Sunday 23 December 2007

Cheap cells

Tuesday, September 12, 2006

Not everyone gets a solar cell named after them: but Michael Gratzel did. He says his novel technology, which promises electricity-generating windows and low manufacturing costs, is ready for the market.
By Kevin Bullis

Michael Grätzel, chemistry professor at the Ecoles Polytechniques Fédérales de Lausanne in Switzerland, is most famous for inventing a new type of solar cell that could cost much less than conventional photovoltaics. Now, 15 years after the first prototypes, what he calls the dye-sensitized cell (and everyone else calls the Grätzel cell) is in limited production by Konarka, a company based in Lowell, MA, and will soon be more widely available.

Grätzel is now working on taking advantage of the ability of nanocrystals to dramatically increase the efficiency of solar cells.

Technology Review asked him about the challenges to making cheap solar cells, and why new technologies like his, which take much less energy to manufacture than conventional solar cells, are so important.

Technology Review: Why has it been so difficult to make efficient, yet inexpensive solar cells that could compete with fossil fuels as sources of electricity?

Michael Grätzel: It's perhaps just the way things evolved. Silicon cells were first made for [outer] space, and there was a lot of money available so the technology that was first developed was an expensive technology. The cell we have been developing on the other hand is closer to photosynthesis.

TR: What is its similarity to photosynthesis?

MG: That has to do with the absorption of light. Light generates electrons and positive carriers and they have to be transported. In a semiconductor silicon cell, silicon material absorbs light, but it also conducts the negative and positive charge carriers. An electric field has to be there to separate those charges. All of this has to be done by one material--silicon has to perform at least three functions. To do that, you need very pure materials, and that brings the price up.

On the other hand, the dye cell uses a molecule to absorb light. It's like chlorophyll in photosynthesis, a molecule that absorbs light. But the chlorophyll's not involved in charge transport. It just absorbs light and generates a charge, and then those charges are conducted by some well-established mechanisms. That's exactly what our system does.

The real breakthrough came with the nanoscopic particles. You have hundreds of particles stacked on top of each other in our light harvesting system.

TR: So we have a stack of nanosized particles...

MG: ...covered with dye.

TR: The dye absorbs the light, and the electron is transferred to the nanoparticles?

MG: Yes.

TR: The image of solar cells is changing. They used to be ugly boxes added to roofs as an afterthought. But now we are starting to see more attractive packaging, and even solar shingles (see "Beyond the Solar Panel"). Will dye-sensitized cells contribute to this evolution?

MG: Actually, that's one of our main advantages. It's a commonly accepted fact that the photovoltaic community thinks that the "building integrated" photovoltaics, that's where we have to go. Putting, as you say, those "ugly" scaffolds on the roof--this is not going to be appealing, and it's also expensive. That support structure costs a lot of money in addition to the cells, and so it's absolutely essential to make cells that are an integral part.

[With our cells] the normal configuration has glass on both sides, and can be made to look like a colored glass. This could be used as a power-producing window or skylights or building facades. The wall or window itself is photovoltaicly active.

TR: The cells can also be made on a flexible foil. Could we see them on tents, or built into clothing to charge iPods?

MG: Absolutely. Konarka has a program with the military to have cells built into uniforms. You can imagine why. The soldier has so much electrical gear and so they want to boost their batteries. Batteries are a huge problem--the weight--and batteries cost a huge amount of money.

Konarka has just announced a 20-megawatt facility for a foil-backed, dye-sensitized solar cell. This would still be for roofs. But there is a military application for tents, and Konarka is participating in that program.

TR: When are we going to be able to buy your cells?

MG: I expect in the next couple of years. The production equipment is already there. Konarka has a production line that can make up to one megawatt [of photovoltaic capacity per year].

TR: How does the efficiency of these production cells compare with conventional silicon?

MG: With regard to the dye-cells, silicon has a much higher efficiency; it's about twice [as much]. But when it comes to real pickup of solar power, our cell has two advantages: it picks up [light] earlier in the morning and later in the evening. And also the temperature effect isn't there--our cell is as efficient at 65 degrees [Celsius] as it is at 25 degrees, and silicon loses about 20 percent, at least.

If you put all of this together, silicon still has an advantage, but maybe a 20 or 30 percent advantage, not a factor of two.

