MIT chemists report storing method of solar power

by William Atkins

Saturday, 02 August 2008

Page 1 of 2 ! The two Massachusetts Institute of Technology chemists have discovered a better way to extract hydrogen from water, and to store hydrogen and oxygen in fuel cells when the Sun isn’t shining, using an improved technique called electrolysis. The two American chemists are Matthew W. Kanan and Daniel G. Nocera, both from the Department of Chemistry at Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A. Kanan and Nocera use a new catalyst to produce oxygen, which is used in fuel cells (along with hydrogen) that are used to generate electricity. Their new method provides a way to store oxygen and hydrogen. It also is a more efficient way to generate electricity. Nocers states, “If you can only have energy when the sun is shining, you're in deep trouble. And that's why, in my opinion, photovoltaics haven't penetrated the market. If I could provide a storage mechanism, then I make energy 24/7 and then we can start talking about solar." [Reuters: "MIT develops way to bank solar energy at home”] According to Nocera, as reported in the Science News article (subscription required) “Small steps toward big energy gains,” “… the method should make it feasible to store large amounts of energy obtained from renewable sources that are not available 24/7, such as solar or wind. The hydrogen could also be used as a clean fuel for cars, whose exhaust would be just water vapor.” He adds, "I can turn sunlight into a chemical fuel, now I can use photovoltaics at night.” [Reuters] The electrolysis method extracts hydrogen from water by using an electric current to split water (H2O) into hydrogen (H) and oxygen (O) The method of electrolysis uses an electric current running between two electrodes immersed in water. One electrode is coated with a catalysis, which helps to break up water molecules into oxygen molecules, electrons, and protons (hydrogen nuclei). The new catalyst the MIT team uses is cobalt, along with phosphate-buffered water, on an indium tin oxide electrode. This new catalyst produces oxygen using about 90% less electricity than traditional methods that use platinum, which is in small supply and, thus very expensive. To produce hydrogen nuclei, a platinum catalyst is still used, but in smaller quantities. Cobalt costs about US$2 per ounce and phosphate costs only about one nickel (US$0.05 ) per ounce, while platinum costs over US$1,700 per ounce. The cobalt-phosphate electrode sends the electrons through a wire to the other electrode. The protons move through the water to the other electrode. At this second electrode, the protons and electrons recombine to form hydrogen gas. They are then made into water with the use of oxygen, which produces an electrical current. Please read on. << First page <   1 2 Next page > Last page - Post your comment >>

 

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