Evaluating the Cleanliness of Solar Photovoltaics Can Be Complicated
I am a frustrating individual who likes to delve deeply into decision making computations and hates easy answers that sound like sales pitches. One of the best compliments I ever received came from one of my division officers when I was serving as the Engineer Officer on a submarine – he told me “Eng, you ask hard questions.”
As vocal advocate for nuclear fission power I recognize that it has many associated questions, but I after 30 years of study, I have determined to my own satisfaction that most of the important questions have reasonably good answers. In contrast, I have not yet found reasonable answers for many of my questions related to other renewable energy sources. (Yes, I – perhaps controversially – classify fission as renewable, but that is a discussion for a different post.)
Solar photovoltaic (PV) cells are a popular and often discussed (see, for example Atlantic City Convention Center Plans Largest Solar Roof in U.S., 10% of U.S. Electricity From Solar by 2025, SF Passes Largest City Solar Program in U.S. (Finally), all of which were published within the past week) form of “renewable” or “green” energy, but a casual scratching of the surface knowledge that many people have about the technology reveals some troubling details.
Not only are the panels expensive sources of electricity, but they do not last as long as advertised, they do not provide as much energy as the nameplate capacity implies, they consume significant quantities of energy in their production, installation and transportation, and they often use some very nasty materials in their manufacturing process.
The longevity of a solar panel will vary greatly depending on where it is installed, but any customer should remember that they are buying a product that will inherently need to spend as much time as possible fully exposed to the sun and weather. Though there are no visibly moving parts in a solar PV panel, there are many parts of the system where continuous chemical and physical reactions take place that can eventually lead to system degradation and failure.
Take a good look at panels that have been installed for several years and you will notice discontinuities and shiny areas where the components have been damaged and where the power production is reduced. If you have any panels, might want keep a record of the current production so that you can see this effect – or perhaps you will not want to find out just how fast that long term investment is decaying.
The literature accompanying most solar panels provide customers with numbers related to their peak capacity – what I call “noon on a clear day at the Equator”. That quantity of power is only available when the sun is directly overhead, when the panel is perfectly clean and when there are no clouds shading the cells. The cleaning part is important, any panel owner that wants maximum performance needs to set up a routine for cleaning and clearing the panels of any debris.
Leaves and snow are particular nuisances for rooftop solar panels, but sand and bird droppings can be important in some areas as well. Not that the article was specifically discussing PV panels, but I recently read about the 4,000 gallon water tanker trucks that are part of the maintenance equipment at some desert solar power plants.
Some of the most energy efficient solar panels, in terms of both the energy required to produce the panel and the panel operating efficiency are made of a semiconductor material called CdTe (Cadmium Telluride). Companies that make CdTe cells like to brag about the quality of their products, but they have also recently had to warn their investors that they may not be able to sell their panels in the EU for much longer because of rules about using toxic heavy metals in electronics. What they have not made clear yet is what their long term liability is for the panels that they have already sold. What will happen in 5, 10 or 20 years when the panel output is no longer useful and the materials need disposal? Can they be recycled without releasing the heavy metals? Will their customers be able to return the panels to the original producer? Will they make the effort or simply take the systems to the dump like many consumers do with batteries made of similar materials? (Those are the kinds of questions that my former division officer was talking about.)
There are definitely answers to some of the questions that I have about solar PV, but that does not mean that the issues are fully solved. If you are in the market for solar PV systems, please ask the hard questions and realize that anyone who wants you to buy the systems without good answers is just a salesman who is not much different from any other salesman.
Photo credit – The Sun Works (photos to be shared)
You Might Also Like
Wind Turbines Off the North Carolina Coast Could Supply State with 100% of Its Power
Solar Parking Lots for Electric Bikes in Tokyo
Aluminium Giant to Make Solar CSP Cheaper
U.S. Sen. Mark Udall Unveils Community Solar Gardens Bill
June 19th, 2008 at 7:15 am
Finally someone asks the hard questions! I’ve watched all of the alternative energy solutions quickly loose their luster under the glare of real time use. We have an energy solution in nuclear power but vocal scare mongers without any formal nuclear education are regularly spouting off half-truths and manufactured “facts” to support their cause. In this website we have an educated person who has lived with nuclear power for 30 years. Just maybe we should listen to what he has to say. We are running out of time and we don’t have time to pin our future on the energy fad of the moment.
