On Jan 27, 2009, at 9:57 AM, Jed Rothwell wrote:
By the way, LNG powered automobiles are common in Japan, especially
taxies. LNG is liquid at room temperature.
- Jed
You must be thinking of heavies like propane. Even at 3000 psi
natural gas is not a liquid at room temperature. See:
http://en.wikipedia.org/wiki/Compressed_natural_gas
"CNG's volumetric energy density is estimated to be 42% of LNG's
(because it is not liquefied), and 25% of diesel's."
LNG at atmospheric pressure, or slightly above, boils at about −260
°F. See:
http://en.wikipedia.org/wiki/Liquefied_natural_gas
"LNG is principally used for transporting natural gas to markets,
where it is regasified and distributed as pipeline natural gas. LNG
offers an energy density comparable to petrol and diesel fuels and
produces less pollution, but its relatively high cost of production
and the need to store it in expensive cryogenic tanks have prevented
its widespread use in commercial applications. It can be used in
natural gas vehicles, although it is more common to design vehicles
to use compressed natural gas."
I think an LNG trucking fleet is very feasible, but the trucks would
probably best be implemented as dual fuel, because LNG does not store
well in truck sized containers, and continually boils off creating a
hazard for statinary trucks. Excess LNG would have to be offloaded
before a truck were brought out of service for a while, due both
safety and economic considerations.
The following energy density chart is quite amazing:
http://en.wikipedia.org/wiki/File:Energy_density.svg
This shows the huge potential for silicon based fuels, like silane,
because they have high energy density and do not produce CO2 or any
gas byproducts from oxidation. I think this kind of fuel might best
be used in external combustion engines, which are also easily made
multi-fuel, even solid fueled. The potential of silicon compounds has
long been recognized by some, but apparently is not well known in the
energy industry. See:
http://www.dbresearch.com/PROD/DBR_INTERNET_EN-PROD/
PROD0000000000079095.pdf
http://tinyurl.com/cuaryk
As I mentioned here:
http://www.mtaonline.net/~hheffner/BigPicture.pdf
Silane (SiH4), the silicon equivalent to natural gas, can clearly be
produced using hydrogen feed stock created using solar power, and is
environmentally friendly, but it has all the shipping and storage
problems associated with natural gas. Tetrasilane (Si4H10) boils at
84.3 deg. C. so can be shipped and stored as a liquid. One of the
products of tetrasilane combustion, SiO2, is a solid and is valuable
for many things, including the making of solar cells. The other
principle product of tetrasilane combustion is water.
It seems to me likely a high energy density means of storing hydrogen
will be found before conversion to silicon based energy storage
occurs. If a Manhattan style energy research program is launched then
clearly silicon and ammonia based energy storage and transportation
means should still be evaluated.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
