Artificial Photosynthesis

Artificial photosynthesis is one of the newer ways researchers are exploring to capture the energy of sunlight reaching earth.

As I’ve mentioned on another page, almost all energy used on earth, including fossil fuels, ultimately derived from the sun (the exceptions being tidal power and nuclear energy).

Human attempts to capture solar energy are by direct thermal gain (for example, passive hot water systems, using focused sunlight to heat an engine, etc) or a photovoltaic reaction in a solar panel. .

Plants capture the sun’s energy through a much more elegant process – photosynthesis. In my crude understanding of it, photosynthesis takes CO2 and water and, driven by energy derived from sunlight, chemically transforms these molecules into sugars and oxygen. The oxygen is released into the atmosphere and the sugars become the plant structure and provide energy for the biochemical reactions of cell growth.

The possibility of mimicking this biochemical process has been the subject of considerable research in the last decade, and the idea of “artificial photosynthesis” more and more appears to be practical.

The basic principle is to use the sun’s energy to force a chemical reaction that takes CO2 from the atmosphere and converts the carbon into a carbohydrate that could be used for fuel while releasing oxygen.

Plants use organic compounds that need to be continuously renewed. Researchers are looking for inorganic compounds that catalyze the needed reactions and are both efficient and widely available.

The research has been significantly boosted by the application of nano technology. It’s a good example of the step wise progress in the scientific world.

Studies earlier in the decade showed that crystals iridium efficiently drove the reduction of CO2, but iridium is extremely rare so technology that required its use would be expensive and could never be used on a large scale.

Cobalt crystals were tried. They worked, and cobalt is widely available, but the original formulations weren’t at all efficient.

Things changed with the introduction of nano technology.

The initial experiments used crystals on a micron scale. Just as a reminder, 1 micron = 1/1,000,000 of a meter, while 1 nanometer = 1/1,000,000,000 of a meter).

Researchers found that crystals measured in nanometers were much more efficient. They grew rod-shaped cobalt crystals measuring 8x50 nanometers that they then formed into spheres with a diameter of 35 nanometers. They believe the ratio on surface area to volume of the sphere is part of the reason for the increased efficiency. The usual “more research is needed” tag line applies here.

The main point is that this unique approach increasing appears to be feasible. It has the advantage of harnessing solar energy in a form that can be stored and used with greater efficiency than batteries and it is at least carbon neutral.

I suppose it’s the optimist in me, but exciting research like this gives me confidence that we’ll be able to solve of energy problems while protecting the environment. Artificial photosynthesis appears poised to become part of the solution.


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