Nanomech in Photovoltaics

What to do with solar in the economic turndown

2009-03-21T15:32:00.005+01:00

As you may have noted, I am in the process of developing a new blog (Heliotactic.org). The reasons? First, the Sun allows for a plethora of possibilities, and I wanted to work with a bigger canvas! Second, I feel the need to open up the blog to entries from guests, to create a diverse perspective of all things tied to solar (including energy efficiency, green roofs, passive solar design, energy recovery and cogeneration). And third, and most frankly, PV is the most expensive solar investment for the individual. In this economic depression, we need to know what technologies are affordable and offer the highest rewards for the initial investment. I’ve been told again and again that solar hot water is the most obvious, no-brainer tactic in the solar arsenal. It’s cheap (< $6000 for everything), it’s easy, and by replacing/complementing your electric or gas (or fuel oil) water tank (with federal and state incentives), payback is often less than 5 years.

My recent experiences have included teaching solar energy conversion, developing tools for solar resource assessment, and leading a great team to design, build, and operate a solar-powered house (

Solar Jobs = Green Collar Jobs!

2008-12-28T16:13:00.004+01:00

As a researcher and instructor dealing with solar energy conversion, I am acutely aware of the immediate need (or ASAP) for a smart, flexible labor force--capable and trained to install and maintain our new solar technologies. Solar energy will be the heart of the new green collar job sector, as we will need to deploy PV and solar hot water technologies to residential and commercial buildings for a carbon-constrained future.

Analogy:
I want to use the familiar example of technologies for indoor air quality and thermal comfort: HVAC systems (Heating, Ventilation, and Air Conditioning). Think about how many air conditioning units are now an integral part of buildings in the country. Consider the labor force that is required for AC/heating installation, duct installation, monitoring and control systems (e.g. thermostats), and maintenance or repairs (hint: it is a huge industry). Now think about how little you think about these systems (because they just work). There is similar (perhaps even greater) potential for green collar jobs--earning a paycheck and helping society and the environment!

The Very Near Future:
Green collar jobs for solar technologies are here! Training is in full gear in states like California, New Jersey, and Florida, and is ramping up in Wisconsin and Pennsylvania. At Penn State, we are already working on a training course for PV installation, as well as an upper level college course in solar energy technology design.

Additional reading: NYT article on PV installers as the new wave of green collar jobs.

Solar technologies are really diverse

2008-12-25T16:38:00.001+01:00

In preparing for my annual Spring course “Design of Solar Energy Conversion Systems”, I am reminded of just how many diverse technologies can be derived from our nearest large-scale fusion reactor. I will make exceptions to the obvious: horticulture and wind energy are derived from the sun too.

Here are some ideas beyond PV and concentrating PV (CPV):

1. Passive/Active Solar Water Heating Systems (in your showers, dishwashers, heating your floors)

2. Commercial/Distributed Space Heating Systems (using Solar Walls, Phase Change materials, Pebble-bed hot air storage).

3. Solar Cooling (Yes! you can cool with the sun and heat pumps, dessicants, refrigeration cycles).

4. Solar Industrial Process Heat and Solar Ponds (Do you own a mine or a refinery? Look into ways that you could dramatically reduce your energy bills!)

5. Solar Thermal Power Systems (Also called Concentrating Solar Power--CSP--this is the technology with the best odds at being the next wave of electric power from the sun).

6. Don’t forget solar chemistry (not just growing plants) to make hydrogen and other fuels!

Solar is very close to breaking out. Why not invest in solar tech?

Educational Links on Photovoltaics and Solar Energy

2008-11-09T15:44:00.004+01:00

Where would be the best place to get an update of solar energy conversion, and photovoltaics in particular? That would be in a classroom, where you can ask questions and sort through the multiple topics of materials, sources of photovoltaic action (drift, diffusion, electrokinetic phenomena), and the difference between a cell, module, and an array. You would also be able to see that PV is only a tiny segment of an otherwise broad portfolio of technologies to make use of the sun for heating, cooling, making chemicals, making electricity from turbines, and so on. I offer two core courses at Penn State that deal with these subjects, but obviously there is a larger audience out there that would like information. Thankfully, we will be producing a web-based course dealing with photovoltaics, but that will be about a year off.

Therefore, I would recommend two web-based books for the curious, right now! The first is an educational project that began as an international collaboration between the University of Delaware and the University of New South Wales, funded by an IGERT grant. The site is called Photovoltaics: Devices, Systems and Applications CD-ROM, and the authors are Christiana Honsberg and Stuart Bowden. This includes interactive diagrams, movie clips of the silicon manufacture process, and a good review of solar energy. You will need to download Shockwave from Adobe. Up until recently, the Shockwave addition did not work for Macintosh systems, so I was more hesitant at recommending the site. But now: go for it! You will be busy for weeks. Note that the site is dedicated to silicon devices, and will not provide a comprehensive description of thin film PV devices and the principles of operation. That being said, the site is a gem.

The second book is not as web savvy, but does contain fantastic fundamental information on solar energy conversion. The resource is Power from the Sun by by William B. Stine and Michael Geyer, at California State Polytechnic University in the USA and IEA SolarPACES in Spain. This text is more like the classic paper text by John Duffie and William Beckman: Solar Engineering of Thermal Processes, in which multiple solar energy conversion technologies are described.

There you go, solar energy enthusiasts! Go to school and get informed on solar energy. But if you are tied up with other things (like life), in the mean time do some winter reading and find out how much potential solar energy has as a sustainable technology!

More Photovoltaics to come...

2008-08-31T15:43:00.002+02:00

It looks like there is interest in the principles of photovoltaics. I will be reviewing and revising my older posts on the subject in the next few days. Come back shortly for more!

Photovoltaics: Levels of Irradiance

2008-08-02T18:54:00.008+02:00

Let’s talk about light interacting with a semiconductor to yield electricity. Today’s topic is to distinguish between low levels of irradiance and high levels of irradiance. Effectively, we are asking for an estimate of the concentration of photons being delivered from a high energy source to a low energy absorber/collector.

