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Here in the arid, expansive American West, we're are all too aware of two of the most pressing problems confronting humanity worldwide: energy and water. Both are predicted to become increasingly scarce and expensive: many areas are already experiencing shortages of clean, drinkable water, and fossil fuels' unacceptable environmental unfriendliness makes their continued use untenable.
But a brace of papers published recently in the journal Science may cast a light into those dark, frightening tunnels -- and may help alleviate both problems at the same time.
The first paper, authored by Matthew Kanan and Daniel Nocera breaks the exciting news of a more efficient catalyst for hydrolysis - the splitting of water into hydrogen and oxygen. The use of cobalt and phosphorous, two cheap and abundant elements, as the catalyst for the reaction would make a commercialized hydrolyzer very cheap and very efficient -- perhaps so efficient that solar energy could plausibly be used to drive the reaction. The resulting hydrogen would be usable as a carbon-free fuel. Its cheap and efficient generation go a long way to address many criticisms of hydrogen fuel -- which typically requires so much more energy to generate than is eventually released by a fuel cell that renewable energy is insufficient to produce it in relevant volumes.
Unfortunately, even if hydrogen can be created cheaply and with renewable energy, the fuel cells required to turn it into electricity are often prohibitively expensive because they rely on platinum, an expensive metal. A fuel cell to power a vehicle, for example, can be more expensive than the entire rest of the car. Another paper, in the same issue of Science, may address this problem -- by using a nonmetal catalyst called PEDOT in lieu of platinum.
Bjorn Winther-Jensen and his colleagues at Monash University in Australia note that, at this time, their technology only replaces the cathode of the fuel cell, and that the anode still requires platinum -- but hold out the strong possibility that further development may solve this issue as well. They also mention that with further development, these technologies could be paired -- to create an exceptionally inexpensive source of purified water.
A cheap, efficient phosphorous/cobalt electrolysis system could use solar energy to create hydrogen, which might then be fed into a likewise cheap platinum-free PEDOT fuel cell. The output of this system would be pure water, requiring less energy than current desalinization systems, and electricity -- which could be fed back into the system to improve its efficiency. More development -- to confirm that the electrolysis system can be used with seawater, and to remove the platinum from the PEDOT cell's anode -- is required, but indications are that those hurdles are not insurmountable. |