We've known since before 1800 that electric current can split water molecules into their component elements hydrogen and oxygen, but due to that pesky Second Law of Thermodynamics the process always uses more energy than the resulting hydrogen fuel can provide. The Santa Barbara firm HyperSolar isn't saying they've found a way around the immutable laws of physics, but they do claim they may have found a way to use sunlight to generate potentially cheap hydrogen from polluted water.
HyperSolar's technique was inspired by a similar process that takes place every day: photosyntheses. Plant cells use sunlight to split water, then immediately combine the resulting hydrogen with carbon from atmospheric carbon dioxide. That process transforms sunlight into the chemical energy we all use to survive, not to mention the oxygen we breathe. Scientists estimate that the Earth's plants use 130 terawatts of solar energy to split water, and it's all done at a microscopic scale.
HyperSolar says its staff have developed a kind of artificial photosyntheses, in which microscopic structures use solar power to split water. Instead of folding the resulting hydrogen into hydrocarbons, though, the gas can then be captured and used as carbon-free fuel -- or for whatever other use you might have for hydrogen.
HyperSolar's technology involves solar panels on a nano scale. Microscopic pieces of PV material are fitted into what the company calls "nano-size self-contained photoelectrochemical particles," which are then themselves incorporated into extremely small, coated "electrolysis particles" that will create hydrogen when submerged in sunlight water.
HyperSolar just completed a "proof-of-concept" trial run in the California desert, using their nanotechnological products in an appealingly low-tech way. In the words of a press release the firm sent out yesterday:
In this demonstration, the HyperSolar particles were submerged in a low cost plastic bag reactor filled with wastewater obtained from the Salton Sea in California. During the day, water molecules were split into hydrogen and oxygen gas, which filled up the plastic bag. Then the hydrogen gas was easily extracted from the bag, stored and used in a conventional fuel cell that converted the hydrogen into electricity on demand. Unlike conventional solar panel systems that only produce electricity when the sun is shining, a renewable hydrogen solar power system creates and stores hydrogen during the day and produces electricity day or night on an as needed basis.
Of course, the product's viability will depend in part on the amount of energy it takes to create the nanoparticle-sized reactors. But the prospect of using wastewater and sunlight to create hydrogen fuel is an appealing one -- especially as the oxygen released in electrolysis could be used to kill biological contaminants in wastewater such as treated sewage.