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A close up of a single ball, 300 nm across. The ball is made up of 15 nm grains.  (Source: University of Washington)

Millions of the balls compose a layer of the solar cell.  (Source: University of Washington)

The thin light-absorbing zinc oxide surface, pictured here in a picture from a scanning electron microscope, is about 10 um thick, and composed of the popcorn ball like structures.  (Source: University of Washington)
While not very tasty, these balls are extra efficient

With gas prices going up, refining capacity stretched to its max, and the reality that fossil fuels will eventually be depleted settling in, interest in alternative energy solutions of various types is at an all time high.  Among these is renewed vigor in the solar power industry.  From building massive new plants to new ground breaking research, the rather old field of solar power, is adapting quickly to the latest tech.

The University of Washington just made another breakthrough in solar power, that while humorous sounding, certainly offers serious gains.  Researchers at the university studying solar cell configurations discovered that by implementing a popcorn ball design -- tiny spheres clumped into bigger porous spheres -- efficiency in cheap solar cells was near doubled.

The dramatic improvement was included in findings presented at the national meeting of the American Chemical Society in New Orleans.  Lead author Guozhong Cao, a UW professor of materials science and engineering, states, "We think this can lead to a significant breakthrough in dye-sensitized solar cells."

Dye-sensitive cells have been in vogue since early pioneering research in 1991.  The cells have the advantage of being flexible, cheaper, and easier to manufacture than brittle silicon solar cells.  Rough surfaces have been a focus in the dye-sensitive field's research, with researchers reach efficiencies of approximately 10 percent capture of the suns energy absorbed.  This efficiency is only about half that of traditional silicon solar cells found on roof tops and calculators but with the lower price its is enough to stay competitive with the silicon cells.

The University of Washington researchers looked to compare homogeneous rough surfaces with various clumped designs, instead of trying to maximize the efficiency of the well researched homogeneous rough surface.  One dilemma that researchers faced was the size of the grains used.  Bigger grains, closer to the visible wave length of light cause the light to bounce around inside the thin-light absorbing surface, increasing the probability that it will be absorbed.  On the other hand, small grains have a bigger surface area per volume, increasing absorbtion.

Explains Cao, "You want to have a larger surface area by making the grains smaller.  But if you let the light bounce back and forth several times, then you have more chances of capturing the energy."

Other researchers have tried unsuccessfully to improve efficiency by mixing small and large grains.  The UW researchers instead took tiny 15 nm grains and clumped them together into 300 nm agglomerations, essentially making large grains composed of small grains, an approach that resembles macroscopic scale popcorn balls.

Each gram of the material has an incredible surface area of 1,000 square feet per gram covered in light absorbing pigment.  Thanks to the complex design light also gets trapped inside the larger balls, increasing absorption remarkably.  The researchers were surprised at their success, saying it surpassed even their best hopes.  Says Cao, "We did not expect the doubling.  It was a happy surprise."

The overall efficiency was 2.4 percent for small grains only, the current highest efficiency achieved for the material (there are higher efficiency materials, hence the 10 percent in commercial designs).  The popcorn-ball design showed an overall efficiency of 6.2 percent, a 258 percent increase in efficiency.  Cao states, "The most significant finding is the amount of increase using this unique approach."

The research used the pigment zinc oxide, which is of lower efficiency than the commercially used titanium oxide, but easier to work with during experiments.  Titanium oxide layers are expected to show similar gains.  Cao gives an update on this explaining, "We first wanted to prove the concept in an easier material. Now we are working on transferring this concept to titanium oxide."

While titanium oxide cells currently have a record efficiency of 11 percent, the researchers hope that by using the new method they can by far surpass this old record, possibly even surpassing silicon cell efficiencies.  Such progress could make silicon cells, used for decades, obsolete, replaced by cheaper, more efficient, flexible cells.

The research was funded by the National Science Foundation, the Department of Energy, Washington Technology Center and the Air Force Office of Scientific Research.  The postdoctoral research was co-authored by Qifeng Zhang, research associate Tammy Chou and graduate student Bryan Russo all in the UW material sciences department, and Samson Jenekhe, a UW professor of chemical engineering.


