Scientists advance search for greener energy

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renewable-energyScientists have recorded four major recent breakthroughs in the search for greener and cleaner energy with the development of a highly effective method for converting carbon dioxide (CO2) into methanol; an “artificial leaf” that mimics a real leaf’s chemical magic with photosynthesis- but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks; a battery made from a sliver of wood coated with tin that shows promise for becoming a tiny, long-lasting, efficient and environmentally friendly energy source; and an inexpensive catalyst that uses the electricity generated from solar energy to convert carbon dioxide, a major greenhouse gas, into synthetic fuels for powering cars, homes and businesses.

Researchers at the Universite Laval (Laval University), Canada have developed a highly effective method for converting carbon dioxide (CO2) into methanol, which can be used as a low-emissions fuel for vehicles.

The team led by Prof. Frédéric-Georges Fontaine presents the details of this discovery in the latest issue of the Journal of the American Chemical Society. Researchers have been looking for a way to convert carbon dioxide into methanol in a single step using energy-efficient processes for years.

Fontaine explained: “In the presence of oxygen, methanol combustion produces CO2 and water. Chemists are looking for catalysts that would yield the opposite reaction. That would allow us to slash greenhouse gas emissions by synthesizing a fuel that would reduce our dependence on fossil fuels.”

The catalyst developed by Frédéric-Georges Fontaine and his team is made of two chemical groups. The first is borane, a compound of boron, carbon, and hydrogen. The second, phosphine, is made up of phosphorus, carbon, and hydrogen. “Unlike most catalysts developed thus far to convert CO2 into methanol, ours contains no metal, which reduces both the costs and toxic hazard of the catalyst,” added the chemistry professor at the Faculty of Science and Engineering.

CO2 to methanol catalysis requires a source of hydrogen and chemical energy. The researchers had the idea of using a compound called hydroborane (BH3), and the results have been spectacular. The reaction achieved is two times more effective than the best catalyst known – and it produces little waste. What makes the discovery even more compelling is the fact that the chemical reaction does not damage the catalyst, which can be reactivated by adding new substrate.

The only downside of the operation is the price tag. “Our approach to creating methanol is highly effective from a chemistry standpoint, but for now the process is expensive,” explained Professor Fontaine. “It takes a lot of energy to synthesize hydroborane, which makes it more expensive than methanol. We are working on ways to make the process more profitable by optimising the reaction and exploring other hydrogen sources.”

Meanwhile, scientists are making progress toward development of an “artificial leaf” that mimics a real leaf’s chemical magic with photosynthesis- but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks. That is among the conclusions in a newly available report from top authorities on solar energy who met at the first yearly Chemical Sciences and Society Symposium.

The gathering launched a new effort to initiate international cooperation and innovative thinking on the global energy challenge. The three-day symposium, which took place in Germany this past summer, included 30 chemists from China, Germany, Japan, the United Kingdom and the United States. It was organised through a joint effort of the science and technology funding agencies and chemical societies of each country, including the U. S. National Science Foundation and the American Chemical Society (ACS), the world’s largest scientific society.

The symposium series was initiated though the ACS Committee on International Activities in order to offer a unique forum whereby global challenges could be tackled in an open, discussion-based setting, fostering innovative solutions to some of the world’s most daunting challenges.

A “white paper” entitled “Powering the World with Sunlight,” describes highlights of the symposium and is available along with related materials here.

“The sun provides more energy to the Earth in an hour than the world consumes in a year,” the report states. “Compare that single hour to the one million years required for the Earth to accumulate the same amount of energy in the form of fossil fuels. Fossil fuels are not a sustainable resource, and we must break our dependence on them. Solar power is among the most promising alternatives.”

The scientists pointed out during the meeting that plants use solar energy when they capture and convert sunlight into chemical fuel through photosynthesis. The process involves the conversion of water and carbon dioxide into sugars as well as oxygen and hydrogen. Scientists have been successful in mimicking this fuel-making process, termed artificial photosynthesis, but now must finds ways of doing so in ways that can be used commercially. Participants described progress toward this goal and the scientific challenges that must be met before solar can be a viable alternative to fossil fuels.

