(PRWEB) October 17, 2003
"There is a great deal of interest in hydrogen as the new energy medium, because hydrogen can be extracted from many sources, using fossil fuels, nuclear power, and alternative energy sources such as wind, solar or biomass." said Jim Beyer, CEO of Vision Instruments. "But the physical characteristics of hydrogen gas are not favorable for storage. Hydrogen is very difficult to store even for stationary use, let alone for use in vehicles." Much effort has been expended to find a storage medium for hydrogen. These efforts have led to chemical hydrides, metallic hydrides, and even carbon nanotubes. To date, none have achieved the DOE weight, density and cost requirements for a fuel medium of the future.
"Hydrogen, while it looks attractive, may not be the best medium for transporting energy," says Atreya. "The most efficient and convenient medium depends on the renewable sources we can eventually congregate. For example, it may be that we can produce bio-fuel from cellulosic feed stock and develop appropriate machines to use it directly without adding a step first to convert it into hydrogen."
"Our approach is radical, perhaps even heretical," continues Beyer. "We've analyzed the hydrogen economy and found it wanting. And we aren't the only people who have noticed this." Recent articles in 'Science' and elsewhere have begun to question the efficacy or practicality of a hydrogen economy. "We propose instead to use two gases, methane and carbon dioxide, to support an energy economy. Instead of a single pipeline or tank of hydrogen, there are two pipelines or tanks, forming a circuit, much like an electrical circuit." Since the current infrastructure already supports natural gas, a methane economy could be readily incorporated in the current energy system. "The interesting thing is that the storage and transportation costs of the two gases are less than moving hydrogen singly. Furthermore, the physical characteristics of either gas is much more favorable than storing pure hydrogen. Methane or carbon dioxide can be stored today in existing gas well formations" says Beyer.
The carbon dioxide sent back to the energy source is reacted with hydrogen (produced from electrolysis) to produce methane. This is done in a device called a Sabatier reactor. The technology has been around for a hundred years, but has never been used in this application. "This means fuel cells are not required, no huge infrastructure changeovers, just carbon dioxide needed to fill the return pipe. This can include carbon-neutral sources such as ethanol production facilities. We've analyzed the overall system, and determined that it will be more efficient and less expensive than a pure hydrogen economy, will better motivate renewable energy development, and will better lower overall carbon dioxide emissions," says Beyer.