Harry Braun, Chairman of the Hydrogen Political Action Committee, has written article laying out some costs and arguing for the use of windpower to generate hydrogen for a hydrogen economy.
With state-of-the-art electrolyzers, about 55 kWh will be needed to manufacture the energy content of a gallon of gasoline in the form of gaseous hydrogen. Assuming electricity costs of 3 cents/kWh, the electricity costs alone would be $14.00/mBtu, which is equivalent to gasoline costing $1.60 per gallon. The cost and maintenance of the electrolyzer and related hydrogen storage and pumping system also needs to be factored in to the equation.
One problem that Braun brings up about liquid hydrogen as a transportation fuel source is that while a gallon of gasoline has 115,000 Btus of energy a gallon of liquid hydrogen has only 30,000 Btus. Therefore liquid hydrogen tanks would need to be much larger and at the same time stronger and insulted in order to hold the extremely cold liquid hydrogen. Not exactly an appealing prospect. Also, liquifying the hydrogen itself takes energy that boosts the costs by nearly a quarter.
Even if we accept his assumptions for how far down windpower costs could drop if mass produced his calculations take little account of the infrastructure costs for hydrogen for the huge transition that he envisions. Also, windpower seems a worse choice than photovoltaics for the United States in the long term in part because the wind farms have to be built where the wind is. Whereas with the move of people in the US toward the Southern parts of the country people have been moving toward where there is more solar power to be tapped. Eventually, (eventually? how long is eventually? er, I don't know) thin film photovoltaics will allow electric power to be generated much closer to where it is used.
Given the drawbacks of hydrogen as a power source it still seems possible that a big advance in battery technology could make batteries a viable alternative to hydrogen fuel cells.
An EE Times article from 2001 surveyed the field of battery development and experts think batteries viable as automotive power sources are still years away.
Similar efforts are in progress at Massachusetts Institute of Technology (MIT), where researchers have developed a competing lithium-polymer battery that could ultimately achieve energy densities of 300 W-hr/kg, according to its developers. The technology, which uses a multiple-layer configuration of polymer and metal resembling a potato chip bag, is funded by the Office of Naval Research and is said to be 5 to 10 years from commercialization.
That article does a good job of describing how far a battery technology would have to advance in order for it to become competitive for automotive applications. The MIT effort, if successful, would create batteries that would have about 4 times more power density than the nickel-metal hydride batteries found in the most expensive uncompetitive electric vehicles (whose market prices are way below manufacturing costs btw). That would make the batteries dense enough. The cost is a question though.
In a more recent article Donald Sadoway and John Heywood (director of MIT's Sloan Automotive Lab) are noticeably lacking in enthusiasm for hydrogen as an automotive power source.
“Their state of development is oversold,” said Heywood. Sadoway put it another way: “In the context of portable power, fuel cells are not a technology, they’re a laboratory curiosity.”
Among other things, fuel cells are now far too expensive for use in mainstream applications like cars. That’s because they’re made partly of platinum, the same metal used in expensive jewelry. And an alternative to platinum will be difficult to discover, said Sadoway; “that’s Nobel Prize-winning work.”
Another key challenge: “How are we going to produce, distribute and store the hydrogen” for fuel cells, asked Heywood. He pointed out that the production of hydrogen itself involves generating various greenhouse gases. “So when people argue that the fuel cell produces only water vapor, that’s deceptive in the context of a complete transportation system,” he said.
Battery technology is appealing from an infrastructure standpoint because batteries could be recharged at night when existing electric power plants run well below maximum capacity. Then when photovoltaics become cost effective vehicles could be recharged during the day.
Stationary applications for alternative power sources are not as hard. There are lots of future possibilities for better ways to get energy for stationary uses. Some NASA researchers think thin film batteries and thin film photovoltaic cells could be integrated into roof tiles that would collect and store electrical energy.
There are also numerous applications that could exploit integrated power devices. Examples of these include: battery and solar cell devices integrated into a roof tile to provide a total power system for homes, or solar-rechargeable power systems for the military, for recreational vehicles, for cell phones or for other consumer products designed to be used in remote locations. In summary, the same considerations that provide performance edges for space applications make these power technologies applicable for terrestrial needs both individually or used in tandem.
|Share |||Randall Parker, 2003 March 04 05:33 PM Energy Tech|