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Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 01:12:57
by EdwinSm
I know this is not the silver bullet, but it might work out to be a small part of a diverse approach to energy storage.

The article says that the company building admits it is too small (at 5MW), but it is a trial facility and the idea needs to be scaled up to be worthwhile:


The world's largest cold energy storage plant is being commissioned at a site near Manchester.

The cryogenic energy facility stores power from renewables or off-peak generation by chilling air into liquid form.

When the liquid air warms up it expands and can drive a turbine to make electricity.

The 5MW plant near Manchester can power up to 5,000 homes for around three hours.
http://www.bbc.com/news/science-environment-37902773

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 01:33:11
by Outcast_Searcher
EdwinSm wrote:I know this is not the silver bullet, but it might work out to be a small part of a diverse approach to energy storage.

The article says that the company building admits it is too small (at 5MW), but it is a trial facility and the idea needs to be scaled up to be worthwhile:


The world's largest cold energy storage plant is being commissioned at a site near Manchester.

The cryogenic energy facility stores power from renewables or off-peak generation by chilling air into liquid form.

When the liquid air warms up it expands and can drive a turbine to make electricity.

The 5MW plant near Manchester can power up to 5,000 homes for around three hours.
http://www.bbc.com/news/science-environment-37902773

I don't "get" this in terms of timing and efficiency.

Per the article, the liquid air needs to be stored at -190 degrees Celcius or colder. So, you either have to spend a lot of resource on building a super-efficient "thermos" to keep the liquid air at least that cold and/or use a lot of energy to keep it that cold (i.e. lots of waste).

So this sounds really expensive. If we know one thing about energy, it's that costs matter.

Since this is about the intermittency of green sources, the problem I see is those are highly unpredictable. So while you wait to need it (maybe for weeks in some cases), you have this super cold tank to keep super cold.

At least for pumped hydro (which the article talked about this being a substitute for, where pumped hydro would be inconvenient), I get it. You pump the water uphill, and it sits there until you are ready to let it run downhill and turn a turbine. There will be small losses from evaporation, but it could generally sit weeks or even months with relatively minor losses, if the storage tank is fairly deep compared to the surface area.

OTOH, given some of the other ideas in this space like keeping a giant flywheel spinning very rapidly (which also sounds expensive, wasteful, and potentially quite dangerous) -- as long as there were some VERY ROBUST safety features so if the cooling breaks down, loses power, etc., the gas (air) produced as the liquid warms can be reliably released without incident, at least perhaps it could be very reliable and safe.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 04:15:44
by diemos
Dewar technology is quite mature so storage should not be a problem but I doubt you have good round trip efficiency. It takes a lot of energy to get air cold enough to liquify.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 06:13:12
by SeaGypsy
Flywheels are so dangerous what? They are a core element of every combustion engine & are not explosive.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 12:24:50
by diemos
SeaGypsy wrote:Flywheels are so dangerous what? They are a core element of every combustion engine & are not explosive.


Ones that are designed to store a lot of energy ... well ... store a lot of energy. So when they fail they tend to release a lot of energy all at once.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 17:07:17
by Outcast_Searcher
diemos wrote:
SeaGypsy wrote:Flywheels are so dangerous what? They are a core element of every combustion engine & are not explosive.


Ones that are designed to store a lot of energy ... well ... store a lot of energy. So when they fail they tend to release a lot of energy all at once.

Exactly. And keeping such flywheels running at high speeds for years to decades, and having things set up so that when there is a significant mechanical failure that something dangerous doesn't happen would cost what? I don't know, but it doesn't sound cheap to me. (Or highly efficient).

I didn't say flywheels explode. Like diemos pointed out, I was implying that releasing a lot of energy very quickly, with a (or many) massive high speed moving objects involved, sounds like is has meaningful risks over time.

If that's completely wrong - I'm open to a substantive demonstration of that.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 17:20:17
by Outcast_Searcher
pstarr wrote:exploding tractors don't do it for you outcaste? You have some fancy standards.

Your signal to noise ratio approaches zero with such posts (based on the context of the discussion upthread). Congratulations.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 17:32:38
by Outcast_Searcher
pstarr wrote:exploding tractors don't do it for you outcaste? You have some fancy standards.

Just for grins, I just did a quick search on "engine flywheel danger" and got a lot of credible looking hits. I noticed phrases like "engine destroyed" related to flywheel failure.

Now, instead of a tiny flywheel used for, say, a fan belt, imagine a large millstone spinning at thousands of RPM's on fancy bearings. The mass involved might be thousands of times that of the small fan flywheel.

So what happens if the bearings seize? What happens if there are a bunch of such flywheels in a big room or cavern or whatever "storing energy" and such a failure causes a chain reaction? Do YOU want to sign up to be the full time maintenance person in such an area, while it's under normal operation?

So now, do you want to sign up to have lots of these stored in your house because you can reel off the quip "exploding tractors"? :roll:

It's amusing to me how people who constantly cite the "danger" of a global economic collapse any time now can't seem to imagine any problem from a sudden failure of massive equipment undergoing constant angular acceleration.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 17:51:25
by SeaGypsy
https://en.m.wikipedia.org/wiki/Flywheel_energy_storage

The modern idea is there are no friction points (in storage mode), instead magnetic levitation. True there must be potential for failure in clutch mechanisms for drive + draw cycles, but one would assume a better monitoring system than an old Massey tractor.

Re: Cyrogenic Energy Storage

Unread postPosted: Sat 10 Dec 2016, 23:55:38
by diemos
I suspect that they are proposing this not as a stand alone system but as an add on to existing cryogenic liquid plants.

Making and selling cryogenic liquids is profitable in its own right. Running the refrigerators when power is cheap and storing the unsellable liquids for use generating power at peak demand would squeeze out some additional profit. As it is they just dump the stuff they can't sell.