Apologies for reviving a dead body – I was researching the feasibility to marry a domestic wind turbine with a pressurized pneumatic/hydraulic hybryd system, for decoupling energy generation/storage and actual usage at home (wind patterns versus power usage patterns at home), and found this very interesting site/discussion. I have some suggestions/questions that might put this into possibly slightly different light (well maybe not the original idea, which I consider a “pipe” (sic!) dream myself , but domestic-size hybrid system):
1. Why hydraulic/pneumatic hybrid? From what I’ve learnt doing my research, hydraulic motors/pumps efficiency is way better than pneumatics. But then, coupling hydraulic fluid after the compressor with hydraulic accumulator, seems to me is 1:1 conversion in pressure, I can’t see where loses could come from apart from compression heat loses. Just different way of pumped hydro, one might say, possibly feasible on a domestic scale – where water head pressure is replaced by pneumatic pressure . Obviously though, one would need both the accumulator and the fluid storage tanks scaled appropriately to the energy consumption needs, so I don’t see it happening in the original idea discussed here, for practical reasons

2. Someone mentioned refrigerator above – a heat pump, in general (I personally think that line of thought should be reinforced and pursued whenever possible). Going back to the discussion – well, one need to be extra careful when providing any definitive efficiency figures for the system as a whole, traditionally ruling out the potential to tap on the heat of environment, and IMHO many (if not all) systems that involve pneumatic pressure transformations, could potentially benefit from that concept, a stationary system in particular (air car, dismissed briefly above as well, is worth at least brief Wikipedia research, regarding overall system efficiencies, engine concepts and how it taps on the heat of the environment – person(s) who dismissed it above certainly didn’t do that part of their homework – no offence meant, but check for yourself, it is worth it, it actually is quite clever idea). Depending on design and use case, but heat pumps potential, in yet more ingenious and maybe yet to be invented designs, is IMHO enormous… So one need to be very careful, again, dismissing compressed air as a storage medium, as it is a well established practical fact, that overall COP of commercially available heat pumps is in the range of 300%-400%, and let’s do not forget that traditional phase-changing process and supersonic expansion valve in mainstream heat pumps are hardly very high-efficient things!

Is it possible to scale enough to be feasible for grid applications – I don’t know, but if we are not ruling that factor a’priori out of the equation, we could end up with very interesting overall efficiency figures indeed . Again, I am not a trained engineer, only a fellow that liked and kinda understood basic physics up until high school (my high-school class was profiled for mathematics/physics), when my fascinating encounter with physics ended (went into software side of things, sometimes I really regret this ).

What do you think about it, does it possibly shed some new light/sparks new ideas in your educated minds? Any criticism welcomed, though I will not be able to argue based on equations and tables and specific figures, and would rather welcome higher level/layman terms discussion, kindly. Basically, is there anything that stops us from (let’s say as a figure of thought) to introduce heat pump BEFORE the compressor to cool down the air being compressed (so effectively we would be putting more gas/energy into the storage tank), and another to heat up the air from the tank BEFORE it “hits the road” (does our usable work)?

Best Regards

        Tweenk said:

It’s ironic that the most rational government at the moment when it comes to energy policy (and several other things) is the Chinese Communist Party. It shows some important weaknesses of democracy.

Yeah, I think The West has been in decline since the early 1970’s. I put the symbolic peak at the moon landings, say 1969. With a few exceptions, things have been pretty much downhill since then. People seem to be less well educated, in the sense that they don’t really understand how the world works. And, they’re less motivated, more willing to strive for the minimum. Democracy can be a great system, but it has morphed into the notion that 100 million people can’t be wrong. We are doomed…

        Tweenk said:

BTW I also think it won’t work as a power transmission system or as a large scale storage system. I think it might work as a peaking storage system (e.g. store energy for at most 1-2 hours to protect against events like 30 million people turning on their electric teapot simultaneously during a commercial break).

A while ago I read an article about such a pressurized air peak storage system. They had refined the idea and used a special two-part gas turbine instead of just a pressure engine for electricity generation. If they had pressurized air in storage, they would shut down the compressor part of the turbine – if not, they could still run it as a regular peak-power gas turbine but at a lower power rating because they had to couple in the compressor. During nighttime, the compressor would run alone on electrical power to fill the reservoir.
They also stored heat in a liquid medium to warm up the cold, expanding air coming up from the reservoir.

Of course, energy storage is always at a big loss, but there are only so many places you can build a pumped storage plant.

