Researchers from the Technion-Israel Institute of Technology have developed a bio-photo-electro-chemical (BPEC) cell that produces electricity and hydrogen from water using sunlight, by using a simple membrane extract from spinach leaves. The raw material of the device is water, and its products are electric current, hydrogen and oxygen. The findings were published in the August 23 online issue of Nature Communications.
The extraordinary combination of a human-made BPEC cell and plant membranes, which absorb sunlight and convert it into a flow of electrons with high efficiency, paves the way for the development of new technologies for the creation of clean fuels from renewable sources: water and solar energy.
The basic concept involved in the development of a BPEC cell is based on the naturally occurring process of photosynthesis in plants, in which electrons are driven by light and give rise to storable chemical energetic molecules that act as fuel at the cellular level.
An iron-based compound was added to the solution by researchers, in order to utilize photosynthesis for producing electric-current. The compound mediated the transfer of electrons from biological membranes to the electric circuit. The electric current thus created was then channeled to form hydrogen gas through the addition of electric power from a small photovoltaic cell that absorbed the excess light. This made it possible to convert solar energy into chemical energy that was stored as hydrogen gas formed inside the BPEC cell. This energy could be converted when required into heal and electricity by the burning the hydrogen in the same way hydrocarbon fuels are used.
The interesting part lies in the fact that unlike hydrocarbon fuels, which emit greenhouse gases when burnt (which pollutes and harms the environment), the product of hydrogen combustion is clean water.
Therefore, this is a closed cycle that begins with water and ends with water, allowing the conversion and storage of solar energy in hydrogen gas, which could be a clean and sustainable substitute for hydrocarbon fuel.
The study was conducted by doctoral students Roy I. Pinhassi, Dan Kallmann and Gadiel Saper, under the guidance of Prof. Noam Adir of the Schulich Faculty of Chemistry, Prof. Gadi Schuster of the Faculty of Biology and Prof. Avner Rothschild of the Faculty of Material Science and Engineering.
"The study is unique in that it combines leading experts from three different faculties, namely three disciplines: biology, chemistry and materials engineering," said Prof. Rothschild. "The combination of natural (leaves) and artificial (photovoltaic cell and electronic components), and the need to make these components communicate with each other, are complex engineering challenges that required us to join forces."
Source: American Technion Society