
Old salt mine is the first emission-free compressed air energy facility (2019) - luu
https://www.cbc.ca/news/canada/london/goderich-ontario-compressed-air-energy-storage-1.5369478
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kevin_b_er
Sometimes I hate the quality of science reporting due to obvious mistakes.

> The Hydrostor facility can keep up to 10 megawatts of power, enough to keep
> the lights on in about 2,000 homes, or approximately half the town of
> Goderich for about five hours.

Megawatts instantaneous power, but the sentence wording makes it sound like
capacity. That's how much energy it can supply at any moment vs how big the
battery is.

And they talk about X number of homes for Y hours. Did they mean 10 megawatt-
hours? Or did they mean 10 megawatts for 4 hours? That's 40 megawatt-hours or
MWh.

Judging from this other site, it is 1.75 MW max and a capacity of 10 MWh.
Which means someone messed up units in the article. Possibly even they read
"MWh" from a technical summary and just guessed it meant megawatts. Because
they spelled it out in the article.

[http://www.energystoragejournal.com/hydrostor-and-nrstor-
ann...](http://www.energystoragejournal.com/hydrostor-and-nrstor-announce-
worlds-first-commercial-advanced-caes-facility/)

~~~
Reason077
It seems to be very common to not understand, or misunderstand, the difference
between _power_ (watts) and _energy_ (watt-hours). Even amongst technically-
minded people who should know better.

A respected UK newspaper once printed a dramatic article claiming "20 new
nuclear power plants" would be needed to power electric vehicles in the UK.
This was nonsense and all based on confusing the estimated energy use of an EV
fleet (in GWh) for instantaneous power (in GW).

They did publish a tiny sheepish apology several days later[1], and changed
the online version of the article, but the damage was done and the claim still
gets repeated today.

[1]
[https://twitter.com/dpeilow/status/831717762259099648](https://twitter.com/dpeilow/status/831717762259099648)

~~~
eru
I don't even know why we need Watt-hours? Joule work just fine, don't they?

~~~
Reason077
They're measuring the same thing. Except a joule is one watt- _second_ , which
is an inconveniently small unit when talking about large energy storage like
an EV battery.

It would be like road signs measuring distances between cities in inches.

Besides, energy has long been accounted for in hour-based units. Your power
bill, for example. It's just easier to use those same units when thinking
about storage, rather than rebasing everything around seconds.

~~~
eru
I know that they are both measuring energy. It's just that Watt is usually
defined as Joule / second, so Joule seems more fundamental.

> They're measuring the same thing. Except a joule is one watt-second, which
> is an inconveniently small unit when talking about large energy storage like
> an EV battery.

That's what we have SI-prefixes for.

A Watt-Hour is also pretty small. We usually use Megawatt-hours or so. Using
Giga-Joule instead wouldn't be too much of a difference.

> Besides, energy has long been accounted for in hour-based units. Your power
> bill, for example. It's just easier to use those same units when thinking
> about storage, rather than rebasing everything around seconds.

Yes, tradition seems to be the real reason.

~~~
__s
Unfortunately seconds & minutes & hours aren't metric

~~~
eru
True scientists use natural units anyway.
[https://en.wikipedia.org/wiki/Natural_units](https://en.wikipedia.org/wiki/Natural_units)
;)

------
yabones
This type of storage, whether it be water reservoirs or compressed air, is
especially important in Ontario. We have a very strong base supply from our
three large nuclear facilities and hydroelectric dams, but the rest is largely
made up of wind, solar, and gas.

Because the peak supply from solar is midday and the peak load is often in the
evening [1], you're left running the 'peakers' (gas plants) for most of the
night to make up the difference. If we were able to store more energy short
term, we could conceivably remove natural gas energy production and be 100%
green/renewable. As of 2018 we were 96% renewable [2] so it's really not some
pipe dream.

[1]
[https://en.wikipedia.org/wiki/Duck_curve](https://en.wikipedia.org/wiki/Duck_curve)

[2] [https://www.cer-rec.gc.ca/nrg/ntgrtd/mrkt/nrgsstmprfls/on-
en...](https://www.cer-rec.gc.ca/nrg/ntgrtd/mrkt/nrgsstmprfls/on-eng.html)

And honestly, I'm okay with paying a little more on my energy bill for the
next couple years knowing that my province has made the decision to be part of
the solution.

~~~
hervature
You are aware that nuclear power is not considered renewable by the majority
of people correct? That puts Ontario at less than 50% renewable.

~~~
yabones
You're technically correct, and what I should have said was 'zero-carbon
emitting sources' as was in the source.

But for practical purposes there is so much Uranium on this planet that we'll
most likely never even use 1% of it. Especially when you factor in newer or
experimental reactor designs such as fast breeder reactors [1] that can
generate even more power and use waste materials from current systems.

So yes, it is technically not a renewable source of energy, but there is such
abundance of fuel that it's not 'non-renewable' the way Coal or Gas is.

[1]
[https://en.wikipedia.org/wiki/Breeder_reactor#Fast_breeder_r...](https://en.wikipedia.org/wiki/Breeder_reactor#Fast_breeder_reactor)

~~~
marmaduke
Aren’t waste disposal sites effectively non-renewable uses of natural space?

~~~
kobbe
The same is true for solar that is not easily recyclable.

~~~
pfdietz
What part of solar is not easily recyclable? The glass? Oh noez, now the world
is being polluted with silicates!

------
cjhveal
In case anyone is curious, hydro is the general term for electrical power from
a utility, at least in the part of Canada where I grew up.

