Nature offers key lessons on harvesting solar power, say chemists

ScienceDaily (Sep. 24, 2011) — Clean solutions to human energy demands are essential to our future. While sunlight is the most abundant source of energy at our disposal, we have yet to learn how to capture, transfer and store solar energy efficiently. According to University of Toronto chemistry professor Greg Scholes, the answers can be found in the complex systems at work in nature.

"Solar fuel production often starts with the energy from light being absorbed by an assembly of molecules," said Scholes, the D.J. LeRoy Distinguished Professor at U of T. "The energy is stored fleetingly as vibrating electrons and then transferred to a suitable reactor. It is the same in biological systems. In photosynthesis, for example, antenna complexes composed of chlorophyll capture sunlight and direct the energy to special proteins called reaction centres that help make oxygen and sugars. It is like plugging those proteins into a solar power socket."

In an article in Nature Chemistry to be published Sept. 23, Scholes and colleagues from several other universities examine the latest research in various natural antenna complexes. Using lessons learned from these natural phenomena, they provide a framework for how to design light harvesting systems that will route the flow of energy in sophisticated ways and over long distances, providing a microscopic "energy grid" to regulate solar energy conversion.

A key challenge is that the energy from sunlight is captured by coloured molecules called dyes or pigments, but is stored for only a billionth of a second. This leaves little time to route the energy from pigments to molecular machinery that produces fuel or electricity. How can we harvest sunlight and utilize its energy before it is lost?

"This is why natural photosynthesis is so inspiring," said Scholes. "More than 10 million billion photons of light strike a leaf each second. Of these, almost every red-coloured photon is captured by chlorophyll pigments which feed plant growth." Learning the workings of these natural light-harvesting systems fostered a vision, proposed by Scholes and his co-authors, to design and demonstrate molecular "circuitry" that is 10 times smaller than the thinnest electrical wire in computer processors. These energy circuits could control, regulate, direct and amplify raw solar energy which has been captured by human-made pigments, thus preventing the loss of precious energy before it is utilized.

Last year, Scholes led a team that showed that marine algae, a normally functioning biological system, uses quantum mechanics in order to optimize photosynthesis, a process essential to its survival. These and other insights from the natural world promise to revolutionize our ability to harness the power of the sun.

"Lessons from nature about solar light harvesting" was written by Scholes, Graham Fleming of the University of California, Berkeley, Alexandra Olaya-Castro of University College, London UK and Rienk van Grondelle of VU University in Amsterdam, The Netherlands.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Toronto.

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Gregory D. Scholes, Graham R. Fleming, Alexandra Olaya-Castro, Rienk van Grondelle. Lessons from nature about solar light harvesting. Nature Chemistry, 2011; 3 (10): 763 DOI: 10.1038/nchem.1145

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Nature offers key lessons on harvesting solar power, say chemists

ScienceDaily (Sep. 24, 2011) — Clean solutions to human energy demands are essential to our future. While sunlight is the most abundant source of energy at our disposal, we have yet to learn how to capture, transfer and store solar energy efficiently. According to University of Toronto chemistry professor Greg Scholes, the answers can be found in the complex systems at work in nature.

"Solar fuel production often starts with the energy from light being absorbed by an assembly of molecules," said Scholes, the D.J. LeRoy Distinguished Professor at U of T. "The energy is stored fleetingly as vibrating electrons and then transferred to a suitable reactor. It is the same in biological systems. In photosynthesis, for example, antenna complexes composed of chlorophyll capture sunlight and direct the energy to special proteins called reaction centres that help make oxygen and sugars. It is like plugging those proteins into a solar power socket."

In an article in Nature Chemistry to be published Sept. 23, Scholes and colleagues from several other universities examine the latest research in various natural antenna complexes. Using lessons learned from these natural phenomena, they provide a framework for how to design light harvesting systems that will route the flow of energy in sophisticated ways and over long distances, providing a microscopic "energy grid" to regulate solar energy conversion.

A key challenge is that the energy from sunlight is captured by coloured molecules called dyes or pigments, but is stored for only a billionth of a second. This leaves little time to route the energy from pigments to molecular machinery that produces fuel or electricity. How can we harvest sunlight and utilize its energy before it is lost?

"This is why natural photosynthesis is so inspiring," said Scholes. "More than 10 million billion photons of light strike a leaf each second. Of these, almost every red-coloured photon is captured by chlorophyll pigments which feed plant growth." Learning the workings of these natural light-harvesting systems fostered a vision, proposed by Scholes and his co-authors, to design and demonstrate molecular "circuitry" that is 10 times smaller than the thinnest electrical wire in computer processors. These energy circuits could control, regulate, direct and amplify raw solar energy which has been captured by human-made pigments, thus preventing the loss of precious energy before it is utilized.

Last year, Scholes led a team that showed that marine algae, a normally functioning biological system, uses quantum mechanics in order to optimize photosynthesis, a process essential to its survival. These and other insights from the natural world promise to revolutionize our ability to harness the power of the sun.

