Converting heat directly to electricity? Thermoelectric nanomaterials are the answer

Getting Closer To THe Magic Number Of "30%"

If you have read any of the previous postings, the current standard for solar energy conversion is roughly 30%. That is what current solar cells provide using non-nano materials.

The following article was filed this week:

(Nanowerk News) IMEC has realized a single-junction GaAs solar cell on a Ge substrate with a record conversion efficiency of 24.7%. The efficiency was measured and confirmed by NREL (National Renewable Energy Laboratory, US). GaAs solar cells are used in satellite solar panels and earth-based solar concentrators.
IMEC realized this record on a single-junction GaAs cell, grown epitaxially on a Ge substrate with an improved micro-defect distribution. The record cell measures 0.25cm², and shows an efficiency of 24.7%, with an open-circuit voltage (Voc) of 999 mV, a short-circuit current (Jsc) of 29.7 mA/cm², and a fill factor of 83.2%. The cell was made under the ESA-IMAGER project. Umicore, a leading materials technology group, produced the Ge substrate through an optimized manufacturing technology, aimed at improving the intrinsic germanium crystal quality.
Improving the efficiency of this single-junction GaAs cell is a further step in the development of a hybrid monolithic/mechanically stacked triple-junction solar cell. This type of solar cells consists of stacks of solar cells made of different semiconductors, carefully chosen to absorb the solar spectrum as efficiently as possible. Among the many possible combinations, IMEC focuses on stacked cells consisting of top cells with III-V materials and bottom cells made from Ge. With this combination, IMEC is targeting a conversion efficiency of 35% and more. The resulting stacks can be used in satellites and earth-based concentrators, where high-efficiency energy conversion is paramount.

The benefits of being able to move solar energy ventures into the nano arena are mostly cost related. However, when you consider the new graphene production that allows for sheets that are actually fairly large (6'X3'....you could make a twin sheet out of one), and its possible use as a substrate, it gets more exciting.

Special Anode Coating Nearly Doubles Efficiency Of Nanosolar Cells

This is separate work. It would be interesting to see an amalgomation of these guys work. It would seem that if they communicated, they could achieve.

Where is our resident nanotechnologist, fuelcell?

Would you not believe that applying the anode coating to the above results could possibly see a possible improvement over the 24.7%? Possibly exceeding the 30% benchmark seen using conventional technology?

In contrast to earlier approaches for anode coating, the Northwestern nickel oxide coating is cheap, electrically homogeneous and non-corrosive. In the case of model bulk-heterojunction cells, the Northwestern team has increased the cell voltage by approximately 40 percent and the power conversion efficiency from approximately 3 to 4 percent to 5.2 to 5.6 percent.
The researchers currently are working on further tuning the anode coating technique for increased hole extraction and electron blocking efficiency and moving to production-scaling experiments on flexible substrates.

[edit on 26-2-2008 by bigfatfurrytexan]

How To Make Graphene

A simple way to deposit thin films of carbon could lead to cheaper solar cells.

Graphene--a flat single layer of carbon atoms--can transport electrons at remarkable speeds, making it a promising material for electronic devices. Until recently, researchers had been able to make only small flakes of the material, and only in small quantities. However, Rutgers University researchers have developed an easy way to make transparent graphene films that are a few centimeters wide and one to five nanometers thick.

Thin films of graphene could provide a cheap replacement for the transparent, conductive indium tin oxide electrodes used in organic solar cells. They could also replace the silicon thin-film transistors common in display screens. Graphene can transport electrons tens of times faster than silicon, so graphene-based transistors could work faster and consume less power.

With gas at 4 dollars a gallon, making cheaper solar panels could push the efficiency threshold that is deemed acceptable down to 20-25% (instead of the current 30% threshold that is currently seen as the holy grail).

This is a very promising development, especially since i live in the desert of West Texas.

Hey guys, if you would like to see another way this is made possible look at www.energy-inventions.com... This was made by my dad, I do not know any specific information on how it works. My dad works in commercial heating and cooling and served in the navy for 8 years on the USS New York nuclear submarine.

