4 ms·

Has anyone analyzed the viability of a compressed-air energy distribution system? It could be simpler and safer than electricity distribution.

ericbarrett 6y ago
In the quantity and pressure required to match even a fraction of the existing energy grid, wouldn’t transportation be insanely dangerous? A cylinder of highly pressurized air is basically a bomb.
- mleonhard 6y ago
  I was thinking more of a pipeline of compressed air.
  - ericbarrett 6y ago
    I think they would have a similar issue. Since the compression of the gas itself is the potential energy, rather chemical bonds (e.g. fossil fuels), the pressures would need to be extremely high. This means any compromise of the pipeline would be catastrophic. That said, natural gas already causes home and pipeline explosions, so I'd be interested in an engineering study.
  - dredmorbius 6y ago
    Live steam is another alternative, also used in industrial applications.
repiret 6y ago
In what ways are compressed air safer and simpler for transmission? Off the top of my head I can only think of advantages for electricity: * Electrical transmission lines are lighter and smaller per watt than compressed air transmission lines. * Electrical transmission has lower inductance than compressed air has equivalent momentum. * Compressed air vessels can fail explosively; electrical stuff just heats up. * One has to contend with adiabatic heating/cooling when exchanging air pressure for flow rate, while there's no analogous concerns when using transformers to exchange voltage for amps. * Electrical equipment tends to be much quieter than air equipment.
controversy 6y ago
Why distribute the compressed air? If you have the ability to store compressed air, you can put a generator on top. When you have an overabundance of power, you run the compressor. It pushes air into large underground holding facilities built in various geologic formations. When you need power, you run the compressed air through your generator. Dot the land with these systems. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.518.81&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.51...
ClumsyPilot 6y ago
This sounds like steampunk fantasy,and very impractical. We have thousands of kilometers of high-voltage transmission lines, imagine that's now carrying compressed air. Firstly, these lines can carry multiple Gigawatts of power, i do not think it's even possible to have a pipe of compressed air that could transport that amount of power. The most powerful air compressor in the world appears to be 28 mW in power consumption! - not output. Secondly, how are you going to look for leaks in that thing? Also any rupture in the line will release the equivalent energy of many kilograms of TNT. How do I power my TV with compressed air, do I have to have a generator in my house? If so, you've just lost a ton of efficiency.
- mleonhard 6y ago
  About 5% of the energy is lost in transmitting power via electricity from generator plants to consumers [0]. Losses in a compressed air energy distribution pipeline would primarily come from friction between the moving air and the walls of the pipeline. Fortunately, we can increase the pipe size to reduce losses from friction. This is because friction increases linearly with pipe diameter, while flow increases quadratically [1]. Electrical power transmission requires large amounts of land. The towers and lines are hazards to aircraft. They are fragile infrastructure sitting out in the open. They start wildfires. Compressed air using buried pipelines has none of these problems. Air streams out of a broken pipe. It emerges from the pipe at high pressure (100 ATM?) and then expands until reaching local pressure (1 ATM). Its flow rate is limited by friction with the pipe wall and cannot be instantaneous. An entire section of pipe will take several seconds or minutes to empty. By comparison, a TNT explosion produces a small amount of 1-billion-ATM gas which expands instantly in one big burst. A broken pipeline is more like a rocket engine than a TNT explosion. How to detect and find leaks? Listen for the sound? Fortunately, compressed air leaks pose no danger of explosion or asphyxiation. Refrigerators can run on compressed air directly and very efficiently. A TV would need a small electricity generator powered by compressed air. The generator could be noisy, so it would probably be in another room or outside the home. The generator could cool your home in summer. To be efficient in winter, it could use some buried pipes to draw heat from the ground. Coal-powered and natural-gas power plants are essentially electricity generators powered by compressed air (actually steam). They are adiabatic engines and have the same efficiency problems as a small generator in your home. -- [0] https://www.eia.gov/tools/faqs/faq.php?id=105&t=3 https://www.eia.gov/tools/faqs/faq.php?id=105&t=3 [1] https://www.fluidmechanics.co.uk/hydraulic-calculations/pipeline-flow-2/ https://www.fluidmechanics.co.uk/hydraulic-calculations/pipe...
dredmorbius 6y ago
Hydraulic power distribution systems did and do exist. Your dentist and auto mechanic both very likely have one based on compressed air, and they're popular among certain Amish for shop power. Large-scale systems were built in the 19th century, especially in ports, where large intermittent loads were required, especially for lifting and operating canal locks. Disadvantages include size, limited range (up to several kilometres, but generally far less) leaks, limited capacity (high applied force but limited energy storage), controls, etc. Electric power distribution is the diect analogue of such systems, and is in virtually all regards superior, more flexible, cheaper, and more readily and precisely controlled, though hydraulic power distribution existed in London, England, as late as 1977. https://en.wikipedia.org/wiki/Hydraulic_power_network https://en.wikipedia.org/wiki/Hydraulic_power_network
flyinghamster 6y ago
When the original Niagara Falls power station was in its planning stages, the planners were uncertain on how they would distribute power, and were considering using compressed air before they decided to generate electricity instead. Unfortunately, they specified turbines that operated at 250 RPM, making it impractical to directly produce 60 Hz AC, or 30 Hz for that matter, which would have made frequency converters relatively cheap. Instead, 25 Hz became a North American standard for industrial power, and a few legacy customers remained as late as 2006. [0] Much of Amtrak's Northeast Corridor, and SEPTA's rail network in the Philadelphia area, still use 25 Hz for traction power, provided from converters or from a few hydroelectric plants that have 25 Hz generators. [0] https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948 https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948
KSteffensen 6y ago
Yes, apparently that has been done. https://www.lowtechmagazine.com/2018/05/history-and-future-of-the-compressed-air-economy.html https://www.lowtechmagazine.com/2018/05/history-and-future-o...
- mleonhard 6y ago
  Thanks for sharing that article. I think the most promising application of distributed compressed air is in refrigeration, especially if the power source is not an adiabatic process.

