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Sandia labs - hydrogen from water using solar power
Production, Nov 25 2009 (The Hydrogen Journal)
- Scientists at Sandia National Laboratories in New Mexico, have developed a machine which can turn water into hydrogen, using concentrated solar energy, according to MIT's Technology Review.
It can also be used to convert carbon dioxide into carbon monoxide. The carbon monoxide could then be combined with hydrogen to make 'syngas', which could be used to make transportation fuels.
A hand built demonstration machine has been built in the laboratory.
The challenge now is to improve the efficiency of the system, with a short term goal to get the system to an efficiency of "a few percent", researchers say. This compares to a theoretical maximum efficiency of photosynthesis of 5 per cent, and a usual efficiency of 1 per cent - so the system would have an efficiency much higher than natural photosynthesis.
with an estimated 15-20 years befroe the technology is ready for commercialisation. Scientists hope to develop a new prototype every 3 years, each time getting an improvement in efficiency and a decrease in cost.
The system uses concentrated solar power to trigger a chemical reaction in an iron rich composite material, which gives up an oxygen molecule when exposed to extreme heat.
Much of the development work will be in making new ceramic composites which can release oxygen molecules at lower temperatures.
The machine has two chambers, one hot and the other cool. Between the chambers are 14 rings like frisbees, rotating at one revolution per minute. The outer edge of each ring has an iron oxide composite on it, supported by a zirconium matrix.
Using a solar concentrator, the inside of the hot chamber is heated to 1,500 degrees C. This causes the iron oxide on one side of the ring to give up oxygen molecules.
As this side of the ring slowly moves to the other chamber, it cools down, and reacts with water or carbon dioxide being pumped in. The iron oxide will then steal oxygen molecules from the water molecules (leaving hydrogen behind), or steal oxygen from CO2 converting it to carbon monoxide.