When we say low levels of irradiance, we are estimating a scale of light concentration that is typical of the diffuse and direct component of unconcentrated “global” or “total” solar radiation, or the light from a standard incandescent lamp or fluorescent lamp. This could be anywhere <1000 mW/cm², or 10x the sun’s concentration (remember, this is just a crude scale, not a hard and fast rule--don’t take this back to your classes). The standard for testing solar cells inside the earth’s atmosphere is called Air Mass 1.5 Global (AM 1.5G), because the light from the sun passes through 1.5 lengths of a generic Earth’s atmosphere to generate a convenient irradiance of ~ 100 mW/cm². Low levels of light such as this provide a sufficient number of photons (packets of light) to excite the electrons into an unoccupied level of energy (the conduction band). However, the population distribution of the majority carriers does not change significantly. That’s okay: the key player in a photovoltaic absorber is the minority carrier (n-type semiconductor: a hole; p-type semiconductor: an electron), and the population of minority carriers does change significantly with light absorption. Minority carrier transport gets the job done, in fact, because they are the limiting rate in the absorber reactor. You can find out more about charge carriers and carrier transport in the Photovoltaics CDROM from Honsberg and Bowden, Chapter 3 (although it doesn’t work completely for Macs, sadly)

What is high irradiance? You’ve heard the warnings about strong lasers pointing into others’ eyes? A laser is a coherent, collimated light source (the photons’ waves are in phase and heading the same direction), such that the photons can be very concentrated. If sufficient numbers of photons are absorbed by a semiconductor, the population of photoexcited charge carriers can be much greater than the majority carriers, and there a population inversion occurs, leading to stimulated emission (Light Amplification by Stimulated Emission of Radiation).

The photons from light bulbs and suns are neither coherent nor collimated, although they can be concentrated significantly to potentially cause a population inversion and stimulated emission (yes, there is the possibility for a solar laser). However, before that stage there are other phenomena that occur, making it a bit more complicated.

Concentrating cells allow an increased flux of photons to the smaller receiver/absorber using a larger aperture to collect the solar light. The geometric concentration ratio is the ratio of the area of an aperture to that of the absorber (C=A_apt/A_abs).^1,2 For a perfect concentrator (as a point on the surface of Earth), the radiation from the Sun on the aperture-receiver assembly is only a fraction of the total radiation emitted by the Sun, given a half-angle subtended by the Sun of 0.27°. Assuming a blackbody, the absorber would have a maximum theoretical concentration ratio of 45,000 (for a circular concentrator) or 212 (for a linear,trough concentrator).¹ The higher the concentration,the higher the photon flux (including increasing temperature),and the more precise the optics of the collector must be to deliver. This is an extreme energy flux for any semiconductor. Under high illumination levels, one will observe a decrease in minority carrier lifetimes and related diffusion path lengths. However, 45.6% of the suns power is contained in the infrared band (the part that makes things "hot"). Thermally, an imaging concentrator (C>> 10; analogous to camera lenses) can produce temperatures from 500 to 1500 °C at the absorber.² This increased temperature can be used to drive thermal work (steam generation) or thermophotoelectrochemical reactions for concentrating solar power (CSP, not to be confused with CPV), but is not necessarily good for photovoltaic performance. High temperatures tend to decrease the efficiency of a photovoltaic device. In particular, this is why members of the microelectronics industry are getting into the concentrating photovoltaics field (CPV)--they know how to cool superhot microelectronics, and will do the same with CPV devices.

It is so interesting to see how this is all a great spread of possibilities that one can derive from our nearest fusion reactor!

Text sources:
1. Rabl, A. Active Solar Collectors and Their Applications. 1985 Oxford University Press, New York

2. Duﬃe, J. A.; Beckman, W. A. Solar Engineering of Thermal Processes. (3rd Ed.) 2006 John Wiley & Sons Inc, Hoboken, NJ, USA.

3. Andreev, V. M.; Grilikhes, V. A.; Rumyantsev, V. D. Photovoltaic Conversion of Concentrated Sunlight. 1997, John Wiley & Sons Ltd, Chichester, England.

Surfing more and more photovoltaics!

2008-07-23T19:36:00.005+02:00

In just a few years since returning from France in 2006, I have noticed some significant improvements in the world of PV within the United States. In fact, it seems that there is a wave of solar development and deployment that is rolling across the country!

Let me preface this glowing remark by commenting that not all was so great even two or three years ago. I had been working for a year in a laboratory in France that specialized in basic research for silicon and eta-cell (extremely thin absorber) thin film photovoltaic devices. While there, I was working with members of industry, the French government and power company, and the French national lab system. It seemed that there was a great vertical integration of research, industry, and deployment in France (and even more occurring in Germany). It was therefore a bit of a let down to return and learn how far behind the US was in terms of this integration. Yes, there are two major centers for research in Colorado (NREL) and Florida (FSEC), but as a national whole, the system seemed a bit worn, frumpy, and patchwork in nature. In truth, the USA went through about a 25 year period where not much was visible at all in solar research. The funding had dried up, leaving room only for the biggest four or five names in materials research and computer simulation (who supplemented their funding with studies in refrigeration). Now, many of the notable solar researchers are either retired scientists, microelectronics specialists, or emeritus professors.

However, in the two years since I returned there has been a dramatic bootstrapping occurrence. Just as we are looking to “next generation” PV technology, so are we seeing “next generation” researchers, educators, and industrial developments! Gunther Portfolio is a great blog for keeping us informed about developments for investing, and SolarBuzz and PVNews/Greentech Media also have regular installments of more and more PV industry growth.

In education, Penn State launched a new Spring 2008 course from the Dept. of Energy & Mineral Engineering, focused on solar energy conversion (with emphasis on photovoltaic conversion). Penn State also has plans to develop another more hands-on course in photovoltaics for extended education in the near future. Prof. Tonio Buonassisi of MIT has also announced a course in photovoltaics set for this Fall 2008 semester. The students have spoken, and they want more information on the current state of the art in solar and photovoltaics!

