From Wiki wrote:Worldwide, there were 12.6 million natural gas vehicles by 2010, up 11.6% over the previous year
CNG is made by compressing natural gas, to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 200–248 bar (2900–3600 psi), usually in cylindrical or spherical shapes.
There is an ISO standard for such storage tanks, ISO 11439. One might surmise that there has been some solid engineering behind the setting up of that standard.
SG wrote:At CNG fueling stations the gas is compressed before being provided to vehicles at 3000 to 3600 pounds per square inch (psi). Stations can deliver a “fast fill” to vehicles in minutes or, using a “slow fill” strategy, in a few hours to overnight.
In the US natural gas vehicles are subjected to the same federal government crash tests as other vehicles. CNG vehicle fuel systems must meet Federal Motor Vehicle Safety Standards 303 and 304. Natural gas cylinders are much thicker and stronger than gasoline or diesel tanks. Cylinders are designed not to rupture when fully fueled over six times a day, 365 days a year.
CNG vehicles have been used in the US since the early 1980s. Yet there has been only one fatality in the US caused by an CNGV fueling system failure in all that time. Insurance companies consider CNG fuelled vehicles lower risk than gasoline fuelled vehicles.
The CNG experience is directly applicable to compressed air engines, the tanks, pressures, re-fulling systems and infrastructure are all similar EXCEPT that CNG is volatile.
Atmospheric engines “suck” the piston up in the cylinder instead of pushing it down. The clever part of the French motor is that it takes advantage of the low temperature decompressed air to extract energy from air at the ambient temp.
The ignorance and prejudice on this Fred is remarkable only for it's similarity to discussions of atmospheric science
Compressed air may well be the truly green solution 'air heads' have been seeking for energy storage on a local level, imagine using sun/wind/water power to compress air into local storage tanks, overnight and/or when there's no wind the process could be reversed via the Negre atmospheric engine to GENERATE electricity.
Far less polluting than the manufacture, maintenance and disposal of batteries, however efficient.