Cow manure + sunlight + metal ore = hydrogen fuel?
A safe way for storing hydrogen
Rhett A. Butler, mongabay.com
August 11, 2005
The Solar Tower laboratory at the Weizmann Institute of Science.
Image from the Weizmann Institute of Science
Researchers led by Michael Epstein at the Weizmann Institute of Science in Israel think they may have an energy efficient way of collecting solar energy to generate hydrogen, a key input for green energy technologies like fuel cells. Currently, most hydrogen is produced by processes that require the combustion of fossil fuels which produce polluting greenhouse gases. Further, to date, finding safe and cost-effective means for the storage and transportation of hydrogen gas have proved elusive. Epstein’s process has the potential to address a number of these issues by “creating an easily storable intermediate energy source form from metal ore, such as zinc oxide,” according to a release from the Weizmann Institute of Science.”
The process works as follows. A beam of sunlight, concentrated using mirrors that track the sun, “heats up the zinc ore to about 1,200°C in a solar reactor in the presence of wood charcoal,” although charcoal produced from agricultural wastes like manure can also be used. “The process splits the ore, releasing oxygen and creating gaseous zinc, which is then condensed to a powder. Zinc powder can later be reacted with water, yielding hydrogen, to be used as fuel, and zinc oxide, which is recycled back to zinc in the solar plant.”
In their recent experiments, a “300-kilowatt installation produced 45 kilograms of zinc powder from zinc oxide in one hour, exceeding projected goals” says the release.
“The process generates no pollution, and the resultant zinc can be easily stored and transported, and converted to hydrogen on demand. In addition, the zinc can be used directly, for example, in zinc-air batteries, which serve as efficient converters of chemical to electrical energy. Thus, the method offers a way of storing solar energy in chemical form and releasing it as needed.”
The results from the project were presented at this week’s International Solar Energy Society 2005 Solar World Congress in Orlando, Florida. More information can be found at Weizmann Institute of Science or the ISES 2005 Solar World Congress
This news brief used quotes from a Weizmann Institute of Science press release and information from the Aug 11th 2005 edition of The Economist.