Hydrogen fuel from sunlight: artificial photosynthesis

artificial photosynthesisEarth receives more energy in one hour’s worth of sunlight than all of humanity uses in an entire year. Through the process of photosynthesis, green plants harness solar energy to split molecules of water into oxygen, hydrogen ions (protons) and free electrons. The oxygen is released as waste and the protons and electrons are used to convert carbon dioxide into the carbohydrate sugars that plants use for energy. Scientists aim to mimic the concept but improve upon the actual process.

No sustainable energy technology yet matches the ultimate potential of artificial photosynthesis. Bionic leaves that could produce energy-dense fuels from nothing more than sunlight, water and atmosphere-warming carbon dioxide, with no byproducts other than oxygen, represent an ideal alternative to fossil fuels but also pose numerous scientific challenges.

At least one step toward meeting these challenges has been achieved by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) working at the Joint Center for Artificial Photosynthesis (JCAP).

While artificial photosynthesis can be used to generate electricity, fuels can be a more effective means of storing and transporting energy. The goal is an artificial photosynthesis system that is at least 10 times more efficient than natural photosynthesis. “In coupling the absorption of visible light with the production of hydrogen in one material, we can generate a fuel simply by illuminating our photo-cathode,” Moore says. “We look forward to adapting our method to incorporate materials with improved properties for converting sunlight to fuel. We believe our method provides researchers at JCAP and elsewhere with an important tool for developing integrated photo-cathode materials that can be used in future solar-fuel generators as well as other technologies capable of reducing net carbon dioxide emissions.”

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