TR: The main advantage of your cells is cost?

MG: A factor of 4 or 5 [lower cost than silicon] is realistic. If it's building integrated, you get additional advantages because, say you have glass, and replace it [with our cells], you would have had the glass cost anyway.

TR: How close is that to being competitive with electricity from fossil fuels?

MG: People say you should be down to 50 cents per peak watt. Our cost could be a little bit less than one dollar manufactured in China. But it depends on where you put your solar cells. If you put them in regions where you have a lot of sunshine, then the equation becomes different: you get faster payback.

TR: Silicon cells have a head-start ramping up production levels. This continues to raise the bar for new technologies, which don't yet have economies of scale. Can a brand-new type of cell catch up to silicon?

MG: A very reputable journal [Photon Consulting] just published predictions for module prices for silicon for the next 10 years, and they go up the first few years. In 10 years, they still will be above three dollars, and that's not competitive.

Yes, people are trying to make silicon in a different way, but there's another issue: energy payback. It takes a lot of energy to make silicon out of sand, because sand is very stable. If you want to sustain growth at 40-50 percent, and it takes four or five years to pay all of the energy back [from the solar cells], then all of the energy the silicon cells produce, and more, will be used to fuel the growth.

And mankind doesn't gain anything. Actually, there's a negative balance. If the technology needs a long payback, then it will deplete the world of energy resources. Unless you can bring that payback time down to where it is with dye-cells and thin-film cells, then you cannot sustain that big growth. And if you cannot sustain that growth, then the whole technology cannot make a contribution.

TR: Why does producing your technology require less energy?

MG: The silicon people need to make silicon out of silicon oxide. We use an oxide that is already existing: titanium oxide. We don't need to make titanium out of titanium oxide.

TR: An exciting area of basic research now is using nanocrystals, also called quantum dots, to help get past theoretical limits to solar-cell efficiency. Can dye-sensitized cells play a role in the development of this approach?

MG: When you go to quantum dots, you get a chance to actually harvest several electrons with one photon. So how do you collect those? The quantum dots could be used instead of a [dye] sensitizer in solar cells. When you put those on the titanium dioxide support, the quantum dot transfers an electron very rapidly. And we have shown that to happen.

TR: You are campaigning for increased solar-cell research funding, and not just for Grätzel cells.

MG: There's room for everybody.

I am excited that the United States is taking a genuine interest in solar right now, after the complete neglect for 20 years. The Carter administration supported solar, but then during the Reagan administration, it all dropped down by a factor of 10. And labs like NREL [National Renewable Energy Laboratory in Golden, CO] had a hard time surviving. But I think there is going to be more funding.
Copyright Technology Review 2006.

Wednesday 28 November 2007

Solar technology to dye for

By Claire Gorman

As the urgency of addressing global warming increases, so does the race to find a cheap method of collecting 'clean' energy.

While you've certainly heard of some methods of gathering solar energy - like solar thermal and silicon cells - others are less well known.

One local business has honed a solar technology based on photosynthesis and nanotechnology.

This type of solar cell was first created in 1991. However, Queanbeyan company Dyesol has perfected a technique for making the components and is now a world leader in the field.

Dyesol does not actually sell solar panels but instead creates the components, most of which are exported overseas.

666 ABC Canberra's environment reporter, Claire Gorman, met up with managing director Sylvia Tulloch in a lab full of test tubes and glass vessels.

"In photosynthesis chlorophyll is absorbing all the energy in the red part of the spectrum and reflecting the blue and the yellow, so a leaf looks green.

"Our solar technology mimics photosynthesis, so we use a dye to capture the energy," Sylvia explained.

"This dye is not easy to synthesise and it is not easy to purify with good yields," she said.

Sylvia said while the dye had been modified, it came from the same family of dyes used for archival photographs because these lasted a long time.

"We need our solar panels to last for decades," she said.

The second ingredient in the solar panels a nanoparticulate paste - a creamy substance with titanium dioxide nanoparticles in it - which is screen printed onto glass and then baked.

On the topic of nanoparticles, Sylvia said they were not as mysterious as they might sound.

"It's really just limiting the growth of the crystals before they grow too big," she said.

This component is then dyed and put in a sandwich with glass on either side to let the light in and a liquid electrolyte which acts like a battery.

