Hybird Solar Converter Harvests Both Sunlight and Heat At 85% Efficiency (newatlas.com) 55
Engineers have developed a new type of hybrid solar energy converter, which uses energy from the Sun to create both electricity and steam. The device reportedly has high efficiency and runs at low cost, allowing industry to make use of a wider spectrum of solar energy. New Atlas reports: The device looks like a satellite dish, with a small device suspended over the center of a parabolic collector. The dish part is mirrored, and focuses the sun's rays onto the box in the middle. The bottom of this section contains multi-junction solar cells, which collect and convert visible and ultraviolet light into electricity. But the clever part is that these cells redirect the infrared light -- the heat energy -- to a separate thermal receiver, higher up in the device. This receiver is essentially a cup-shaped cavity surrounded by pressurized water, which captures the heat and turns into steam.
The team says that the total collection efficiency is 85.1 percent, meaning a very high amount of the Sun's energy is converted into either electricity or heat. The steam can be heated up to 248C (478F), which is a much higher temperature than many other thermal energy collectors. This means it's hot enough for many industrial processes, such as drying, curing, sterilizing, and pasteurizing. The other advantage is cost. The team reports that once scaled up, the hybrid device could run for as little as 3 cents per kilowatt hour. The research was published in the journal Cell Reports Physical Science.
The team says that the total collection efficiency is 85.1 percent, meaning a very high amount of the Sun's energy is converted into either electricity or heat. The steam can be heated up to 248C (478F), which is a much higher temperature than many other thermal energy collectors. This means it's hot enough for many industrial processes, such as drying, curing, sterilizing, and pasteurizing. The other advantage is cost. The team reports that once scaled up, the hybrid device could run for as little as 3 cents per kilowatt hour. The research was published in the journal Cell Reports Physical Science.
There is only one thing to say (Score:2)
Imagine a Beowulf cluster of these.
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Not sure why you'd need that many hot grits.
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3 cents per kilowatt hour ... (Score:2)
compares well to cost of generation by other sources [wikipedia.org]. It does not sound as if the capital costs would be huge.
I'm a little dubious [Re:3 cents per kilowatt...] (Score:2)
Heat can be collected from sunlight with pretty much 100% efficiency, of course. The question is, can us use the heat? Some of the heat energy recovered is at "less than 100 C" (this is "hot water" temperatrue- they don't mention that point in the summary); this is low grade heat and not very valuable. But if I'm reading the figure 5E right, it's a LOT less than 100 C: the "low temperature heat" is actually only 35 C-- not even body temperature. (And the "high temperature heat" is o
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Solar thermal well below 100% efficiency (Score:2)
Heat is captured from sunlight at well below 100% efficiency -- always has been, always will be.
A heat-collecting solar panel such as for heating water for warming air needs some manner of transparent cover to let sunlight into the device yet prevent all the collected heat from escaping. That cover is often a pane of glass but it could be plastic or other optically transparent material. It is possible to apply a high amount of thermal insulation to the back and sides of this collector, but the front of
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So you've never heard of having a vacuum between two panes of glass. This is how the solar water heaters used on arctic bases are made - a glass tube inside another glass tube with a vacuum between.
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A vacuum gap doesn't stop radiative loss, we only know how to make partially 1way valves for radiant energy. The vacuum stops conductive loss, allowing much higher working fluid temperatures. What does the heavy lifting is moving the fluid and it's captured heat away from the capture site before it can radiate away. Higher temperatures make heat transfer more effective for the same volume of working fluid.
You can go the other way, shift the heat faster than it can be lost. In practical passive air heating,
Never heard of a vacuum between panes of glass (Score:2)
I was in a trance state when I wrote "it may be cost effective to use a double glass with a vacuum gap to greatly reduce conductive heat loss."
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What about using something like a VantaBlack-style absorber/insulator instead of split insulator and absorber? Or, melanin? (yes, melanin. [arstechnica.com])
The researchers also discovered the secret to this highly efficient light absorption: melanin, a pigment also found in human skin that protects us from damage from sunlight. The melanin is stuffed into granules known as melanosomes, which in turn are contained within cells known as melanophores. They form a continuous layer in the dermis (the deeper layers of skin), according to Osborn. "This arrangement provides a continuous and unbroken layer of pigment-containing cells and ensures that this layer is the first thing encountered by light hitting the fish," she said. "The pigment effectively absorbs most of the light that strikes the granule."
The size and shape of those granules also matters, since they scatter any light that isn't immediately absorbed sideways into the pigment layer so it can be absorbed by neighboring pigment-containing cells. It's essentially a very thin, highly efficient light trap. "The blackest fish was as black as VantaBlack," said Osborn—that is, as black as one of the darkest substances yet known. "VantaBlack traps light in tightly packed carbon microtubules while these fish absorb the light with the pigment and do it extremely efficiently by optimizing the size and shape and packing of the pigment granules themselves."
