SCIENCE & TECHNOLOGY
Where SOME SEE POLLUTION, Andrew Bocarsly sees products BETHANY HALFORD, C&EN NORTHEAST NEWS BUREAU ANDREW BOCARSLY’S LAB at Princeton
you’re looking at commodity markets University looks like any photoelectrowhere products are made at large scale. We chemistry lab you might stumble into. were attracted to this technology because Crumpled pieces of aluminum foil cloak it displayed factors that generally indicate light-sensitive chemical reactions. Threeit has potential. necked flasks decorate the benchtops like “Ultimately what we’d like to do is make vases sprouting electrodes instead of flowCO2 a feedstock for producing fuels and ers. But it’s a chemical you can’t see that’s chemicals. That’s the ultimate vision,” become a focus for the Bocarsly lab in Teamey says. For that to happen, Bocarsly’s recent years—carbon dioxide, specifically process needs to compete costwise with the CO2 pollution that pours out of cars traditional methanol production. It’s not and power plants each day. enough to be doing something that’s enviTwo years ago, Bocarsly reported that ronmentally friendly by removing excess with the help of a pyridinium catalyst he CO2 from the air. Liquid Light needs to was able to use visible light to transform compete financially. CO2 into methanol (J. Am. Chem. Soc. 2008, One area where the company has had to 130, 6342). The process uses a light-driven make modifications is in the photochemical gallium phosphide semiconductor approach to the reaction. electrode to reduce carbon dioxide While interesting, Bocarsly METHANOL MAKER gas that’s bubbled through a pyrisays, it’s the hard thing to Bocarsly shows off dinium solution. do. “The much easier thing the photoelectroSince that time, the research has chemical cells that to do would be to build an convert CO2. spun off in two directions: In Boelectrochemical cell that carsly’s lab at Princeton, there’s been an intensive effort to understand the mechanism behind this process and in a research park five miles north of campus, a small company called Liquid Light is trying to capitalize on it. Bocarsly, Liquid Light’s founder and chief scientific officer, confesses that he had no plans to start a company based on his chemistry. “I didn’t go to them,” he says of Liquid Light’s financial backers, “because I didn’t think I had anything to sell. They came to me.” In 2008, Kyle Teamey, Liquid Light’s chief operating officer, was working as an entrepreneur-inresidence with Redpoint Ventures. He read Bocarsly’s Journal of the American Chemical Society communication and thought the technology had promise. “With any catalytic process there are certain things you look for,” Teamey says. “You look for energy efficiency, the stability of the catalyst, the kinetics. Several factors need to come together for a catalytic process to work efficiently, particularly when WWW.CEN-ONLINE.ORG
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BACK IN THE Bocarsly lab at Princeton,
what may seem like a more esoteric effort has been under way. They’ve been trying to understand the mechanism by which pyridinium takes CO2 to methanol. “What we learned as we started to do this mechanistic work is that we didn’t have one catalyst—pyridinium—for the conversion of CO2 to methanol. Rather, we had three catalysts,” Bocarsly explains. “It turns out pyridinium is a catalyst in three separate reactions, totally independent of one another.” It converts CO2 into formic acid; it takes formic acid to formaldehyde—a reaction it performs so efficiently the group rarely even observes the acid; and it transforms formaldehyde to methanol. “It’s all free radical chemistry and it’s the cleanest thing in the world,” Bocarsly says. The fact that pyridinium even does this is something of a surprise, Bocarsly points out. You’ve got to shove six electrons and six protons into CO2 in order to make methanol, he explains. “And everybody, including me, has said that if you’re going to do a multielectron process you can’t do it one electron at a time because the energy is too great. As a result of that, everybody has been looking at reagents that will undergo multiple oxidation-state changes, which means transition metals.” As it turns out, pyridinium—an inexpensive, one-electron chargetransfer reagent—does the job better than anything anyone has designed, Bocarsly notes. “We convert 96% of B RIAN WILSON/PRINCETON U.
THE VALUE OF CO2
uses standard metal electrodes and then use an alternative energy source, such as solar panels or wind, to power it,” he explains. At the moment, that’s the avenue Liquid Light is taking. “I think we’ve made a lot of progress,” Teamey says of Liquid Light’s efforts to commercialize the CO2 conversion process, but he adds that the company, which started full-time operations in October 2009, is only just getting on its feet. “We want to make sure we can really prove this thing out before we make any grandiose claims,” he says. “There are too many cleantech start-ups that make grandiose claims and then never deliver. Ten years down the line they’ve chewed up $100 million and never made anything. We’re not those people.”