June 19th, 2008 at 11:04 am
BOBG wrote:”In this website we have an educated person who has lived with nuclear power for 30 years.Just maybe we should listen to what he has to say.”
What does “educated” mean? Working for the International Atomic Energy Agency (IAEA) or the nuclear industry?
This text is pure bad faith. Of course solar photovoltaic devices require technologies which are not completely “green” but actually which electric device is completely green today? As far as I know no solar device will produce waste which will remain dangerous for centuries just as nuclear power does (and not only in power plants but also during extraction and enrichment). But just think about this: if solar energy had been backed by governements as much as nuclear has been, who knows how much more efficient and “clean” solar devices could be?
And about cleanliness, just ask people in Belarus and Ukraine how clean it is to live in the neighborhood of a nuclear power plant which has exploded more than 20 years ago? How many dead people in the neighborhood of a solar device?
Last but not least, if you can explain to me how Al Qaeda could build a dirty bomb with anything used in a solar device just let me know! You cannot put solar in balance with nuclear (which is the case in this text actually) without considering safety.
June 19th, 2008 at 11:10 am
I like the fact that you are asking hard questions, but I think your skepticism about the longevity of PV modules is misplaced.
The basic technology used in most photovoltaic modules is not fundamentally different than what has been available for decades. You can find some longitudinal studies of module performance that show that degradation of electrical output is less than 1% per year. Most PV module manufacturers offer warranties of 20 years or more that include assurances of electrical output, so the manufacturers are backing up their claims with their own money.
It is valid to question the claims of PV manufacturers, but the questions you raise have been asked and answered.
June 19th, 2008 at 1:23 pm
Roald:
Can you tell me how long Cadmium remains toxic to human beings?
If you would like to find out about the state of the environment in Belarus or Ukraine, I highly recommend reading a carefully researched book titled Wormwood Forest, by Mary Mycio. You can find it via Amazon.com.
My initial nuclear education is not with the industry, but as an Engineer Officer in the nuclear navy. I completed the nuclear training pipeline, served as a division officer, attended graduate school, and served as the Engineer Officer of a 22-26 year old submarine for 40 months. In 1993, I left active duty and formed Adams Atomic Engines, Inc.
June 19th, 2008 at 1:50 pm
I totally agree, nothing but pure bad faith…
Especially when the whole world talks about this
http://www.ecogeek.org/content/view/1329/
June 19th, 2008 at 2:26 pm
I respect the author’s pro-nuclear, stance, which I share. I think that nuclear power is crucial.
However, his solar-skeptic stance is unfair, and it smacks of the fear-mongering used by anti-nuclear activists.
One can be pro/anti-nuclear only after working the numbers. How big is the waste problem? What are greenhouse gas emissions involved in mining? What is the energy amplification factor of mining Uranium and burning it?
One has to be be similarly rigorous when criticizing (or embracing) solar. This article doesn’t do that, and is essentially anti-solar fear-mongering.
June 19th, 2008 at 2:28 pm
I have wondered about this issue too, but the article does not get me much closer to the answer. The CdTe arrays the author mentions have awful downsides, including cost and environmental issues. That said, I don’t think anyone is seriously advocating CdTe arrays for general consumption. More likely silicon ribbon technology that is actually pretty clean to make.
Does anyone know the life cycle costs and impacts for a modern production photovoltaic? wind turbine? coal plant? nuclear plant?
Here is a study from the university of wisconsin that provides some numbers (and where they came from)
http://fti.neep.wisc.edu/presentations/sww_energy_ctr.pdf
Slide 8 is informative, in that it says wind gives back 23 times more energy than you put into it, fission 16 times, coal 11 times. Solar is not on the chart though..
June 19th, 2008 at 3:05 pm
“…no solar device will produce waste which will remain dangerous for centuries just as nuclear power does (and not only in power plants but also during extraction and enrichment).”
This material was not made dangerous from use in a nuclear power plant. It was dangerous from before we pulled it out of the ground. I never understood why we have such an issue either recycling nuclear waste back into fuel or putting that material back into the ground from which it came. There is a lot of uninformed and unwarranted fear causing inaction on this issue.