"It's normal glass but it has a conductive coating on it because an important thing in a solar panel is to have a conductor so you can capture the electrons and then send them to the circuit," she said.

"In a solar panel a cells is only about half a volt and that is a very low voltage, so you need to build up a number of cells to give you a useful voltage."

The next step for Dyesol, Sylvia said, was turning metal into solar cells so that rooves and fences could generate energy too.

Saturday 22 September 2007

$1 a watt coming of age

Sept. 10, 2007 -- Colorado State University's method for manufacturing low-cost, high-efficiency solar panels is nearing mass production. AVA Solar Inc. will start production by the end of next year on the technology developed by mechanical engineering Professor W.S. Sampath at Colorado State. The new 200-megawatt factory is expected to employ up to 500 people. Based on the average household usage, 200 megawatts will power 40,000 U.S. homes.

Produced at less than $1 per watt, the panels will dramatically reduce the cost of generating solar electricity and could power homes and businesses around the globe with clean energy for roughly the same cost as traditionally generated electricity.

Sampath has developed a continuous, automated manufacturing process for solar panels using glass coating with a cadmium telluride thin film instead of the standard high-cost crystalline silicon. Because the process produces high efficiency devices (ranging from 11% to 13%) at a very high rate and yield, it can be done much more cheaply than with existing technologies. The cost to the consumer could be as low as $2 per watt, about half the current cost of solar panels. In addition, this solar technology need not be tied to a grid, so it can be affordably installed and operated in nearly any location.

The process is a low waste process with less than 2% of the materials used in production needing to be recycled. It also makes better use of raw materials since the process converts solar energy into electricity more efficiently. Cadmium telluride solar panels require 100 times less semiconductor material than high-cost crystalline silicon panels.

"This technology offers a significant improvement in capital and labor productivity and overall manufacturing efficiency," said Sampath, director of Colorado State's Materials Engineering Laboratory.

Sampath has spent the past 16 years perfecting the technology. In that time, annual global sales of photovoltaic technology have grown to approximately 2 gigawatts or two billion watts -- roughly a $6 billion industry. Demand has increased nearly 40% a year for each of the past five years -- a trend that analysts and industry experts expect to continue.

By 2010, solar cell manufacturing is expected to be a $25 billion-plus industry.

Tuesday 4 September 2007

Dyesol acheives more targets

Dyesol Achieves Third Major Milestone with Corus Ahead of

The collaborative development project between Dyesol and Corus Colors achieved another leap forward on 30 th August when Corus approved the third Milestone of the development project to demonstrate rapid production of DSC films on metal substrates. Achieving good performance of the titania films
on metal substrates at high curing rates was considered the key technical challenge in bringing DSC to production as a steel based construction product. For this Milestone, Dyesol demonstrated scientifically and with demonstrable examples that the target specifications are within reach.

Dyesol achieved the Milestone well in advance of the end of September contract date and has declared high confidence to meet the final Milestone in December. Each Milestone triggers a payment by Corus of 25% of the contract value.

Project Director, Dr Gavin Tulloch, President Dyesol International said, ‘Once again our team has shown the benefit of commitment, enthusiasm and professional excellence in meeting the Corus goals ahead of schedule. The demonstration of prototype product has been a bonus that certainly encouraged
Corus management”

For this review, Dyesol was represented by a larger team than normal. As well as the Project Technical leader, Olivier Bellon and Chief Scientist, Hans Desilvestro, Dyesol Senior Projects Engineer, Niall Howe and VP Marketing, Dyesol International, Ken McKeen were also present as part of the planning team
for establishment of Dyesol’s technology and demonstration facilities in UK. The team was rounded out by Dyesol UK Ltd directors, Andrew King and Gavin Tulloch.

As part of the formal project review Corus and Dyesol also accelerated the planning for the next phase of the project, subject of a recent invited bid to the Carbon Trust. The project team for the next phase involves Oxford University. During the next three months there will be increased effort associated
with planned expansion of the project in 2008 to accelerate introduction of the steel based products.

Dr Desilvestro and Dr Bellon also met with the research team from Bangor University, recently expanded to carry out R&D for the project, to assist with planning of the next generation development programme. Dyesol has recently supplied test and analysis equipment to Bangor and Swansea Universities as part
of their R&D programmes. Dyesol continues its strategic partnership with these universities in providing DSC materials and components to assist expansion of the technology base in Wales.

