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Researchers aim to harvest the sun’s energy in cheap, new ways

Dr. Ted Sargent, Canada Research Chair in Nanotechnology at the University of Toronto poses in his solar cell technology lab where he and his team are developing new nature inspired solar cell technology that will absorb and utilize the light waves across the entire sun's spectrum.

Glenn Lowson/The Globe and Mail

To a Grade 4 science class the idea of photosynthesis could hardly be more straightforward: It's that thing plants do when they turn sunlight into food.

But with world demand for energy expected to double by mid-century and scientists warning that fossil fuel emissions must be throttled back at the same time to avoid the worst effects of climate change — photosynthesis is increasingly looking like a road map to the future.

That promise is the motivation for a new Canadian-led research collaboration that aims to draw lessons from photosynthesis in the quest for ways of harvesting the sun's energy far more cheaply than any current technology. If the effort is successful it will accelerate progress towards a long term energy solution to the world's energy needs.

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"As a planet we need to solve this problem," said Alan Bernstein, president of the Canadian Institute for Advanced Research (CIfAR), which is behind the new initiative.  "And I think most people would agree that the solution is not going to be asking people to please stop using energy."

To jump start the problem-solving, CIfAR convened a meeting in Toronto last week, where some of the world's leading researchers in so-called "bio-inspired" technologies gathered to talk photosynthesis. The goal is not to come up with a new type of solar energy device in the near term, but to lay the scientific groundwork for a next-generation revolution in solar power that may be exactly what the world needs a few decades from now as pressure mounts to shift to renewables in a big way.

The question is whether scientists have something to learn from what happened billions of years ago, when certain groups of microbes began producing specialized pigments that can convert solar energy into chemical bonds. Eventually, one group — the cyanobacteria —  combine two separate forms of photosynthesis into one elaborate process that maximizes energy yield with staggeringly high efficiency. That process was later co-opted by plant cells, making life as we know it possible.

Fast forward to the present and the power output represented by all the photosynthesis going on in the world today is about 10 times what human civilization collectively consumes.

"It's such a compelling example, and we're so far from having really figured that out properly," said Ted Sargent, a professor of engineering at the University of Toronto who is leading the CIfAR program.

The new collaboration will bring together researchers who are already working in the field. An early participant in the start up phase of the program is Greg Scholes, a prize-winning chemist who recently left Toronto for a professorship at Princeton University.

The challenge for researchers is that unlike conventional solar energy — which use a silicon based semiconductor to convert light into electricity — photosynthesis is exquisitely complex and involves dipping into the spooky realm of quantum physics, where particles that carry electric charge can seem to be in more that one place at a time.

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Recent progress by Dr. Scholes and others has begun to reveal how this molecular sleight of hand can achieve things that scientists so far can only dream of — including ripping carbon out of the air and using it to build sugar with the bare minimum of energy expended to get a far higher return.

But even if the intricacies of photosynthesis can be understood in perfect detail, it may not be possible to duplicate them at the molecular level. What is more relevant for practical purposes is pulling out the right set of design rules that can then be applied to human engineered versions of photosynthesis.

"It's surprising how much has been done with much cruder structures," said Sir Richard Friend, a physicist at Cambridge University who will chair the new program's advisory panel.

While many researchers who attended the Toronto meeting expressed enthusiasm about how rapidly the field has advanced in recent years, there were plenty of caveats about how much further the science has to go before it can offer the world an economically viable energy solution.

"We need to find out how to minimize losses, lower cost and increase the lifetime of our devices," said Alán Aspuru-Guzik, a theoretical chemist at Harvard University who was among the participants.  "Silicon is really cheap, and we need to be cheaper and better to make a difference and help transform the economy into a renewable economy. "

The history of energy research is littered with examples where practical solutions have proved much harder to attain than expected. But Dr. Bernstein said the complexity of the problem is one reason why CIFAR selected energy as the focus of one of four new programs it expects to launch in the next year following a call for proposals to "tackle complex questions of global importance." (The remaining three will probe the biological basis of consciousness, the origins of life and the role of microbes in human health.)

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The tougher the problem, the bigger the risk that efforts to solve it will come to naught, Dr. Bernstein acknowledged. But risk is a feature of cutting-edge research that often requires looking at a technical problem in new ways.

"We don't want to take on something that's totally insoluble, but we also aren't looking to do what is merely incremental," he said.  "Of course you want it all to succeed, but if everything does you've got to wonder if you're really taking enough risks."

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