Posted on 12/17/2015 4:48:46 AM PST by thackney
Solar heat could help generate both electricity and hydrogen fuel at the same time in a system that scientists in Switzerland and the United States call "hydricity." Such a system could supply electricity round-the-clock with an overall efficiency better than many photovoltaic cells, researchers add.
There are two ways solar energy is used to generate electricity. Photovoltaic cells directly convert sunlight to electricity, while solar thermal power plants--also known as concentrating solar power systems--focus sunlight with mirrors, heating water and producing high-pressure steam that drives turbines.
Photovoltaic cells only absorb a portion of the solar spectrum, but they can generate electricity from both direct and diffuse sunlight. Solar thermal power plants can use more wavelengths of the solar spectrum, but they can only operate in direct sunlight, limiting them to sun-rich areas. Moreover, the highest conversion efficiencies reported yet for solar thermal power plants are significantly less than those for photovoltaic cells.
Scientists now suggest that coupling solar thermal power plants with hydrogen fuel production facilities could result in "hydricity" systems competitive with photovoltaic designs.
Today's solar thermal power plants operate at temperatures of up to roughly 625 degrees C. However, the researchers noted that solar thermal power plants are more efficient at higher temperatures. What's more, when they reach temperatures above 725 degrees C they can split water into it's constituents, hydrogen and oxygen.
An integrated "hydricity" system would produce both steam for generating electricity and hydrogen for storing energy. And each makes the other more efficient. Set to produce hydrogen alone, its production efficiency approaches 50 percent, the researchers claim. This is because the high-pressure steam the system generates can easily be used to pressurize hydrogen. The substantial amount of power needed to compress hydrogen fuel for later transport and use is often neglected when it comes to calculating hydrogen production efficiency.
Furthermore, this new solar thermal energy design can generate electricity with standalone efficiencies approaching up to an unprecedented 46 percent, researchers say. This is because the high-temperature steam leaving high-pressure turbines can run a succession of lower-pressure turbines, helping make the most of the solar thermal energy the system collects.
Moreover, the hydrogen fuel the system generates can be burned to generate electricity after nightfall, for round-the-clock power. The researchers say the efficiency of this hydrogen-to-electricity system could reach up to 70 percent, comparable to the highest reported hydrogen fuel cell efficiencies.
Altogether, the researchers say the sun-to-electricity efficiency of hydricity, averaged over a 24-hour cycle, might approach roughly 35 percent, nearly the efficiency attained using the best multijunction photovoltaic cells combined with batteries. In addition, they note that the hydrogen fuel the system produces could find use in transportation, chemical production, and other industries. Finally, unlike batteries, stored hydrogen neither discharges over time nor degrades with repeated use.
The scientists at Purdue University in West Lafayette, Ind., and the Federal Polytechnic School of Lausanne in Switzerland detailed their findings online 14 December in the journal Proceedings of the National Academy of Sciences.
A self-contained water system pumped threw an affixed turbine which rotates a shaft to two high output alternators and the electricity generated then goes to a battery bank is far more simple and applicable to what is available to every person . I have been using this system for my house and garage for over four years ... it has paid for itself at this point and I will be connecting my neighbors garage this year and getting a small payment which will cover any maintenance ....these complex systems are just that complex to the point that they leave no space for independence . With all of the ideas they keep playing with the cardinal “KISS” rule is ignored....for such an essential commodity to ignore it is a prime example of book smart street stupid.
what powers the pump?
Isn’t “Hydricity” somehow connected to the endless ways women try to hydrate their faces?
What drives the water?
It’s called, in most places, a “swamp cooler”, right?
Been around for several decades, right?
Assuming that they can find an insurer willing to deal with large volumes of pressurized hydrogen storage, then it would be far more efficient to convert the hydrogen to electricity with fuel cells than to simply burn it. Molten carbonate fuel cells are cheap, work at these elevated temperatures and do well with pure hydrogen.
How many acres per kilowatt will they have to purchase?
How do they plan to store the power generated?
How big is the demand for Hydrogen?
How much will they charge per hydrogen unit?
How many decades to recover initial costs?
How big a taxpayer subsidy will they need?
Does any of these ‘hydricity’ plants generate as much as one modestly sized coal fired plant?
Does the coat per kilowatt even approach that of a coal or gas plant?
That is not a problem. We already have hydrogen storage and hydrogen pipelines used in the Refining and Petrochem Industry.
http://www.airproducts.com/Microsites/h2-pipeline-supply.aspx
The issue is the cost. It is not more cost effective than other energy sources.
That very-high pressure hydrogen leaks directly through most conventional (ie, “affordable”) pipe steels.
But, this is green energy. Who cares how much it costs, and high inefficient it really is?
Hydrogen Pipelines and associated facilities already exist. It is used in the Petrochem and refining industry. Read down in this thread for links.
It is not a technical problem anymore, just a matter of cost.
imho greatest way to use this tech is to combine it with water desalination like waterfx does.
http://waterfx.co/
http://www.businessinsider.com/california-waterfx-solar-desalination-technology-aaron-mandell-2014-3
A water desalination plant is efficient when set up for continuous operation.
Shutting it down at sunset and back up a dawn leave a lot of equipment not operating a lot of time.
You have to build it twice or more as big to produce the same 24 hour output from a different energy source.
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