Sunlight turns seawater into fuel
TUT brings to the Solarogenix project its recognized expertise in the area of ultrafast spectroscopy. Professor Lemmetyinen’s research group will create computational models of photoelectrochemical water splitting as more detailed measurement data becomes available.
Hydrogen has been hailed as a sustainable alternative to fossil fuels. The world’s oceans are an inexhaustible source of hydrogen, but the process of splitting water into hydrogen and oxygen is still too expensive to scale up. The answer may lie in sunlight.
Researchers at TUT are currently taking part in a three-year EU project that aims to demonstrate the feasibility of pilot-scale hydrogen production from water and natural light.
In addition to TUT’s Supramolecular Photochemistry Research Group, the Solarogenix project brings together six universities and research institutions from Germany, Poland, Switzerland, Italy and Spain.
Part of everyday life in a few years’ time
The most common method of hydrogen production in use today is steam methane reforming, which is carried out at temperatures of 800–1,000 degrees Celsius and pressures of 10–50 atmospheres. The fertilizer industry remains the largest consumer of hydrogen in the world, but the petroleum industry has become a close second.
“The industrial-scale production of solar water-splitting cells is expected to begin in the next 5−7 years,” says Professor Helge Lemmetyinen from the Department of Chemistry and Bioengineering at TUT.
“This isn’t a case of unfounded optimism, as the technology is ready for large-scale commercialization. We only need to find the ideal catalyst to speed up the chemical reactions.”
The industrial-scale production of solar water-splitting cells is expected to begin in the next 5−7 years.
Hydrogen is easy to store and transport
The sunlight-induced reaction that decomposes water into its constituent hydrogen and oxygen molecules has been known for more than four decades, but it has taken this long for the technology to catch up. Helge Lemmetyinen says that photoelectrochemical hydrogen production is now technically feasible, owing to the remarkable progress that has been made in developing electrochemical measurement techniques and new methods for controlling the properties of materials.
Lemmetyinen estimates that the sun will become the world’s dominant source of energy in the next 20–30 years. The use of solar power has soared in recent years: the global installation of new solar PV capacity equalled the output of about 15 nuclear power plants in 2013.
In contrast to solar power, hydrogen can be stored. It can also be transported as easily as natural gas.
World-class measurement expertise
The industrial partners involved in the Solarogenix project include Siemens and Sachtleben, a German company that is counted among the world’s leading producers of titanium dioxide.
“We’re studying the properties of photoactive materials that are capable of oxidizing water to generate oxygen. As the electrons travel to the counter electrode, they reduce water to form hydrogen,” explains Project Manager Kimmo Kaunisto.
The Swiss and Italian partners are mainly responsible for the development of metallic materials and semiconductors that differ in terms of their chemical composition, crystal structure and surface properties.
TUT’s role in the project is to determine the immediate reactions that occur when a beam of light hits the surface of an electrode. The researchers are aiming to achieve an efficiency rate of 5 per cent, meaning that for every 100 photons absorbed, five hydrogen molecules are produced. The phenomena take place at the interface between electrodes and water on a time scale ranging from less than a picosecond – or less than one millionth of one millionth of a second – to thousandths of a second.
“The faster the electrons flow between the electrode and water, the more powerful the reaction is likely to be,” says Helge Lemmetyinen.