
Construction begins on world’s biggest liquid air battery - zeristor
https://www.theguardian.com/environment/2020/jun/18/worlds-biggest-liquid-air-battery-starts-construction-in-uk
======
paledot
The technology sounds fantastic. The synergy with heat power plants is
particularly cool (heh). The same goes for desalination: waste heat can be
reduced by recycling heat between the processes, increasing the overall
efficiency of the system.

Now for the rant: reputable news organizations need to stop enabling "creates
x jobs" propaganda through repetition. It doesn't create 200 jobs, it briefly
employs 200 to build the thing. Maybe 5-10 full-time jobs will be "created" to
maintain a giant mechanical battery. This lie is particularly popular around
pipeline projects. "You don't think we should spend billions of dollars on
this pipeline? Do you want tens of thousands of imaginary people to lose their
imaginary jobs?"

End rant.

~~~
ryanwaggoner
I think the "creates 200 jobs" usage is completely fair here. The thing is due
to be operational in 2022, so that's two years of work for 200 people, and the
ongoing operation jobs will be "a few dozen", not 5-10. The article makes all
this clear.

More broadly, infrastructure jobs are still jobs, even if they only last a few
years instead of indefinitely. The average tenure of a software engineer at a
big tech company is less than that; is it fair to say they don't have jobs?
It's not like we're ever going to run out of projects to improve the world, so
these 200 workers will hopefully finish this job and move onto the next "job-
creating project".

~~~
take_a_breath
==The average tenure of a software engineer at a big tech company is less than
that; is it fair to say they don't have jobs?==

I don’t follow, after a software engineer leaves the big tech firm, the job
still exists. They hire someone else to do it. In this instance the job
doesn’t exist after 2 years. It’s also probably not 2 full years for those
jobs as they are typically brought in with teams to perform their function
(dig, foundation, build, framing, electrical/water/gas, finishing) then move
on.

~~~
rjsw
Software projects finish just like civil engineering ones do.

~~~
take_a_breath
Hiring a software engineer as a full-time employee for a temporary software
project, then firing them, is a poor use of company resources.

If you are talking about a contract software engineer, then you are correct
that the worker rolls off. We typically don't see those considered "full-time
jobs created" because they have a well-defined term and are never employees of
the company.

------
arussellsaw
Compressed air storage seems like a really appealing method, especially
considering the low carbon footprint and massively longer lifetime than
lithium batteries. This post covers it quite well
[https://solar.lowtechmagazine.com/2018/05/ditch-the-
batterie...](https://solar.lowtechmagazine.com/2018/05/ditch-the-batteries-
off-grid-compressed-air-energy-storage.html) , I’d be really keen to see if
compressed air can also be successful for independent households looking to go
off grid or reduce dependence on the grid.

~~~
lend000
While it is appealing compared to many alternatives and is more portable for
smaller settings, when used on an industrial scale like this giant battery, I
wonder how it compares in overall utility to gravity batteries [0].

The nice thing about gravity batteries is that they can form a closed loop
with water supply, too, pumping reclaimed water back up into reservoirs when
there's excess power. I'd expect compressed air to have much higher energy
density, but it would be interesting to see if anyone has the numbers.

[0]
[https://en.wikipedia.org/wiki/Gravity_battery](https://en.wikipedia.org/wiki/Gravity_battery)

~~~
gnramires
Those methods are actually quite similar, they're all ultimately related
(limited by) tensile strength of materials. So costs and specific energy
densities (per construction material unit) are similar. An important figure is
cost/tensile strenght I guess.

(Compressed air: limited by container tensile strength; gravity batteries:
limited by strength of cables)

I suspect even the constants involved are the same (given the materials are
almost uniformly under nominal load), although I don't have time to
investigate right now (a good curiosity research topic!).

~~~
trickstra
I believe these ones are not limited by tensile strength:
[https://interestingengineering.com/concrete-gravity-
trains-m...](https://interestingengineering.com/concrete-gravity-trains-may-
solve-energy-storage-problem/). They are a bit limited by available geography,
but far less than say pumped hydro.

~~~
gnramires
Indeed! In this case it's the integrity and friction of the soil (of the hill)
that's keeping the potential energy contained, and this hill soil is "free".