In the federal government realm, we are still sadly lacking a signal to encourage PV via incentives. The residential tax credit is slated to expire at the end of this year (following an extension). You will find much better luck for incentives on a state by state basis (see DSIRE). However, we did just receive a call to action by former Vice President Al Gore that may put more senators and representatives “in the mood” for renewable electricity generation. Also, the Solar Decathlon is to continue until 2015, the projected year for levelized cost of electricity generation from PV to be competitive with coal-fired electricity generation. The sponsor (DOE/NREL) projects half a billion visitors to the Mall area over a three-week period in September 2009, and anticipates global exposure to the Solar Decathlon concept to over one billion people. The Solar Decathlon is also exerting a viral effect on solar engineering and design, as it is inspiring similar competitions globally. Even now, a Solar Decathlon Europe is planned for 2010 in Madrid, Spain. The city of Beijing will be holding the 2009 Delta Cup – International Solar Building Design Competition, where the winning homes will be deployed in the earthquake-hit areas of Sichuan.

Keep up the good work, solar community! Let’s continue to work together to provide more information and more incentive for the broad public to adopt solar renewable energy. Of course, if a major component of that is photovoltaics, I would be pretty ecstatic!

What is disruptive technology?

2008-07-02T21:10:00.003+02:00

Quick question: would you interpret quantum dots as disruptive technology for light absorbing solar energy, or concentrating solar power (CSP)? One is a fairly recent topic in the photovoltaic world, and the other has been around for over one hundred years.

A quantum dot is a nanoparticle in which the excited states (high energy electrons and holes) are "confined" by the very small dimensions of the particle. This leads to increased energy in the excited states (no where to go but up in energy), and has resulted in many new technologies. One proposed technology would use quantum dots as light absorbers for a photovoltaic effect, where one could collect mulitiple electrons (increased photocurrent) or very high energy electrons (increased photovoltage). The up side is that quantum dots sound sooo cool, why not make them into PV devices? The down side is that the rates of charge carrier extraction (collecting the electrons to do work) are still way too high to get much efficiency out of them. A lot of research needs to occur before you start seeing purely quantum dot PV. The disruption appears to be far away.

On the other side, if you concentrate the sun's power, you can use it effectively for multiple applications, and often you don't need radical new technologies. Rather, a combination of straight forward technologies in a new way may lead to something disruptive. You can concentrate the sun's visible light (48% of the suns power, or 656 W/m2) for photovoltaics, OR you can concentrate the sun's infrared light (45.6% of the total power, or 623 W/m2) and use the thermal heat to do work! Either way, by concentrating you take a diffuse source and, well, concentrate it. Certainly, you would need to cool a PV collector, but what about a thermal collector powering a turbine to generate electricity? In 1878, a solar power collector was exhibited at the World's Fair in Paris, France. Between 1907 and 1913, an American engineer (F. Shuman) developed solar powered hydraulic pumps with a concentration ratio of about 4.5:1.¹

And the kicker, CSP is getting closer and closer to being the first economically viable solar technology--opening the doors to the following technologies? Is this disruption, by opening the possibilities of solar power beyond the single junction photovoltaic device?

1. D. Y. Goswami, F. Kreith, and J. F. Kreider Principles of Solar Engineering 2nd Ed. (2000) Taylor & Francis, Philadelphia, PA.

Natural Fusion recap

2008-04-19T15:25:00.004+02:00

It has been a very busy semester at Penn State. I've served as the faculty director for the Solar Decathlon 2009 effort (Natural Fusion project), I'm developing a course in solar energy conversion, I'm establishing my materials research laboratory, and I'm the outreach and recruiting coordinator for my department. Even so, one of the fun aspects of my job is that so many things overlap each other, and there seems to be an unusually high rate of "moments of synchronicity". The class overlaps with the project, and the project helps with recruiting, and I've gotten to know more people on campus than I ever would have hoped for in my first year at University Park. What a blast!

In the Natural Fusion project, I have 15 amazing students serving as project managers from multiple colleges. They all have the vision and energy to turn this competition into a brilliant learning experience for integrated design, green building, and entrepreneurship. We also already have a team of over 100 (!) students that are helping in our design and marketing process.

I am also fortunate to have two other experienced faculty members deeply involved in the mentoring experience, and several more faculty available for support in the future. The team has been out to several industries seeking support in mentoring, materials, and direct funding--and things are looking very good. Even in the first four months, it appears that we will be testing and deploying many new technologies in photovoltaics and energy efficient materials. It's not without its stressful periods, but I feel that we have a really great thing going that will be both memorable and valuable to all of our futures.

Solar Decathlon...ho!

2007-12-11T22:44:00.000+01:00

The Solar Decathlon is a progressive competition, offered to selected universities across the nation and outside of the USA every other year, in which students from multiple disciplines design and build a home completely powered by the sun. The focus of the competition is to combine BIPV (Building Integrated PhotoVoltaics) with new energy efficient architecture and its engineering systems. The competition was initiated in 2002 by NREL/DOE in conjunction with major sponsorship by British Petroleum, and the official two-year cycle was continued as of 2005 (SD2005).

The Decathlon operates within the general goals of the Solar America Initiative of the DOE, to make photovoltaic solar energy cost-competitive with conventional energy forms by 2015 (levelized costs of $0.10/kWh for PV). A major focus is to encourage relations between Academia and Industry for integrated design of photovoltaics within standard building practices. However, it includes the incorporation of the project into the curriculum of the students, as well as their involvement with industry. The Decathlon is projected to continue until 2015.

The winner of SD2007 was: Technische Universität Darmstadt. That’s correct; Germany won the USA solar home competition on their first try (why shouldn’t the biggest PV player in Europe be a strong competitor?). Perhaps this was an appropriate challenge to wake up integrated PV education in the states.

My own new home, Penn State University, took 4th place on their first attempt, Morningstar Pennsylvania. We’re looking forward to the opportunity to return and improve upon that standing in SD2009. It’s a great opportunity for students and faculty alike, and all products displayed in the Solar Decathlon homes are commercially available, which will make the project pretty interesting as the competitions progress to 2015.

Goals in Interdisciplinary Research

2007-09-17T23:04:00.000+02:00

In today’s research society, there is value in we. I don’t really know that this premise has changed over the years, but the message seemed to have been lost or mixed up in the pressures for making an independent name of your research in university life. Young researchers are fed information from senior researchers that they need to stay focused—and maybe it gets misinterpreted as staying isolated.

