Posted on 05/09/2021 4:51:37 PM PDT by dynachrome
“stable at normal temperature liquid form”
Stable be the key word. I’ve worked with the gas and it scared me.
A large container of compressed air seems much more dangerous than a big tank or resevoir of water at an elevation higher than the pump and turbine.
Another worthless technology looking for a subsidy.
Liquid Organic Hydrogen Storage
Is that anything like, say, oil?
I do too, Outside the box is the way. But air compressed is heated when it is compressed and once it cools it losses about 50% of it’s pressure and stored energy capacity.
Freeflow without any pressure such as heat exchange thermal mass is different. That works well to help maintain an even keel. :)
Yep...
When you compress air you generate a lot of heat. If you do not use that heat and/or use the cooling that occurs when you release the air I cannot see how this makes sense. They could be doing this, but their website is very vague and makes no mention of dealing with this big issue.
Right. The Carnot cycle requires that pressure and temperature be managed simultaneously for such a process to be efficient.
Same as Raccoon Mt in southeast Tennessee.
In my thermodynamics class we calculated the maximum theoretical efficiency of compressed air storage. It was awful. Main problem is it generates enormous amounts of heat when compressing, then absorbs an equal amount when expanding. And that heat is hard to contain.
Maybe they figured out a workaround, but people have tried it for 100 years, and it always fails.
“A-CAES utilizes renewable energy or excess grid energy to compress air. This compressed air is then funneled into underground purpose-built caverns, displacing water and creating storage capacity. Heat created by this process is captured and stored to reheat the compressed air when energy is needed.”
They are displacing water as the liquid seal and it makes for a great thermal storage medium having one of the highest latent heats of any substance on earth. Running the out going air through coils of pipe in the heated water would make this process isothermal and drastically increase the carnot efficiency. Conventional CAES systems are 60 to 80% efficient with isothermal compression and expansion and 10% more. What matters is cost of energy added vs sale price of energy sold less O&? plus deprecated capital.
If they can get wind power that is surplus at 1 cent per kWh or at times in Texas negative rates which means they get paid to take the power by the grid ops. And then sell it at peaker rates of 40 to 90 cents per kWh it doesn’t matter if the process is only 70% round trip. Peaker rates in Texas routinely hit 50+ cents per kWh. As was pointed out the Germans have used CAES systems for decades it’s well established tech. Cost has always been an issue but the Germans pay four times what the average American pays for power so they have a lot of head room for capital costs. CAES systems pair well with gas turbines as the gas compressor of the head unit of the turbine train are exactly the kind needed for CAES while the turbine sections are the same types by going isothermal with reheat they could even add in supplemental gas heating and boost output on discharge by at least double plus once the air caverns are empty you can run at half output on just the natural gas alone. Think of it as a gas turbine peaker plant with a big a$$ airtank. Off loading the gas compression side of the brayton energy cycle which all gas turbines run on means you load shift that energy from natural gas from the turbines to surplus electricity from the grid then blow down the air bank heated into the turbines when you need the power later it’s elegant and quite efficient again Germans have the tech down. Using engineered air caverns and water heat plus sealing is the secret sauce for this group. By going engineered they open nearly all rock strata to air storage space removing the need for preexisting salt mines or deep aquifers or salt domes. They are right an Ops geologist has the skills needed for these caverns.
There is a loss of energy each time it is converted. Compressing the air produces heat and takes energy. Loss of air pressure under storage is inevitable. Using the compressed air to turn a turbine that drives a generator more energy loss due to heat. While this method of storage is possible the net loss makes this storage highly inefficient. The windmills themselves capture only about 25% of the winds energy. These green pipe dreams are just pits for taxpayer money and have no possibility of providing the steady reliable and scalable electrify we need to maintain our society.o
Yep, this company is probably looking for taxpayer/government subsidies...after they get them, oops, too inefficient...move on to next boondoggle!
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