'Hydricity' concept uses solar energy to produce power round-the-clock

December 15, 2015 by Emil Venere
Solarkraftwerk Waldpolenz, the first Solar 40-MW CdTe PV Array installed by JUWI Group in Brandis, Germany. Credit: JUWI Group

Researchers are proposing a new "hydricity" concept aimed at creating a sustainable economy by not only generating electricity with solar energy but also producing and storing hydrogen from superheated water for round-the-clock power production.

"The proposed hydricity concept represents a potential breakthrough solution for continuous and efficient power generation," said Rakesh Agrawal, Purdue University's Winthrop E. Stone Distinguished Professor in the School of Chemical Engineering, who worked with chemical engineering doctoral student Emre Gençer and other researchers. "The concept provides an exciting opportunity to envision and create a to meet all the human needs including food, chemicals, transportation, heating and electricity."

Hydrogen can be combined with carbon from agricultural biomass to produce fuel, fertilizer and other products.

"If you can borrow carbon from sustainably available biomass you can produce anything: electricity, chemicals, heating, food and fuel," Agrawal said.

Findings are detailed in a research paper appearing this week (Dec. 14) in the online early edition of Proceedings of the National Academy of Sciences.

Hydricity uses solar concentrators to focus sunlight, producing high temperatures and superheating water to operate a series of electricity-generating steam turbines and reactors for splitting water into hydrogen and oxygen. The hydrogen would be stored for use overnight to superheat water and run the steam turbines, or it could be used for other applications, producing zero greenhouse-gas emissions.

"Traditionally electricity production and have been studied in isolation, and what we have done is synergistically integrate these processes while also improving them," Agrawal said.

The PNAS paper was authored by Gençer; former chemical engineering graduate student Dharik S. Mallapragada; François Maréchal, a professor and chemical process engineer from École Polytechnique Fédérale de Lausanne in Switzerland; Mohit Tawarmalani, a professor and Allison and Nancy Schleicher Chair of Management at Purdue's Krannert School of Management; and Agrawal.

In superheating, water is heated well beyond its boiling point – in this case from 1,000 to 1,300 degrees Celsius - producing high-temperature steam to run turbines and also to operate solar reactors to split the water into hydrogen and oxygen.

"In the round-the-clock process we produce hydrogen and electricity during daylight, store hydrogen and oxygen, and then when is not available we use hydrogen to produce electricity using a turbine-based hydrogen-power cycle," Tawarmalani said. "Because we could operate around the clock, the steam turbines run continuously and shutdowns and restarts are not required. Furthermore, our combined process is more efficient than the standalone process that produces electricity and the one that produces and stores hydrogen."

The system has been simulated using models, but there has been no experimental component to the research.

"The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-hour cycle, is shown to approach 35 percent, which is nearly the efficiency attained by using the best photovoltaic cells along with batteries," Gençer said. "In comparison, our proposed process stores energy thermo-chemically more efficiently than conventional energy-storage systems, the coproduced has alternate uses in the transportation-chemical-petrochemical industries, and unlike batteries, the stored energy does not discharge over time and the storage medium does not degrade with repeated uses."

Agrawal said, "The concept combines processes already developed by other researchers while also improving on these existing processes. The daytime and night-time systems would use much of the same equipment, allowing them to segue seamlessly, representing an advantage over other battery-based solar technologies."

Explore further: Method could make hydrogen fuel cells more efficient

More information: Hydricity: A Sunshine Route to Sustainability. Proceedings of the National Academy of Sciences.

Related Stories

Method could make hydrogen fuel cells more efficient

September 23, 2015

With the growth of wind and solar energy and the increasing popularity of electric vehicles, many people in the U.S. may have forgotten about the promised "hydrogen economy." But in research labs around the world, progress ...

Recommended for you

'Personal flying machine' maker plans deliveries this year

April 24, 2017

A Silicon Valley "flying car" startup, Kitty Hawk, reportedly backed by Google co-founder Larry Page, released a video Monday of its airborne prototype and announced plans for deliveries of a "personal flying machine" this ...

26 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Eikka
3 / 5 (6) Dec 15, 2015
but there has been no experimental component to the research.