We’ve been told that “once upon a time”, someone starting out into the academic world was open to develop one’s personal, independent ideas. Funding was talked about as plentiful (or at least more probable to acquire by writing a grant proposal than today). But now we know, those of us trying to break upward into a stable research program. It’s just not a good strategy for a newcomer in grant writing and fund-seeking. Today’s research is cut-throat competitive, and even more so if you try to go it on your own. Working alone is an invitation to blow out your tire before you even get rolling.

You can’t know everything, even regarding a particular subject like solar energy (especially with solar energy). Help from others is needed to strengthen your research. It is important to build a network of skeptical, critical thinking colleagues who can look at your goals from unusual angles. You want a collective of shared interests, because there is power in numbers. They have the same urgent goals for support as you do.

So how does one make unique contributions while maintaining a source of funding? Work in bigger circles. Be open to defining your colleagues by a broader set of criteria. Communicate outside of your discipline and be positive of your own abilities.

It’s scary to look out across that void between disciplines, to reach out and communicate with someone you don’t know when you’re not even remotely an expert. But in order to support modern research, we need to span that void as another form of exploration. Because it very possible that we’re not even aware of the potential from the expert on the other side.

On a road to somewhere!

2007-08-18T23:03:00.000+02:00

Greetings all. My delay in contributing to these posts was for a very good reason. After many years of graduate school, and after experiencing the transient life of a postdoc, moving from Wisconsin to France and then back to Wisconsin for positions as a research scientist, I believe I will be staying put for a while.

We're in the process of relocating the whole family to State College, Pennsylvania for my new position as an assistant professor at Penn State, in the Department of Energy and Mineral Engineering. I will be pursuing my dream of environmentally aware materials science in the pursuit of new photovoltaic devices. I admit, I'm excited and terribly nervous at the same time. I plan to work hard and make progress in my research, and in extending my network of connections with academia, government, and industry. I also really want to be a good mentor to both undergraduates and graduate students. So much of this, you just have to do it rather than make the perfect plan. The system is dynamic and fun, and more like surfing than following a recipe.

So wish me luck, and keep an eye out for new posts from the bench of the new nanomech professor!

PV Documetaries: The Power of the Sun vs. Saved by the Sun

2007-05-13T19:35:00.000+02:00

When making a science documentary, shouldn't a good science background be involved in the production?

Please note: The solar power of today is not the solar power of the 1970s (or the 80s, or the 90s...)!

I have viewed the two recent big documentaries on solar power: The Power of the Sun and Saved by the Sun. In comparison, my summary argument: a scientific background goes a long, long way to gelling the message of a science documentary.

For those short on time: watch The Power of the Sun and show it to all of your friends. You can purchase the DVD for US$10 +shipping (half price if you are a teacher!). It provides the scientific background of silicon photovoltaics (PV), as well as a future for solar power. The latter documentary is a highly-diluted and out-dated science commentary with a generous mix of 60s and 70s nostalgia to mask the lack of content and vision.

Both films are produced in the US, and deal with the recent boost in development and financial interest in solar power. The executive producer of The Power of the Sun was Nobel Laureate Walter Kohn, while Saved by the Sun was produced by Steven Latham, Larry Klein, and Evan I. Schwartz (scientific backgrounds unknown) under the NOVA series of PBS television.

While the NOVA special has some value in getting people aware of commercially available PV, there is a distinct lack of presentation of the science and the broad range of industries already involved in major PV businesses. They don't give credit where it is due, and misplace other credits by a lack of depth of inquiry. Instead of talking about the fact that PV in Japan is now unsubsidized, and many new Japanese homes have PV funding incorporated into home loans, the film implied how "curious" the Germans are for creating a heavily subsidized solar market and entire farms of PV. Skeptical economists are called in to reassure us that solar energy is still a long way off folks. That could never happen in the USA, economic analysts scoff. Except that it is happening in the rest of the world, and we've woven ourselves into a global economy. A market with a 37% cumulative growth rate (meaning a doubling time of 2.2 years), and a 2006 peak power output of ~2.5 GW (Gigawatts) is not an economic fringe commodity.

Following this disjoint, Prof. Nate Lewis of Cal Tech is interviewed for his contributions to photoelectrochemistry (which are very significant). However, instead of going into the new chemistry his group works on, he is essentially given credit for recently creating dye-sensitized solar cells (that were first developed by Brian O'Regan and Michael Grätzel in Switzerland and reported in Nature in 1991). Couldn't the filmmakers have asked Nate, so how long has this been around?

Add on top of all of this, a penchant for 1960s and 1970s counter cultural pop tunes including the word "sun" or "sunshine", and you have officially alienated the new generation of PV consumers. Thank you NOVA and PBS.

Prof. Kohn had informed us at the American Chemical Society's viewing of The Power of the Sun, that PBS turned down the opportunity to show this film. It was deemed too controversial, due to a comment by narrator John Cleese that the world was "dangerously dependent on fossil fuels, even addicted to them", and due to a suggestion that fossil fuel combustion may even be linked to "global warming". Curiously, one G. W. Bush did see The Power of the Sun in a personal viewing, and something of that phrase slipped into one of his speeches.

Hmm, I guess good science does have an influence on policy.

* Plot developed by JRSB from data by PVNews and the Prometheus Institute for Sustainable Development.

A change of scenery...

2007-04-03T01:23:00.000+02:00

As a curious turn of events, I will be cross-posting my future blog entries at Nature Network.

I heard about this new science-based social network being established at the American Chemical Society conference in Chicago (Mar. 28, 2007), and I was determined to give it a try. I've been a member of the Connotea online publication reference program for a year now (approximately as long as it's been in public existence I believe). And while I admit that I haven't observed a major shift in the physical science-based links at Connotea, I am sure that social networks, tagging, and other aspects of Web 2.0 design will percolate through the science community soon enough.

So please, feel free to enjoy the site here. But with all good luck, Nanomech in Photovoltaics may see a migration in the future solely to Nature Network.

The Nature of David Suzuki

2007-03-31T18:20:00.000+02:00

Last week I had the privilege of listening to a special lecture by Professor D. Suzuki for the Distinguished Lecturer series from the University of Wisconsin. Prof. Suzuki is a geneticist and ecologist from the University of British Columbia, and is very well know for his hosting of the television science show The Nature of Things, on the Candian Broadcasting Corporation (CBC) since the late-1970s. He is also renowned for his strong support of the environmental movement and his activism toward influencing governmental policy regarding the environment. I can still remember watching his show in the 80s while living in North Dakota (as we received the CBC in our television line-up). He really did inspire a love for nature and science for me.

