Artificial photosynthesis refers to artificial chemical processes which are intended to synthesize the photosynthesis process which plants use to produce oxygen and nutrients from carbon dioxide, sunlight and water. To date researches have yet to develop many energy-efficient artificial photosynthesis mechanisms for practical applications, but artificial photosynthesis holds exciting potential as a new field of alternative energy.
Photosynthesis is the natural process by which plants and some types of algae produce energy. Plants absorb sunlight using a pigment called chlorophyll, which appears green to the human eye because it absorbs red and blue wavelengths of light. A chemical reaction occurs in which carbon dioxide, water and energy from sunlight are used to produce oxygen and carbohydrates. The oxygen is released back into the atmosphere and the carbohydrates are used by the plant as an energy source.
Artificial photosynthesis, then, refers to any attempt to duplicate this reaction using technologies designed by human beings. Of course, artificial photosynthesis experiments have no need for carbohydrate production - humans can easily obtain necessary food energy from other sources. Instead, groups like the Centre for Interface Science and Catalysis at Stanford University and the Artificial Photosynthesis Group at Brookhaven National Laboratory are hoping to develop new photosynthesis-like processes that lead to other organic chemicals which are much more useful.
For instance, that Centre says, one obvious application of artificial photosynthesis would be to produce hydrocarbon fuels like oil and natural gas. These fuels are normally known as "fossil fuels" because they are normally recovered from subterranean deposits made up of the collected remains of long-dead organisms.
Fossil fuel use is controversial because climate scientists believe the carbon dioxide which burning of fossil fuels emits into the atmosphere contributes to global warming. However, if the same fuels were produced by artificial photosynthesis, then they would take out of the atmosphere the same carbon dioxide that they were putting into it. At least in theory, Stanford's idea would be a carbon-neutral fuel source, with the main input being solar power. Many more radical possibilities for artificial photosynthesis can also be imagined. The idea would be to absorb some or most of the carbon emitted into the atmosphere by burning the fuel, in much the same way that some types of biofuel production hope to achieve.
For the moment, however, this area of applied science remains in its infancy. The first artificial methods for undergoing photosynthesis were researched only in the 1960s. Today researchers are examining a number of quite different technologies which all fall under the broad mantle of "artificial photosynthesis." One area of research, for example, are photoelectrochemical cells that use sunlight to generate electricity. Other systems might be able to produce hydrogen, which could then be used as fuel for hydrogen fuel cells. If these researchers succeed over the long term, artificial photosynthesis could yield a solar power solution far more efficient than the photovoltaic method of solar power production which is currently being adopted as an alternative energy source. For now, however, any large-scale practical application of this research is still years away.