Further, the dangerous material from a nuclear plant is centralized at the nuclear plant. That makes the waste from a nuclear plant far easier to manage than waste from solar. Any dangerous material in a solar cell is going to be where the cells are located – namely, at your home or at the dump in 20 years.
That said, I wouldn’t paint all solar technologies with the same brush. Yes, some may be made of toxic materials, but various technologies are going into solar these days, not all of which are toxic. Namely, what kind of cells are Europe going to be making or buying in the future?
I am certainly of the opinion that we need both nuclear and solar. Few other technologies will be as cheap or effective for most places. Wind only really works in windy areas. Hydro is good, except people live everywhere now, making new dam construction difficult. Geothermal is good, but limited and with its own set of issues. Nuclear can provide the base load our civilization needs 24/7. Solar provides energy for daytime spikes, when people want to run heaters and air conditioners.
June 19th, 2008 at 4:11 pm
Peter:
The link that you provided is informative, but it does not really say that fission gives back 16 times the input energy/
What it says is that pressurized water reactors using 3% fuel enrichment provided by gas centrifuge enrichment plants that operate with a capacity factor of 75% for a total lifetime of 40 years will provide 16 times the energy input.
If the plant lasts 60 years, you can add 50% more to the return. If the average capacity factor is 80, 85, or 90% you can add some more back. If you shift from a once through then out fuel cycle, you can achieve a better return. If you shift technology to something like a high temperature gas reactor combined cycle, you can improve both fuel utilization and thermal efficiency.
In other words, the graph uses 1950s vintage nuclear fission technology.
When it comes to fusion’s placement on the graph, I have no idea what the source of the data could be since there has not yet been a fusion plant that provided a net power output for more than a few milliseconds.
June 19th, 2008 at 4:49 pm
Looking at the “Adams Atomic Engines” website, anyone can see you have a commercial activity based on nuclear engines, so how can you pretend having any dispassion in such a discussion?
Also, it’s easy to recommend a book about trees and bees around Chernobyl (trees grow fast when there’s nobody to pull them up). I would rather recommend one about people, people who are sick and die from the atomic contamination : “Le Crime de Tchernobyl : Le goulag nucléaire” (which means “Chernobyl’s crime : the nuclear gulag”) from Wladimir Tchertkoff. Unfortunately, it’s in French and it seems there is no translation to English (but you can buy it from Amazon.fr). It contains facts about many people living in contaminated land and their health condition is not very good.
Your question suggests that you want to raise the fact that cadmium cannot be degraded into something less toxic – cadmium is a chemical toxic – and this is true. Cadmium is an heavy metal and the human body has the property to accumulate heavy metals and this concentration can become dangerous. But interestingly, uranium, the most common fuel for atomic fission, is also an heavy metal. Therefore, its radiotoxicity left aside, it is also dangerous because of its chemical properties.
Two facts to show that its chemical properties makes uranium certainly more dangerous than cadmium :
- cadmium has no effect on health below 3 mg and its lethal dosis is between 350 and 500 mg;
- the lethal dosis for depleted uranium (which is not much radioactive) is 2 mg/Kg, which means something like 140 mg for a man.
And of course cadmium is not radioactive while the kind of uranium used in most power plants (PWR) is highly radioactive (and I do not even talk about the plutonium mixed with uranium in Mox) hence dangerous.
June 19th, 2008 at 9:13 pm
Rod,
Your comments about increasing the efficiency of an a fission plant are interesting, and same applies to wind, solar, coal, or any energy process.
I guess in light of all of these, I keep seeing wind come up as heads and shoulders the best option. The down side is that it is irregular. That said, it seems the 20% wind power option congress is going for now seems awfully rational as a first step.
Roald,
I would not worry about the comparison between cadmium and uranium. I think you will get no argument from anyone that uranium (or any radioactive fuel, even if it is spent) is much much more dangerous than cadmium.
The question is, what should we as a society invest our research efforts, tax dollars, and buying power into supporting? What are we buying and what are the consequences?
My suggestion would be low tech and simple. Conservation can reduce our power demand. It is working in cambridge MA and it is cost effective today:
http://www.cambridgeenergyalliance.org/support.htm
Drive less, walk, ride your bike more.
