Nano-sized Green Energy Solution

 

Direct from sunshine to a fuel cell: This has to be the ultimate leap forward in Green Energy.

All electric power generated by burning of fossil fuels, is simply the release of energy captured long, long  ago from the sun’s rays by photosynthesis of plants.

So rather than waiting hundreds of millions of years for plant material to become transformed through geological pressure into coal, oil or gas, why not convert the sun’s rays into electricity today? That’s the thinking behind artificial photosynthesis, which seeks to copy the power of plants to capture solar energy — but to turn it straight into electricity, rather than storing that energy through the creation of  carbon-based compounds.

Could nanomaterials convert sunshine to power?

Could nanomaterials convert sunshine to power?

Artificial photosynthesis remained a dream for decades. But now the advent of nano-materials has made this reaction possible in the laboratory, where solar energy can be made to react with water to generate hydrogen and oxygen.

A group of Brazilian researchers at the Institute of Chemistry of the University of Campinas (Unicamp) is developing nanometer-scale materials capable of carrying out artificial photosynthesis to produce energy.

According to Jackson Dirceu Megiatto Júnior, professor at Unicamp, “light-induced water splitting” is on the threshold of becoming a reality. In a presentation made at the Chicheley seminar centre of Britain’s Royal Society, Prof. Megiatto said the emergence of silicon-based nanomaterials has opened the door to connecting these photoactive materials to conventional fuel cells – electrochemical cells that convert chemical energy into electrical energy by combining hydrogen and oxygen to re-form water molecules.

“The challenge now is to connect these materials to a fuel cell. If we can use the hydrogen and oxygen produced by these new materials in a fuel cell, we’ll be able to generate water along with electricity and complete the cycle of artificial photosynthesis,” Megiatto explained.

The Brazilian scientist presented his artificial photosynthesis research at a UK-Brazil-Chile Frontiers of Science conference organised by the Royal Society in early 2014. The event promotes scientific and interdisciplinary collaboration among young scientists of the three nations.

Because silicon solar panels are expensive and difficult to process to the level of purity required for this purpose, Brazilian researchers have been looking to nature itself to synthesize and reproduce the workings of chlorophyll.

“These molecules are nature’s way of absorbing sunlight. Their process of chemical synthesis, however, is difficult and expensive,” Megiatto said.

To overcome these barriers, the researcher learned how to synthesize artificial chlorophyll molecules called porphyrins during his post-doctoral studies in the United States. In addition to being easier to synthesize than natural chlorophyll, the artificial molecules of the pigment are also easier to manipulate, Megiatto explained.

Mimicking the action of chlorophyll to "split water"

Mimicking the action of chlorophyll to “split water”

“When connected to catalysts, these materials have been shown to be very promising in transforming sunlight into chemical energy through the oxidation of water molecules; but right now, they are only being studied in aqueous solution and not in an actual photosynthetic device,” stated Megiatto.

“What we’re trying to do now is to form a photoactive polymeric film with these molecules to develop a solid material to put on the metal plates and semiconductors [electrodes] needed to operate a solar cell,” he added.

“The challenge now is to connect these materials to a fuel cell. If we can use the hydrogen and oxygen produced by these new materials in a fuel cell, we’ll be able to generate water along with electricity and complete the cycle of artificial photosynthesis,” Megiatto explained.

If artificial photosynthesis does take off, it could save more than the time it takes to convert sunshine into carbon and then into energy.

Nature's sunshine conversion is not too efficient

Nature’s sunshine conversion is not too efficient

According to Megiatto, plants waste large amounts of solar energy during the natural photosynthetic process. He goes on to note that because plants burn up a part of the energy they capture for a series of needs, such as growth and survival. Sugarcane, for example, uses only a small percentage of solar energy to convert carbon dioxide into sugars.

“The maximum efficiency of natural photosynthesis is approximately 10%,” said Megiatto. “Terrestrial plants have less than 1% photosynthetic efficiency, although some are capable of carrying out photosynthesis with an efficiency somewhere between 4% and 5%.”

In fact there’s a whole branch of research dedicated to boosting the efficiency of photosynthesis in plants such as rice. To pursue this goal, the international research consortium ‘C4 Rice’ funded by the Bill & Melinda Gates Foundation, the International Rice Research Institute (IRRI) and research institutions in the United Kingdom, is working on genetic modifications to transform the  process of photosynthesis.

Harvesting sunshine - a decades old dream of scientists

Harvesting sunshine – a decades old dream of scientists

You can read a full article on artificial photosynthesis by Brazilian journalist Elton Alisson, by clicking here.

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