彭蒙惠英语：20110131 MP3在线课程 Making Energy Like Plants Do
Making Energy Like Plants Do
by Robert S. Boyd / (c) 2008. Distributed by McClatchy-Tribune Information Services.
Scientists making progress on artificial photosynthesis
Scientists who are seeking new sources of clean energy are trying to mimic the way plants and trees do it, by converting sunlight into fuel.
Unlike standard solar panels on rooftops or arrays of solar collectors in the desert, this is a form of "artificial photosynthesis." It tries to imitate the elaborate system that microbes, algae and green plants use.
If it works, artificial photosynthesis could help reduce the world's dependence on fossil fuels without generating climate-warming greenhouse gases.
Daisy-chain molecules generating hydrogen
Tom Mallouk, a professor of chemistry and physics at Pennsylvania State University, has built an experimental device that uses light to launch a daisy-chain of tiny molecules that pass electrons the particles that carry electrical energy from one to another. When the electrons reach the end of the chain, they take part in a chemical process that generates hydrogen, which can be stored for use later as a fuel, he explained.
Mallouk's molecular clusters are about 2 nanometers (billionths of a meter) in size. They float amid red-orange dyes that absorb sunlight and use its energy to split water into its basic elements, oxygen and hydrogen.
Manganese atoms break water molecules
Yet another preliminary technique is being tested by an international team of scientists. They use a molecular cluster containing atoms of manganese, a chemical used in plant photosynthesis to help break water molecules apart into hydrogen and oxygen.
Later, the oxygen and hydrogen may be recombined in a fuel cell, creating carbon-free electricity to power a house or electric car, day or night.
"We have copied nature, taking the elements and mechanisms found in plant life and re-creating one of those processes in the laboratory," said Leone Spiccia, one of the team's leaders. "The production of hydrogen using nothing but water and sunlight offers the possibility of an abundant, renewable, green source of energy for the future."