"In pretty much all ultra-black materials you need both scattering and absorption," said co-author Alexander Davis, a graduate student at Duke. "In all other animals that we know of, the scattering in ultra-black coloration comes from either a chitin or keratin matrix, like a bird feather or butterfly scale, and the absorption comes from melanin embedded within those matrices. In these fishes, the scattering and absorption are both coming from the melanosomes themselves. This makes the mechanism a bit simpler because there is no structural scaffold necessary."
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Heat is captured from sunlight at well below 100% efficiency -- always has been, always will be.
Damn close to 100%. The low level heat the are crowing about is 37C. The reradiative loss at that temperature is very close to nothing.
Stefan-Boltzmann T^4 not the only loss (Score:2)
A thermal solar panel can have significant conductive loss. Even a vacuum gap can have sneak-path conductive loss where the two sides of this gap are joined together.
I don't have all of the efficiency and loss figures at my finger tips because I was studying all of this 40 years ago when a lot of young whippersnappers were just an aspiration. But thermal solar panels have losses, and I was mentioning this, not to denigrate solar panels but in response to "why are these guys bragging about only 85% effi
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A thermal solar panel can have significant conductive loss. Even a vacuum gap can have sneak-path conductive loss where the two sides of this gap are joined together.
And this has all those conductive and other losses too. They just don't mention them.
...The article, by the way, was about a concentrating collector offering much higher than 37C temperature.
No, the summary was about a concentrating collector offering much higher than 37C temperature.
The article shows that they got 85% efficiency by including as "energy collected" the heat that everybody else would call "waste heat", at 35C.
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It depends upon the climate. In areas where more heating is required than cooling upon a year round basis, really handy for them. In a region where more cooling is required than heating, yeah, not so useful. Still useful for commercial laundries and all those places that boil food. Then you have all those industrial cleaning processes, they can also use heat.
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Graph 5E is literally just for cooling the PV modules... that heat would be useful depending on where your particular application is for instance that heat could be dumped into melting driveway ice etc... instead of doing it electrically or keeping your bathroom floor warm.
They count waste heat as useable power (Score:2)
You are in fact reading it wrong.... the outlet temp of graph 5F is 200C... and they state that 250C is possible with some work on increasing how much heat the PV modules can handle.
Nope. Read it again. They are counting that energy as having been harvested.
Here is the accounting in the section "Hybrid System Performance":
"the electric power, tCPV cooling, and thermal receiver heat make up 5.4% ± 0.2%, 35.2% ± 2.1%, and 44.5% ± 2.6% of the total dish incident power, with a total average power capture of 2,180 W. The average power output for electricity, hot water, and high-temperature steam is 138 ± 5, 903 ± 45, and 1,139 ± 57 W, respectively."
The
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Capital costs for users depends on the scale at which you manufacture the thing.
<car_analogy>Consider the Chevy Spark; you can buy one brand new for under $13,000. But if you had to *build* just one from scratch, it'd cost you millions. The engineering and tooling costs of a manufactured product are amortized across the units you sell, and in a case of a car that's tens of thousands a year..</car_analogy>
So the economic practicality of this thing depends on how many users need a source of ther
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compares well to cost of generation by other sources [wikipedia.org]. It does not sound as if the capital costs would be huge.
No mention of the cost / kW at night ... :-)
Both electricity *and* steam? (Score:2)
Bullshit sense is tingling (Score:2)
I have a feeling something about this would put that efficiency number in perspective, I just can't put my finger on it.
If it's not snakeoil, yay for us all?
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It is not snakeoil. There is not really a physical limitation why such a device cannot reach 85% efficiency.
But hold on with the yay just yet. This is based on a parabolic mirror. So it gives you electricity and steam under two conditions: The sun is shining (cloud cover reduces both visible and infrared components a lot) and you need a mechanical system to move the mirror. So instead of the more or less simple installation of solar panels on your rooftop you need a large dish with a tracking system in your
Re: Bullshit sense is tingling (Score:1)
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Yes, absolutely. The thing is that a rail or tracking system that can support large parabolic mirrors under potentially strong loads from wind might be the most expensive component of the entire system. Not that it can't be done but compare this with a simple solar panel mounting rack without any movable parts.
There is a niche for something like this but in the large majority of cases you want to avoid any system that needs to track the sun.
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I think at some point the same will be said about solar panel mounting racks. All that expensive metal in the rack and panel to get rigidity, when you can just roll out a flexible panel across the desert floor, "inflate" with some foam it to give it some angle and steak it down.
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Re: Bullshit sense is tingling (Score:1)
It's for industrial use. What is a homeowner going to do with the steam? Drive a turbine in the backyard?