------
robocat
Here’s an article with some of the technical details of chilling the air to
liquify it:

[https://www.bbc.com/news/science-
environment-19785689](https://www.bbc.com/news/science-environment-19785689)

“IMechE says this process is only 25% efficient but it is massively improved
by co-siting the cryo-generator next to an industrial plant or power station
producing low-grade heat.“

“More energy is saved by taking the waste cool air when the air has finished
chilling, and passing it through three tanks containing gravel“ as a thermal
store.

“their kits could be up to 70% efficient, and IMechE agrees this figure is
realistic.”

------
gizmodo59
Sorry for the rant but this is just so poorly designed that I don't see any
relevant content when I open the link without scrolling right away:

With adblocker: [https://imgur.com/a/fWuoJEi](https://imgur.com/a/fWuoJEi)

Without adblocker: [https://imgur.com/a/cvmu3dm](https://imgur.com/a/cvmu3dm)

Plus ublock origin says it blocked 30% of requests. I'm all up for paying for
good journalism but part of me wonders their paid customers aren't getting a
great experience either.

~~~
luma
I've found the Fanboy Annoyance List to be pretty effective vs the sort of
GDPR cookie acceptance things you see in your blocked version:
[https://easylist.to/easylist/fanboy-
annoyance.txt](https://easylist.to/easylist/fanboy-annoyance.txt)

------
nayuki
I mistakenly interpreted the headline as a battery with some kind of liquid
electrolyte and outside air as a reactant. Kind of like a
[https://en.wikipedia.org/wiki/Zinc%E2%80%93air_battery](https://en.wikipedia.org/wiki/Zinc%E2%80%93air_battery)
. But nope, it's just the liquefaction of air, no chemical reactions involved.

~~~
sandworm101
Yes. The term "battery" is being thrown around too much. Are hydroelectric
dams to be called "rain batteries"?

~~~
vikramkr
Yep. A lot of people call pumped storage "water batteries" or the like[0]. It
baffles me as well, but now that language is evolving to redefine a battery as
pretty much anything that generates electrical power than can be recharged
with electrical power, I guess that's the world we're walking into and I
should get used to that.

[0]
[https://www.hydropower.org/sites/default/files/publications-...](https://www.hydropower.org/sites/default/files/publications-
docs/the_worlds_water_battery_-
_pumped_storage_and_the_clean_energy_transition_2.pdf)

~~~
icegreentea2
Have you seen where "battery" comes from? Electrical batteries are called that
since they were made of sets of electrical cells working together, analogously
to a battery of artillery.

~~~
vikramkr
Yes I'm aware of that - good point. I could have included that in my post
above to highlight that this word itself has gone through plenty of language
change already, from meaning "a number of pieces of artillery used together"
to "electrochemical energy storage" to "energy storage." While it keeps most
of those original definitions as well - including "to strike" etc. The only
definition I don't think has really survived to the current day that I see
when looking at its etymology is "metal articles wrought by hammering."
Wonderful word.

------
jcims
Wondered what they were doing with the thermal energy from the process. The
manufacturer has a video here that helps explain the technology a little bit:
[https://www.youtube.com/watch?v=kDvlh_aG7iA](https://www.youtube.com/watch?v=kDvlh_aG7iA)

------
sandworm101
The "air" gets stored in liquid form... but what I don't understand is what
parts of the air? The gasses in air mix as gasses, no so much when liquid.
Will the tanks include a layer of liquid oxygen? What prevents those layers
vaporize selectively as the tank temperature is raised again? That would seem
very dangerous. Or am I misreading this and they are only liquefying nitrogen
and aren't playing around with liquid O2?

~~~
robocat
This article says they remove CO2 and water because they freeze solid, and it
implies oxygen remains in the mix: [https://www.bbc.com/news/science-
environment-19785689](https://www.bbc.com/news/science-environment-19785689)

I am guessing they pump the liquid air and then “boil” it, so there is no risk
of selective vapourisation as they are not boiling the bulk liquid within the
tank.

~~~
zamalek
If they did something with that CO2, the whole setup could be carbon negative.