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Encouraging But ...
By misterk2dt on 4/13/2008 6:30:30 PM , Rating: 3
25 years ago I remember writing a paper in my high school English class about the merits of solar energy. I don't remember everything, but the biggest roadblock at that time was high cost and low efficiency. If this makes it cost effective than that's great. I hope I don't have to wait another 25 years to see solar energy start seriously replacing fossil fuels. I also wonder what the Government will do to tax solar energy if it takes off and the home owner can replace much of their utiltity costs with local generation.




RE: Encouraging But ...
By oab on 4/13/2008 8:53:55 PM , Rating: 1
Solar can never "replace" fossil fuels (which I am using as a term for "conventional" power), because the sun is only out for 12 hours a day. The other 12, the cells do nothing, or DRAIN power (in some cases).

The clean sources of energy we have are:
solar (doesn't work in clouds or at night)
wind (doesn't work when there is no wind, or too much wind)
hydro (which environmentalists hate because dams damage ecosystems)

Two of those can't be guaranteed to run 24/7. Imagine a doctor saying "I'm sorry, we need to postpone your operation, because the sun has hidden behind a cloud and the lights in the OR won't work anymore". It just doesn't work like that, hospitals have diesel generators, but that makes the whole "renewable energy" a joke.

You need some dirty power, as things stand right now. And the cleanest dirty power sources are natural gas, and nuclear. Nuclear is cleanest "burning", and it is the cheapest (excluding startup costs, nuclear plants produce energy for about 1.6-1.8c/kwh). Natural gas is clean, as far as fossil fuels are concerned, but expensive (around 15c/kwh, depending where you live). Might as well trap the methane gas from cow excrement and use that in your plants. Natural gas is mostly methane anyway, it would work, though efficiency would go down.


RE: Encouraging But ...
By Some1ne on 4/13/2008 9:44:24 PM , Rating: 4
quote:
because the sun is only out for 12 hours a day


No, the sun is out 24 hours a day. Just not 24 hours in any single spot on the planet's surface. Even discounting that, the duration of sunlight that a given spot recieves in a single day is not 12 hours, it's a variable duration depending upon time of year and latitude, and may be anywhere from 0 to 24 hours of sinlight in a day. The point being that the fact that a given spot on the earth's surface will not ever be in perpetual sunlight is not a valid reason to decry solar power. If it's dark where you are, it's light where someone else is, and it's entirely feasible to send the power out from where they are to where you are, negating the need for 24/7 generation in your locality (or anyone else's, for that matter). It would probably require a massive overhaul of the existing power distribution infrastructure, and international cooperation on a massive scale, but it's theoretically possible.


RE: Encouraging But ...
By masher2 (blog) on 4/13/2008 11:22:23 PM , Rating: 4
It's not even possible in theory at present. Most power generated today is consumed within a couple hundred miles of where it's produced, and even still we waste some 7% in transmission. Piping power halfway around the globe would require major scientific advances in superconducting power transmission, followed by the rebuilding of the world power grid from the ground up.

And even still, I don't see it being feasible to run gigawatt-capacity superconducting lines under the ocean. We don't even run super high-voltage lines underground at present...putting them in storm-ridden highly-conductive saltwater would be a challenge, to say the least.

I'm sure we'll be able to do it one day. But not in the next 50 years.


RE: Encouraging But ...
By dug777 on 4/14/2008 12:21:30 AM , Rating: 2
That's not true even now, masher.

HVDC is used under the ocean quite regularly, and is capable of transferring significant amounts of power.

The Basslink is just one example:

http://www.pti-us.com/pti/company/eNewsletter/2004...

Some further info on others (yeah it's wikipedia, get over it, you can follow all the links if you're concerned that it's all a pack of lies):

http://en.wikipedia.org/wiki/Submarine_power_cable


RE: Encouraging But ...
By masher2 (blog) on 4/14/2008 2:39:32 AM , Rating: 4
> "HVDC is used under the ocean quite regularly, and is capable of transferring significant amounts of power."

