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Material advantages of pneumatic Motors

 


Between on premise thermal energy store as in sand batteries and 1000s of kilometers long transmission of electrical energy there is a need for mechanical energy that can be used in mid range(<100 km) from the point of origin. 

Compressed air energy storage fills this need exceedingly well. 


[Generally mechanical energy can’t be transmitted over long distances but with compressed air it's possible to store mechanical energy in the form of pressure and use it later after it has been transmitted over pipes to destination. ]



Precedent for compressed air storage goes back 150 years.During that time 550 kpa of compressed air was used to operate industrial pumps ,printing presses ,handled and household tools. Compressed air was distributed 50 kilometers from production source. 


Presently compressed air systems have been a hit in industrial tools like hammers ,saws, lifts,screwdrivers etc so already we can appreciate its value.


Some areas where we would like to expand the use of compressed air devices


In ceiling fans and hvls(high volume low speed) systems for Air based cooling.


In pumps for water transport in buildings and Municipal pipes


Motors for doing miscellaneous mechanical work


Mills for grinding dispersion stirring


Advantages


Works well with Stirling engines where the engine can power the compressor and provide 1Mpa of compressed air to households enhancing the range of mechanical energy from stored heat. 


Pneumatic Motors can be made entirely from polymers at operating pressures of 10s of MPa but at a temperature range of ~300 degree Celsius. No metals, conductors, composites, required. Full polymer mechanical stack : pipe, tanks ,Motors etc.


It allows us to realize our objective of separation of electrical and mechanical work. All essential mechanical requirements can continue to be met without the need for electricity, while we use electrical energy in things that really need it. 


There is a possibility for using pneumatic machines for generation of electricity as well ,if required, but since electrical energy is good at being transported (negative the major advantage of compressed air) it does not make sense to use compressed air for electrical generation when heat powered Stirling engine /wind /water turbine can do that much more effectively at source.


Compressed devices offer better power density than electrical energy devices. They are lighter and reasonably mechanical efficient at 40 to 60% range. This is decent when entire production ,transmission, consumption of electrical energy is considered.Though it still falls short of thermally generated electrical energy and way below wind energy but there is no need for metals, wires or magnets. Overall operation is simplified. Best of all no need for electronics no ‘smart devices’ simple pure mechanical systems.


Compressed air systems can be used to power lightweight two wheelers like bicycles for short to mid distance transport.Stirling engines have been demonstrated to work for longer distances at better speeds through.


Compressd air systems have the potential to be used for energy storage at megawatt scale.This could be an option for colder regions where wind is plentiful and a compressor can be coupled directly to a turbine rather than going through mechanical - electrical -heat storage cycle. it does not make sense in areas where heat is plenty there direct thermal energy storage is much much better.


Its clear that compressed air systems would work well with external heat engines and extend our possibilities.We will be able to do more things effectively and we will be able to transport mechanical energy at the city level.This could be a big win.


Challenges


Materials for designing compressed air infrastructure and devices


Design of the compressor itself


Design of storage tanks


Design of Motor Parts shafts gears etc




Some questions and notes 


Does a liquid fluid offer any advantage over gaseous fluid? what? tradeoffs?


What would be the efficiency of generation and distribution of compressed air on premise?


Does this design lock in the success of pneumatic systems with polymer technology? How can it be uncoupled? To what extent?


Which motor type is the best fit for table top devices? which is best for larger devices?


Can pneumatic Motors also work as a colloidal mill?


What possibilities might exist for efficiency improvements at device level?


Could compression technology be an area Stirling and pneumatic groups can cooperate?


Could pneumatic devices help in building machines fo

r Air based heat exchangers that can improve the efficiency of SEs?

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