FIgures.

The reason why steam turbines don't commonly work with 1000-1300 C steam is because it becomes highly corrosive to just about any metal between 500-800 C.

In practice they'll also run into the same problem as the Ivanpah solar concentrator. In theory, they have so many sunny days a year and should produce so much electricity, but the theory assumes that a sunny day means continuous sunshine.

In practice they got cloud coverage that rolls over the mirrors and modulates the sun input, and due to the thermal inertia of the system their collector temperature goes down and the efficiency goes down.

It works like a dimmer switch on a lightbulb - you get full power but it goes on-off-on-off faster than the bulb can react, so it gets dimmed by the on/off ratio.
cmbasak
5 / 5 (2) Dec 15, 2015
"in this case from 1,000 to 1,300 degrees Celsius" I think it is wrong. It might be pressure term not temperature. Might be in Psig.
tear88
4.8 / 5 (6) Dec 15, 2015
Well, this is encouraging: ""The overall sun-to-electricity efficiency of the hydricity process, averaged over a 24-hour cycle, is shown to approach 35 percent, which is nearly the efficiency attained by using the best photovoltaic cells along with batteries,".

Or not: "The system has been simulated using models, but there has been no experimental component to the research."

Models can be very useful, but, until a system has actually been constructed, we won't know how feasible it is.
gkam
2.3 / 5 (10) Dec 15, 2015
Well, it beats this:
http://www.utilit.../410826/

We are subsidizing the coal and nuke plants of a greedy utility which made BAD decisions, and now wants us to bail them out.

antialias_physorg
5 / 5 (9) Dec 16, 2015
Models can be very useful, but, until a system has actually been constructed, we won't know how feasible it is.

Well, that's the point then, isn't it? Model something and see if it could make sense - then go out and test the model.
Much better this way than to just build something and then find out that one could have seen, from theretical work, that it doesn't make sense.
Caliban
5 / 5 (5) Dec 16, 2015
The reason why steam turbines don't commonly work with 1000-1300 C steam is because it becomes highly corrosive to just about any metal between 500-800 C.


Gee, eikka, maybe they'll figger that out, somehow. Coal- and gas-fired plants use steam generated from water heated via the combustion of those fuels to drive turbines --so there's absolutely no reason why this can't be incorporated into the hydricity process.

In practice they'll also run into the same problem as the Ivanpah solar concentrator. In theory, they have so many sunny days a year and should produce so much electricity. but the theory assumes that a sunny day means continuous sunshine.

In practice they got cloud coverage that rolls over the mirrors and modulates the sun input, and due to the thermal inertia of the system their collector temperature goes down and the efficiency goes down.


Duh-gain: stored H/O can be burned to keep the boilers'n'turbines a-turnin'

What is your real objection?
Caliban
5 / 5 (6) Dec 16, 2015
The reason why steam turbines don't commonly work with 1000-1300 C steam is because it becomes highly corrosive to just about any metal between 500-800 C.


Gee, eikka, maybe they'll figger that out, somehow. Coal- and gas-fired plants use steam generated from water heated via the combustion of those fuels to drive turbines --so there's absolutely no reason why this can't be incorporated into the hydricity process.

In practice they'll also run into the same problem as the Ivanpah solar concentrator. In theory, they have so many sunny days a year and should produce so much electricity. but the theory assumes that a sunny day means continuous sunshine.

In practice they got cloud coverage that rolls over the mirrors and modulates the sun input, and due to the thermal inertia of the system their collector temperature goes down and the efficiency goes down.


Duh-gain: stored H/O can be burned to keep the boilers'n'turbines a-turnin'

What is your real objection?
Eikka
2.3 / 5 (6) Dec 17, 2015
Gee, eikka, maybe they'll figger that out, somehow. Coal- and gas-fired plants use steam generated from water heated via the combustion of those fuels to drive turbines --so there's absolutely no reason why this can't be incorporated into the hydricity process.


Those turbines have the exact problem I described. You can't superheat the steam past about 500 degrees because the turbine blades start to dissolve. That's why simple steam turbines are limited in their efficiency to about 35-40% due to the limited temperature they're able to operate at.