~~~
trickstra
Dry ice is actually a precious commodity among algae growers - another
alternative energy source - algae diesel. Or any frozen food dealers - and
sometimes they run into shortages: [https://www.marken.com/alerts/dry-ice-
shortage/](https://www.marken.com/alerts/dry-ice-shortage/)

~~~
teruakohatu
Not just alge but ag in general. CO2 makes plants grow fast, farmers would buy
it for greenhouses if it was produced on a large scale, although finding a way
to stop it going back into the atmosphere would be better.

------
MaxBarraclough
> will use spare green energy to compress air into a liquid and store it.

Is that really right? It's not just green energy sources that benefit from
energy-storage. Fossil-fuel plants and nuclear plants prefer to run at a
constant output, but demand varies depending on the time of day.

See the 'Duck curve'
[https://en.wikipedia.org/wiki/Duck_curve](https://en.wikipedia.org/wiki/Duck_curve)

~~~
pjc50
This seems like useless pedantry on the word "green", no? The electric field
is not coloured, you can't really attribute grid power to a specific source
sensibly.

Coal is almost entirely gone from the UK. Nuclear does indeed prefer to run at
constant output, but almost all the remaining fossil generation in the UK is
CCGT which can ramp up and down fairly quickly.

------
Mvandenbergh
Cool. Technology like liquid air, compressed air, electrolysed hydrogen etc.
has a very different use case to lithium ion batteries.

Batteries are good for short cycle times, if you need to balance your grid and
even to some extent if you need to correct for diurnal patterns, you want
batteries. The high capital cost is compensated for by the high round-trip
efficiency.

For seasonal storage or even inter-year storage, batteries do not work. You
spend a fortune on them and then cycle the system once a year or less.

The advantage of these other systems is you can decouple three elements:

The conversion in

The storage

The conversion out

and match the capacity of each to what you need. For long term storage of
hydrogen for instance, you want relatively small electrolysers with fast
response times so that you can use excess electricity during sunny windy
periods, a massive geological storage that can hold a year+ of production, and
modestly sized fuel cells to turn it back into electricity in the winter (in
Europe anyway) with good heat recovery.

In the case of this technology, you can again size the charging, discharging,
and storage separately. The scaling for tanks is much cheaper than batteries.

Flow batteries use a similar idea by separating out the charging/discharging
membrane and the electrolyte tanks but I don't think anyone has gotten
satisfactory performance from them yet.

You can't build a lithium ion battery where you specify the storage capacity
separately from the charge and discharge rates with anything like that kind of
freedom. You can adjust the battery chemistry of course but nothing like the
same.

~~~
sitkack
This is why pumped hydro using existing dams is so nice. I think constructing
enough storage to handle months of lower solar output will be difficult.

Phase locking human activity, including economic to the energy cycle would
obviate the need for many technical solutions. We should just hibernate.

~~~
Mvandenbergh
Pumped hydro using existing dams is brilliant and should be maximally
exploited but we already have dams on all the really good sites. We can
improve by adding the pump-up stage to many of them but there is simply no
scope for massive expansion in total reservoir / energy storage capacity.

------
yowlingcat
I was looking into this briefly when I was investigating molten salt
batteries. Can anyone who has expertise in this field tell me a bit about why
molten salt batteries aren't more common? From what I can tell, the materials
used are more renewable than Lithium Ion batteries, and with comparable
(potentially higher) density. I can see why molten salt isn't as common in the
more portable form factor, but it seems like it would be a great fit for large
energy reservoir/grid type applications.

~~~
alexpotato
I believe the main use of molten salt batteries is for high heat applications
e.g. in solar collectors

The heat is essentially "free" which makes the molten salt heat retention
properties perfect for storing energy overnight.

------
d_silin
I wonder what is the round-trip efficiency for this cycle. I read that you can
improve it by matching with large scale but low-grade heat source.

~~~
swebs
The article says 25%.

~~~
luma
That’s a pretty tough sell versus pumped hydro which is generally 70%+

------
Mvandenbergh
The power cycle used here is quite an interesting one.

The heat from the compression cycle and cold from the expansion cycle are
stored separately and re-used which substantially increases storage
efficiency.

Waste heat from co-located industrial plants is used to further boost
expansion performance. A lot of "low grade" industrial heat is available but
when you're re-heating from cryogenic temperatures, 100 C is actually high
grade heat.

I suspect that the time over which it's efficient to store is limited by
losses from the temperature stores.

~~~
jhayward
> Waste heat from co-located industrial plants is used to further boost
> expansion performance.

Let's not greenwash this. The "waste heat" is fossil fueled.

~~~
Mvandenbergh
That's not "greenwashing" because it's obvious. Thermal input in industrial
processes is essentially all fossil fuel, high temperature input is 100%
fossil fuel. To the extent that we need these processes, we may as well get as
much bang for our CO2e buck as we can. Even if and when these processes can be
driven using hydrogen combustion or other heat sources, there will still be
low grade waste heat to use.