That evening, he did not disappoint (a few summary points that stuck with me):

ECO is derived from the Greek oikos, meaning “home”

Hence:
ecology is the study of the home

and

economy is the management of the home

“It’s time to put the ‘eco-’ back in economics.“ Exponential constant growth is unsustainable, and the ecology should guide the economy--not the reverse.

People used to say think globally, and act locally. But "thinking globally" is too overwhelming, and people just throw up their hands and say, 'Well, there's nothing I can do about it. The problem is just too big.' Instead, we should really do as David Barry says: 'think locally, and act locally', because then the problem becomes more tangible, and people feel less intimidated by the prospect of bringing about change.

MY THOUGHTS: His suggestion to link the schools of economy with those of environmental studies and ecology really hit home. In that system, I believe there is a natural opportunity for linking materials science and technology into the process. In such a way, the materials produced are guided by with environmentally aware design and marketing of that product to an economy that understands the concept of a limited reservoir of energy, water, and materials on Earth's accessible crust. In an educational sense, this means incorporating coursework in ecology and geoscience into the fields of economics and materials science. I have a strong hunch that environmental engineering will be a passing term on the way to the next generation of modern society. Very soon, ALL engineers and scientists will be required to be environmental engineers in the context of their own discipline, just out of the influence of limited reserves.

Please note: Prof. Suzuki has a foundation to address sustainability and global climate change: the David Suzuki Foundation. This site is a wonderful tool for education on issues of sustainability. The site also contains simple, easy personal changes that will help diffuse the footprint of modern human society on Earth.

* Image copyright Ronica Skarphol Brownson (2006)

Are you Sustainable?

2007-03-31T10:51:00.000+02:00

The looming question of sustainable practices in chemistry and materials was a central topic at the American Chemical Society this week in Chicago. There were several symposia related to chemical education of sustainability, sustainability in water resources, and (my particular favorite): sustainability and energy. The 2007 ACS president, Dr. Katie Hunt, has made sustainability one of her core issues, and you can hear (or read) all about her in this interview on Science and Society.

Prof. Art Nozik of Center for Basic Sciences at the National Renewable Energy Laboratory (NREL) arranged a top notch session on Realizing the Full Potential of Solar Energy Conversion through Basic Research in Chemistry and Biochemistry on Tuesday (Mar. 26, 2007), with speakers Nathan Lewis, Michael Graetzel (of the dye-sensitized solar cell), A. Paul Alivisatos, and A. Nozik himself (speaking on quantum dots and multiple exciton generation from high energy photons). Prof. Nathan Lewis has presented this data to President Clinton in the past, and his talk on alternative energy was shocking, alarming, and invigorating all at once. In short, the only source of power that we have enough supply for is : solar. We don’t have enough wind, wave, geothermal, nuclear, biomass, etc. in our resources to cut our CO₂ levels and to create enough energy for only 2x the amount required to feed every human by 2050. You can find a link for the talk here.

Michael Graetzel’s talk was very interesting, and I’m delighted to hear progress has been made on dye stabiliy in UV, and new electrolytes have been developed using ionic liquids that remove the sealing problem encountered in acetonitrile-based electrolytes. In Graetzel’s words, dye-sensitized cells can be made now to withstand a 20 year life cycle (estimated), and have maximum performaces at 11% efficiency. Not too bad for an inexpensive alternative!

In addition, we were treated to a wonderful movie produced by Nobel Laureate Walter Kohn (UCSB) called The Power of the Sun. The short film is narrated by John Cleese, and can be obtained for only $10 from the University of California Santa Barbara website. The package includes an educational film for students as well. This film would be appropriate for high school science classes through college or university, and could be a very useful as an educational tool. It could be combined in an educational section on energy, or solar power, and the website has additional supplemental educational materials online.

I was disappointed in most of the other talks outside of the sustainablity symposia. Often the researcher/presenter did not gear the presentation toward a more general science audience. Hence, the context of the study was lost to the outside listener, and the importance that a study may have to a peripheral research topic.

For all of the hot talk about the importance of solar energy and the importance of third generation PV technologies, almost no mention was given of studying the interface between quantum dots and the electron/hole collectors necessary for doing work as a third generation photovoltaic cell. Considering that the interface is where the electron transfer occurs (aka: "chemistry"), I was quite surprised at the vacancy in that subsection of research.

The elephants of new PV technology were also in the room: the toxic heavy metal cadmium used in new solar materials (CdSe, CdS, CdTe by A. Paul Alivisatos), and the proposed superiority of CIGS (copper indium gallium selenide) PV cells, despite the very relevant indium shortages from limited supplies and competitive markets in flat panel displays. I felt these topics were not properly addressed, or maybe the main scientists are just not aware of the environmental implications of their research. We should present these materials issues to international audiences such as the ACS conference--as they are being developed--to create an environmental and ecological awareness of the most probable impact of our materials research should they be implemented on a national or global scale.

However, the meeting was indeed a recharging event for me. I left with a lot of positive momentum from the discussions on sustainability and the surrounding research that photovoltaic solar cell materials research. Most definitely PV is a strong route of scientific pursuit, and has many opportunities for new lines of research. If Prof. Nathan Lewis is correct, it will become one of the largest industries of our generation, and we should need a considerable amount of minds working toward sustainable solutions.

Environmental Chemistry in Review

2007-03-05T01:30:00.000+01:00

I was recently reading a the introductory statements in an older issue of the American Chemical Society’s journal Chemical Reviews. The issue was devoted to Environmental Chemistry, and the guest editor was Prof. István T. Horváth, currently a professor at the Institute of Chemistry at Eötvös University, in Budapest, Hungary (formerly a senior staff chemist at the Exxon Research and Engineering Company). I admit, I was originally looking for an article on dye-sensitized solar cells, but this introduction has an outstanding comment on ethical behavior in materials development. Something to mull over:

*Introduction: Chemists should be aware of the environmental implication of their chemistry.

