Friday, June 17, 2011

Major Advancement in Hydrogen Production

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Recently, I read about two major scientific advancements in the field of alternative fuels. The first involved the production of hydrogen, and the other is a major breakthrough in the production of cellulosic Ethanol. In this post, I’ll talk about the hydrogen production breakthrough.
Hydrogen Filling Station, Iceland.
By Jóhann Heiðar Árnason (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons
Others have already demonstrated “artificial photosynthesis” where light is used to cleave water into hydrogen from oxygen. A so called hydrogen economy would be ideal because its main byproduct would be the production of water vapor as opposed to carbon dioxide or particulate pollution. Artificial photosynthesis would allow for the cheap production of hydrogen and is one part of many missing parts in converting into a hydrogen based economy. (Other problems include how to store hydrogen effectively, how to transport it and how to retrofit the existing infrastructure, including gas stations and cars.)

One of the major drawbacks with producing hydrogen from water is up till recently, these processes required fresh water. Unfortunately, we live in an era where there are many competing demands for an increasingly limited supply of fresh water. An increasing human population, the challenges of feeding that population and improving standards of living have all increased demands for fresh water. The ability to use relatively unlimited supplies of sea water would reduce growing pressures on fresh water supplies.

A team led by Dr Daniel Nocera of MIT previously showed that they could utilize a Cobalt-Phosphate (Co-Pi) catalyst to function similarly to the Oxygen Evolving Complex of plants, and that they could use this in both fresh and sea water. Furthermore the deposition of Co-Pi on various semiconductor materials increases the efficiency of the system.

Silicon is one of the most abundant elements on earth, and as anyone with a solar panel on their roof can tell you, silicon is effective at absorbing light energy. In fact, the artificial leaf has shown that silicon immersed in water and exposed to sunlight will split water. However, until recently the main problem with using silicon to split water has been that the very oxygen released by water splitting would react with the silicon and over time the silicon would lose its effectiveness.

In a paper published in the Proceedings of the National Academy of Sciences, Dr Nocera reports that by combining the CoPi catalyst and a silicon based solar cell he was able to make hydrogen and reduce silicon oxidation using sea water. The next challenge is to scale this up. Dr Nocera has previously announced a deal with the Indian mega corporation Tata Group to build a large proof of concept reactor.

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