ericbarrett 6y ago

In the quantity and pressure required to match even a fraction of the existing energy grid, wouldn’t transportation be insanely dangerous? A cylinder of highly pressurized air is basically a bomb.

mleonhard 6y ago
I was thinking more of a pipeline of compressed air.
- ericbarrett 6y ago
  I think they would have a similar issue. Since the compression of the gas itself is the potential energy, rather chemical bonds (e.g. fossil fuels), the pressures would need to be extremely high. This means any compromise of the pipeline would be catastrophic. That said, natural gas already causes home and pipeline explosions, so I'd be interested in an engineering study.
- dredmorbius 6y ago
  Live steam is another alternative, also used in industrial applications.

repiret 6y ago

In what ways are compressed air safer and simpler for transmission? Off the top of my head I can only think of advantages for electricity: * Electrical transmission lines are lighter and smaller per watt than compressed air transmission lines. * Electrical transmission has lower inductance than compressed air has equivalent momentum. * Compressed air vessels can fail explosively; electrical stuff just heats up. * One has to contend with adiabatic heating/cooling when exchanging air pressure for flow rate, while there's no analogous concerns when using transformers to exchange voltage for amps. * Electrical equipment tends to be much quieter than air equipment.

controversy 6y ago

Why distribute the compressed air? If you have the ability to store compressed air, you can put a generator on top. When you have an overabundance of power, you run the compressor. It pushes air into large underground holding facilities built in various geologic formations. When you need power, you run the compressed air through your generator. Dot the land with these systems. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.518.81&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.51...

