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article imageNew steps for low cost energy generation

By Tim Sandle     Oct 5, 2016 in Science
Physicists have taken the first steps of generating lower cost ‘green’ electricity through a combination of concentrating solar power and thermoelectric materials.
The experiments have taken place at University of Houston and Massachusetts Institute of Technology, and the aim was to test out alternative solar energy technology. This consisted of concentrating solar power (the conversion of light into heat, and from heat electricity) together with segmented thermoelectric legs. The ‘legs’ are composed of two different thermoelectric materials working across different temperature ranges.
The efficiency of the process was boosted by the use of optical concentrators designed to increase the heat and improve the energy density. This was achieved by using two compounds: skudderudite (a cobalt arsenide mineral that has variable amounts of nickel and iron) for the top half of the legs, and bismuth telluride for the lower half (importantly each compound functions at a different temperature.) These are both types of thermoelectric materials. They function to produce electricity by directing the flow of heat current from a warmer area to a cooler area.
The study is not intended to come up with a system that can replace large-scale power plants but rather something that can be used in isolated area that are connected to a main electrical grid.
This was a proof-of-concept study to evaluate if the process is feasible. This consisted of constructing a prototype device that measures the efficiency of the optical concentration. The outcome was an efficiency rating of 7.4 percent. Research projections suggest that an efficiency of a round 10 percent is possible. Given the positive outcome a larger study will now proceed.
The lead researcher Dr. Zhifeng Ren told Controlled Environments magazine: “Our work suggests that concentrating STEGs (solar thermoelectric generators) have the potential to become a promising alternative energy technology.”
As well as generating electricity, a secondary function is to produce hot water. The experimental results are published in the journal Nature Energy. The research paper is titled “Concentrating solar thermoelectric generators with a peak efficiency of 7.4%”
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