Discovery opens door to efficiently storing and reusing renewable energy (electrolyzing water)

[kristopher]

6. A question for OKSensei

Last edited Thu Mar 28, 2013, 04:53 PM - Edit history (1)

They tout their advantage by saying their catalysts "are 1,000 (of) times cheaper" than those now on the market while being at least as efficient.

What is the current level of round trip efficiency being seen with this process in current products?

ETA: Is this article reasonably accurate?

Electric round-trip efficiency of hydrogen and oxygen-based energy storage
International Journal of Hydrogen Energy (February 2005), 30 (2), pg. 105-111

An electrolyzer and a fuel cell have been integrated in a small-scale stand-alone renewable energy system to demonstrate that hydrogen can be used for long-term stationary energy storage. The economic and environmental performance of such a system is strongly related to the ability of the electrolyzer to convert electrical energy to hydrogen and the ability of the fuel cell to convert hydrogen back to electrical energy, which together define the round-trip efficiency of the hydrogen storage system. One promising way to improve the efficiency as well as to decrease the capital costs of the fuel cell is to recuperate the oxygen from the electrolyzer and use it as the fuel cell oxidant instead of compressed air. This paper presents the modifications made to the system in order to implement oxygen recuperation. The round-trip system efficiency was found to be 18% with oxygen recuperation and 13.5% without it.

http://journals2.scholarsportal.info/details.xqy?uri=/03603199/v30i0002/105_ereohaoes.xml

If this is reasonably accurate it means that this process has very limited use as a storage medium since the electricity it produces would be about 5X the cost of the input energy without yet counting the cost of the system itself.
It seems probable that the technology in batteries for EVs will be more competitive. Of course, efficiency improvements could be in the hydrogen cycle's future, and battery technology may not deliver on the cost reductions that are anticipated. We'll have to wait and see.