Nov 6 2009
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 1st Annual 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 organized 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 symposium focused on four main topics:
- Mimicking photosynthesis using synthetic materials such as the "artificial leaf"
- Production and use of biofuels as a form of stored solar energy
- Developing innovative, more efficient solar cells
- Storage and distribution of solar energy
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 fulfil 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.
Among the "take-home messages" cited in the report:
- There's no single best solution to the energy problem. Scientists must seek more affordable, sustainable solutions to the global energy challenge by considering all the options.
- Investing in chemistry is investing in the future. Strong basic research is fundamental to realizing the potential of solar energy and making it affordable for large-scale use.
- Society needs a new generation of "energy scientists" to explore new ways to capture, convert, and store solar energy.
"The meeting was an experiment worth trying," said Teruto Ohta, executive director of the Chemical Society of Japan.
Conference organizers expressed hope that the symposium will be the first of several to tackle "the global challenges of the 21st century and the indispensible role that the chemical sciences play in addressing these issues," said Klaus Mullen, president of the German Chemistry Association.
"Building on the success of this first symposium, we're now gearing up for the future, convening top chemical scientists to address other, equally pressing global challenges," said Julie Callahan of the ACS Office of International Activities and principal investigator on the project. "It is an exciting time to be a chemist!"