AND BOCARSLY has something else up
his sleeve. Using this photoelectrochemical process, his group can make more than just methanol. “We can make isopropanol in our cell,” he tells C&EN. The trick is this: They don’t use pyridinium as the catalyst. Instead, they use substituted pyridinium. “This is something we’re very excited about,” Bocarsly says. “When you talk to chemists, they say, ‘Oh, three carbons. We can do something with this.’ ” Although Bocarsly’s group hasn’t done all the experiments to verify that all three carbons in the isopropanol originate with CO2, he says he’s pretty certain that’s where they’re coming from. His group is currently trying to pin down that mechanism. “We’re very eager to get that mechanism because we want to understand how you make carbon-carbon bonded species from CO2,” he says. “If I can put carbons together to make something with three carbons, and presumably if I understand the mechanism—which I admittedly have very little understanding of at this point—then I can make anything.” ■
SHU T T ERSTO CK
the electrons we’re generating into methanol,” he says. “That’s huge.” “Professor Bocarsly’s recent discovery that the pyridinium cation itself is an electrocatalyst for reducing CO2 to methanol is potentially a paradigm-shifting discovery with respect to our society’s energy problem,” notes University of Richmond electrochemistry professor Raymond N. Dominey. Dominey points out that in order for solar energy to replace fossil fuels and meet mankind’s long-term energy needs, it must overcome two hurdles: its high cost and its intermittency. “Although much has been made about the former, in my opinion the latter is the real show-stopping problem that prevents solar energy from becoming our dominant source of energy: Electrical energy—specifically photovoltaic output—must be consumed as it is generated.” If you can convert that solar energy into methanol in a truly scalable manner, you can store massive amounts electrical energy, which, he says, “can revolutionize our use of solar energy, making it a viable and realistic replacement for all of our energy needs.” “In my opinion, the 96% electron efficiency of professor Bocarsly’s CO2 to methanol process means that, if the kinetics are good, this process could turn out to be a silver bullet in terms of our energy problem,” Dominey concludes.
GREEN FOR ETERNITY Start-up companies introduce two routes to stay
ENVIRONMENTALLY FRIENDLY after you’re dead and gone SARAH EVERTS, C&EN BERLIN
FEW PEOPLE like thinking about their own
death and less so the details of their body’s eventual fate in a coffin underground or in a cremation chamber. Yet as people consider their environmental footprint during life, concerns about one’s posthumous impact has inspired entrepreneurs to develop green alternatives to standard Western practices. Two such alternative technologies will soon launch in either North American or European markets. Environmentally minded individuals have several concerns about Western death practices. Some worry that the formaldehyde and other chemicals undertakers use to prepare bodies for burial may leach into the water table. When it comes to cremation, they worry about energy usage: To sustain temperatures of nearly 1,000 °C, cremation of one body on average consumes so much fuel that 573 lb of carbon dioxide is released into the atmosphere, says biochemist Sandy Sullivan, who has developed a cremation alternative with his company, Resomation Ltd., based in Glasgow, Scotland. Perhaps topping the list of environmental concerns about cremation is that crematorium smokestacks release mercury found in dental amalgam fillings into the air. Regulators in at least seven European countries, including Germany and Sweden, require that crematoria filter mercury out of smokestacks. The U.K.’s Department for Environment, Food & Rural Affairs is also WWW.CEN-ONLINE.ORG
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establishing regulations, and it notes in a position paper that “without intervention, mercury emissions from crematoria in the U.K. will increase by two-thirds from 2000 to 2020,” and without regulations, crematoria will also be “by far the biggest single contributor to national mercury emissions” by 2020. Crematoria emissions are expected to reduce naturally by 2055, as mercury fillings fall out of use. But currently, Sullivan says, cremation is responsible for some 16% of the mercury in the U.K.’s air. The U.S. Environmental Protection Agency does not regulate mercury from crematoria smokestacks. “Good empirical data on the magnitude of mercury emissions from crematoria are lacking,” according to EPA’s website. But the agency’s website also notes that one study found that, in 2005, crematoria in the U.S. released about 6,600 lb of mercury into the environment. Sullivan got the idea for his alternative to cremation when working on a European Union-funded project to invent safe ways to dispose of cattle contaminated by bovine spongiform encephalopathy (also known as mad cow disease) and other prion diseases. Sullivan decided to apply the technology he developed to human remains and started Resomation two-and-a-half years ago. The Resomation process breaks down a corpse using alkaline hydrolysis instead of extremely high heat. The body is placed in a steel chamber along with potassium hydrox-
