Thermochemical Water Splitting as a Means for a Clean Energy Source
Since the beginning of the Industrial Revolution fossil fuels and oil have been our main sources of energy, and until recently that has been acceptable. After the oil crisis in the 1970’s, people began to grow concerned about the future state of our energy supplies. That culminating concern combined with the new concern of human initiated alteration of the atmospheric composition, encouraged scientists to try and come up with a new source of clean fuel that produced no emissions. Thermochemical Water Splitting was first conceptualized in the mid 1960’s1. At the time is wasn’t necessary because oil was so cheap there was no need for an alternative, so it faded away. The hunt for clean energy source led to a revitalization of the thermochemical water splitting system. A system that if fully developed, could efficiently produce hydrogen and oxygen fuel without the harmful emissions of gasoline and coal2.
Thermochemical Water Splitting
Thermochemical water splitting is the process of converting water into hydrogen and oxygen through a series of chemical reactions initiated by extreme heat3. This can be done using either nuclear power or concentrated solar power as the heat source. The nuclear method uses the heat generated from a nuclear reactor to start the chemical reactions. There is a large number of slightly different nuclear methods being used, but the most popular nuclear method is the Sulfur-Iodine (SI) cycle2. The SI cycle is made up of three chemical reactions that result in the dissociation of water molecules. Direct thermolysis of water requires temperatures exceeding 2500 degrees Celsius3, but the nuclear thermochemical systems can accomplish the same task at significantly lower temperatures. The SI cycle in particular can operate efficiently and safely at only 1000 degrees Celsius2. A closed-loop operation can be used to recycle all of the materials aside from the water, hydrogen, and oxygen to continue the process without wasting anything2. Thermochemical systems can have as much as a 90% yield of hydrogen and oxygen evolution, and they also show no signs of deactivation after multiple cycles1. The evidence supports nuclear thermochemical systems as a promising method of clean energy for the future.
The concentrated solar power method works very similarly to the nuclear method. The only difference is how the heat is generated. In the nuclear method the heat is a byproduct of the chemical reaction created by the radioactive material, but in the solar method the heat comes from the sun. First the device focuses sunlight using concentrating systems which creates a concentration ratio equal to 5,000 suns. The solar radiation is then put into thermal reservoirs at temperatures around 1700 degrees Celsius8. From there the process is very similar to the nuclear method, where the heat is used to spur on chemical reactions that split the H2O (water) molecules...