Highlights of the symposium include a talk by Kazunari Domen, Ph.D., of the University of Tokyo in Japan. Domen described current research on developing more efficient and affordable catalysts for producing hydrogen using a new water-splitting technology called “photocatalytic overall water splitting.” The technology uses light-activated nanoparticles, each 1/50,000 the width of a human hair, to convert water to hydrogen. This technique is more efficient and less expensive than current technologies, he said.

Domen noted that the ultimate goal of artificial photosynthesis is to produce a liquid fuel, such as methanol, or “wood alcohol.” Achieving this goal would fulfill the vision of creating an “artificial leaf” that not only splits water but uses the reaction products to create a more usable fuel, similar to what leaves do.

Also, taking inspiration from trees, scientists have developed a battery made from a sliver of wood coated with tin that shows promise for becoming a tiny, long-lasting, efficient and environmentally friendly energy source.

Their report on the device-1,000 times thinner than a sheet of paper- appears in the journal Nano Letters.

Liangbing Hu, Teng Li and colleagues point out that today’s batteries often use stiff, non-flexible substrates, which are too rigid to release the stress that occurs as ions flow through the battery. They knew that wood fibers from trees are supple and naturally designed to hold mineral-rich water, similar to the electrolyte in batteries. They decided to explore use of wood as the base of an experimental sodium-ion battery. Using sodium rather than lithium would make the device environmentally friendly.

Lead author Hongli Zhu and other team members describe lab experiments in which the device performed successfully though 400 charge-discharge cycles, putting it among the longest-lasting of all sodium-ion nanobatteries. Batteries using the new technology would be best suited for large-scale energy storage applications, such as wind farms or solar energy installations, the report indicates.

Meanwhile, University of Delaware (UD) chemist Joel Rosenthal is driven to succeed in the renewable energy arena. Working in his lab in UD’s Department of Chemistry and Biochemistry, Rosenthal and doctoral student John DiMeglio have developed an inexpensive catalyst that uses the electricity generated from solar energy to convert carbon dioxide, a major greenhouse gas, into synthetic fuels for powering cars, homes and businesses.

The research is published in the June 19 issue of the Journal of the American Chemical Society.

Gold and silver represent the “gold standard” in the world of electrocatalysts for conversion of carbon dioxide to carbon monoxide. But Rosenthal and his research team have pioneered the development of a much cheaper alternative to these pricey, precious metals. It’s bismuth, a silvery metal with a pink hue that’s a key ingredient in Pepto-Bismol, the famous pink elixir for settling an upset stomach.

An ounce of bismuth is 50 to 100 times cheaper than an ounce of silver, and 2,000 times cheaper than an ounce of gold, Rosenthal says. Bismuth is more plentiful than gold and silver, it is well distributed globally and is a byproduct in the refining of lead, tin and copper.

Moreover, Rosenthal says his UD-patented catalyst offers other important advantages: selectivity and efficiency in converting carbon dioxide to fuel.

“Most catalysts do not selectively make one compound when combined with carbon dioxide- they make a whole slew,” Rosenthal explains. “Our goal was to develop a catalyst that was extremely selective in producing carbon monoxide and to power the reaction using solar energy.”

Carbon monoxide is used industrially in the water-gas shift reaction to make hydrogen gas. It also is a prime feedstock for the Fischer-Tropsch process, which allows for the production of synthetic petroleum, gasoline and diesel.

Commercial production of synthetic petroleum is under way or in development in a number of countries, including Australia and New Zealand, China and Japan, South Africa and Qatar.

Rosenthal says that if carbon dioxide emissions become taxed in the future due to continuing concerns about global warming, his solar-driven catalyst for making synthetic fuel will compete even better economically with fossil fuels.

 

Information from Guardian was used in this report.