When is a Gas,not a gas?


#1

Just wondering Folks,have we had the discussion about the pros and cons of cyrogenic gases as an energy storage medium for cars or anything else for that matter?(sure would make AC easy)-Kevin


#2
When is a Gas,not a gas?

When it’s a liquid or solid? Plasma?


#3

Do a search for “LNG”, there was a recent discussion with comments about natural gas for trucks.


#4

Cryogenic gas as an energy storage media? From where would come the energy to keep it liquid?
Sounds counterproductive to me. Is this something under serious study? Got a link?


#5

Here’s the other discussion, includes LNG:
community.cartalk.com/discussion/2298017/lpg-cars-fuel-in-america/p1

So yes, for long haul trucking LNG is being used.

As for ‘making AC easy’, it already is: a liquid/gas cycling system.


#6

Actually it wouldnt be around long,I was just wondering how much energy you could store in a cyrogenic liquid(because spills wouldnt be around long and there were serious proposals for compressed air energy storage) Well if the containment vessel were strong enough,I suppose you could keep it liquid a long time,but we are talking enormous pressures and a rarified high temperture gas like a plasma probaly wouldnt store much energy at normal pressures-Kevin


#7

It’s good but you can’t leave it unvented or the pressure would keep on building. You don’t want the final tank to pop. There is some work involved with mass production of cryogenic gases. You have to pressurize a big container of the gas, cool it down a lot and release pressure until the gas liquefies. Releasing the pressure causes the gas to get even colder which is the final step and causes the gas to turn into liquid.

If you get cold enough with carbon dioxide, you can make dry ice.


#8

Thanks@PDV,I guess I was thinking the spring effect,does dry ice have any potential then?The solid form is fairly stable as long as cold temps are maintained,I’m pretty sure that you cant get more out of a reaction or vessel,then you put in it(thats why “Tick Tock” couldnt wind himself up) but maybe as a matter of effiecency it would make something very wastefree,got to be a better method to store power then Hydrocarbon bonds-Kevin


#9

Liquid hydrocarbons are some of the most energy dense things out there.

Not sure what you mean by spring effect.


#10

Spring in my terminology,is something under tension or stress or compression its a crude method for storing energy,in gases its the work that compressed gases can perform when allowed to expand to ambient or natural state,mechanically it can the be spring that powers a watch or the CO2 powered pellet gun,eg;-Kevin


#11

An ICE still needs a fuel to oxidize. Liquefying methane and storing it at a higher than normal pressure (about 100 psi) only allows you to store more of it that in a CNG system at 3600 psi. CNG requires a cold temperature to remain liquid so it is stored in a big container with a vacuum jacket; like a thermos bottle. As the CNG vaporizes, pressure increases, which leads to more vaporization. An interesting feature of CNG storage tanks ofr vehicles is that they are automatically vented to maintain proper operating pressure. This means you can’t park them in a garage without providing an exhaust system to vent the evaporated methane out of the garage. Basically, you just park on the street.


#12

Here’s my “kevin-mobile”: You drive up to an “air station” and fill your cryogenic tank in your car with liquefied air. To go, you push the throttle and the liquid air is metered through an air-exchanger to heat and vaporize it to, say, 600(?)psi which can easily run an appropriately designed air engine. This would technically work, but what is the energy balance and economics?


#13

Actually ,I wasnt referring to combustion(maybe something along the line of a force accumulator-Kevin


#14

If you want to understand why gasoline is such a good fuel for cars, take a look at this discussion of ‘energy density’:

For example, a pound of gasoline has the same amount of energy as about 10 pounds of TNT, or about 100 pounds of lithium ion batteries…


#15

It takes a lot of energy to compress methane to 3600 psi. Why not use a steam engine style decompressor to recover most of the energy used to compress it as well as using the methane for fuel.


#16

That is wy LNG is used instead of CNG. Once cooled, it continues to cool itself as long as the pressure does not increase. But you have to vent the boil-off if it is not burned.


#17

“Actually ,I wasnt referring to combustion…”

Neither am I. I was referring to a pneumatic engine like on the Peugeot “air car.”


#18

Why not combine a pneumatic engine with an ICE? That way we can use CNG/LNG as a fuel as well as recovering the energy needed to compress or liquefy it.

Natural gas pipeline companies are already expanding natural gas by running it through pneumatic turbines which in turn generate electricity instead of simply lowering the pressure for distribution by letting it go through a simple expansion valve, in turn, recovering some of the energy used at the other end of the pipeline in compressing the gas.


#19

Ii read recently that Toyota is developing an LNG car. According to the article, Toyota considers LNG to be a likely fuel in future vehicles. By “likely” I understood that they had a higher confidence level in it being a fuel than just “viable”. The seem to believe LNG cars will be common. The article didn’t specify, but they might be looking at the fleet market. There are already successful LNG fleets being used by municipalities.


#20

Not LNG, hydrogen fuel cell, I think, from Toyota.