ClumsyPilot 6y ago

This sounds like steampunk fantasy,and very impractical. We have thousands of kilometers of high-voltage transmission lines, imagine that's now carrying compressed air. Firstly, these lines can carry multiple Gigawatts of power, i do not think it's even possible to have a pipe of compressed air that could transport that amount of power. The most powerful air compressor in the world appears to be 28 mW in power consumption! - not output. Secondly, how are you going to look for leaks in that thing? Also any rupture in the line will release the equivalent energy of many kilograms of TNT. How do I power my TV with compressed air, do I have to have a generator in my house? If so, you've just lost a ton of efficiency.

mleonhard 6y ago
About 5% of the energy is lost in transmitting power via electricity from generator plants to consumers [0]. Losses in a compressed air energy distribution pipeline would primarily come from friction between the moving air and the walls of the pipeline. Fortunately, we can increase the pipe size to reduce losses from friction. This is because friction increases linearly with pipe diameter, while flow increases quadratically [1]. Electrical power transmission requires large amounts of land. The towers and lines are hazards to aircraft. They are fragile infrastructure sitting out in the open. They start wildfires. Compressed air using buried pipelines has none of these problems. Air streams out of a broken pipe. It emerges from the pipe at high pressure (100 ATM?) and then expands until reaching local pressure (1 ATM). Its flow rate is limited by friction with the pipe wall and cannot be instantaneous. An entire section of pipe will take several seconds or minutes to empty. By comparison, a TNT explosion produces a small amount of 1-billion-ATM gas which expands instantly in one big burst. A broken pipeline is more like a rocket engine than a TNT explosion. How to detect and find leaks? Listen for the sound? Fortunately, compressed air leaks pose no danger of explosion or asphyxiation. Refrigerators can run on compressed air directly and very efficiently. A TV would need a small electricity generator powered by compressed air. The generator could be noisy, so it would probably be in another room or outside the home. The generator could cool your home in summer. To be efficient in winter, it could use some buried pipes to draw heat from the ground. Coal-powered and natural-gas power plants are essentially electricity generators powered by compressed air (actually steam). They are adiabatic engines and have the same efficiency problems as a small generator in your home. -- [0] https://www.eia.gov/tools/faqs/faq.php?id=105&t=3 https://www.eia.gov/tools/faqs/faq.php?id=105&t=3 [1] https://www.fluidmechanics.co.uk/hydraulic-calculations/pipeline-flow-2/ https://www.fluidmechanics.co.uk/hydraulic-calculations/pipe...

dredmorbius 6y ago

Hydraulic power distribution systems did and do exist. Your dentist and auto mechanic both very likely have one based on compressed air, and they're popular among certain Amish for shop power. Large-scale systems were built in the 19th century, especially in ports, where large intermittent loads were required, especially for lifting and operating canal locks. Disadvantages include size, limited range (up to several kilometres, but generally far less) leaks, limited capacity (high applied force but limited energy storage), controls, etc. Electric power distribution is the diect analogue of such systems, and is in virtually all regards superior, more flexible, cheaper, and more readily and precisely controlled, though hydraulic power distribution existed in London, England, as late as 1977. https://en.wikipedia.org/wiki/Hydraulic_power_network https://en.wikipedia.org/wiki/Hydraulic_power_network

flyinghamster 6y ago

When the original Niagara Falls power station was in its planning stages, the planners were uncertain on how they would distribute power, and were considering using compressed air before they decided to generate electricity instead. Unfortunately, they specified turbines that operated at 250 RPM, making it impractical to directly produce 60 Hz AC, or 30 Hz for that matter, which would have made frequency converters relatively cheap. Instead, 25 Hz became a North American standard for industrial power, and a few legacy customers remained as late as 2006. [0] Much of Amtrak's Northeast Corridor, and SEPTA's rail network in the Philadelphia area, still use 25 Hz for traction power, provided from converters or from a few hydroelectric plants that have 25 Hz generators. [0] https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948 https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948

KSteffensen 6y ago

Yes, apparently that has been done. https://www.lowtechmagazine.com/2018/05/history-and-future-of-the-compressed-air-economy.html https://www.lowtechmagazine.com/2018/05/history-and-future-o...

mleonhard 6y ago
Thanks for sharing that article. I think the most promising application of distributed compressed air is in refrigeration, especially if the power source is not an adiabatic process.