(photo credit: INGIMAGE)
Technion-Israel Institute of Technology researchers have developed a new method for the production of hydrogen from water that uses solar energy in a centralized way at the point of sale, such as a gasoline station for electric cars fueled by the gas.
This eliminates the need for “solar farms” whose hydrogen has to be trucked a long distance, making the process cost effective, safe and efficient.
The study was recently published in Nature Materials, and was led by Avigail Landman, a doctoral student in the Nancy & Stephen Grand Technion Energy Program and Dr. Hen Dotan from the electrochemical materials and devices lab.
Landman is working on her doctorate under the guidance of Prof. Avner Rothschild from the faculty of materials science and engineering, and Prof. Gideon Grader, dean of the faculty of chemical engineering.
Hydrogen is considered one of the most promising energy carriers for vehicles and various other uses because it can be produced from water, so production does not depend on access to non-renewable natural resources.
The use of hydrogen fuel would reduce dependence on fossil fuels such as oil and natural gas, whose availability depends on geographic, political and other factors. Furthermore, unlike diesel and gasoline engines that emit considerable pollution into the air, the only byproduct of hydrogen fuel use is water.
Because of these advantages, many countries, including the US, Germany and Japan, are investing vast sums of money to develop environmentally friendly technologies for hydrogen production.
Currently, most hydrogen is produced from natural gas in a process that emits carbon dioxide into the air. It is also possible to produce hydrogen from water by using electrolysis to split the water molecules into hydrogen and oxygen.
But electricity production itself is an expensive and polluting process, so Technion researchers have been working to develop a hydrogen production method that does not rely on an external power source: a photoelectrochemical (PEC) cell that uses solar energy to split water into hydrogen and oxygen directly.
“According to our cost estimate, our method could successfully compete with existing water splitting methods and serve as a cheap and safe platform for the production of hydrogen,” said Landman.
To do so, the hydrogen and oxygen must be separated; the hydrogen must be collected from millions of PEC cells; and the gas has to be transported to the point of sale.
The Technion team solved these challenges by developing a new method for PEC water splitting where the hydrogen and oxygen are formed in two separate cells – one that produces hydrogen and another that makes oxygen.
In the traditional method, the hydrogen and oxygen are produced within the same cell and separated by a thin membrane that prevents them from intermixing and forming a flammable and explosive mixture.
The new process allows for geographic separation between the solar farm, which consists of millions of PEC cells that exclusively produce oxygen, and the site where hydrogen is produced.
To achieve this, the Technion team used a pair of auxiliary electrodes made of nickel hydroxide, an inexpensive material used in rechargeable batteries, and a metal wire to connect them.