True, but it's still very far from a solution for intercontinental power transfer. If you notice, all the existing links are in the 250km or less range. Why?

HVDC loses roughly 10% every 1000km, plus an additional 1.5% fixed from conversion overhead. That means powering the nightime US from the daytime in Asia or Eastern Europe would waste more than 60% of the total power generated. Put another way, you'd have to generate 2.5X as much just to break even.

And then there's the cost. Massive capital costs for the converters at each end, plus the costs of the cable itself.

According to the figures in your link, an 8GW 40 km link between the UK and France would cost in the range of $2B dollars. Even assuming costs are linear with distance (they're not -- they rise faster), a trans-global cable capable of powering the US would cost in the realm of $20 trillion dollars. That's 150X the cost of the Apollo program. Plus annual maintenance of nearly $1T/year

And that's just to transport the electricity...not to generate it. And that assumes demand doesn't rise. If we start replacing petroleum with electric or hydrogen-powered cars, electric demand will rise dramatically.


RE: Encouraging But ...
By dug777 on 4/14/2008 3:15:13 AM , Rating: 2
That's a bit of a straw man and you know it ;)

I was simply rebutting your assertion that it was unfeasible or unlikely to ever work under the ocean:

I don't see it being feasible to run gigawatt-capacity superconducting lines under the ocean. We don't even run super high-voltage lines underground at present...putting them in storm-ridden highly-conductive saltwater would be a challenge, to say the least.

FWIW, I'm in general agreement with everything you said in your reply to me :)


RE: Encouraging But ...
By masher2 (blog) on 4/14/2008 9:37:55 AM , Rating: 2
> "I was simply rebutting your assertion that it was unfeasible or unlikely to ever work under the ocean"

Ah, point taken. However, I didn't say it would never work, just that it was unfeasible at least for the next 50 years.

By 2100 or so, though, who knows?


RE: Encouraging But ...
By mattclary on 4/14/2008 10:51:32 AM , Rating: 3
I think you need to brush up on what "Straw Man" means. He countered your point, deal with it.

http://www-personal.umich.edu/~lilyth/strawman.htm...


RE: Encouraging But ...
By dug777 on 4/14/2008 8:12:32 PM , Rating: 3
Fair enough.

I was labouring under a misapprehension that the concept of a straw man extended to countering someone's correction of your factual error with an argument that certainly didn't address any of the points you made, or were trying to make.

I simply felt that a statement masher made was inaccurate.

I provided a correction to that inaccuracy. I made no attempt to discuss the economics of the technology, merely pointed out that submarine HVDC power transfer was quite feasible with current technology.

Masher then proceeded to 'counter' my feasibility comment with a brief economic analysis of the situation, extrapolated to larger and longer examples, which I generally agree with. However it's not something I had initially suggested was economically feasible in longer and larger examples. His point did not counter anything I had said, hence my apparently erronous reference to a straw man.

I'm not quite sure as to what I need to 'deal with' here, and it's that kind of mindless angst and aggression that drives people away from posting on DT.

I also struggle to understand why I've been downrated, I've been perfectly civil throughout, and I don't actually disagree with anything masher is saying at this stage.


RE: Encouraging But ...
By mattclary on 4/15/2008 12:50:45 PM , Rating: 2
My apologies for the "deal with it" comment. Wanted to delete that after I posted it... I have been seeing a lot people cry "straw man!" at the drop of a hat (and in error) on every forum I visit, I think I was being overly pissy about it. ;)


RE: Encouraging But ...
By dug777 on 4/15/2008 7:55:58 PM , Rating: 2
Thankyou, much appreciated.

I've learnt something into the bargain :)


RE: Encouraging But ...
By andrinoaa on 4/14/08, Rating: 0
RE: Encouraging But ...
By Chernobyl68 on 4/24/2008 1:33:11 PM , Rating: 2
some designs of breeder reactors gereate waste with a relatively short half life. We're simply not building them. Japan does though...