Heating Plug-in Hybrids

Heating and air-conditioning systems that use thermoelectrics could make plug-in hybrids more practical.

The potential of plug-in hybrids and electric vehicles to curb petroleum use has grabbed a lot of attention lately. But there is still a big obstacle to clear before such cars can become the dominant vehicles on the road: automakers will need to find an efficient way to supply them with heat and air conditioning. That's because conventional heating and cooling systems either don't work or are inefficient in such vehicles, significantly lowering their range in hot and cold weather.

One of the leading candidates for an alternative system is based on thermoelectrics, semiconductor devices that can provide either heat or cooling, depending on the direction the electric current is flowing. Major automakers, such as GM and Ford, are now developing systems based on existing thermoelectric semiconductors, and experimental materials that use nanotechnology promise to make such systems even more appealing.

with gas at $4.00 a gallon, the push will get greater and greater for alternative solutions.

Now we are using our food to feed our energy infrastructure. The machines are eating our crops. LOL.

We are seeing solutions, and they are not just trickling out anymore. The spigot is turned on full blast, it seems, and new innovations abound daily.

Now, if we could just get all these institutions to work together. They are reinventing the wheel time and time again, it seems. But, then again, maybe they are just building a better mousetrap. Regardless, the sooner we get solutions, the better.

This entire thread is off topic. It starts with an article about impractical thermoelectric materials and then every other post afterwards deals with the topic of solar panels.

Converting heat into electricity is not new. Most of NASA's remote controlled rovers have some sort of nuclear battery on them. A nuclear batter is nothing but a sandwich of some radioisotope (making heat) and thermoelectric materials.

Now some common sense. Most of the uses of thermoelectric material posited by people in this thread will never work. Thermoelectric materials work because there is a strong temperature gradient present in the material. Most of the uses cited in this thread attempt to take waste heat from something that is doing work and returning the waste heat as electricity to help it do said work.

The problem with this is easy to see in the computer example. Computers have fans and heat sinks on their hot components to keep them within a usable temperature range. The whole purpose of those heat sinks is to pull the heat away from the chips and transmit it to the air.

This goes against the very nature of thermoelectric materials which would require you to keep the heat on one side and NOT transmit it to the other side. They say in the article that the challenge is finding a good electrical conductor that is a poor thermal conductor. Put a poor thermal conductor on top of a computer chip and watch what happens.

So you could not use thermoelectric materials to make use of waste heat from a processor, or a motor, or even a gas-burning engine with any efficiency because all of those things need to be actively cooled and not encased in a thermal insulator.

Finally, the idea that you can power a house off the temperature gradient present between hot-air and air-conditioned-air is completely bonkers. You are using massive amounts of energy to cool the air in the first place and will only get a few watts per hour out of it.

Solar panels just make sense. Provided we can make them cheaply. Not cheap as in end-user cost but cheap in resources and energy requirements for manufacture. It doesn't really matter if a roof full of solar panels could provide for all the energy requirements of a home if the factory making them consumes 100kw/h in the manufacture of one sq. ft. of panel.

Jon

reply to post by Voxel


This man speaks the truth.

There are, however still plenty of applications for thermocouples, and if these nanotech thermocouples are cheaper or more efficient, they might come in handy. For example; the exhaust manifolds of a car don't need to be cooled; they're just steel pipe to take the exhaust away from the engine. You could stick thermocouples on them so that you can get away with a smaller alternator. (or no alternator, if you plan on running the engine for several hours each run) That could save you a horsepower or two.

You could stick thermocouples on a heat resistant black sheet, and attach a heat sink to the other end, and focus some mirrors at it for a solar collector that requires less advanced materials and more basic materials than a nanotech thin foil PV collector.

if you could effectively transfer heat to energy we would kind of have unlimited energy cause the motion creates the heat back and energy doesn't disappear.


This is how "Free energy" could acualy work.

reply to post by Voxel

Originally posted by Voxel
This entire thread is off topic. It starts with an article about impractical thermoelectric materials and then every other post afterwards deals with the topic of solar panels.

well....i am about the only one posting here and it IS my thread. I figure a little off topic, approved of by the OP, is ok. Wanna make a few more posts so that your complaint is relevant?

