has any information.

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occamrazor
My memories of thermodynamics theory are old and full of gaps, but from what I
remember both steps, if performed at "normal” temperatures, necessarily
produce a waste of energy. The first step, i.e. using electricity to drive a
heat pump, is efficient only if the temperature differential between the cold
body and the hot one is small. On the other side, conversion of thermal energy
into electricity is efficient only if the temperature differential is large.
How does Malta overcome this problem?

~~~
londons_explore
Your memories are wrong...

An ideal heat pump is fully reversible with no energy loss.

~~~
occamrazor
Maybe, but I clearly remember that it is not possible to have a reversible
process wich _only_ transfers heat from a colder body to a warmer one. The
third law also gives quantitative bounds to the reversibility of such
processes.

Heat pumps with efficiency above 1 rely on heat transfer between external
bodies (e.g. from a subterranean water source to the atmosphere forhome
heating systems), but this does not seem to be the system described by Malta.

~~~
londons_explore
You are thinking of the carnot limit.

>It provides an upper limit on the efficiency that any classical thermodynamic
engine can achieve during the conversion of heat into work

The word 'efficiency' here is misleading... If one reverses the process,
converting work back into heat, you get back all the original energy in an
ideal machine (and real machines, for example gas turbines, are within ~15% of
ideal for the temperature & pressure change between input and output)

~~~
occamrazor
Thanks for the clarification. I still have issues understanding the
intermediate stage, where the world is entirely and reversibly converted into
a temperature differential. I might have to go back to drawing T-S diagrams.

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jfoster
> Now X designs projects with two primary goals: to become a standalone
> Alphabet division or spin out into an independent company.

The difference being that Alphabet retains 100% vs retaining X%? Presumably
they're spinning out whenever the capital required would be much more than
they want to put in, or the tech seems promising but perhaps not as profitable
as they would like?

~~~
Eridrus
Maybe they want strategic investors who bring more than just capital.

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ElijahLynn
How does this compare with Energy Vault?

[https://qz.com/1355672/stacking-concrete-blocks-is-a-
surpris...](https://qz.com/1355672/stacking-concrete-blocks-is-a-surprisingly-
efficient-way-to-store-energy/)

[https://energyvault.ch/](https://energyvault.ch/)

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PaulHoule
I have been thinking of ways a "new nuclear" company could have a business
plan that gives them an exit in case they run into regulatory or other
roadblocks and molten salt handling was one of the ones that seemed most
promising.

(Too bad there doesn't seem to be any non-nuclear market for Brayton cycle
turbines.)

------
beaner
I'm pretty naive about this stuff, but wouldn't an easy solution for storing
energy to be, just use energy to lift something very heavy into the air, and
then extract energy when it's lowered?

~~~
wyattpeak
That's an avenue that's also being pursued, but it's not obviously superior to
other storage plans. You've got lots of moving parts under high load, you need
enough structural support to ensure that the top-heavy structure is stable.

It also doesn't contain a huge amount of energy - 1 ton of liquid NaCl
contains about 700MJ of usable energy, you'd have to lift 700 tons of material
100m to contain the same in gravitational potential.

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hinkley
Has anyone looked at waste heat recovery for these sorts of things? If you
already have a heat engine on premises I could see industrial applications for
energy efficiency.

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andbberger
On a related note - could someone please develop a mass-produced stirling
engine for low-temp differential residential use??

~~~
TaylorAlexander
I’ve dreamed of this too, as it would be very easy to deploy. However I think
someone mentioned that low differential sterling systems just don’t have much
power in them period. I’m not sure though.

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dannyr
Where are the molten salts coming from?

~~~
hwillis
Typical mixtures use eg potassium nitrate, sodium nitrate, and calcium
nitrate. Salts are one of the most produced substances on earth. For instance,
potassium nitrate is in virtually every fertilizer. I couldn't find how much
is used annually, but it's made from potash, and US reserves of that are ~270
million tons[1]. At 40 to 110 kWh/ton[2] that's a minimum of 10.8 billion kWh
(10.8 TWh), or a full day of storage.

[1]:
[https://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs...](https://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2017-potas.pdf)

[2]: [https://www.solarthermalworld.org/content/molten-salt-
storag...](https://www.solarthermalworld.org/content/molten-salt-
storage-33-times-cheaper-lithium-ion-batteries)

~~~
tkahnoski
This is interesting from a sustainability model. Both lower tech to
manufacturer and I'd assume less damaging to the environment than a lithium
mine.

~~~
londons_explore
This design also needs almost double the amount of hexane...

Not so environmentally friendly...

Neither are used up though, and probably won't devalue with time, so the
financial cost of them is just interest payments, and the environmental cost
is zero.

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sahin-boydas
dupe:
[https://news.ycombinator.com/item?id=18716821](https://news.ycombinator.com/item?id=18716821)

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fierro
loving all these armchair scientists thinking they've found "the" flaw in a
company they read one article about

~~~
anonuser123456
To be fair, for every 1000 claimed energy breakthroughs, 1 succeeds. Being
skeptical of any claim before it scales in the market is somewhat rational.

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moltensalt
Molten salt nuclear reactor technology documentary

[https://www.youtube.com/watch?v=s8iRl1CkuK8](https://www.youtube.com/watch?v=s8iRl1CkuK8)

~~~
ogrisel
I believe the molten salt technology used for thermal energy storage is not
directly related to molten salt nuclear reactors:

[https://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_...](https://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_salt_technology)
(sodium nitrate, potassium nitrate and calcium nitrate)

[https://en.wikipedia.org/wiki/Molten_salt_reactor#Fused_salt...](https://en.wikipedia.org/wiki/Molten_salt_reactor#Fused_salt_selection)