“I hope that dedicating an issue of Chemical Reviews to environmental chemistry will increase environmental awareness among chemists. For example, it is no longer sufficient to make “marvelous” new molecules solely on the basis of their marketable properties. Although marketability is an appropriate goal, we, as scientists, must also be concerned with our creations’ potentials for environmental impact. At the same time, we should constantly tighten our scientific standards for generating experimental data, so that any conclusions drawn from such are and will be unambiguous ...

It is in our interest, indeed, in the interest of all of society, to remain vigilant to the impacts of chemicals on the environment. We would strive to keep environmentally acceptable processes alive and minimize our activities that involve unmanageable environmental risks.“

I find it interesting that over 10 years after his comments, we are only beginning to realize the huge environmental influence that chemists and materials scientists hold in their hands when they introduce ”marvelous“ new materials (including photocatalytic nanoparticles, quantum well lasers, ultracapacitors, and carbon nanotubes). Once a material is introduced and developed on a global scale, the waste component arises for material disposal, followed by issues of materials fate in the environment. As scientists and engineers, we have a responsibility to remain aware of the global environment when we make new materials for society.

*From Chemical Reviews, 1995 (95)1, pg. 1

New Member of the Sidebar Community

2006-12-19T18:57:00.000+01:00

After a break during the holidays, I'd like to point out that there is a new sidebar member reporting on photovoltaics in industry that all can access from the Nanomech in PV site. GUNTHER Portfolio is a blog focused on reports from industry regarding international photovoltaic technology, companies in the solar industry, and marketing. Ed Gunther presents a much needed layman's/businessman's portfolio of the rapidly developing solar energy industry, and his blog is worth taking a read. Enjoy.

2006 US Solar Energy Report and Silicon Report

2006-12-10T08:20:00.000+01:00

OK, for those of you interested in the bottom line of solar production this year (and not just photovoltaics), please look at the free download from the Prometheus Institute. Consider that photovoltaics have seen 20% growth in installed modules over the past year in the US alone--not too bad!

But wait! That's not all; for those of your interested in the progress of the global purified silicon shortage, and how soon we should expect to overcome the shortage, read the report on silicon.

Note that I've replaced Monkeysign's blog link in the sidebar with that of the Prometheus Institute. If you have the funds available and are interested in the progress of the solar industry, I would recommend getting a subscription to their monthly report, PVNews. This is a gem of a trade journal, and digests important progress into manageable numbers for discussions with friends and colleagues.

Sad News: Monkeysign's Blog is Unavailable

2006-12-06T17:14:00.000+01:00

Monkeysign, where are you?

"Monkeysign" is (was?) the moniker of a science blogger who consistently reported on the progress of the global photovoltaics industry. Unfortunately, the blog appears to be gone for now. Hence, the link in the sidebar leads to nowhere.

The user tag apparently came from a description of the ampersand in an email address as a "monkeysign" from a friend. It was funny, yet distinct, and it easily set him or her apart from the rest of the crowd (not to mention the excellent news updates). This is unfortunate news for those of us who enjoyed reading it, and especially for those who did not have the chance to see Monkeysign's blog. My thanks to Eugene H. for notifying me of the situation.

Postdoctoral Research Aspirations

2006-10-30T18:10:00.000+01:00

In the previous post, I was asked by reader and fellow scientist Riverie to comment on my experience in finding and securing postdoctoral research scientist positions. Submitted under the category of scientific philosophy, I have chosen the following response as a separate entry.

Like most employment successes, my postdoctoral opportunities have been initiated through positive connections between my former advisor (or myself) and interested parties. My credibility for scientific research improves with each year of additional research (improved network and letters of recommendation) and with successive publications (improved CV). In my experience, one improves the odds of selection for an initial postdoctoral position by searching within the known network of one's advisor(s), and by always requesting the advisor to make initial inquiry contact regarding a position. With successive years, you should be developing your own network, but this process takes some time to “seed”.

Although I have a second position now, I can attest to the difficulty of a "cold call" to another professor (especially outside of their field) expressing your interest in a research position. Professors have exceedingly busy schedules, and often don't have the time to confirm your credentials without some advanced confirmation from a peer, expressing that a candidate is worthy of consideration. Given the inadequate time allotted to the selection process by the professor in need, the risk for selecting a poor candidate is high and one must expect them to be very conservative in drawing their short list. Even so, if the prospective position has no funding and you have no funding, there can be no opportunity, and professors should inform the advisor right away of such a limitation.

If you are selected as a candidate and if it is possible, visit the lab. This was not possible for me to do for my experience in France, so it was extremely fortunate that my postdoc was both highly successful in research and that I had an excellent working environment with the group and group leader. I know the lab that I am currently working in, so I was certain I would be able to adjust and work efficiently.

The truth is, you need to be at the right place and time, with the additional nod from a peer, to garner consideration for a position. As much as they may be though of in terms of inexpensive labor from the point of view of the graduate student, a postdoctoral researcher is substantially more expensive to support and is required to accomplish much more than a student. There are also expectations from the postdoctoral researcher that some mentoring will occur, as an apprenticeship to managing your own future research team (in academia or business). The collaboration is an additional time investment for the professor, and can be looked upon as a means for the postdoctoral researcher to become more efficient at what she/he already does well. So, one should be able to make a good case for an independent work initiative, and expect to perform the majority of the assigned research on your own (with critiques along the way).

Once you are in the research position, expect that a mentoring professor is there to correct your form; you must be open to listen to what they suggest, even if you want to stubbornly adhere to your own hunch. On the other hand, you should continue to express your own opinions regarding the research to spur scientific discussion. If you don’t have the data to back up your claims, be prepared to listen to suggestions and go back to the bench to find that data that clarifies the discussion. Often, you will be surprised by the results of the compromise.

Finally, never underestimate the network of people that are in the surrounding group and laboratories. These people will all be potential connections. Keep your mind open to interdisciplinary connections, even if the moment is not ripe now. And remember that you are the transient in the laboratory; more so than the graduate students, even. Respect that the laboratory and office is your temporary home, and keep the peace. A postdoctoral position is not the place for the great revolt against the machine, and you are expected to behave according to the internal rules of the lab (provided they do not breach ethical standards of scientific behavior).

Bearing all that in mind, good luck!