Regardless, there are a few thermoelectric links. not just one. but they have areas that are inter related.

Regarding them being "impractical"....of course. it is early research. if it were practical it would be in use right now, and wouldn't be news.

Converting heat into electricity is not new. Most of NASA's remote controlled rovers have some sort of nuclear battery on them. A nuclear batter is nothing but a sandwich of some radioisotope (making heat) and thermoelectric materials.

no, this isn't "new". Its "new and improved". With the new advances, it is seen as being a possibly viable solution. It is getting cheaper and more efficient.

Now some common sense. Most of the uses of thermoelectric material posited by people in this thread will never work.

I guess MIT disagrees, as "Technology Review" is their publication.

Thermoelectric materials work because there is a strong temperature gradient present in the material. Most of the uses cited in this thread attempt to take waste heat from something that is doing work and returning the waste heat as electricity to help it do said work.

That is exactly what is being proposed. Once again, i think MIT disagree's with you, based on their own publication.

Turning Waste Heat Into Electricity

The problem with this is easy to see in the computer example. Computers have fans and heat sinks on their hot components to keep them within a usable temperature range. The whole purpose of those heat sinks is to pull the heat away from the chips and transmit it to the air.

now what is being proposed is converting this thermal energy into electrical energy, instead of just wasting it into the air and allowing thermodynamics to cool the processor.

This goes against the very nature of thermoelectric materials which would require you to keep the heat on one side and NOT transmit it to the other side. They say in the article that the challenge is finding a good electrical conductor that is a poor thermal conductor. Put a poor thermal conductor on top of a computer chip and watch what happens.

So you could not use thermoelectric materials to make use of waste heat from a processor, or a motor, or even a gas-burning engine with any efficiency because all of those things need to be actively cooled and not encased in a thermal insulator.

well, that heat isn't turned into cotton candy. and the electricity doesn't come from the tooth fairy.

Finally, the idea that you can power a house off the temperature gradient present between hot-air and air-conditioned-air is completely bonkers. You are using massive amounts of energy to cool the air in the first place and will only get a few watts per hour out of it.

that is not anyone's premise. it IS part of a multifaceted approach whereby it produces what energy it can (at that scale you will get much better than a few watts per hour) to help the overall "cause".

Solar panels just make sense. Provided we can make them cheaply. Not cheap as in end-user cost but cheap in resources and energy requirements for manufacture. It doesn't really matter if a roof full of solar panels could provide for all the energy requirements of a home if the factory making them consumes 100kw/h in the manufacture of one sq. ft. of panel.

Jon

this last paragraph tells me you didn't read the solar panel stuff at all. Making them cheaper, using cheaper materials like silicon, is what they are all about. in this thread i am discussing ways to generate energy more cheaply, primarily from the world of nanotech. i want to help get people excited about nanotech, too.

We are going to have to learn to use ALL waste heat and energy to survive. Now I am not saying that the waste heat from a computer is going to make a huge difference.

I think that the temp difference from solar panels on a roof and air temp under your house or underground have a huge potential for producing electricity.

Look what you can do with a peltier module and a computer cpu heatsink. Just the difference in temperature is enough to run the small motor. I was thinking why not hook some copper pipes in the ground and mount a solid black surface lit by the sun to heat up the other side creating a larger temperature difference.



This one uses body heat.



[edit on 22-5-2008 by Freezer]

reply to post by Freezer


WOW, and someone in this thread said that this was impossible.

That video must be CGI or something, huh?

Nice find!!!!

I thought of this idea a few years ago. Molecules which "ratchet" brownian motion and convert it into electrical potential... in other words, "electricity".


You could run an air-conditioner in your house, and instead of consuming electricity, it would GENERATE it.


Think about that!

As i pull my own thread off topic with solar energy, i will post this as well:

Sunrgi claims that its concentrated photovoltaic system outshines the competition.