~~~
elric
That's ... weird. But thanks for clarifying that, that really confused me.

~~~
52-6F-62
It's weird on the surface, but it's because our entire electrical utility has
roots in hydroelectric power.

Adam Beck was one of the people chiefly responsible for the creation of a
public electrical utility in Ontario. I like one of his quotes "the gifts of
nature are for the public" referring to his slogan "Power at cost".

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

~~~
cjhveal
Thank you for this context. I vaguely knew of the term's connection with the
names of utilities, but this is some fascinating Canadian history.

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walrus01
At a certain point if photovoltaic panels become very, very cheap (far below
the $0.20-$0.35/watt STC price to buy panels in huge quantities today), it
will be economical to crack hydrogen from water and compress it into tanks,
then use it to run massive fuel cells to feed power back into the grid.

Because of the significant engineering challenges in storing, transporting and
refueling hydrogen at very high pressures, I am much more optimistic about the
use of hydrogen in medium to large sized fixed, professionally-run facilities
than I am about people driving around with hydrogen fuel cell powered cars. Or
home use of hydrogen fuel cells.

~~~
Mvandenbergh
Tank storage is challenging because at that scale you're competing with
batteries which have much better round-trip efficiency. There was a DNV GL
paper earlier this year which quoted a time of about 24 hrs as the cross-over
point between H2 and battery tech.

Underground cavern storage lets you do inter-seasonal storage at a very low
cost per MWh.

It's critical to understand that liquid and gas fuels have uncoupled per MW
and per MWh costs in a way that batteries don't. You can adjust battery
chemistry of course but fundamentally you're stuck with a narrow range of peak
MW / MWh performance which means that if you want to build a massive battery
for inter-seasonal storage (needs MWh >>> MW) you end up "buying" discharge
capacity in MW that you don't need.

Hydrogen decouples the size of the production (in MW), the storage (MWh), and
the fuel cell (MW) which lets you size them independently of each other.

I am also sceptical of the need for home use or vehicular hydrogen (certainly
in passenger cars). You get a lot of efficiency improvement if you are able to
use the waste heat from fuel cells. Yes that can be done domestically, but
putting them in large urban centres and driving district heating schemes from
them seems like a much more natural fit. Especially in places like Europe
where total energy demand (heat and electricity both) peak at the same time in
the winter as renewable generation decreases.

N.b. there are already times in the UK grid when prices are negative
wholesale. Even one of the retail energy suppliers here had a few half hourly
periods of negative prices a few months ago. The subsidy for hydrogen
electrolysers in The Netherlands was set assuming 2,000 hours a year of
operation (using the cleanest and cheapest 2,000 hrs) since that maximises the
environmental benefit with the current Dutch grid.

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52-6F-62
Goderich is a beautiful town—I've been looking at getting out of the city for
a while. Maybe we should look to head that way and I should start looking for
a job with these guys.

This, to my naive understand, seems like an enormously good idea and seems
like they would have a lot of opportunity for relatively cheap resources and
developing solutions for stabilizing fluctuating power generation resources
like wind/solar.

Please someone with more knowledge in this domain explain further what might
be the benefits and shortfalls and pragmatism of this group.

~~~
propter_hoc
Been tracking them for a long time. They've been at "pilot" stage since at
least 2011.

Personally I don't think that any form of alternative energy storage has much
chance against Li-ion, which has experienced unbelievable declines in cost
(driven mostly by cell phones and electric cars).

A bunch of extremely well funded compressed air storage companies have already
run aground against this problem: Lightsail (Thiel & Gates backed), SustainX,
etc.

I'd be skeptical unless they can somehow actually prove economics against Li-
ion, but these media pieces always seem to skirt that question.

~~~
KSteffensen
From the article:

"compared to a similar capacity battery, it's not only half the cost, the
facility has a service life of 50 years, five to 10 times longer than a
battery."

It doesn't explicit say what kind of battery, but a service life of 10 years
suggests Li-ion.

------
rmason
Left me wondering whether this would also work in Detroit? Detroit sits atop a
huge abandoned salt mine. There's a mine across the border in Windsor (Canada)
but that's still actively being mined.

~~~
colomon
Goderich also has active salt mines... I'm presuming this project is using a
played out branch of them.

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1over137
I know people that live there. Many worry about the safety of using compressed
air below the town and wonder if it would cause collapse of any tunnel in the
current salt mine.

~~~
Cthulhu_
I'm definitely not a geologist but I can imagine the "breathing" motion of
pressurizing and depressurizing the mines causes some movement and damage over
time.

What pressures are we talking about anyway?

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ericvanular
This is in my backyard (ish)! Strange given that I started
[https://collective.energy](https://collective.energy) to create more dialogue
around innovative climate solutions but never even saw the old salt mine as an
opportunity

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mleonhard
Has anyone analyzed the viability of a compressed-air energy distribution
system? It could be simpler and safer than electricity distribution.

~~~
KSteffensen
Yes, apparently that has been done.

[https://www.lowtechmagazine.com/2018/05/history-and-
future-o...](https://www.lowtechmagazine.com/2018/05/history-and-future-of-
the-compressed-air-economy.html)

~~~
mleonhard
Thanks for sharing that article.

I think the most promising application of distributed compressed air is in
refrigeration, especially if the power source is not an adiabatic process.

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JoeAltmaier
But is it scalable?

~~~
hokkos
To get a salt cavity just pump in water in salt deposit and pump out brine. It
can be used to store H2, CH4 or compressed air, from 70 to 200 bars. H2 is way
more energy dense, but has a lower efficiency round trip. There is many salt
deposit around the world.

~~~
Scoundreller
Disposing of the brine is a bit complicated when you have nothing but
freshwater lakes around :)

I'm guessing they're planning on using the existing caverns from mining.

Unsure if they plan on expanding.

~~~
joncrane
Can't they just evaporate off the water and use the remaining salt to treat
roads in the winter?

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sunkenvicar
66% efficiency sounds amazing for compressed air. I was expecting 10%.