Invest in local power that you would like to live near. If this means nuclear power, go for it. If this means coal, your choice. Wind anyone? Insulation?
June 20th, 2008 at 1:30 am
Roald:
I have never claimed to be dispassionate about energy and never try to hide the fact that I am interested in making a living, perhaps someday even making a lot of money, from better applications of atomic fission power. I use my real name and tell people about my focused company. I am also recognize that my critiques of other energy sources just might have the effect of making fission more valuable – the more questions that people ask about competitive sources, the more likely they are to at least consider fission as part of the solution.
Peter – if your rational first step is for wind to work towards a 20% market share of the electricity part of the energy mix, what is your plan to reduce the use of coal, oil and gas in the 55% or so of the market that would still be supplied by fossil fuels, assuming that nuclear and hydro maintain their current non emitting shares of the market? How will we work to reduce coal, oil and gas in transportation and process heat, other energy markets that are roughly as large as the electricity market and thus represent about 2/3 of our total energy use today?
I walk, ride a bike whenever possible and use sails or paddles when I participate in water sports. However, I also travel quite a bit, consume plenty of electricity at odd hours, like hot showers, enjoy backyard swimming pools (not currently, but I have owned two homes with pools and plan to again), love eating fresh fruit and vegetables year round, want my indoor climate to be controlled, and like for my neighbors (and I have a rather expansive definition of that term) to have good jobs and a comfortable way of life.
The US consumes about 1.2 billion tons of coal each year to provide electricity. Replacing that with something that is clean enough to run inside a submarine is something worth doing.
Finally, my point about the cadmium or other heavy metals in solar cells is simply that they exist, there is at least one large solar panel producer whose entire production is based on CdTe, and that there are few controls that will prevent the material from someday entering the environment when the panels are no longer useful.
In contrast, I have no doubt about our ability to retain the leftovers from nuclear power operation and I am deeply aware of our legal and moral responsibility to do so. Properly handling the leftovers from nuclear power is already part of the internal cost. That same standard is not applied to other energy sources.
June 20th, 2008 at 1:44 am
Peter,
I totally agree about conservation as a first step to reduce the power demand.
Investing in local power you would like to live near is certainly a good principle. The problem comes from the fact that most individuals do not have the choice because they cannot produce their own electricity and the choices are made by companies producing and/or delivering the electricity. Even installing basic installations like solar panels or wind turbines costs much and some simple solutions cannot be applied in cities, where most people live (urban wind turbines are only experimental at the moment).
Therefore, most people living near an atomic plant haven’t chosen to do it. A recent german scientific study has shown that there is a measurable incidence of atomic plants on child leucemias in a radius of 50 km around a nuclear plant. Yes, 50 km (31 miles)!
So who wants to live near an atomic plant?
It is possible that we’ll have to go on with nuclear fission to win the climate change challenge but one cannot forget it’s a dangerous technique producing huge amounts of no less dangerous waste. And also it costs much. The situation might be different in the U.S. but here in Europe nuclear power plants wouldn’t have been build without a huge financial support from governments. So if similar amounts must be invested to fight against climate change there might be better investments to do. Last but not least, much time is requested to plan and build an atomic plant, so atomic power is certainly not a panacea.
June 20th, 2008 at 1:58 am
Peter,
The link you provided is interesting. However I wonder what has led the calculations to produce exactly the same values of C02 emissions for nuclear fission and wind.
More information would be welcome.
Rod,
You wrote : “the more questions that people ask about competitive sources, the more likely they are to at least consider fission as part of the solution.”
I understand this position, but in my humble opinion I could tell you that “the more questions the people ask about nuclear fission, the more likely they are to consider less dangerous solutions.”
June 20th, 2008 at 2:19 am
Roald:
I have different definitions of “huge” and “expensive”. If you put all of the high level waste that US nuclear plants have produced while supplying 18 Trillion kilowatt-hours (1956 through 2007) in a single place, it would take up far less space than a single football stadium (American or European version.)
The production costs for electricity in the US as of 2007 were as follows (all in US dollar cents per kilowatt-hour):
Coal – 2.47
Gas – 6.78
Nuclear – 1.76
Petroleum – 10.26
Stated another way – if the 807 billion kilowatt-hours produced in US nuclear plants had instead been produced by burning coal, the cost would have increased by $5.7 BILLION dollars. If that same electricity had been produced by burning gas instead of fissioning uranium in commercial nuclear fuel, the total production cost would have been $54.7 billion instead of $14.2 billion!