Sunrgi estimates that its system will be capable of producing electricity at a wholesale cost of five cents per kilowatt-hour. Prototypes have been built and tested both in the laboratory and in the field, and the company expects to start commercial production in 12 to 15 months. "It's quite an aggressive claim," says Daniel Friedman, a solar-energy researcher at the U.S. National Renewable Energy Laboratory (NREL). He says that most others in the space are still working toward seven or eight cents per kilowatt-hour. "I can't say Sunrgi won't achieve what it's claiming, but right now, it's just on paper, and costs like that are only going to be a reality at the large manufacturing level," he says. "Even then, the five-cent figure sounds really optimistic."

Avalanche effect noticed in nanosize solar material?

In conventional solar cells, one photon (light particle) can release precisely one electron. The creation of these free electrons ensures that the solar cell works and can provide power. The more electrons released, the higher the output of the solar cell.

In some semiconducting nanocrystals, however, one photon can release two or three electrons, hence the term avalanche effect. This could theoretically lead to a maximum output of 44 percent in a solar cell comprising the correct semiconducting nanocrystals. Moreover, these solar cells can be manufactured relatively cheaply.

44%? The "holy grail", as mentioned, is 30%. If they can produce 44%, we begin to see a way to replace fossil fuels entirely.

the downside is you may not want to put it on a car for power, as it is a lead based nanomaterial. I am unsure the scale, however.

Electricity from your exhaust pipe

Researchers are working on a thermoelectric generator that converts the heat from car exhaust fumes into electricity. The module feeds the energy into the car’s electronic systems. This cuts fuel consumption and helps reduce the CO2 emissions from motor vehicles.

Someone mentioned this as a possibility. Now it is becoming a reality.

Spray on solar cells

Abstract:
Posted by Martin Roscheisen, CEO

As we are busy ramping our operation, we almost forgot to recognize achieving a major milestone in solar technology: The solar industry's first 1GW production tool.

Nanosolar Achieves 1GW CIGS Deposition Throughput
San Jose, CA | Posted on June 18th, 2008
Most production tools in the solar industry tend to have 10-30MW in annual production capacity. How is it possible to have a single tool with Gigawatt throughput?

This feat is fundamentally enabled through the proprietary nanoparticle ink we have invested so many years developing. It allows us to deliver efficient solar cells (presently up to more than 14%) that are simply printed.

Printing is a simple, fast, and robust coating process that in particular eliminates the need for expensive high-vacuum chambers and the kinds of high-vacuum based deposition techniques from industries where there's a lot more $/sqm available for competitive manufacturing cost.

Our 1GW CIGS coater cost $1.65 million. At the 100 feet-per-minute speed shown in the video, that's an astonishing two orders of magnitude more capital efficient than a high-vacuum process: a twenty times slower high-vacuum tool would have cost about ten times as much per tool.

Plus if we cared to run it even faster, we could. (The same coating technique works in principle for speeds up to 2000 feet-per-minute too. In fact, it turns out the faster we run, the better the coating!)

All they have to do is hit "print", huh?

Hi BFFT,

Electricity from a car exhaust excellent idea

Thermal Electric Generators, earlier versions were known as Thermal piles, are nothing new, I wonder why we do not hear more about them.

Thermopile by Pouillet: circa 1840.
Thermopile by Ruhmkorff: circa 1860.
Markus's thermopile: 1864.
Becquerel's thermopile
The Clamond Thermopile
The Noe Thermopile
Hauck's thermopile
Gülcher's thermopile: c 1898Commercial thermopile: 1898.
The Thermattaix: circa 1925.
The gas-fired thermo-electric generator: 1930s.
A Russian thermo-electric generator based on a kerosene lamp.

With previous discussions on splitting water into hydrogen and oxygen to run an internal combustion engine using electrolysis the argument against seems to be that you will always use more energy, ie electricity to produce the gases than you will get out of them.

It seems to me that a TEG would provide the electricity to power the electrolysis process using the waste heat from the exhaust.

I have not seen anything on the net to indicate that anyone has tried this but if I had the room and facilities I would try this myself.