Using a simple membrane extract from spinach leaves, 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. The raw material of the device is water, and its products are electric current, hydrogen and oxygen.

The combination of a man-made BPEC cell and plant membranes, which absorb sunlight and efficiently convert it into a flow of electrons, paves the way for the development of new technologies for the creation of clean fuels from renewable sources: water and solar energy.

The combination of a man-made BPEC cell and membrane extract from spinach leaves was used to absorb sunlight and efficiently convert it into a flow of electrons. Image credit: Pixabay.The combination of a man-made BPEC cell and membrane extract from spinach leaves was used to absorb sunlight and efficiently convert it into a flow of electrons. Image credit: Pixabay.The BPEC cell was developed by doctoral students Roy Pinhassi, Dan Kallmann and Gadiel Saper under the guidance of Noam Adir, professor of chemistry; Gadi Schuster, professor of biology; and Avner Rothschild, professor of material science and engineering. It is based on the naturally occurring process of photosynthesis in plants, in which light drives electrons that produce storable chemical energetic molecules, which are the fuels of all cells in the animal and plant worlds.

In order to utilize photosynthesis for producing electric current, the researchers added an iron-based compound to the solution. The compound mediates the transfer of electrons from the biological membranes to the electrical circuit, enabling the creation of an electric current in the cell.

The electrical current can also be channeled to form hydrogen gas through the addition of electric power from a small photovoltaic cell that absorbs the excess light. This makes possible the conversion of solar energy into chemical energy that is stored as hydrogen gas formed inside the BPEC cell. This energy can be converted when necessary into heat and electricity by burning the hydrogen, in the same way hydrocarbon fuels are used.

However, unlike the combustion of hydrocarbon fuels—which emits greenhouse gases into the atmosphere and pollutes 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.

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