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Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - haikuman - 08-17-2013
http://news.yahoo.com/sustainable-energy-breakthrough-hydrogen-fuel-sunlight-140037620.html
This Research in Action article was provided to LiveScience in partnership with the National Science Foundation.
A University of Colorado Boulder research team has moved closer to what some call the Holy Grail of a sustainable hydrogen economy — splitting water with sunlight.
The CU-Boulder team has devised a solar-thermal system designed to use a vast array of ground mirrors to concentrate sunlight onto a single point atop a central tower up to several hundred feet tall. The tower would gather heat to roughly 2,500 degrees Fahrenheit (1,350 Celsius) and then deliver it into a reactor containing chemical compounds known as metal oxides.
As the metal oxide compound heats up, it releases oxygen atoms, changing its material composition and causing the newly formed compound to seek out new oxygen atoms. The team showed that adding steam to the system would cause oxygen from the water molecules to adhere to the metal oxide surface, freeing up hydrogen molecules for collection as hydrogen gas. To get the steam, the concentrated sunlight beamed to the tower would heat the water to boiling.
Conventional theory holds that producing hydrogen through the metal oxide process requires 1) heating the reactor to a high temperature to remove oxygen 2) then cooling it to a low temperature before 3) injecting steam to re-oxidize the compound and release hydrogen gas for collection. The innovation here is that no swing in temperature is required. The whole process can be undertaken at the same temperature, and can be driven by turning a steam valve on or off.
With the new method, the amount of hydrogen produced to power fuel cells or for storage is entirely dependent on the amount of metal oxide (a combination of iron, cobalt, aluminum and oxygen), and how much steam is introduced into the system.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - Filliam H. Muffman - 08-17-2013
That would make it about 150 F lower than H2 production from hydrocarbon based feedstocks, and minus the cost of the feedstocks. I wonder if it is worth signing up for an account to see if they give even rudimentary calculations of how many Kcal/mole it takes in comparison to electrolysis of water.
If it does turn out to be within 200% of the cost of battery powered cars, it would be a very welcome breakthrough.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - DRR - 08-17-2013
GO BUFFS! YEAH SCIENCE!
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - davester - 08-17-2013
Sounds interesting, though there are two major unsolved issues of hydrogen as a fuel. The first is the outlandish cost of getting it from renewable sources, which this solution seems to be aiming at. However, the other massive issue is that hydrogen storage and transmission by pipeline is still economically unfeasible because the very small molecules leak out of most storage and piping setups. The most technically feasible hydrogen transmission technology is cryogenic (i.e. liquefying the hydrogen and transporting in refrigerated trucks), but that consumes more than a third of the energy present in the hydrogen in the first place.
My gut feeling is that these are such huge hurdles that it will be many decades, if ever, before hydrogen becomes an economically feasible fuel, and by that time battery technology will have evolved so far that hydrogen will be irrelevant. I think the smart money today is going into batteries.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - Speedy - 08-18-2013
Hydrogen is conveniently stored underground where it can be used in a power station and 'transported' as electricity. Make hydrogen, wind turbines are my favorite method of making electricity for electrolysis, store it underground until needed in a power station. An analog is our common methane power stations.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - GGD - 08-18-2013
Speedy wrote:
Hydrogen is conveniently stored underground where it can be used in a power station and 'transported' as electricity. Make hydrogen, wind turbines are my favorite method of making electricity for electrolysis, store it underground until needed in a power station. An analog is our common methane power stations.
So, with this method of making hydrogen, would there be more efficient ways of turning the same concentrated thermal energy into electricity (maybe by creating steam) rather than producing hydrogen and then burning it.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - ztirffritz - 08-18-2013
There are already solar concentrators that utilize molten sodium to store solar energy for later use. It makes steam in the day and uses the molten sodium to continue production at night. I think the system has limited application. I still think that wind and solar should be used to store power for later regulated retrieval rather than directly contribute to the grid. Even if it is terribly inefficiently, who cares? Wnd and sun light are free. The problem having the systems directly connected to the grid is supply is not reliable. Stored hydrogen, elevated weight, charged batteries, compressed air etc all have know amounts of potential energy and known rates of distribution.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - cbelt3 - 08-18-2013
Hydrogen is a logical replacement for natural gas in the worlds energy systems. Making ocean bordered deserts a good candidate.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - Speedy - 08-18-2013
ztirffritz wrote: I still think that wind and solar should be used to store power for later regulated retrieval rather than directly contribute to the grid. Even if it is terribly inefficiently, who cares? Wnd and sun light are free. The problem having the systems directly connected to the grid is supply is not reliable.
Agreed. Direct connection to the grid is the worst thing for renewables. But storage isn't happening and that paradigm shift will not happen as long as other (dirty) energy producers can convince the public that renewables are not a dependable source of electric power. It's all about the hydrocarbon economy when it should be about the hydrogen economy.
Re: Sustainable Energy Breakthrough: Hydrogen Fuel from Sunlight - AllGold - 08-18-2013
Other than the obvious fact that it requires an ocean which most of the country (and world) doesn't have, I wonder why we don't use more tidal power, which is consistent.