For further information contact Dyesol’s managing director Mrs Sylvia Tulloch on 61 2 6299 1592 or Viv Hardy at Callidus PR on 61 2 9283 4113

Background Information for Media Release

DYESOL Limited is located in Queanbeyan NSW (near Canberra) and in August 2005 was listed on the Australian Stock Exchange (ASX Code ‘DYE”). Dyesol manufactures and supplies a range of Dye Solar Cell products comprising equipment, chemicals, materials, components and
related services to researchers and manufacturers of DSC. The Company is playing a key role in taking this third generation solar technology out of the laboratory and into the community.

Corus Group Plc (LSE/AEX: CS; NYSE: CGA) is one of the world’s largest metal producers with annual turnover of £9 billion and major operating facilities in the U.K., the Netherlands, Germany, France
and Norway. Corus’ four divisions comprising Strip Products, Long Products, Distribution & Building Systems and Aluminium provide innovative solutions to the construction, automotive, rail, general engineering and packaging markets worldwide. Corus has 41,100 employees in over 40 countries and sales offices and service centres worldwide. Combining international expertise with local customer service, the Corus brand represents quality and strength.

Thursday 2 August 2007

Next-Generation Photovoltaics: Dye-Sensitised Solar Cells

Next-Generation Photovoltaics: Dye-Sensitised Solar Cells: "The Australian company Dyesol Inc, the first in the world to manufacture DSC modules commercially, organised a conference in February 2006 in Canberra on the Industrialization of Dye-Sensitised Solar Cells, which presented an impressive demonstration of how far this new photovoltaic contender has progressed in less than 16 years after the author’s first scientific publication on this topic. The enthusiastic and upbeat mood of the meeting revealed a consensus among the numerous international participants that the DSC has reached the end of its gestation period and moved forward with its first commercial applications. Building integrated photovoltaic and lightweight flexible applications offers particularly attractive near-term opportunities. Figure 4 exemplifies the possibilities of multicolour modules and see-through power-producing windows using DSC technology.

The walls of the Toyota Dream House have installed DSC panels (Figure 5), offering a building-integrated source of solar power to the inhabitants. Dyesol has started pilot production of DSCs in Australia, while British company G24I has built a 20MW plant for flexible DSC fabrication in Cardiff, Wales.

Mesoscopic solar cells suit a whole realm of applications ranging from the lightweight low-power market to large-scale applications. Their excellent performance in diffuse light gives them a competitive edge over silicon in providing electric power for both indoor and outdoor standalone electronic equipment. Application of the DSC in building-integrated photovoltaic has already started and will become a rich field for future commercial development.

The future is renewable

The energy mix of the future will be more regenerative and sustainable. The generation and storage of renewable energy will be the fastest growing sector in energy market for next 20 years. The market volume of renewable energy worldwide will increase from US$ 95.8 billion in 2007 to US$ 124.4 billion in 2010 and reach US$ 198.1 billion in 2015. These figures and developments are based on the whole value chain. The energy efficiency will increase by 1 to 3 percent per year and there will be more then 120000 direct jobs by 2010 and two times more indirect.

The major market driving forces.

Climate change and economic damage depending on the country between 1 and 5 percent of the gross domestic product. The governmental policy and social awareness. In many countries, environmental protection and energy security are the key political concerns which favour the use of clean energy. In most countries governments sponsor programs for using hydropower, wind power and biomass as well as set regulations & standards for emission so that biofuel, solar energy, hydrogen based energy and other environmental friendly energy are adopted.

Second is the pricing factor. Whereas the oil and gas price is rising in the long term and extremely volatile, the price for renewable energy is stably going downward. The material benefits will naturally attract more and more industrial and residential consumers.

Sunday 29 July 2007

The future is solar

Or more precisely, the future should be electric.

I have done a lot of research lately into various alternative diesel technologies as I was working on my renewable diesel chapter. One thing that became very clear to me is that the world will not be able to displace more than a fraction of our petroleum usage with biofuels. I already knew that this was the case with ethanol, but now I think this will be a general limitation for all liquid biofuels. Consider this sneak preview (still in draft form) from the book:

There are approximately 4 billion arable acres in the world. There are many different feed stocks from which to make renewable diesel, but most biodiesel is made from rapeseed oil. Rapeseed is an oilseed crop that is widespread, with relatively high oil production.

