Liquefied Air Could Power Cars and Store Energy from Sun and Wind

[leveymg]

15. That doesn't answer the question: how much to chill down to -200 degrees?

Come on, let's play the game, give it try.

Here's an answer: Wiki Liquid Nitrogen Vehicle

Liquid nitrogen production is an energy-intensive process. Currently practical refrigeration plants producing a few tons/day of liquid nitrogen operate at about 50% of Carnot efficiency.[6] Currently surplus liquid nitrogen is produced as a byproduct in the production of liquid oxygen.[4]

So, if this is accurate, how good is 50% Carnot efficiency? A lot better than current steam engines, gas-fueled turbine steam generators, and internal combustion engines, according to another source: http://web.mit.edu/newsoffice/2010/explained-carnot-0519.html

At the time of Carnot’s work, the best steam engines in the world had an overall efficiency of only about 3 percent. Today, conventional steam engines can reach efficiencies of 25 percent, and gas-fired turbine steam generators in power plants can reach 40 percent or more — compared to a Carnot Limit, depending on the exact heat differences in such plants, of about 51 percent. Today’s car engines have efficiencies of 20 percent or less, compared to their Carnot Limit of 37 percent.

See how easy that can be? However, I wouldn't mortgage the house on the first estimate of 50% efficiency, as that's right at the theoretical limit, and apparently there is no mass production of liquid nitrogen.

All I wanted was an answer, not an argument.