Duh-gain: stored H/O can be burned to keep the boilers'n'turbines a-turnin'


The issue hasn't got anything to do with the hydrogen - it's the problem of getting the steam up to those high temperatures when the sun is shining intermittently between clouds. When the cloud passes, the temperature starts to rise, but then another cloud comes by and the collector never reaches the 1000 C required for the process to work.
Eikka
2.1 / 5 (7) Dec 17, 2015
What is your real objection?


The theory of the system is obviously the thermal decomposition of water - there's no other reason why you would need to heat it to 1000-1300 C - because water starts to split spontaneously at over 800 C - that is also the reason why it turns corrosive because of the free oxygen. At lower temperatures between about 500-800 C it splits catalytically in the presence of metals, especially iron, upon touching the turbine blades and pipe walls, and that corrodes the turbine blades like running it on acid vapors. The steam has to be cooled before passing into the turbine.

The extra heat is supposed to go into making the hydrogen, but burning hydrogen to keep the temperature up would be like blowing into your own sail.

The objection is that their theoretical consideration doesn't seem to take into account the fact that they may not always get full temperature output from the solar collectors.
Eikka
2.5 / 5 (6) Dec 17, 2015
Basically, you have a solar concentrator that makes superheated steam at >1000 C which is piped into a "reactor" that contains some catalyst that helps to break and separate the hydrogen and oxygen, and the leftover heat from this reaction is used to run electric generator turbines operating at lower temperatures. Then at night-time the stored hydrogen and oxygen are burned to run the turbines.

The case of the Ivanpah CSP facility illustrates the problem with that. It's a similiar system that has molten salt as the storage medium. When the sun shines steadily, the turbines get high temperature input and operate at high efficiency. When the sun doesn't shine steadily, the temperature at the turbine drops and the efficiency drops.

The difference between theory and practice was that the entire facility got the right amount of sunshine, but made less electricity than predicted. For this new case, that would mean generating less hydrogen than theorized.

gkam
2.8 / 5 (8) Dec 17, 2015
Yeah, Eiklka, and nuclear power turned out not to be "too cheap to meter". Let's see how many of each are built in the future.
Zzzzzzzz
4.1 / 5 (8) Dec 17, 2015
"The reason why steam turbines don't commonly work with 1000-1300 C steam is because it becomes highly corrosive to just about any metal between 500-800 C."
We routinely use superheated steam up to 1200 F or 600 C in thermal power plants the world over. This steam temperature is contained in P91 grade piping, enters steam turbines, and spins the rotors. The GE site mentions these temperatures as suitable for their D600/D400 reheat turbines.
Not sure you are as knowledgeable on this subject as you pretend to be, Eikka.....
Zzzzzzzz
4.4 / 5 (8) Dec 17, 2015
"You can't superheat the steam past about 500 degrees because the turbine blades start to dissolve."
Just check out what GE thinks about your assertion @ https://powergen....nes.html
where they advertise their reheat turbines, at those temperatures, and high pressures at the same time. GE doesn't "dissolve" their turbine blades.....
Zzzzzzzz
4.4 / 5 (7) Dec 17, 2015
""in this case from 1,000 to 1,300 degrees Celsius" I think it is wrong. It might be pressure term not temperature. Might be in Psig."

More likely Fahrenheit. The GE turbine models I mentioned above are capable of 2400 psi and 1800 psi, at 1200 F. The reheat systems I am used to dealing with supply turbines with superheated steam in the 1100 F and 1100 psi range.
Frosted Flake
1 / 5 (6) Dec 18, 2015
Bad idea.

You want to use discarded electric car batteries as your storage medium. You want to use thorium nuclear power to generate high temperatures for those other purposes.

Never heard of Thorium? It's one proton lighter than Uranium. And what nuclear power would have been if we had wanted power instead of bombs. Inexpensive, inexhaustible and idiot proof. Let's see if I can post you a link.

All you need to know about Thorium in 5 minutes.
https://www.youtu...67T7h6ZY
Eikka
2.3 / 5 (6) Dec 18, 2015
We routinely use superheated steam up to 1200 F or 600 C in thermal power plants the world over.


