For years, solar energy researchers have tried to imitate the success of photosynthesis by building devices like an artificial leaf and a solar cell that hijacks chemistry of photosynthetic bacteria. Now researchers at MIT have come up with an innovative technique that also happens to be very cheap: all you need is some “stabilizing powder” and plant waste. Mowed your lawn lately?
The stabilizing powder is a mix of safe, easily attainable chemicals that preserves photosystem I, a protein complex that captures light energy in plant cells. (In contrast, the newest photovoltaic cells in solar panels require metals that are rare or toxic.) The powder is mixed with plant matter such as grass clippings and crushed, and the resulting green goo is spread onto glass or metal substrate. Hook up wires to capture the electric current and that’s your solar panel.
The efficiency of these solar panels is only 0.1%, compared to the 15 to 18% efficiency of solar panels out in the market right now. Lead researcher Andrew Mershin says the technology still needs to improve 10-fold to become practical. After all, being able to power only one lightbulb with a whole house covered in solar panels isn’t much help. But the great advantage of all this is that it’s easy and dirt grass cheap. Because the barrier to entry is so low, anyone would be able to order a bag of chemicals and make their own solar panel. Mershin hopes home tinkerers experiment with the cells and find new ways to make improvements.
Correction, February 6: We eliminated a reference to mulch in the headline: mulch is low in chlorophyll, so it wouldn’t actually work for these plant-powered solar cells.
Biologists have recently had cause to wonder whether the molecules they know and love are pulling some quantum trickery while they’re not looking: one of the large proteins that captures light in photosynthesis was observed in several studies apparently using coherence, one of the hallmarks of quantum mechanics, to determine the best possible route for shunting energy through its atoms. Now, further experiments that use lasers to tweak such proteins and observe their response have provided more evidence that this is happening—an exciting indication that the strange laws of quantum mechanics can affect the behaviors of large agglomerations of atoms.
Our own Sean Carroll of Cosmic Variance explained how coherence works when this phenomenon was observed in real plants at room temperature last year: (more…)
What’s the News: This week, scientists say that they’ve passed a chemistry milestone by creating the world’s first practical photosynthesis device. The playing-card-sized photosynthetic gadget uses sunlight to split water molecules into oxygen and hydrogen, which can then be used to produce energy, and is reputedly 10 times more efficient than a natural leaf. Researchers say they expect it to revolutionize power storage, especially in remote areas that don’t currently have electricity. “A practical artificial leaf has been one of the Holy Grails of science for decades,” says lead researcher Daniel Nocera, who’s presenting this research at the National Meeting of the American Chemical Society this week.
How the Heck:
- The artificial leaf uses nickel and cobalt as catalysts to split water molecules into hydrogen and oxygen by facilitating oxygen-oxygen bonding.
- Oxygen and hydrogen molecules are then sent to a fuel cell that can produce electricity. If the device is placed in a one-gallon bucket of water in bright sunlight, it can reportedly produce enough electricity to power a house in a developing nation.
What’s the Context:
- The very first artificial leaf was created by John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colorado, over a decade ago. The device lasted for only one day and was made of expensive metals, making it impractical.
- This new artificial leaf uses nickel and cobalt, which are relatively cheap, and has so far operated continuously for at least 45 hours, making it the first practical artificial leaf.
- In 2008, Nocera announced a way of splitting water using cobalt and platinum, a breakthrough at the time. Now, by using nickel instead of the more expensive platinum, he’s made the entire process economically feasible, in addition to combining everything into a working prototype.
- Nocera has appeared in Discover before, including his National Science Foundation briefing on energy storage.
- Many more labs are also working on artificial photosynthesis.
- 80beats has covered other green energies, from wind turbines to natural gas.
Next Up:
- Scientists are working to increase the device’s efficiency still higher.
- Tata Group, an Indian conglomerate, plans on creating a power plant based on this research within the next year and a half.
Reference: Daniel Nocera et al. 241st National Meeting of the American Chemical Society. March 27-31, 2011 Anaheim, California, USA
Image: Wikimedia Commons / Daniel Schwen
“It’s a catastrophe. Relax!”
