Liquefied Air Could Power Cars and Store Energy from Sun and Wind

[OKIsItJustMe]

http://www.technologyreview.com/news/514936/liquefied-air-could-power-cars-and-store-energy-from-sun-and-wind/

[font face=Serif][font size=5]Liquefied Air Could Power Cars and Store Energy from Sun and Wind[/font]

[font size=4]A 19th-century idea might lead to cleaner cars, larger-scale renewable energy.[/font]

By Kevin Bullis on May 20, 2013

[font size=3]Some engineers are dusting off an old idea for storing energy—using electricity to liquefy air by cooling it down to nearly 200 °C below zero. When power is needed, the liquefied air is allowed to warm up and expand to drive a steam turbine and generator.

The concept is being evaluated by a handful of companies that produce liquefied nitrogen as a way to store energy from intermittent renewable energy sources. Liquefied air might also be used to drive pistons in the engines of low-emission vehicles.

One company, Highview Power Storage of London, has raised $18 million and built a pilot plant that will use liquid air to store power from the grid. Highview has teamed up with Messer, the large industrial gas company, to help develop the technology. If all goes well, the U.K. government may fund the development of a larger plant that could establish its commercial viability. Meanwhile, the engineering consultancy Ricardo is developing two types of engines that could use liquid nitrogen, based on technology from a Highview Power spinoff called Dearman Engine.

Storage for the power grid is becoming more important as use of renewable energy increases. In the near term, natural-gas power plants and fast-responding storage technologies such as batteries can keep the grid stable (see “Wind Turbines, Battery Included, Can Keep Power Supplies Stable”). But if renewables are to reach a very large scale, or if we want to reduce the use of fossil-fuel backup power plants, technologies that can store hours’ or days’ worth of power will be needed.

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[leveymg]

1. How much energy does it take to cool nitrogen down to -200 degrees and keep it there?

Hmmm?

[OKIsItJustMe]

2. Gosh! I bet they never thought of that!

You’re so much smarter than these people!

[leveymg]

3. Just try answering the question, you posted the OP.

Snark attack on the first commenter. Classy.

[OKIsItJustMe]

6. Snark attack, eh?

Go back and read your “comment.”

You can store liquid nitrogen in a “dewar” (essentially a really good thermos bottle) with relatively little “static evaporation.”
http://www.princetoncryo.com/liquid-nitrogen-storage-dewars.html

In this case, though they’re using a large tank, which will have smaller ratio of surface area to volume (i.e. even more efficient.)

[longship]

7. An entirely appropriate question, my friend.

Snark response probably not in the best interest of your thread's lifetime here.

I, too, think that the energy available would likely be less than the energy needed to liquefy the air.

Thermodynamics is an important part of the energy equation. Nobody is immune to such questions. This might be an energy source at all otherwise. It could, however, be an energy storage medium.

Also, I have heard of compressed air engines. I understand that they are not very quiet. In fact, quite the contrary.

And that doesn't even begin to address the question of energy density which speaks to how far such a vehicle can travel on a full charge and how long it would take to recharge compared to running the damned thing. Gasoline has very high energy density which is why we use it.

[OKIsItJustMe]

10. Did that strike as a serious inquiry?

“Hmmm?”

[longship]

12. More snark? Really!?

Bye to this thread.

[kristopher]

13. We're used to people who have a somewhat better knowledge base...

...or who know the limits of their expertise.

[OKIsItJustMe]

14. I guess you missed my point

I did not see “Hmmm?” as a serious inquiry.

[OKIsItJustMe]

11. Perhaps investing a few seconds to read the article will answer your questions

For example:

…

Liquid air stores energy at about the density of nickel–metal hydride batteries and some lithium-ion batteries, the kind used in hybrid and electric cars now. …

[leveymg]

15. That doesn't answer the question: how much to chill down to -200 degrees?

Come on, let's play the game, give it try.

