Artificial Photosynthesis: Machines that Mimic Natural Processes

Mimicking natural processes in nature has been one of the most elusive pursuits in technology, since it almost breaks the unseen barrier that separates what is artificial and what is natural. The field of nanotechnology for example, is an attempt to recreate the smallest units of natural life (bacteria, viruses, and organic cells) with the objective of artificially modifying it to perform a specific task.

But perhaps one of the most important natural processes that are being researched today is the “magical” energy-producing capabilities of photosynthesis. As we have first known it in the concept of ecological food chains, plants hold the highest energy yield within the entire system, because it obtains and converts energy very efficiently from its surroundings.

Studying photosynthesis to create an artificial machine that mimics the process is no easy task. However we have already gone quite far into its research, and in fact we could even say that we are already quite near into unlocking its secrets.

The “Greenest” Alternative Energy Source

There are two important sub-processes in photosynthesis that should be properly recreated before the energy-producing cycle of the artificial version can be made, and these are:

• The oxidization of water to produce oxygen and extra protons via sunlight. This would be the most important first step to efficiently produce hydrogen.
• The reduction and simplification of carbon dioxide via carbon fixation. This is a crucial process that would enable an artificial photosynthetic system to produce biofuel.

In artificial photosynthesis, most of the compounds naturally used by plants as reaction catalysts are replaced with other compounds to improve and enhance the chemical reactions. For example, the “blue dimer” oxidation catalyst is widely used as a substitute to the natural catalysts used when plants synthesize water, sunlight and carbon dioxide.

Artificial photosynthesis is completely different from photovoltaics because the processes do not necessarily directly produce usable energy. They can, like what the hybrid photoelectrochemical cell does, but they are usually designed NOT to for maximum energy transfer efficiency. It instead focuses on the creation of a usable product that can be used to produce energy.

In a sense, artificial photosynthesis aims to manufacture a type of “solar fuel”, be it hydrogen and/or biofuels, depending on the reactions that it would mimic and recreate.

Why it is Difficult to Mimic Photosynthesis

The primary reason why it is very difficult to mimic photosynthesis is that you simply can’t use the exact same catalysts used naturally by plants. As mentioned, earlier, scientists have to use other catalysts that could imitate the chemical reactions made by the original catalysts. In fact, the research in finding usable catalysts for a specific part of the photosynthetic process has led the field NOT to have that many real significant breakthroughs in almost 30 years.

Another reason for the apparent difficulty in recreating this natural process is that even if they found the proper substitute catalyst, the reaction was usually a lot slower than what could be done naturally. In energy production terms, this a big disadvantage, since energy produced over a unit length of time is one of the most important criteria that determines the efficiency of an alternative energy source.

Current Status of Artificial Photosynthesis Research

As of 2012, the search for the proper system and catalyst that would perfectly recreate the natural process is still on. A major breakthrough however, happened just recently that promises to accelerate artificial photosynthesis to speeds almost equal of its natural counterpart.

Researchers at the Department of Chemistry at the Royal Institute of Technology in Stockholm, Sweden have successfully developed a fast molecular catalyzer that enabled their artificial photosynthetic system to achieve process cycle speeds of about 300 turnovers per second (natural photosynthesis is set at 100-400 turnovers per second.). The announcement was made last April 12, 2012, in an official news article that provides the details of the breakthrough.

The most important use of artificial photosynthesis today is the (economically) efficient production of hydrogen. With a properly developed artificial photosynthetic system, all the raw materials that you’ll ever need to create hydrogen would be water and sunlight (CO2 can be easily found in ordinary air), and the system would provide itself with the energy needed to keep it operational.

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Christian Crisostomo (251 Posts)

Christian Crisostomo is just your average tech geek that loves to see man's newest and most recent technological exploits. He holds great interest in the potentials of green technology, and is enthusiastic about the continuous development of environment-friendly alternative energy.

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