That might be. I wasn't being too specific about the temperature where water becomes corrosive, but it nevertheless does. By 800 C it definitely is corrosive and no turbine runs that high on steam.

More likely Fahrenheit.


Nope. It says Celsius in the source.
Eikka
1.7 / 5 (6) Dec 18, 2015
You want to use discarded electric car batteries as your storage medium


You won't have any, because lithium will be in such a short supply that any used battery will have to be recycled immediately.
betterexists
1 / 5 (4) Dec 18, 2015
We have so much DNA from Varieties of microorganisms, but still not able to get abundant gasoline made by them!
antialias_physorg
5 / 5 (6) Dec 19, 2015
We have so much DNA from Varieties of microorganisms, but still not able to get abundant gasoline made by them!

This might shock you, but organisms prioritize survival over 'producing stuff others need'. This means that efficiency of energy conversion/storage in plants is pretty low.

Also organisms do not optimize for "best" via evolution. They optimize for "better than" (as in "better than other organisms"). If a plant is 3.1% efficient at converting sunlight then it outperforms all the others that hover around 3.0% and will outbreed them. But at that point there is very little evolutionary pressure on that species of plant to get even better.
DavidW
1.8 / 5 (5) Dec 20, 2015
800F is about 1000 psi. Pin hole in a pipe would cut your arm off just by waving your arm over it unseen. Achieving 1400F over a 1" diameter with a slightly diffused focal point of a 4' square parabolic dish using reflective polyester (inflated under a glass cover) 12' away, is fairly straight forward and dirt cheap. So now we have potential dangers from the pressures at those temperatures and the death ray itself that would blind any eye not protected. These numbers require serious caution for safety.
EnricM
not rated yet Dec 21, 2015
Nice thread! You guys rock! Lot's of more interesting information in the comments than in the article itself, THX!
postfuture
1 / 5 (5) Dec 21, 2015
again with good intentions straight to hell -
e.g. - California's new solar power plant is actually a death ray that's incinerating birds mid-flight - http://www.extrem...d-flight -
how about stop and think a little about the whole planet and every creature on it. When we stop thinking only about our convenience and comfort?
gkam
3 / 5 (4) Dec 21, 2015
Do you live or work in a building with windows?

Look up how many birds are killed by them and put it into perspective.
Vietvet
5 / 5 (3) Dec 21, 2015
@postfuture

Did you read the entirety of your link?

"While it might sound like BrightSource has created some kind of bird-blasting death ray, it's important to keep things in perspective. Back in January, it was estimated that — in the US alone — between 365 million and 988 million birds are killed every year by crashing into windows. We're mostly talking about domestic, low-rise windows, too — not skyscrapers. Likewise, a study last year showed that domestic cats — yes, your beloved Fluffy — are killing more than a billion birds per year in the US."
http://www.extrem...d-flight

Zzzzzzzz
5 / 5 (2) Dec 21, 2015
We routinely use superheated steam up to 1200 F or 600 C in thermal power plants the world over.


That might be. I wasn't being too specific about the temperature where water becomes corrosive, but it nevertheless does. By 800 C it definitely is corrosive and no turbine runs that high on steam.

More likely Fahrenheit.


Nope. It says Celsius in the source.


If you don't know the numbers, don't talk as if you do. Many articles on this site have mixed up units of measure - temperature being the most common. The correct unit can usually be determined by logic. In this case, the right unit is degrees Fahrenheit.
antigoracle
1 / 5 (4) Dec 21, 2015
@postfuture

Did you read the entirety of your link?

"While it might sound like BrightSource has created some kind of bird-blasting death ray, it's important to keep things in perspective. Back in January, it was estimated that — in the US alone — between 365 million and 988 million birds are killed every year by crashing into windows. We're mostly talking about domestic, low-rise windows, too — not skyscrapers. Likewise, a study last year showed that domestic cats — yes, your beloved Fluffy — are killing more than a billion birds per year in the US."
http://www.extrem...d-flight


Brilliant. Billions of birds are killed by domesticated cats, so what's a few 100 thousand more kills, in a small concentrated area. I say, look for the number of dead decreasing as the local population gets wiped out.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.