Consider how much petroleum could be displaced if all 4 billion acres of arable land were planted in rapeseed, or an energy crop with an oil productivity similar to rapeseed. The average rapeseed oil yield per year is 127 gallons/acre. On 4 billion acres, this works out to be 33 million barrels per day of rapeseed oil. The energy content of rapeseed oil is about 10% less than that of petroleum diesel, so the petroleum equivalent yield from planting all of the world's arable land in one of the more popular biofuel options is just under 30 million barrels per day. This is just over a third of the world's present usage of petroleum, 85 million barrels per day. Yet this is the gross yield. Because it takes energy to grow, harvest, and process biomass into fuel, the net yield will be lower, and in some cases may even be negative (i.e., more energy put into the process than is contained in the final product).

The fundamental problem here is that photosynthesis is not very efficient. Consider the rapeseed oil yield above. Gilgamesh made a table that is basically the solar capture/conversion to oil from various crops. The gist is that only a few hundredths of a percent of the incoming solar energy gets converted into liquid fuels. Of course some did get converted into other biomass, which could be otherwise used for energy, but generally we get a very low capture of the sun's energy for use as liquid fuels. (This exercise can still be proven by assuming the theoretical limit for photosynthesis. One must just make more assumptions and it is not as easy to follow for a general audience).

Consider instead direct solar capture. Let's not even consider the record 40+% efficiency that Spectrolab announced last year. Let's not consider any of the more exotic technologies that are pushing the envelope on direct solar capture efficiency. BP's run of the mill silicon solar cells operate with an efficiency of 15%. That's about 250 times better than the solar to rapeseed oil route. Or, to put it a different way, you can produce the same amount of energy with direct solar capture in a 13 ft. by 13 ft. area that you can by photosynthesis in 1 acre of rapeseed. And odds are that you have a roof with an area that size, which could be used to capture energy without the need to use arable land.

Of course the disadvantages are 1). The costs for solar are still relatively high; 2). We have a liquid fuel infrastructure; 3). Storage is still a problem. But in the long run, I don't see that we have any chance of maintaining that infrastructure. If we are to embark on a Manhattan Project to get off of our petroleum dependence, we should direct our efforts toward an eventual electric transportation infrastructure.


After posting this essay at my blog, it got linked to from a number of places. Between those links and the original blog entry, some of the comments I read were largely in left field, and many of them didn't come close to representing my actual position or arguments. Maybe that's partially my fault for spending all of 20 minutes writing the post. Which brings up another point: It seems like the less time I spend on a post, the more comments and hits it gets. But I digress.

So, let me clarify a few things.

1. I am not against biofuels. In certain situations, biofuels may be (and probably are) an appropriate solution to the problem. In fact, I continue to work on solutions to biofuel problems, and I wouldn't waste my time doing this if I didn't think there were some applications. My argument is that we won't, as many people believe, displace large amounts of petroleum with biofuels. Presuming we can is presuming that technology that does not currently exist will inevitably be invented.

2. I am not against technology. I love technology - especially biotechnology. But I am well aware of the "technology will save us mentality." Technology doesn't always proceed as you think it should, and it doesn't always respond to monetary incentives. If it did, cancer and AIDS would no longer be with us, and 40 years after the moon landing, a manned Mars expedition wouldn't still be a distant dream.

3. This is not a new revelation for me. I have long believed that our future must be electric for at least 4 reasons. First, is the photosynthetic efficiency that I discussed. Second, internal combustion engines are notoriously inefficient relative to electric motors. Third, we have a lot of rooftops available that will not compete with arable land. And finally, electricity can be produced from a tremendous diversity of sources. Start with biomass, solar, wind, hydro, nuclear, natural gas, coal - all are easily converted into electricity. Contrast that with the uncertainty of a future based on cellulosic ethanol and algal biodiesel.

4. As one person argued, "solar collectors don't self propagate." True, but biofuels don't self-harvest and convert themselves to useful end products. Once the solar panels are in place, they keep giving for a long time.

