American researchers improve the method of solar storage2018-05-31
Solar energy is an inexhaustible clean energy source, but to make full use of the solar energy, it is necessary to solve the key problem of how to store the solar energy at a lower cost at any time. A team at the Stanford University reported in October 31st that they have improved the method of storing solar energy by breaking water molecules, making the method 30% of its energy efficiency, which is the most efficient of the current similar methods.
The scientific principle of this approach is not complex: first, using a solar cell to decompose water molecules into oxygen and hydrogen, and then release the chemical energy stored in the process as needed, by recombining the generated oxygen and hydrogen to produce water, or in combustion of hydrogen in an internal combustion engine.
This energy storage principle has been put forward, but how to make it an efficient industrial process is a difficult problem. An interdisciplinary team from Stanford University published a paper in the British Journal of nature communication that they made three improvements to the above methods. First of all, the three junction solar cells they use are different from conventional silicon based solar cells. The solar cell, made of 3 uncommon semiconductor materials, can absorb the blue, green and red light of the solar light in turn. The efficiency of the solar energy conversion to electric energy is raised to 39%, while the photoelectric conversion efficiency of the conventional silicon based solar cells is only about 20%.
Secondly, the researchers focused on improving the catalyst used to decompose water molecules, greatly improving the catalytic efficiency. In addition, they combined two same electrolysis devices to react and prepare two times of hydrogen, which used only one electrolyzer before. The experiment shows that the energy storage efficiency of the improved method is 30%, which exceeds 24.4% of the industry's similar methods.
Thomas Jaramilo, an associate professor of chemical engineering and photon science at the Stanford University, said the result is a step closer to the development of a practical and sustainable industrial process that decomposes water molecules into a practical and sustainable industrial process. The next step will continue to study how to achieve similar energy storage efficiency with lower cost materials and devices.