"Lessons from nature about solar light harvesting" was written by Scholes, Graham Fleming of the University of California, Berkeley, Alexandra Olaya-Castro of University College, London UK and Rienk van Grondelle of VU University in Amsterdam, The Netherlands.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Toronto.

Journal Reference:

Gregory D. Scholes, Graham R. Fleming, Alexandra Olaya-Castro, Rienk van Grondelle. Lessons from nature about solar light harvesting. Nature Chemistry, 2011; 3 (10): 763 DOI: 10.1038/nchem.1145

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Atomic Gardens, the Biotechnology of the Past, Can Teach Lessons About the Future of Farming

When radioactive tomatoes were the crop of the future
Atomic Seeds Life Magazine via Pruned

One look at the wedge-shaped rows of plants and anyone could tell the circular garden was not grown under normal conditions. Plants sown in concentric circles displayed wildly different vitality and viability.

The innermost circle of plants, gathered around a central pole, were dead; slightly farther away, the plants were stunted and tumor-ridden; and past that, the plants may have looked right, but possessed strange new mutations.

It was the latter part of the archetypal “gamma garden” that most interested plant researchers in the 1950s and 1960s. The central pole contained a radioactive source, commonly cobalt-60, so that scientists could see how the gamma rays affected plants.

Before scientists learned how to modify genes, they induced mutations with radiation. It was a sincere effort to feed the world, and amaze home gardeners, by modifying plants to have desirable traits.

Nanotechnologist Paige Johnson shares the history of atomic gardening on her blog, Garden History Girl. Writer Alexander Trevi interviewed Johnson for his own blog, Pruned.

“If we think of modern GM as taking a scalpel to the genome, mutation breeding by irradiation was a hammer,” she says. The full interview is well worth a read; click through to it here.

It’s an interesting tale in light of radiation and food safety concerns after the Japanese nuclear disaster. But there are also some interesting parallels between atomic gardening and 21st-century biotechnology, which also promises to feed the world by modifying plants to have new traits. The promises, and the controversies, feel very familiar.

Back in the 1960s, scientists bombarded plants with gamma radiation hoping to see beneficial changes in the plants’ structure and yield. Advocates included entrepreneur C.J. Speas and Englishwoman Muriel Howorth, who started the Atomic Gardening Society to promote mutated varieties. Johnson describes a dinner party in which Howorth served “NC 4x,” North Carolina 4th generation X-rayed peanuts that were produced from seeds exposed to 18,500 roentgen units of X-rays. After the party, Howorth planted the irradiated seeds and they grew like magic beanstalks.

Journalists and sightseers came to visit the mutant plant; garden writer Beverley Nichols called the peanut the “most sensational plant in Britain.”

“To me it had all the romance of something from outer space. It is the first ‘atomic’ peanut. It is a lush, green plant and gives you a strange, almost alarming sense of thrusting power and lusty health. It holds a glittering promise in its green leaves, the promise of victory over famine,” she wrote, as recounted on Johnson’s blog.

As with modern biotechnology, industry was the main driver behind the new plant modifications. Two modern cultivars are the result of atomic gardening, Johnson says — most of the world's mint oil, used in toothpaste, chewing gum and more, comes from the “Todd's Mitcham” peppermint cultivar, which is resistant to a fungus. It was produced in radiation gardens at Brookhaven National Laboratory. And the “Rio Star” grapefruit varietal, which Johnson says accounts for three-fourths of grapefruit production in Texas, is another atomic mutant bred for its dark red flesh and juice.

Gamma garden research was conducted in the U.S., Sweden, India and other countries in the 1960s, leading to untold numbers of new plant varieties. But s far as Johnson can tell, the entrepreneur Speas was the only source for home gardeners to buy irradiated seeds. Seed packets depicted robust flowers and vegetables, calling them “atomic-energized” and offering an interesting definition of what radiation does — “gamma rays tend to shake up the normal balanced system of the embryo inside the plant.”

Atomic Energized Poppy: The seed packet advises gardeners that it may take more than a year for mutations to manifest themselves, and therefore not to destroy stunted plants: “The stunted plants may contain desirable changes when they again regain their hereditary balance in subsequent generations.”  Paige Johnson via Pruned

Eventually, as scientists and the public grew to understand the dangers posed by radiation exposure, gamma gardens fell out of favor. The notion of irradiated plants feeding a hungry world soon wilted, too.

Decades later, scientists would figure out how to make much more precise mutations, inserting new genes and switching them on to make plants do things they couldn’t do before. But this method has its own detractors, some of whom would argue genetic modification is just as bad for health and the environment as radioactivity research.

We know much more about biology today than we did in the 1960s. But will future generations look back on genetic modification like we reflect on atomic gardens, with an amused sense of nostalgia illuminated by hindsight?

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