RE: Encouraging But ...
By Paratus on 4/14/2008 12:33:38 AM , Rating: 3
While that is in theory true, time in insolation is only part of the equation. You also have the efficiency of the cells , which this article addressed, how good your tracking is as power falls off with the cosine of the solar vector, and how much of the incidence solar radiation is reflected off the atmosphere.

In earth orbit you get a maximum of~1300 W/m^2. With all the above factors your lucky to get above 100-200W/m^2. You'll need ALOT of popcorn balls to replace any significant amount of dirty power.

To put it another way if you wanted to replace all the ICE vehicles on the road with solar powered electric vehicles you would need a strip of solar collectors (panels, etc) 10 miles wide by 3000 miles long........

Solar makes a lot more sense in a distributed environment. Where these flexible cells are installed on roof tops all over the country. Just think your electric bill would drop, you could charge your plug-in vehicle, and when the grid went down due to a failure, weather or homeland security scare of the day you would still have a working refrigerator for medicine, food, etc.


RE: Encouraging But ...
By bigjaicher on 4/13/2008 9:48:29 PM , Rating: 2
Very good argument, but there are two things which I feel may be incorrect. Saying that natural gas is a good alternative to fossil fuels is very ironic because it is a fossil fuel. Additionally, why do you feel that nuclear energy is a "dirty power?" To my knowledge, it has no gaseous emissions like CO2, SO2, CO, or others, unless you are talking about the toxic waste and radiation (negated by the cement walls). Apart for human error when it was still developmental technology (Chernobyl, Three Mile Island, Rocky Flats (I live a few miles away from the site)), it is safe. Nuclear energy is 'clean,' but unrenewable energy.


RE: Encouraging But ...
By JKflipflop98 on 4/13/2008 10:27:14 PM , Rating: 3
It's a shame Joe Six-pack is so afraid of the word "nuclear", because that's really our best method of power generation.


RE: Encouraging But ...
By aftlizard on 4/14/2008 10:00:06 AM , Rating: 3
Nuclear energy with new technology isnt exactly unrenewable. In fact new fast breeder reactors create new fuel, more than it needs.

Hate to use wikipedia, but its simple enough to read:
http://en.wikipedia.org/wiki/Fast_breeder_reactor


RE: Encouraging But ...
By oab on 4/14/2008 8:27:36 PM , Rating: 2
Nuclear is "clean" in that there is no emissions, however, eventually no matter how many times the waste is recycled in new reactors, it eventually will need to be put somewhere. It can either be put in a hole in the ground, in water tanks forever, or you can drop it in the middle of the ocean.

It has to go somewhere though, even though it is renewable.


RE: Encouraging But ...
By Alexstarfire on 4/14/2008 11:25:46 PM , Rating: 2
Well, if we ended up using Nuclear power everywhere, then why not just hurl it into the Sun? I'm pretty sure the Sun won't mind.


RE: Encouraging But ...
By RonLugge on 4/13/2008 9:54:37 PM , Rating: 2
I'd say the solution is to make better rechargeable batteries and combine the two.

You know, like the ones they're making for your iPhone, iPod, iTouch (iPDA more like...) and whatever is next. Oh, and all the other competing, (usually superior) products.

(And yes, I know it probably won't be enough, but you can combine the batteries with the other "clean" sources and vastly reduce our dependence on "dirty" energy.)

And, btw, while wind isn't "constant" in most areas, there are places where it comes pretty darned close, hence why CA has several "wind farms".

And, of course, there are viable methods to garner tidal energy... and OTEC -- "thermal" energy from temperature difference between surface water and the water about 30 feet down, or Ocean Thermal Energy Conversion -- is pretty good too.

Lets not forget ethanol fuel... and I'm sure there are others.


RE: Encouraging But ...
By Alexstarfire on 4/14/2008 11:28:10 PM , Rating: 2
Unless we find a cheap way to make ethanol from cellulose, it's never going to take off. Using corn and sugar may sound great, but it's infeasible to use them to make the amount of ethanol we need.


