Storing Energy with Photosynthesis

Technology Review: While researchers and technologists around the world scramble to find cleaner sources of energy, some chemists are turning to nature's own elegant solution: photosynthesis. In photosynthesis, green plants use the energy in sunlight to break down water and carbon dioxide. By manipulating electrons and hydrogen, oxygen, and carbon atoms in a series of complex chemical reactions, the process ultimately produces the cellulose and lignin that form the structure of the plant, as well as stored energy in the form of sugar. Understanding how this process works, thinks Daniel Nocera, professor of chemistry at MIT, could lead to ways to produce and store solar energy in forms that are practical for powering cars and providing electricity even when the sun isn't shining.

What's needed are breakthroughs in our understanding of the fundamental chemical processes that make photosynthesis possible, according to Nocera, a recognized photosynthesis expert. He is studying the principles behind photosynthesis and applying what he learns to making catalysts that use solar energy to create hydrogen gas for fuel cells. Nocera's goal: a world powered by light and water….

Technology Review: Why is photosynthesis attractive in finding a source of clean energy?

DN: [Photosynthesis] does three things. It captures sunlight, and [second,] it converts it into a wireless current--leaves are buzzing with electricity. And third, it does storage. It stores the converted light energy in chemical energy. And it uses that chemical energy for its life process, and then it stores a little.

It turns out [that] photosynthesis is one of the most efficient machines in the world for energy conversion. But it's not great for storing energy because that's not what [a plant] was built to do. It was built to live and grow and reproduce.

And so that's the approach we take. Can we now do what the leaf is doing artificially, which is the capture, conversion, and storage in chemical bonds? But my device doesn't have to live: it can take a lot more of that energy and put it into chemical bonds. …