5. The rapeseed example is merely a thought experiment. Don't spend too much time worrying about all of the implications of planting a majority of our land in rapeseed, or whether instead I should have planted palm oil or corn everywhere. It is just an example to frame the problem. But I do not believe, as some have suggested, that using land that is presently non-arable is going to provide a fraction of the yields you would get from planting all the arable land in rapeseed. So, I think it is a very conservative thought experiment.

6. Several people have suggested that I am just wrong about biofuels; that technological advances will change everything. All I can say is that hope is a wonderful thing. But you better plan for contingencies in case those visions of algal biodiesel fail to materialize.

7. Yes, I know that SI units are better in the context of a scientific paper. And I do use SI units in the chapter. But for most casual readers in the U.S., a yield of gallons per acre is going to be more meaningful than a yield of liters per hectare.

8. I am aware that biomass is stored energy. But you can't harvest all of that stored energy and use it, or you will rapidly deplete the soil. This is why you will never convert anything close to theoretical photosynthetic efficiency into liquid fuels. And theoretical photosynthetic efficiency is still far short of solar cell efficiency.

Wednesday 20 June 2007

Ceramic Fuel Cells Limited

Ceramic Fuel Cells Limited :: Applications: "Fuel Cells, and in particular Solid Oxide Fuel Cells (SOFCs), are suitable for a number of applications that utilise heat. As the SOFC operates at high temperatures (approximately 800 degrees Celsius) there is a significant potential for other technologies and applications to recover some of the ‘waste heat' from the fuel cell to increase the overall efficiency of the unit.

As CFCL strives to increase the electrical efficiency of the fuel cells -less and less heat becomes available for recovery. Depending on heat requirements, most appliances requiring coupled heating devices may therefore need an auxiliary burner."

There is growing demand for energy across the globe. Demand for electricity is forecast to double from 2002 to 2025. Yet the existing supplies may not cope with this demand, and significant investment is needed in new generation systems that also meet higher efficiency and environmental standards.

Ceramic Fuel Cells Limited is providing solutions. I also love this company. CFCL listed on the Australian Securities Exchange (ASX) in July 2004, and on the London Stock Exchange AIM market in March 2006. CFCL's stock code on both markets is ‘CFU'.

Ceramic Fuel Cells Ltd (CFU) was granted a patent in Japan in 2006 for a coating used on electrical interconnects in fuel cells, giving Ceramic Fuel Cells a total of 46 granted patents and therefore significant scope to expand its designs and product options and offers opportunities for future revenue streams.
The company believes this innovation can provide a cost-efficient means of reducing the contact resistance within a solid
oxide fuel cell stack, which increases the power output of the stack,ultimately leading to lower cost and higher efficiency. The Japanese patent joins patents granted to Ceramic Fuel Cells for the same invention in the UK, USA, France, Germany, Italy, Australia and New Zealand.

Ceramic Fuel Cells Limited is supplying German energy company EWE with ten NetGen micro combined heat and power (m-CHP) units as part of an ongoing trial to commercialize m-CHP for the European market.

Monday 18 June 2007

DYESOL has enormous potential

Dyesol has been a pioneer in the field of Dye Sensitised Cells over the last 10 years and is now providing the key dyes and Titania pastes to many of the research and commercial organisations developing DSC applications.

DSC technology can best be described as ‘artificial photosynthesis’ using an electrolyte, a layer of titania (Ti02)(the white pigment used in white paints and tooth paste) and ruthenium dye sandwiched between glass. Light striking the dye excites electrons which are absorbed by the titania to become an electric current many times stronger than that found in natural photosynthesis in plants. Compared to conventional silicon based photovoltaic technology, Dyesol’s technology has lower cost and embodied energy in manufacture, it produces electricity more efficiently even in low light conditions and can be directly incorporated into buildings by replacing conventional glass panels rather than taking up roof or extra land area.

The Company – DYESOL Limited
Dyesol is located in Queanbeyan NSW (near Canberra) and in August 2005 was listed on the Australian Stock Exchange (ASX Code ‘DYE”). Dyesol manufactures and supplies a range of Dye Solar Cell products comprising equipment, chemicals, materials, components and related services to researchers and manufacturers of DSC. The Company is playing a key role in taking this third generation solar technology out of the laboratory and into the community.