Cap and Trade

2006-10-16T04:59:00.000+02:00

California led the way in environmental action once again by signing into law policies (AB32) for greatly reducing climate-affecting greenhouse gases (such as CO₂ from fossil fuel combustion). National Public Radio has an interesting debate on the subject. The name of the game is cap and trade, the very same type of policy that we used in the 1980s to reduce acid rain-causing gases such as NO_x and SO_x. Essentially, the California government will set caps (upper production limits) on the levels of greenhouse gas emissions, and will trade emission levels (higher is some parts of the state, lower levels in other parts) among the state to achieve a net level of emission that meets the state cap level.

Fossil fuels are already heavily subsidized. We need to ask, is there a better way to use our tax dollars that also reduces greenhouse gas emissions and aids reduction in major climate changing forces? In making a comparison of solar and fossil fuel energy, we rarely admit that fossil fuels are hugely subsidized. On top of that, consider the prospects for major coal power plants. What is the one resource that the US has a temporary plentiful abundance of? Coal. What is one of the worst combustion sources for greenhouse gas production? That same material: coal. Texas is planning three new enormous coal power plants, set to make it one of the US's worst states for greenhouse gas emitters. Couldn't we be shifting our subsidies to crop damage, storm recovery, and renewable energy plans?

The NPR show makes a good point that jobs for electricians installing solar modules, or plumbers installing solar water heating modules cannot be subcontracted out to foreign countries for lower rates. This is something that requires American labor resources. As part of my research solar electrical materials in academia, I am aware of the need to know about the ground-level labor that is required for device implementation, and the industrial interest in these new technologies. From my own contacts in the renewable energy sector, I am finding that here in Wisconsin, USA, there is a very progressive interest in building the core structure for solar and wind energy use. There are more and more meetings for large industry, not to dream about solar energy, but to actively plan for the next wave of labor and materials that will be set in place to institute solar module installation in homes across Wisconsin. There are jobs in converting our economy to renewable energy.

Transitions in Perspective

2006-10-01T13:29:00.000+02:00

I have recently returned to the States from a fantastic postdoctoral research experience just outside of Paris, France. There, I was able not only to work on eta-solar cell materials research, but also to learn another culture and language, and to get outside of my comfort zone. The discussions that I have had in the Lévy-Clément research group the past year have been nothing short of brilliant, and I thank all of the researchers sincerely for their friendship and patience to enter into the "what is fire" discussions of PV.

Now, I have returned to Madison, Wisconsin to apply many of the ideas that I'd developed in France in another round of postdoctoral photovoltaic materials research. I find that I am not alone in my interests, as a PhD graduate student and a senior undergraduate in chemical engineering have begun participation in my research projects. It is always exciting to see that fresh interest in the strange but fun subject of photovoltaics. Onward! to la nouvelle vague.

Environmental Technology: What is it?

2006-08-12T10:01:00.000+02:00

I pursue my research interests in solar cells because I find that science is always more interesting at the interface of things (both literally and figuratively). The juxtaposition of materials development, earth science and environmental awareness is termed environmental technology. Because I have developed the building blocks from my multidisciplinary background into unique tools to fuel the opening field of environmental technology, I believe I am well positioned to have a little discussion about the subject.

My research deals with new designs and materials for non-silicon solar cells, and my background is that of a non-traditional environmental chemist and mineralogist (geoscientist). How is it that I find myself extending my education to non-traditional applications? One could say that both geology and environmental chemistry are already interdisciplinary fields of study, and to add another layer of interest only makes the process more interesting. However, the overlay of that additional element may act as a lens to help to focus a field onto those areas that are significantly helpful to mankind and those which may also stimulate the new post-fossil fuel economy. Yes, I believe there are ethical and financial incentives for pursuing environmental technology. But what is it?

Environmental technology is a subfield of research in environmental science concerned with topics of sustainable development in terms of energy, water quality, air quality, and waste treatment. Environmental technology is not necessarily a new topic, but I would have to say it has not yet come into its "own" in the larger umbrellas of environmental science or civil and environmental engineering. Past research in environmental technology has been strongly related to water remediation and waste treatment, and hence has had a close association with civil and environmental engineering. Currently, research has included alternative energy materials development, such as ultracapacitors, inorganic fuel cell membranes, and yes even solar cell development.

There is also a development to fold in the principles of green chemistry developed by chemists (largely organic), with the environmental technology goal of sustainable chemical development "upstream". The metaphor being a river in which any waste products are minimized and with the goal of environmental premediation (including the 12 Principles of Green Chemistry^*). Normally, waste is simply released into the river or sewer system and subsequently remediated, or treated after the fact, "downstream" from the point source of pollution. This goal of materials premediation will require new technologies that adapt learning from the earth sciences and environmental sciences for the common goal of sustainable resource development and low enviromental impact.

I have mixed scientific disciplines before and found that it can reveal amazing new discoveries. For example, if you overlay interests in geochemistry and mineralogy with genetics and microbiology, you have a curious field called geomicrobiology, where scientists have found fascinating results about microbial influences on the chemistry of mines, their survival near toxic "black smokers" in the ocean, and their influence on arsenic removal from groundwater by precipitating nanoparticles. In a similar fashion, if you combine interests in materials science with environmental chemistry and earth science, you have a burgeoning field called environmental technology with much potential for the new science economy.

Note: links of interest and examples of Environmental Technology

Green Pages: The Global Directory for Environmental Technology

Environmental Science and Technology at PNNL

Environmental Technology with Ceramic Membranes (University of Wisonsin--Madison)

National Environmental Technology Institute (University of Massachusetts--Amherst)

* The 12 Principles of Green Chemistry were first published by Paul Anastas and John Warner in Green Chemistry: Theory and Practice (Oxford University Press: New York) 1998.

Modes of Scientific Reason

2006-07-29T17:33:00.000+02:00

How should scientific research and reasoning be carried out? Are there universally- defined rules inherent to scientific discovery, or is it more like modern philosopher Paul Feyerabend¹ suggests, as an anarchistic realm punctuated by domains of apparent organization, each with a limited range of usefulness to scientific discovery?

