A team of researchers from the Technion Israel Institute of Technology has developed a bio photo electro chemical (BPEC) cell that produces hydrogen and electricity from water using sunlight. They used a simple membrane extract from spinach leaves to achieve this feat. The device produces oxygen, hydrogen and electric current using only water as a raw material.

The device, using a unique combination of plant membranes and a man made BPEC cell, paves the way for the development of new technologies for the manufacture of clean fuels from renewable sources: solar energy and water. It is highly efficient in absorbing sunlight and converting it into a flow of electrons.

In plants, photosynthesis occurs naturally and the process uses light to drive electrons. The electrons produce storable chemical energetic molecules, which are the fuels of all cells in the plant and animal worlds. The researchers based the development of their BPEC cell on this process. To use photosynthesis for producing electric current, the researchers added an iron based composite to the solution. This composite facilitates the transfer of electrons from the biological membranes to the electrical circuit. This enables the formation of an electric current in the cell.

When the current produced by a small photovoltaic cell that absorbs the excess light is added to the cells’ current, the combined output can be controlled to form hydrogen gas. This enables the conversion of solar energy into chemical energy, which is then stored as hydrogen gas formed inside the BPEC cell. When required, the energy can be converted into heat and electricity in the same way hydrocarbon fuels are used – by burning the hydrogen.

The product of this hydrogen combustion is however clean water, unlike the combustion of hydrocarbon fuels which release greenhouse gases (carbon dioxide) into the atmosphere and pollute the environment.

This is a closed cycle and could be a clean and sustainable substitute for hydrocarbon fuel. It begins and ends with water, allowing the conversion and storage of solar energy in hydrogen gas in the process.

Prof. Rothschild of the Faculty of Material Science and Engineering notes that the study is unique in that combines leading experts from three disciplines – materials engineering, biology and chemistry. Complex engineering challenges were faced to get artificial (photovoltaic cell and electronic components) and natural (leaves) components to communicate with each other, necessitating this cooperation.

The full study can be found in the journal Nature Communications.