~~~
jhayward
It's greenwashing because it's not obvious, and the wording is deliberately
deceptive. An accurate description would give readers the relevant facts, not
assume they can figure out the hidden catch.

------
lmilcin
The question is, would it be possible to use large scale liquid air storage to
speed up removing CO2 from atmosphere?

I have no idea if removing CO2 is easier in liquid form but if it is feasible
then ff we already had huge infrastructure to store energy that requires
pumping astronomical amounts of air back and forth, it might make sense make
sense to add a bit to it to remove CO2 while in liquid form.

~~~
Tade0
The energy required to liquefy air is probably too large. Say we have 400pm
CO2 in air - that's ~630mg of CO2 per kilogram of air.

Given that the specific heat of air sits at around 1kJ/kg[0], you'd have to
spend over 125kJ of heat energy to get just one gram of CO2 - that's 35Wh.

If you used wind power(14g CO2/kWh) and a heat pump with a coefficient of
performance of 1 (not sure how possible at these gradients) you'd "emit" 0.5g
of CO2 in the process.

[0]
[https://www.ohio.edu/mechanical/thermo/property_tables/air/a...](https://www.ohio.edu/mechanical/thermo/property_tables/air/air_Cp_Cv.html)

~~~
lmilcin
Well, you missed the fact that the plan is already to liquefy the air. So the
air will already be in liquid form.

Also I don't think they are going to cool it but rather compress it. Cooling
would require constant expenditure of energy to keep it cool whereas you can
compress it and leave it in the vessel at room temperature. It takes 33
atmospheres to liquefy nitrogen and 50 for oxygen.

------
imposterr
>The new liquid air battery, being developed by Highview Power, is due to be
operational in 2022 and will be able to power up to 200,000 homes for five
hours, and store power for many weeks.

Is it just they're expecting many leaks in the system? I don't see why they
couldn't just store things for years basically.

~~~
icegreentea2
Liquid air is cryogenic - they'll have to either bleed off or spend energy to
keep it cooled. The "many weeks" measurements is probably some measurement of
bleed off rate assuming no top offs (but I'm just guessing - the company
website
[https://www.highviewpower.com/technology/](https://www.highviewpower.com/technology/)
doesn't seem to call it out clearly).

~~~
imposterr
If the tanks are strong enough, is cooling required? My understanding is that
you'd only need to cool the liquid if the structure holding it wasn't
sufficiently strong enough to handle the pressures.

~~~
icegreentea2
Approximating air as nitrogen... nitrogen cannot exist as liquid phase at room
temperature - it can exist as a supercritical fluid though at 5MPa (so 50
atm). At that point it has a density of roughly 56 kg/m^3. At ~1 atm, nitrogen
becomes liquid at -194C and has a density of roughly 800 kg/m^3. So your mass
density of the system is like 14 times better with liquid nitrogen, and the
pressure loading requirements are stupidly lower.

------
exabrial
When you compress air it produces quite a bit of heat that is usually cooled
off... anyone that has an air compressor can attest.

Help me understand the thermodynamics, are they storing the heat too?

------
mywacaday
What kind of pressure is required to do this?

------
adammunich
This cannot possibly be more efficient than lithium batteries...

~~~
rumanator
> This cannot possibly be more efficient than lithium batteries...

It really depends on what you perceive to be efficiency.

~~~
adammunich
Lifepo4 has 99% coulombic efficiency

------
blackrock
At first, I thought this was interesting. And then I read the part about the
battery only lasting for a few weeks, before it must be recharged. This sounds
terribly inefficient.

I recall reading about a spring type of battery made of diamond nano fibers a
few weeks ago. They were saying this was even more efficient than lithium
ions, since it was a physical process of releasing its energy, instead of a
chemical process. It behaves like a child’s wind up toy, but at the molecular
level.

Would it be better instead to have a physical battery, instead of a chemical
battery?

Perhaps something like a big wind up spring can be built. Then it can hold its
charge indefinitely. And you stack thousands of these together, and they can
just sit there for a long time, until they are needed.

Or even that idea to use large cement blocks stacked into skyscrapers. Each
block holds potential energy, and when released, it can glide down a magnetic
track and generate electrical energy. This is also a concept of a physical
battery.

Even a hydroelectric dam is physical energy. You’re moving the water uphill.

