# Great news for EV / Fuel cell users



## Twilly (Jan 22, 2008)

Looks like MIT has developed "photosynthsis" like solar panels...

http://web.mit.edu/newsoffice/2008/oxygen-0731.html


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## xrotaryguy (Jul 26, 2007)

People have been making hydrogen from solar for years. The problem was not that it could not be done, but rather that it could not be done efficiently. The article says that the process is efficient, but then lots of people say that hydrogen is efficient when the opposite is true. 

The more efficient systems use photo voltaic cells to produce electricity and then the electricity is utilized in an electrolyzer. The electrolyzer is generally only 40% efficient, and the solar cells are generally less than 40% efficient (source). The net result is a process that is less than 16% efficient. Additionally, the hydrogen needs to be compressed into a storage tank. Storage tanks generally hold hydrogen at 3,000 psi or more. Compressing a gas to 3,000 psi is not an efficient process. In the end, the efficiency is probably less than 12%.

Researchers have been working on solar cells that convert water into oxygen and hydrogen withing the solar cell itself, but those systems are as of yet less efficient than the system described above. 

These systems are less efficient than burning gasoline in a piston engine. Heck, the motor in my 30-year-old Rx4 is more efficient. By the way, my Rx4 makes less than 100 hp and gets about 16 mpg. It also smokes a lot. Fun 

The solar generation plant that is being built south of phoenix stores energy in a sodium deposit in the form of heat. Some utilities store energy by pumping water up hill. If electric cars become as prominent as I think they will, then EVs will likely become the next municipal energy storage system.

I doubt that hydrogen will ever have a chance.


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