RE: Encouraging But ...
By hallsy on 4/14/2008 4:10:04 AM , Rating: 2
Are you 100% sure about that comment that solar only works for 12 hours. I have read in several places that the panels can opperate in cloud and in low light because they are powered by other ends of the light spectrum (ill get the links if someone feels the need to link me down). This mean they have an up time of far more then "day time" regardless of how the other posts justify or attack the 12 hour comment


RE: Encouraging But ...
By masher2 (blog) on 4/14/2008 10:10:52 AM , Rating: 2
Panels do operate in cloudy/low light situations, though with reduced output. But that doesn't matter-- every spot on the planet averages 12 hours light/day.

When one factors insolation reduction due to cloud cover an d other such factors, the actual generated power is even lower...which is one reason dry places like Arizona are favored for solar plants.


RE: Encouraging But ...
By Seemonkeyscanfly on 4/14/2008 11:36:51 AM , Rating: 2
Most places average about 12 hours of light per day... What do you do about place like Alaska, where winter is only 2 or 3 hours of sunlight? Summer of course is no problem.


RE: Encouraging But ...
By ChronoReverse on 4/14/2008 11:47:21 AM , Rating: 2
What do you think Average means?


RE: Encouraging But ...
By masher2 (blog) on 4/14/2008 11:50:13 AM , Rating: 2
All places average 12 hours/day. Even northern Alaska-- it receives an hour/day in the winter, and 23 hours/day in the summer...the average remains the same.

Of course, higher latitudes also lose far more in atmospheric losses, making solar power in regions like Alaska even less feasible.


RE: Encouraging But ...
By spluurfg on 4/14/2008 4:17:01 AM , Rating: 2
You have to be joking. You are aware we can store energy, right?


RE: Encouraging But ...
By indiana56637 on 4/14/2008 8:53:17 AM , Rating: 2
Absolutely, I am not sure what sparked this debate, but it is almost irrelevent. Current advances in battery technology will allow the storage of much of the energy required for use overnight. This is far more efficient than transmission allong inter-continental lines. However, the main problem with these solar cells is the low efficiency. The only way to make a real difference is to make it mandatory that all new houses have these or similar on the roof, and to offer significant tax benefits or grants to allow current home owners to upgrade.

Either that or cover an area of the Sahara the size of Germany with light concentrating solar power stations, as this would be enough to power all of the EU (personally Im up for this ;D although there may be some political implications to all of europe relying upon Libia for energy)


RE: Encouraging But ...
By spluurfg on 4/14/2008 9:48:02 AM , Rating: 2
Yeah... transmission and storage is the obvious answer. How exactly to do it is subject to debate (just like generation is still debated), but to simply rule out wind and solar because they have variable output... well... I think you could have thought a bit more about it...

There are some discussions of mechanical storage (i.e. wind farms are used to power a pump to fill a reservoir, etc) and also long distance transmission is much more practical if using direct current (and appropriate transformers).


RE: Encouraging But ...
By masher2 (blog) on 4/14/2008 9:48:23 AM , Rating: 2
> "advances in battery technology will allow the storage of much of the energy required for use overnight..."

Perhaps one day, but its not feasible any time in the near future. Current plans for solar installations which can store power don't even use batteries, but rather thermal-based solutions like molten salt storage.


RE: Encouraging But ...
By Earl E on 4/14/2008 2:26:16 PM , Rating: 2
People who use solar produce more energy than they consume at their homes in some cases.
What you might be saying is that it costs more money than you are willing to spend with all the other things money can buy.
So as the dollar devalues, the installed solar base becomes more valuable. Its nice to know that as the cost of utilities goes up and the value of the dollar declines, that your alternative energy systems payback period shortens.


RE: Encouraging But ...
By Doormat on 4/14/2008 11:23:17 AM , Rating: 2
There are plenty of ways to store solar power as potential or kinetic energy that will last through clouds or nighttime. You'll need to increase the amount of panels or the efficiency of panels, since you can only generate power for 12 on average.

- Transferring water between two reservoirs at different elevations
- Compressed air in caverns (being looked at in SoCal for their solar power stuff)
- Flywheels

And probably more that people can think of.