Those are the words of Michael Beard, the Nobel laureate physicist long past his prime who is the anti-hero of Ian McEwan’s new novel Solar, out this week in the United States. McEwan, no stranger to writing scientist characters or scientific themes, dives this time headlong into climate change. McEwan says he was nervous attempting to write fiction about a subject that has the potential to be, well, dull. But Solar is a laugh-out-loud read thanks to its ridiculous protagonist and willingness to make light of the apocalyptic seriousness of the conversation.
At the book’s outset, in the year 2000, Beard isn’t particularly convinced about climate change. He’s coasting on his reputation as a Nobelist, making money giving repetitive lectures and sitting on various boards, when suddenly he finds himself in charge of a shiny new British government research center out to build the next new thing in alternative energy. In the second part of “Solar,” Beard has become a believer in global warming, working on a way to get non-carbon power from artificial photosynthesis—a new application of a never-quite-explained theory that he came up with in his 20s. Unfortunately, he didn’t discover the application himself. He stole it from his dead assistant [Wall Street Journal], the marvelously enthusiastic (or at least enthusiastic until an unfortunate encounter with a coffee table) Tom Aldous.
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The primary reactions in photosynthesis—the first steps in plants’ conversion of sunlight energy into energy stored in carbohydrates—are incredibly efficient. And in a new study in Nature, chemists reveal that they may have found part of the reason why: quantum mechanics.
A couple years ago, scientists first showed in bacteria proteins that the electrons were moving according to a quantum mechanical phenomenon called coherence, rather than abiding by the classical laws of physics. But where those early experiments had been cooled to 77 kelvins (–196 degrees Celsius)—this experiment was the first conducted at room temperature, 294 K, to replicate such effects [Scientific American]. Thus, the new study, which was done on marine algae, suggests this phenomenon can occur in a living biological system.
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Part animal, part plant, bright green, and totally bizarre: Meet the sea slug Elysia chlorotica.
Biologists already knew that this organism, native to the marshes of New England and Canada, was a thief that somehow pickpocketed genes from the algae it eats. At last week’s meeting of the Society for Integrative and Comparative Biology in Seattle, researcher Sidney Pierce said he has found that the slugs aren’t just kleptomaniacs—they use the pilfered genes not only to make chlorophyll, but also to execute photosynthesis and live like a plant. Said Pierce: “They can make their energy-containing molecules without having to eat anything,” Pierce said. “This is the first time that multicellular animals have been able to produce chlorophyll” [LiveScience].
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In a salty hot spring near Mono Lake, California, researchers have found two new species of bacteria that use arsenic for photosynthesis, and require no oxygen to fuel the process. Researchers say the bacteria may be similar to those that existed on primordial Earth where oxygen was scarce, and may illustrate an important stage of how early life developed in mineral-rich waters over 2 billion years ago.
Arsenic is well-known for its toxicity; it was used so often as tool for homicide in the 1800s that it earned the nickname “king of poisons” [The Scientist]. Yet the newly discovered bacteria can not only tolerate the element, they require it to survive. One of the first steps most organisms perform in photosynthesis is to split water molecules, creating oxygen. Oxygen donates energy in the form of electrons to other molecules, setting off a chain reaction that eventually results in the building of sugars for the organism’s own food. For the red and green bacteria found in Mono Lake, arsenic plays the role of oxygen [Science News].
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Who knew that a white spruce in northern Canada, a red maple in Pennsylvania, and a mahogany tree in Puerto Rico have so much in common? Their environments are certainly very different, with icy winds buffeting the spruce tree’s needles and hot, humid air bathing the mahogany tree’s leaves. But despite these external variations, a new study shows that inside each tree leaf (or needle) it’s always just the right temperature for the delicate and vital process of photosynthesis, and the leaves are responsible for keeping that thermostat steady.
The findings, published in Nature [subscription required], show that trees all across North America favor the temperature of 70 degrees Fahrenheit for the photosynthesis process, which uses sunlight to convert carbon dioxide into oxygen and sugars. To keep in that comfort zone, they’ve come up with some clever adaptations. Trees release water, and during hot times, that botanical sweat cools them down. And trees that grow in cold places tend to cluster their leaves. These tight formations can affect the rate at which leaves lose heat on cold days, just as fingers pressed together in mittens stay warmer than fingers separated by space in gloves [Science News].
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