Yenn Posted February 4, 2019 Share Posted February 4, 2019 I didn't bother looking at the video about compressed air storage. Have you ever used air tools, they take a vast amount of air to do a little bit of work. The iar drill I have uses more electricity than an electric drill by the time I run the compressor. There was a mob in Spain I think that a few years ago tried to run cars on compressed air and it never got off the ground. When you compress air, the first thing is an increase in heat and that has to be stored to maintain the energy in the air. The alternative is to poke a bit of diesel fuel into it and you have got a compression ignition engine. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 I didn't bother looking at the video about compressed air storage. Have you ever used air tools, they take a vast amount of air to do a little bit of work. The iar drill I have uses more electricity than an electric drill by the time I run the compressor.There was a mob in Spain I think that a few years ago tried to run cars on compressed air and it never got off the ground. When you compress air, the first thing is an increase in heat and that has to be stored to maintain the energy in the air. The alternative is to poke a bit of diesel fuel into it and you have got a compression ignition engine. Yenn it is a shame you did not watch the video because there is a thorough analysis of the energy efficiency. Also, there are already 2 plants working now, The Huntorf plant in Germany with (290MWh with a 42% efficiency and the Mcintosh plant in Alabama (110MWh at 54% efficiency.) These are both Diabatic, meaning the heat you mention is dispersed into the atmosphere as waste. Both of these plants require the burning of some gas to heat the air as it is utilized. The experimental plant in the video stores the heat and uses it to reheat the air as it is used. The two plants that are running are doing so commercially and economically. Both of these facilities have been operating successfully for many years. Link to comment Share on other sites More sharing options...
pmccarthy Posted February 4, 2019 Share Posted February 4, 2019 Releasing heat into the atmosphere. But isn't that.......? Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Releasing heat into the atmosphere. But isn't that.......? That is why the latest pilot plants are using systems where the heat created in the compression stage is stored and used to reheat the air in the expansion phase. Near Isothermal Near isothermal compression (and expansion) is a process in which a gas is compressed in very close proximity to a large incompressible thermal mass such as a heat absorbing and releasing structure (HARS) or a water spray. A HARS is usually made up of a series of parallel fins. As the gas is compressed the heat of compression is rapidly transferred to the thermal mass, so the gas temperature is stabilised. An external cooling circuit is then used to maintain the temperature of the thermal mass. The isothermal efficiency (Z)[7] is a measure of where the process lies between an adiabatic and isothermal process. If the efficiency is 0%, then it is totally adiabatic; with an efficiency of 100%, it is totally isothermal. Typically with a near isothermal process an efficiency of 90-95% can be expected. Compressed air energy storage - Wikipedia Storage 1978 – The first utility-scale compressed air energy storage project was the 290 megawatt Huntorf plant in Germany using a salt dome. 1991 – A 110 megawatt plant with a capacity of 26 hours was built in McIntosh, Alabama (1991). The Alabama facility's $65 million cost works out to $590 per kW of generation capacity and about $23 per kW-hr of storage capacity, using a 19 million cubic foot solution mined salt cavern to store air at up to 1100 psi. Although the compression phase is approximately 82% efficient, the expansion phase requires combustion of natural gas at one third the rate of a gas turbine producing the same amount of electricity.[17][18][19] December, 2012 – General Compression completes construction of a 2 MW near-isothermal CAES project in Gaines, TX; the world's third CAES project. The project uses no fuel.[20] Link to comment Share on other sites More sharing options...
nomadpete Posted February 4, 2019 Share Posted February 4, 2019 Wow. Impressive stuff Octave. I'd always believed that compressed air was too lossy to contemplate for energy storage. That was my preconceived notion. What happened to that 2012 pilot plant? Link to comment Share on other sites More sharing options...