RE: Encouraging But ...
By oab on 4/14/2008 8:55:31 PM , Rating: 2
Of course there are ways of storing energy (the grid itself acts as a "battery" on it's own in a round-about sort of way), however there are no real large-scale "battery" technologies on the market currently available that are cost-effective ways of storing all that energy.

Sure, Ontario currently uses a peak of about 18,000MW during the day, and about 14000MW at night. Nothing currently can come CLOSE to storing 14,000MW. How many solar plants will have the sole purpose of simply charging batteries (or other such energy storing methods such as you put out) to be able to have that available? (1)

Quick maths (bad maths too):
12 hours daily of sunlight (sun at 100% power)
12 hours of night time (sun at 0% power)
Assuming no other energy creation methods are being used.

Looking at the graphs, there is approx. 12 hours of 18000MW, and 12hrs 14000MW (it's really more usage than that, but this makes the math easy).

12*14000 = 168,000MW
12*18000 = 216,000MW
Total power used daily:
216,000
168,000
-------
384,000MW Total power used.

Therefore, the amount of power needed to be generated during the day, from solar (alone) is:
384,000/12 = 32,000MW per hour.

A lithium ion cell the power/weight ratio of: 1800W/kg. (2)
32,000MW = 32000000000 Watts.
32000000000 / 1800 = 17777777.7 KG
That's 17,777 TONS of lithium ion cells.

The cost of 1watt of lithium ion power is: 2.8W/US$ (2)
so:
32000000000 / 2.8 = $11,428,571,428.57

11 TRILLION DOLLARS for Ontario ALONE. This is a bad example of course (there would be better methods of storing power other than chemical), but the cost to do so, is so huge, there's no point. It would bankrupt the province to do that with conventional chemical power. Plus, after 1000 days, you would need to spend 11 TRILLION dollars AGAIN to last another 3 years. It's not sustainable.

There are better methods of storing such large quantities of energy, but the best battery cells we have can't do it. The other things you mentioned, nothing practical about them so far.

(1) http://www.theweathernetwork.com/index.php?product...
(2) http://en.wikipedia.org/wiki/Lithium_ion_battery


RE: Encouraging But ...
By AsymmetricGhillie on 4/27/2008 8:23:24 PM , Rating: 2
I don't think anyone is saying we'd replace renewable/clean energy sources with fossil fuels now or in the near future. However there are good renewable/clean sources of energy that can all contribute to energy demands.

As for sources you sighted, you didn't mention geothermal. Geothermal does have the benefit of running 24/7. It is clean (ECS plants) and economical. It is already successfully implemented in Scandanvian countries, the Philippines and has more potential here in the US than presently. Unfortunatley, it suffers from underfunding just like most renewable energy sources. There are many areas in the US that have potential for providing geothermal energy, but not yet known.

Regarding your hospital senario, it happens today in the form of blackouts. This is why all hospitals have onsite generators or small plants.


RE: Encouraging But ...
By phxfreddy on 4/14/2008 8:06:52 AM , Rating: 2
This line of thinking has a kernal of delicious government cheese included theirin. What you miss is that any new energy technology will cost more than the current technology today. New paradigms only engage when the cost structure is such that profitability occurs. Profitability will first occur when prices are high! So if we are LUCKY solar will be clean and renewable but it will NOT be cheap. And in a high cost structure a government so in love with controlling your life through diversion of GNP will be able to do the 1 trick it knows how to do. Skim off the top like any other gangster


RE: Encouraging But ...
By Shadowmaster625 on 4/14/2008 9:32:50 AM , Rating: 2
They've been doing this for 25 years. Always saying this or that is going to make silicon PV obsolete. Silicon PV is here now, and we ignore that at our own peril. There is plenty of room in the market for competing designs, whether they are thin film, polysilicon, thermal, or any of the others...


RE: Encouraging But ...
By Adonlude on 4/14/2008 5:27:38 PM , Rating: 2
So how does this method compare to the thin film method used by market leasder First Solar (ticker FSLR)? People are just dumping money into First Solar, is this going to 1up them?


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