An Einstein fridge that can run without power?

Scientists at Oxford University are working on a 1930 invention by Albert Einstein to develop an environmentally friendly refrigerator which they claim will run without electricity.  

Previous researches have suggested that modern fridges emit greenhouse gases called freons and as a result damage the environment. Now the Oxford team is developing appliances that can work without electricity and thereby reduce the gases.  

In fact, they have already completed a prototype of a type of fridge patented in 1930 by Einstein and his colleague, the Hungarian physicist Leo Szilard, 'The Observer' reported.  The design was partly used in the first domestic refrigerators before more efficient compressors became popular in the 1950s. It avoids the need for freons and instead uses ammonia, butane and water and takes advantage of the fact that liquids boil at lower temperatures when air pressure is lower.  

"If you go to the top of Mount Everest, water boils at a much lower temperature than it does when you're at sea level and that's because the pressure is much lower up there," lead scientist Malcolm McCulloch said.  

At one side is the evaporator, a flask that contains butane. "If you introduce a new vapour above the butane, the liquid boiling temperature decreases and, as it boils off, it takes energy from the surroundings to do so. That's what makes it cold," he said.  Pressurised gas fridges based around Einstein's design were replaced by freon-compressor fridges partly as they were not very efficient.  

But, according to the British scientists, by tweaking the design and replacing the types of gases used it would be possible to quadruple the efficiency of the refrigerators that could well be the GenNext appliances.