Hydrogen is touted to be the fuel of the future, particularly for cars. But a more acccurate view of it is that hydrogen is an energy storage medium. And the most promising form of energy to store using hydrogen is solar energy.
There is a great deal of research going on aimed at developing a solar-driven photoelectrochemical cell – which is a device that converts solar energy into hydrogen. There are various ways to accomplish that feat, but the main challenge is to do it efficiently and to not require the use of exotic, expensive materials.
Researchers at the University of Twente in the Netherlands have recently made significant progress in improving the efficiency of photoelectrochemical technology. Their breakthrough involves the use of silicon microwires less than one tenth of a millimeter long, the tops of which are coated with a catalyst. Light from the sun is collected between the microwires and a chemical reaction takes place on the catalyst at the tips of the microwires, forming hydrogen.
The approach achieved an energy efficiency of 10.8 percent, the highest ever achieved for a silicon-based system. Experts believe that an efficiency of 15% will be required to make the technology economically viable. The researchers think the technology can achieve it.
The potential for a hydrogen economy is predicated on the successful development of economical and environmentally benign ways to make hydrogen. It is certainly possible to get there by using cleanly-produced electricity to run some suitably efficient process that splits water into its component parts. But an integrated device that directly uses the solar energy to produce hydrogen is likely to be the most efficient approach.
Photo, posted August 17, 2009, courtesy of Hiromichi Torihara via Flickr.