One of the very first fuels used by man were trees; thousands of years later it looks like we may be turning back to them to help deal with the future. Small trees that is. Incredibly small in fact.
Developed in the University of California, nano sized trees (that’s 1000,000,000 times smaller than a metre, or to put it into context, 10,000 of these trees could fit on a cross section of a human hair) made from silicon wire and zinc oxide (ergo not of the wood variety) have been shown to split water molecules into their constituent atoms. This is significant as it liberates hydrogen; heralded as the fuel of the future. Pure hydrogen gas doesn’t occur naturally; its low density means it simply rises into the atmosphere, so current methods to obtain it involve electrolysing water, a process requiring an incredible amount of energy which results in the burning of more precious fossil fuels and ultimately, the production of green-house gases. And yet what makes the nanotrees a superior method is that they can use solar energy, mimicking plants, to perform this process.
The very structure of the trees makes them particularly efficient at utilising solar energy; Professor Kenneth Reardon of Colorado State University said, ‘ The tips of the nanotree branches are extremely tiny, the structure provides many more points at which electrical charges, derived from sunlight, can be transferred to water molecules (the fundamental step involved in the splitting of water) with high efficiency ’.
Making them available on a mass scale will inevitably take a good few years however , in the meantime, Professor Wang, who led the team at the University of California, has been tasked with finding an effective way of collecting the hydrogen. In spite of this, it’s truly a momentous step towards a greener future.