So now that we've determined that -- yes -- we can store solar energy in rust and water, we should probably back up a little bit and explain more about how scientists in Switzerland actually made that happen.
As we said, the device contains an oxide semiconductor and a dye-sensitized solar cell. The oxygen evolution (the process of getting molecular oxygen from a chemical reaction) happens on the rust photo anode (where the current flows in) and the hydrogen evolution happens on the cathode side of the device (where the current flows out). When those reactions occur, the electrons are trapped in the dye-sensitized cell where they create a charge, and the hydrogen can be extracted from water. And voila -- energy is stored.
But as we said, the price, not the process, has long posed the biggest challenge. Instead of using a fancy semiconductor (which initiates the oxygen evolution), the team settled on cheap, easy-to-find rust. Unfortunately, rust also happens to be a pretty terrible semiconductor. Researchers at Israel Institute of Technology (Technion) are also attempting to solve this problem, by creating an ultrathin layer of rust in a solar cell that combines more efficient semiconductor silicon [source: Focus]. Likewise, the rust EPFL researchers use is actually designer iron oxide, with silicon oxide added to it, then painted with a layer of aluminum and cobalt oxide that improve the reaction performance.
This means that scientists have found a way to produce electricity and hydrogen that can be stored for use whenever -- not just when the sun is shining.
Pretty cool, huh? Ponder that while you're mowing the lawn and chugging diet soda.
Author's Note: Can you store solar energy in rust and water?
It's pretty exciting to think that the science of using solar energy -- which has always been branded the Energy of the Clean Future -- is actually making really big strides. And while getting a big picture of the efficiency of it is one thing, it's another for scientists to dedicate themselves to making a cheap version that consumers can actually use. Perhaps the idea will catch on, and I can finally get that car that runs on expired diet soda.
- Focus. "Turning Rust into Gold: Solar Energy Breakthrough." Israel Institute of Technology. Nov. 12, 2012. (Jan. 3, 2013) http://www.focus.technion.ac.il/Feb11/newsStory.asp?id=202
- NLAB Solar. "Dye-sensitized solar cells." NLAB Solar. 2012. (Jan. 3, 2013) http://www.nlabsolar.com/dye-sensitized-solar-cells
- Pousaz, Lionel. "Using rust and water to store solar energy as hydrogen." École Polytechnique Fédérale de Lausanne. Nov. 11, 2012. (Jan. 3, 2013) http://actu.epfl.ch/news/using-rust-and-water-to-store-solar-energy-as-hydr/