pmccarthy Posted February 4, 2019 Share Posted February 4, 2019 I wonder there there might be earthquakes induced as for some fracking projects. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Wow. Impressive stuff Octave.I'd always believed that compressed air was too lossy to contemplate for energy storage. That was my preconceived notion. What happened to that 2012 pilot plant? Not sure about the Gaines Texas plant but I did discover a Canadian company called Hydrostor. They are building a demonstration plant at the decommissioned Angus Zinc mine near Adelaide. Canadian long-duration bulk energy storage company enters Australian market RSS Feeds 19 Jun 2018 Hydrostor, a Canadian company specialising in advanced compressed air energy storage (A-CAES), is establishing a new head office and demonstration power plant in Australia. The demonstration power plant, which is in late-stage development, will be located at the decommissioned Terramin Angas Zinc Mine near Adelaide, South Australia. It will be Australia’s first A-CAES system and Hydrostor plans to have the facility in service by 2019. The facility will use Hydrostor’s emissions-free A-CAES technology, have a power rating of 5MW and an energy storage capacity of 10MWh. Canadian long-duration bulk energy storage company enters Australian market This is how it works Link to comment Share on other sites More sharing options...
nomadpete Posted February 4, 2019 Share Posted February 4, 2019 Surprisingly , compressed air storage has managed to get their the electric to electric conversion efficiency up to around the 80% mark. Comparable to batteries and hydro pump storage. And a much lower capital cost to build. Looks very promising. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Surprisingly , compressed air storage has managed to get their the electric to electric conversion efficiency up to around the 80% mark. Comparable to batteries and hydro pump storage. And a much lower capital cost to build. Looks very promising. I read that a majors risk for this company is the declining cost and increasing performance of grid storage batteries. I imagine that the solution to grid level storage will not be a single technology but a range of solutions. What I find attractive about is the use of disused mines. Link to comment Share on other sites More sharing options...
nomadpete Posted February 4, 2019 Share Posted February 4, 2019 Risks not unlike the problem that Peugeot/Citroen hybrid air car. Apparently they made a safer cheaper hybrid that never needs battery replacement (no battery), with 106mpg fuel economy. but the EU has decreed that internal combustion will end and they subsidise electric but not other technology. So, not economically viable Link to comment Share on other sites More sharing options...
Bruce Posted February 4, 2019 Share Posted February 4, 2019 nomad, I always thought that compressed air was too inefficient because when you compress air, you heat it. And then it cools in storage and a lot of energy is lost. Compressing a really big volume to a low pressure minimizes the losses, but you need special caves and stuff to do this. I'd really like to be wrong, and that 80% figure is impressive... how did that happen? Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 nomad, I always thought that compressed air was too inefficient because when you compress air, you heat it. And then it cools in storage and a lot of energy is lost. Compressing a really big volume to a low pressure minimizes the losses, but you need special caves and stuff to do this.I'd really like to be wrong, and that 80% figure is impressive... how did that happen? The process is explained in the video. The heat is harvested by being efficiently stored and then added back to the air in the generation phase. Link to comment Share on other sites More sharing options...
nomadpete Posted February 4, 2019 Share Posted February 4, 2019 Wasted energy in the form of heat has always been the problem. The large scale systems recover the heat during compression (charging the 'battery'), and reapply it during use of the compressed air. this 'reuses' the heat, so the energy is recovered. There are 2 large experimental systems at present. One in USA and one in Germany. Still not quite beating batteries cost wise, but it's early days and improvements are happening. There are plans to set one up at a wind farm somewhere. Also people are toying with small scale systems (home size) but it's not economical unless it is integrated into the hot water heater, air conditioner, and fridge systems in order to use the otherwise wasted heat. Not likely to be practical for existing homes, but has possibilities for new homes. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Round trip efficiency Hydro from 65% in older installations to 75-80% for modern deployments Flywheels80% to 90% Batteries75% to 90% Electrothermal (ETES)65% to 75% Compressed air (CAES)65-75% Round Trip Efficiency Link to comment Share on other sites More sharing options...
nomadpete Posted February 4, 2019 Share Posted February 4, 2019 The compressed air hybrid car used regenerative braking to compress the air, also used a small IC engine running at optimum to charge the cylinder. They didn't explain the heat issue but released the prototypes some years back and quoted 106 English mpg fuel economy. Link to comment Share on other sites More sharing options...