One of the beauties I've found in doing research in another country is that, if you listen closely to the talk of your foreign colleagues, you may find the underlying principles of research are going to be defined differently than your own (even alien to your own scientific reasoning). I had this very experience in France, when my colleague was speaking of a mechanism of a chemical reaction and told me that another scientist had "proven" the mechanism was correct. Stop the press..."Wait, you can't say something is proven in fields outside of mathematics! Everybody knows that you can only disprove a hypothesis, and then only demonstrate strong support for a hypothesis that has not been struck down yet. An experiment has to be falsifiable, but cannot be proven." In fact, my music-teacher wife still remembers the day, in 11th grade Advanced Biology, when her teacher (Mr. Hjelle, pronounced "Jelly"... yes really) told her that there is no such thing as scientific fact; everything is theory, because we cannot prove anything beyond the shadow of a doubt. We can disprove, but to say we've "proven" something is a very arrogant and dismissive view upon scientific research.

The response of my colleague to me was that, in France, it is quite common to refer to something as being proven, as everybody knows that proof is essentially a shorthand or map to express the conditions of the regularities in an extremely well defined experimental setting. In her view, with sufficient support, one can prove something (as an asymptotic narrowing to an accurate description of a regular event). And beyond a certain point, it becomes ridiculous to search for obscure, exhaustive hypotheses to test to disprove something that has been found to be robust from experimentation.

My colleague is the senior researcher in our group, and I admire her scientific rigor and conservative approach in assessing and presenting scientific data to the public. At the time, we had been working together for over nine months. Through her actions, my colleague has repeatedly demonstrated her abilities as a rock-solid scientist. In other words, she is so effective with her approach to science that I have no reason to suspect that her mode of reasoning is any different from my own (which I had learned from my mentors in the USA). Yet it most certainly is different, and the months following have been challenging and enlightening in terms of expanding my approach to scientific discovery. So where was the source of this schism between each of our well-accepted, yet different philosophies of science? Can there be an optimal or universal method of scientific reasoning in scientific discovery, or is there "more than one way to get there"?

As an illustration, if we assume two laboratories on separate continents have expert researchers, well accepted by peer-review and having strong experimental results in the same field, are the two researchers able to arrive at similar results if they have separate scientific philosophies? In other words, as an expert scientist, is your learned approach to scientific reasoning that much better than another's?

I'll take the proposition one step further: assume one researcher has an outstanding pedigree in a field of research (say a chemist, like Marie Curie), while another is a bright, talented, very well-read, but self-taught inquirer (let's say a bookbinder-turned-scientist, like Michael Faraday). The former has been trained to use a rather robust yet strict set of principles based on her own mentor's rubrics to arrive at well reasoned results, while the latter uses an assembly of methods that he has developed on his own thorough experience. The methods of the latter (self-discovered) are a combination of very systematic experiments (not unlike those of the former) and some rather haphazard modes of experimentation and "exploration", that do not have a strict rules of progress, but tend to produce positive results nonetheless. Upon arriving at a successfully scientific discovery, both can communicate the results quite well, and have papers accepted into highly regarded journals in the literature. Now, which researcher was the better scientist? It would be an extreme act of prejudice to say the pedigreed scientist was better because of formal qualifications, given the assumption that the self-trained researcher in fact can have the same qualities of insight, rigor, communication and perseverance. But it would be equally biased to place an overwhelming romantic support for the self-taught individual as an underdog of research (something like Good Will Hunting). The fact is, in my illustration I assume they are both excellent scientists, and deserving of praise.

In considering the history of science in France, Germany, Austria/Hungary, England and America and the philosophies of science that developed in each country (perhaps another post), the answer is that yes, there is a difference in our scientific training and our scientific philosophies from France to the USA. Without really knowing it at the time, I had tripped over a break between a few schools of scientific reasoning. In my subsequent investigation, I found that France is influenced by the two systems of inductive reasoning inherited from Pierre-Simon Laplace, and more recent and practical conventionalism favored by Henri Poincaré^{2, 3} and Pierre Duhem³ (i.e. a hypothesis is neither truly verifiable nor falsifiable, but serves to make generalizations and predictions beyond experience). In contrast, the principle of falsifiability, argued by Karl Popper is in opposition to inductive reasoning. Falsifiability has been eagerly accepted in the USA as a core scientific reasoning tenet to separate "science" from "non-science". Arguably, falsifiability is not really the only manner in which experimentation and inquiry occurs. And even though several modern philosophers have argued against falsifiability as a basis for scientific reasoning and have subsequently suggested alternatives that are more closely related to science in practice, many American scientists have clung to Popper's criterion. To my honest surprise, I also found myself unquestioningly in lock-step with it in the earlier conversation with my colleague.

This led me to think, perhaps there are more important questions than asking why there are different modes of scientific reasoning; such as why was I conditioned to think that there is a fixed and ordained philosophy of science? In essence, I have trained for 15 years within the shadow of a doctrine of scientific reasoning, and in the process it has been necessary to condition (and some would argue brainwash) myself into that doctrine to pass through the hoops of academia. It is the consequence and necessity of a doctorate in science. One of the components in my education that I sought out on my own was information in the history and philosophy of science--something to add awareness to your our scientific preconceptions. As I walk away from the training of the USA and into the sphere of another doctrine of scientific reasoning, I have discovered new tools and perspectives that I believe will make me a better scientist and mentor. Not the least important result of this call to order is the reminder to encourage my future students to read as much as they can in the philosophy of scientific reasoning and the philosophy of science.

One can also find these fixed vantage points in scientific reasoning across various fields of research. In fact, I propose that discovering these differences through interdisciplinary research can hold some of the tools to make scientific breakthoughs. It's the moment of "Huh, I never thought of it that way..." And why?, not because one doesn't have the cognitive skills and imagination to arrive at a certain line of reasoning, but rather because one was not introduced to the extent of using an alternative scientific reasoning by training. Once you've defined a point of view, pick another one and see if you like the scenery. There's plenty more where that came from!

References and suggested readings:
1. Feyerabend, P. 1975 Against Method: Outline of an Anarchistic Theory of Knowledge. London: Verso.
Discussion of Feyerabend's "Against Method" by Paul Newall at the Galilean Library
2. Jules Henri Poincaré (1854-1912). Mauro Murzi, Internet Encyclopedia of Philosophy, July 29, 2006. (including a summary of his perspectives on Conventionalism, science and hypothesis)
3. Howard, D. 2005 Physics Today, December, 34.