The one thing discussed somewhat on the sidelines is how do we even out our demand for electricity in such a way that we never notice increases or decline in need for electricity. Also how do we do it without wasting any of it. Energy Storage.
This idea is not new. Water pumped uphill into a holding pond of some type has been used for decades, but never on any scale to accommodate large cities. We all know about batteries as a way to store electricity There are also capacitors and maybe people have heard of flywheels use to do the same. These types of storage have limitations and would never meet our demand in the future. Batteries wear out from the begin losing storage capacity. Capacitors could never be scaled to handle whole cities, besides their application would be much better in cars and buses to temporarily hold the energy from braking which can be rapidly used to start moving the vehicle agian. Flywheels need to be continuously spinning because bringing them up to speed wastes energy which means you only part of the stored energy back out.
In the future we need to be much smarter and use what is off the shelf that would allow a home, business, or whole cities to store enough energy with little degradation while stored and yet be rapidly available when needed. In my research the only form of storage that can meet scalability and on-demand needs is compressed air.
CAES as it is known – Compressed Air Energy Storage. Many times it is discussed in terms of large underground caverns holding a huge amount of compressed air. All well and good but it is not scalable and how to make sure a cavern is sealed to hold the compressed air. The answer lies in what we already have available, tanks.
We use storage tanks now for a number of gases. There are small propane tanks, to larger ones used in welding and even larger tanks holding Liquid Natural Gas. They are so many types and sizes making it easy to tailor storage for any particular need, from a home, office building to a whole city.
At this time we can go through any city in the U.S. and find empty warehouses. They can be outfitted with tanks that are computer controlled to store compressed air when there is more electricity available than is needed and instantly drive a turbine to produce electricity on demand. These setups can even be designed to an average home.
There is one issue besides storage that would need to be dealt with, heat. When air is rapidly compressed or put under high pressure then heat is created. In one design it talked about a heat exchanger that would capture the heat and hold onto it until the air is released when the heat would be used to expand the air. It didn’t go into much detail but it would eliminate the need for an external source of energy to pull heat out and then create heat to expand the air again as some have proposed.
I’ve had this idea for decades and it is only in recent years anyone has actually agreed it was possible. Here is what I originally envisioned for a home. This would not supply a home for days on end but it would be a way to meet a demand for a few hours or maybe even a day.
In the cellar, or a small shed, would hold storage tanks. They would have computer controlled valves to direct the air into the tanks or toward the turbine. When the house produced more than enough energy for itself with excess it would drive a compressor that would recharge the tanks. Once full the excess electricity would be sent to the grid. When the home needs electricity, like at night, the compressed air would drive a turbine would meet the demand.
Some advantages I see right away are that tanks don’t develop a memory like batteries so their storage capacity would never diminish. Air is plentiful, renewable, plants create it for us, and it is free. Compressed air would never reduce air as a resource – its the same in storage as it outside storage. Also, as I have said earlier, the whole thing is can be scaled to any size at any time as needed with off the shelf items available right now. The cost of such a system could actually be much less when compared to the life of batteries and the need to replace them every so often. What’s also nice about this idea is that everything, just about, is fully recyclable, unlike batteries where only part of them are recyclable and the rest goes to the landfill.
I am not saying this is the end all answer to our needs in the future. We can still use pumped water as a way to store electricity and hydrogen in a limited way could too (with hydrogen you have too much of a loss in energy). We could like they are currently doing in Germany build Biogas plants on farms to accept both crop residue and poop to make methane which is stored until demand for electricity goes up and then a generator is turned on within seconds to meet the demand.
Compressed air the way I envision is can meet demand at an instant, anywhere. Tanks could even be transported to where they are needed. Windmills could be dedicated to compressing air rather than producing electricity to help meet demand when it is there.
An article I read more than a decade ago talked about how at one time (maybe a hundred years ago) compressed air was also sold to homes to run various devices. There is certainly no reason why it couldn’t again. There is absolutely no reason why everything has to run on electricity, the blender could just as well use compressed air.
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