spacesailor Posted February 4, 2019 Share Posted February 4, 2019 Octave, "At the moment the electrons that are powering my computer so that I can type this rubbish are being produced and used straight away. This is not the way we produce and consume other products, it is a "just in time" EASY fix for that problem, Put large,ish battery under a foot-stool, connect to a U,P,S, switch off the power, and type till you are tired, Recharge the battery when Off-peak. Compressed air requires special container's that have a short life-span & require annual inspection, ask any SCUBA diver !. spacesailor Link to comment Share on other sites More sharing options...
spacesailor Posted February 4, 2019 Share Posted February 4, 2019 But Why AIR, other gases are much cooler to compress, and when used, go cold. Also Go Liquid. Nitrogen as a liquid doesn't seem to need a compression cylinder, only a insulated thermal cask. Doctor,s surgery to remove warts. spacesailor Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Compressed air requires special container's that have a short life-span & require annual inspection, ask any SCUBA diver !.spacesailor Space you don't appear to have gone to my links. We are not talking little air tanks we are talking in some cases natural salt caverns. We already store natural gas in natural caverns Natural gas storage - Wikipedia The plants in Huntorf Germany uses a natural salt dome cavern and the plant in Alabama uses a mined salt cavern and have worked for many years. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 But Why AIR, other gases are much cooler to compress, and when used, go cold.Also Go Liquid. Nitrogen as a liquid doesn't seem to need a compression cylinder, only a insulated thermal cask. Doctor,s surgery to remove warts. spacesailor Because all you need is a power source and a compressor. I think the process of producing liquid nitrogen is more complicated and requires more energy. It is a valid question of course but my assumption would be that the already operating plants would for reasons of greater profitability use nitrogen if it were viable. Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 But Why AIR, other gases are much cooler to compress, and when used, go cold.Also Go Liquid. Nitrogen as a liquid doesn't seem to need a compression cylinder, only a insulated thermal cask. Doctor,s surgery to remove warts. spacesailor Actually, I see there is such a thing as liquid nitrogen for energy storage. It looks like its efficiency is similar to compressed air so perhaps it comes down to cost or perhaps the large scale required. Cryogenic energy storage - Wikipedia Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 This power storage facility in Manchester is not liquid nitrogen but liquid air. This demonstration plant opened in Jun 2018 and is connected to the grid. When it comes to our energy systems progress is being made. Link to comment Share on other sites More sharing options...
spacesailor Posted February 4, 2019 Share Posted February 4, 2019 I was thinking more about Home or vehicle use !. A bit like going Solar. spacesailor Link to comment Share on other sites More sharing options...
pmccarthy Posted February 4, 2019 Share Posted February 4, 2019 They had compressed air locomotives in coal mines one hundred years ago. Needed frequent recharging. Link to comment Share on other sites More sharing options...
facthunter Posted February 4, 2019 Share Posted February 4, 2019 Air is a" mixture" of gases Principally oxygen-Nitrogen and the rare gases Argon, Neon Krypton Xenon (and so on.) as my chem .teacher would say which condense at different temperatures and pressures so I don't GET what "liquid air" is. The vid was just about as devoid of information as you could possibly arrange and hope to get away with it. To avoid really high pressures you often make the storage very cold. The mist (smoke) was there . The mirrors must be somewhere around to complete the illusion.. Nev Link to comment Share on other sites More sharing options...
octave Posted February 4, 2019 Share Posted February 4, 2019 Air is a" mixture" of gases Principally oxygen-Nitrogen and the rare gases Argon, Neon Krypton Xenon (and so on.) as my chem .teacher would say which condense at different temperatures and pressures so I don't GET what "liquid air" is. The vid was just about as devoid of information as you could possibly arrange and hope to get away with it. To avoid really high pressures you often make the storage very cold. The mist (smoke) was there . The mirrors must be somewhere around to complete the illusion.. Nev Nev the video I posted was a short introduction to the subject. I had not heard of cryogenic energy storage until it was mentioned here. At the moment I can only post from my phone so a bit hard to post links but there are plenty of links explaining the process and e a evaluating it's performance. Research is being done at Birmingham university. Link to comment Share on other sites More sharing options...
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