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Well that's not totally unthinkable, because in these days we have solar cells on the roofs of our houses, which ancestors started out powering space crafts.
Sometimes we use heat-electricity coupled devices using fossil fuels as well as biogas - a normal "motor" where the mechanical power drives and electrical generator, while the waste heat from the engine is used to heat water for houses.
So why is having a turbine generating electricity for homes that unthinkable for you? If it works correctly it will inc
Re: Bullshit sense is tingling (Score:2)
Cost and complexity.
For people with pools, this might be an interesting way to heat although pool solar heating is dirt cheap already with nothing more than a large black plastic panel with water tubes running through it and a simple pump. Otherwise how much hot water does a home really use? You'd NEVER recover the cost of the system for daily hot water use.
Normal electric home use is already covered for most with a standard solar panel and optional battery system.
Industry, yes. Put this puppy up at larg
Re: Bullshit sense is tingling (Score:2)
Actually, I can see quite a bit of use for that heat in a home.
1. Hot water.
2. Heating.
3. Cooling.
Now you're probably wondering about that cooling statement. For the answer to that, take a look at an absorption refrigerator, which requires a heat source to drive the process instead of mechanical compression of gas. And the process can also be used for air conditioning.
So all year long, the collected heat can be used for hot water and food preservation. When heating is needed during cold weather, the heat ca
Re: Bullshit sense is tingling (Score:2)
I'm not saying you can't heat your home this way. I'm saying it isn't efficient. Right now I have a tank less gas powered water heater. My gas heating bills are trivial. To use this thing I have to buy it, get it installed and hooked into my both power and water lines, I probably need a water tank and now have maintenance costs on this new system which will require special skills and parts to repair.
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Well, a homeowner can heat water during the day or generate electricity with the steam using a turbine, a thermoelectric generator, etc.
For industrial use you want steam available 24/7, so this can provide additional energy but definitely won't be the main source. Unless you combine this with molten salt storage but than you basically replicated the Solana Generating Station on a small scale with all benefits and issues.
Re: Bullshit sense is tingling (Score:2)
See my reply above to other guy. Same answer.
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Tracking systems are already common. Solar thermal plants require them, and a lot of photovoltaic solar farms use them too. That isn't an obstacle compared to current technology.
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Solar thermal collectors have an efficiency of 85+ Percent, however they just collect heat and do not generate electricity.
Whereas solar cells produce electricity normally with 20-25 % efficiency - where this idea tries to fill the gap.
Depends what they mean by "efficiency" (Score:2)
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Minor change - not innovation (Score:2)
Re: Minor change - not innovation (Score:2)
I agree. 85% collection of energy is great, but says nothing about what fraction of that gets converted to usable energy for an end user. Steam/superheated water now needs to be converted to electricity (or I guess stored for hot water usage), which has losses.
My car has 100% efficiency (Score:1)
One part is converted into movement, the rest into heat.
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Hybird (Score:1)
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Hey Lynyrd Skynyrd, play "Hybird" instead of "Freebird"!!!
Pronounced Leonard Skinner (Score:2)
In a PBS documentary on the Muscle Shoals music community, which includes a talented group of studio musicians called "The Swampers" mentioned on their hit recording "Sweet Home Alabama", members of the band explain that their name is a disguised version of their fascist high-school principal with whom band members had "interactions", and they pronounce it "Leonard Skinner." Hence "Hybird" is still pronounce "high-bred."
I guess it is something like the chemically engineered goo inside a junk-food snack
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-Captain Obvious to the rescue.
Heatpump's 2nd life (Score:2)
Repurposed heatpumps to generate electricity with a solar sidekick circumvents solar in-efficiency maybe?
Stop thinking of just electricity (Score:2)
Many people here are thinking of converting the heat collected by this device and converting that heat into electricity. Because, after all, there's only so much hot water a home can use. But that heat can be used for more than hot water. And using that heat can reduce the amount of electricity the house requires. Immediate uses that I can see for the collected heat.
1. Hot water.
2. Food cooling and freezing via absorption refrigeration.
3. Home heating during cold weather.
4. Home cooling during hot weather.
Significant problems with this proposal (Score:2)
So, lots of things to discuss here. Start with the paper itself:
https://www.cell.com/cell-reports-physical-science/fulltext/S2666-3864(20)30139-9
First is their calculation of efficiency. The collector is 2.72 m^2 and AM1.5 is 1000W/m so they are collecting from about 2,720 W of energy. From the paper, they collect 138 W electric power, 903 W hot water, and 1,139 W steam. 139+903+1139 = 2180 W collected. 2180 / 2720 = 80%, not 85%. Which is good, because the Carnot limit is 86%, and anyone that claims that