Here's an answer: Wiki Liquid Nitrogen Vehicle

Liquid nitrogen production is an energy-intensive process. Currently practical refrigeration plants producing a few tons/day of liquid nitrogen operate at about 50% of Carnot efficiency.[6] Currently surplus liquid nitrogen is produced as a byproduct in the production of liquid oxygen.[4]

So, if this is accurate, how good is 50% Carnot efficiency? A lot better than current steam engines, gas-fueled turbine steam generators, and internal combustion engines, according to another source: http://web.mit.edu/newsoffice/2010/explained-carnot-0519.html

At the time of Carnot’s work, the best steam engines in the world had an overall efficiency of only about 3 percent. Today, conventional steam engines can reach efficiencies of 25 percent, and gas-fired turbine steam generators in power plants can reach 40 percent or more — compared to a Carnot Limit, depending on the exact heat differences in such plants, of about 51 percent. Today’s car engines have efficiencies of 20 percent or less, compared to their Carnot Limit of 37 percent.

See how easy that can be? However, I wouldn't mortgage the house on the first estimate of 50% efficiency, as that's right at the theoretical limit, and apparently there is no mass production of liquid nitrogen.

All I wanted was an answer, not an argument.

[OKIsItJustMe]

17. The real question is not how much energy it takes to chill it

Because, then, you have to ask, “how much energy do you get back?”

So, your real question is “what is the overall efficiency of the system?” As “tinrobot” pointed out, the article says, “Highview Power’s process is 50 to 60 percent efficient…”

Of course, that was taken out of context:

…

Highview Power’s process is 50 to 60 percent efficient—the liquid air can yield just over half as much electricity as it takes to make it. Batteries, by contrast, can be more than 90 percent efficient. But the new process can make up for its inefficiency by using waste heat from other processes (see “Audi to Make Fuel Using Solar Power”). Highview has demonstrated that low-temperature waste heat from power plants or even data centers can be used to help warm up the liquefied air. The system can also last for decades, while batteries typically need to be replaced every few years. This longevity could help reduce overall costs.

…

Here’s the key point (once again from the article):

…

“When we’re looking at energy storage mechanisms, we’re looking for something that’s based on extremely low-cost materials and very simple processes we can do in bulk,” says Haresh Kamath, program manager for energy storage at the Electric Power Research Institute. “And this certainly fits the bill.”

…

And now, I have taken 6 paragraphs from the original article, rather than the recommended limit of 4.

[leveymg]

19. Is systems analysis catching on at DU? ;-)

Reading all the estimates for competing technologies is often a study in Find Waldo, the Missing Variable. So much of the stuff posted here on energy issues is advocacy, and not really particularly good advocacy.

But, we keep trying.

(I won't tattle if you go over - I think the 4 para liimit applies to the OP, anyway, not responses broken up over the course of a thread).

[silverweb]

4. Less than drilling for/refining/shipping fossil fuels.

[font color="navy" face="Verdana"]The question isn't always how much energy something takes, but how clean and renewable the energy is that's used.

I'd be quite willing to bet that this method under study is cleaner, more sustainable, and even more efficient than any fossil fuel.

[tinrobot]

5. 50-60% Efficient

"Highview Power’s process is 50 to 60 percent efficient—the liquid air can yield just over half as much electricity as it takes to make it"

So, I guess it is less efficient than using the power directly, but efficient enough to attract investors...

[OKIsItJustMe]

8. Any method of storage is “less efficient than using the power directly”

The question is, is the storage efficient enough to be practical.

[kristopher]

9. And that almost always requires an application specific evaluation. nt

[htuttle]

16. I think there's something to this idea

What other methods of storing large amounts of electricity do we have? Pumping water up to reservoirs that can be tapped and piped to gravity fed hydro-generators or storing it as heat in melted salts and such. Using the power to refrigerate a gas seems a lot more convenient than either of those (and certainly a lot more portable).

[kristopher]

18. There's quite a variety of thermal storage technologies.

Ice batteries and rock batteries; the melted salts you mentioned; and several ideas using ceramics tied to building heat systems are just a few that come to mind.