Jones Beene's excellent treatise on Global Warming is worthy of praise. A Liquid Nitrogen fuel economy (as opposed to hydrogen) for "Cryocars" and other LN2-powered vehicles ranging from scooters to mail trucks would concurrently offer a way to extract CO2 and particulate pollutants from the atmosphere.
LN2-powered vehicles function well at 60 below zero and even better at 100 degrees above (offering great air conditioning to boot). Apparently the effort in this direction (University of Washington) was quashed before it got beyond preliminary trials: http://www.aa.washington.edu/AERP/CRYOCAR/CryoCar.htm "Researchers at the University of Washington are developing a new zero-emission automobile propulsion concept that uses liquid nitrogen as the fuel. The principle of operation is like that of a steam engine, except there is no combustion involved. Instead, liquid nitrogen at �320� F (�196� C) is pressurized and then vaporized in a heat exchanger by the ambient temperature of the surrounding air. This heat exchanger is like the radiator of a car but instead of using air to cool water, it uses air to heat and boil liquid nitrogen. The resulting high-pressure nitrogen gas is fed to an engine that operates like a reciprocating steam engine, converting pressure to mechanical power. The only exhaust is nitrogen, which is the major constituent of our atmosphere" "As with all alternative energy storage media, the energy density (W-hr/kg) of liquid nitrogen is relatively low when compared to gasoline but better than that of readily available battery systems. Studies indicate that liquid nitrogen automobiles will have significant performance and environmental advantages over electric vehicles. A liquid nitrogen car with a 60-gallon tank will have a potential range of up to 200 miles, or more than twice that of a typical electric car." Frederick.