Satan_Klaus

        Tweenk said:

The irrationality crown should go to the European Union (which I’m unfortunately a citizen of). It has very restrictive GMO regulation.

I try not to get too much into the whole national-centrism thing and always point out that all countries have their own brand of stupid. However, in the case of GMO food in Europe, I find it just about comical, coming from an American perspective.

The whole anti-GMO thing in the US is not as strong as in Europe (it exists, but not as much), I think in part that’s because the cat is out of the bag here. The first genetically engineered crops were introduced in the US in the late 1980’s and early 1990’s and basically became ubiquitous within a few years. There’s little point in protesting it at this point. The genie can’t be put back in the bottle and everyone here has been eating it for many years with no ill effects.

For that reason, I think it’s a bit ridiculous seeing these blockades of GM crops at ports or lobbying for bans on it in Europe. I’m sitting here eating food which probably contains gmo crops and I’ve done so for many years.

It’s so annoying hearing this BS about how GM crops are the reason for the American obesity and diabeties problems. No, they have the same caloric and nutritional values in general. The reason everyone is so fat is because more and more people prefer to eat an oversized fried burger and milkshake at a fast food place for dinner instead of making something healthier.

        Gordon said:

However, I’ve seen so much of this stuff in the US, Canada, Europe, Australia and even Japan, that it seems like the industrial societies of the world are all in a big race to the bottom to see who can lose the most money on these idiotic concepts.

Japan seems more rational than the rest. For example their fast reactor program is still operating, and they are continuously developing uranium seawater extraction. The irrationality crown should go to the European Union (which I’m unfortunately a citizen of). It has very restrictive GMO regulation. It has the most anti-nuclear attitude in the world (e.g. in Austria nuclear power is illegal; several countries considered a nuclear phase-out at some point in time; they forced Lithuania to shut down Ignalina as a condition of accession because they were scared of RBMK; similarly they blackmailed Romania into shutting down 4 of 6 units at Kozloduy even though 4 of them were judged safe by IAEA). It pours a lot of money into pointless countryside development projects. Wasteful pseudo-environmental practices like organic farming are popular and even encouraged. The renewable energy scam is stronger than ever. The most tragic development is that as it’s becoming increasingly apparent that renewable energy is a scam, the turn is not towards expansion of nuclear power, which the hordes of brainless anti-nuclear idiots turned into a third rail issue, but towards the planet-killing coal power and untested Rube Goldberg machines like CCS.

It’s ironic that the most rational government at the moment when it comes to energy policy (and several other things) is the Chinese Communist Party. It shows some important weaknesses of democracy.

Back to the article. I think the fact that they mentioned a pipeline is unfortunate. I doubt they are seriously proposing to see this as a transmission system. The quotations from the project leader indicate they’re just reusing an abandoned pipeline as a large storage tank, and the transmission system part was made up by the journalist to make the story sound more interesting.

        drbuzz0 said:

Actually they’re not funding this one.

I mean, they may be funding as ridiculous concepts in the US. In this case, the tax payer money is coming from “Canada Foundation for Sustainable Development Technology Act” – a government subsidy agency for the development of “Sustainable technology.”

So it’s actually Gordon, DV82XL and all their fellow citizens bleeding out on this one.

Well, that really does not make me feel any better! However, I’ve seen so much of this stuff in the US, Canada, Europe, Australia and even Japan, that it seems like the industrial societies of the world are all in a big race to the bottom to see who can lose the most money on these idiotic concepts.

Also, despite the high pressure, by the time the gas reaches its destination, the actual amount of energy from the flow is orders of magnitude less than the chemical energy of the gas when burned.

        Tweenk said:

5. Therefore the ideal gas law does not limit the total efficiency to less than 100%, but there is a trade-off between efficiency and energy extraction rate. The quicker you try to extract the energy, the more losses there will be.

BTW I also think it won’t work as a power transmission system….

In a perfectly insulated system, if the (ideal) gas is not expected to do work theoretical efficiency can approach 100%

The point however is to provide an understandable explanation, to those who may only have a smattering of high school science why this scheme will never work. To that end the simple issue that heat is lost during compression, and must be supplied during expansion, is sufficient to show that the efficiency of the system is very low.

Compressed air works fine, in some applications it is simply the best way to go. But there are limits that will prevent systems employing this energy carrier to grow above certain dimensions, and that in the end is the crux of the matter.