I fully recognize that my data uses production cost that does not include the capital costs, but those annual cost numbers should add a little perspective to the VALUE proposition that is causing so many people to take a much harder look at nuclear power again and ask themselves “I wonder why we took this option off of the table?”
It is my firm belief that the sales and marketing efforts of the coal, oil, gas, wind, and solar companies has something to do with the poor public perception of nuclear power.
Going back to the idea of locally produced power – please understand that you are conversing with a guy who has spent many months underwater with a nuclear plant within 200 feet at all times. I would love to have a fission power plant in my own backyard, especially compared to all other available options.
Talking about construction periods – at one time, when we were still learning how to use fission, it was possible to build a large, commercial nuclear plant in just 4 years. (Shippingport). It was also possible to design, manufacture and assemble a small plant in Antarctica in less than 18 months. The schedule overhead that exists today is a function of a lot of years of effort to handicap a competitor.
June 20th, 2008 at 7:59 am
I have been taken to task for some of my statements in my post. I did not infer that we should abandon all other alternative energies and I admit there are many questions with nuclear as with every other energy source. I saw a documentary from England about a nuclear plant that was being decommissioned. The narrator asked how long it would take to decommission the plant. The answer was 125 years. I don’t have the knowledge nor expertise to support or refute that statement but it causes me concern. When you look at the automobile when it was first invented you will find that it was very unreliable, went less than 10 miles an hour, was terribly expensive for the times, was reviled by a large segment of the population and was considered to be a fad at best. The nuclear industry is where the auto industry was in 1905. The nuclear plant application that was submitted for approval this week was for a nuclear plant that is like no other in existence. It is like comparing a 1905 Ford to a 2008 Ford.
June 20th, 2008 at 8:46 am
Rod,
A few thoughts:
” if your rational first step is for wind to work towards a 20% market share of the electricity part of the energy mix, what is your plan to reduce the use of coal, oil and gas in the 55% or so of the market that would still be supplied by fossil fuels, assuming that nuclear and hydro maintain their current non emitting shares of the market?”
There are two questions here. One is electricity generation for the power grid. The second is liquid fuels for transportation. These can be merged by things like plug in hybrid electric cars (PEVs) or hydrogen fuel sources, and PEVs are produced currently (see DaimlerChrysler Sprinters or after market modified Prius for example)
http://jalopnik.com/cars/alternative-energy/electric-vanliness-sprinter-to-be-daimlerchryslers-first-plug+in-hybrid-247681.php
http://www.eaa-phev.org/wiki/Prius_PHEV
In fact, PEVs have been touted as a global battery for excess wind power, allowing us to go up to higher fractions of wind and solar.
Roaland:
“The link you provided is interesting. However I wonder what has led the calculations to produce exactly the same values of C02 emissions for nuclear fission and wind.”
My interpretation of this is that neither wind nor nuclear power *production* generates any CO2. Mining uranium for fuel does. Making concrete and steel for wind and nuclear does.
Rod:
I like this table:
“Coal – 2.47
Gas – 6.78
Nuclear – 1.76
Petroleum – 10.26″
to put current wind and solar in we would get (as of 2004)
wind: ~4 cents
solar: 20 cents
http://www.er.doe.gov/Sub/speeches/Congressional_Testim/3_17_04_Statement-Robert_Card.htm
All of these numbers are debatable, but they do give a general impression. If we are rational short term cost minimizers we would go nuclear, then coal and ignore the rest.
The question I have is the long term cost. Coal kills us slowly and is not renewable. Nuclear might or might not kill us slowly, but can catastrophically kill us (e.g. chernobyl, nagasaki), and is not renewable.
Wind, solar, and biomass may kill us less slowly, and are less likely to catastrophically kill us.
A food analogy: eat the cheapest thing around because it is cheap energy even if it has possibly bad long term consequences, or pay a bit more to eat a sustainable diet with less catastrophic potential?
June 20th, 2008 at 9:14 am
I looked more into the CdTe designs for solar. One company that uses this design, First Solar, has a nice site on the topic.
http://www.firstsolar.com/recycling.php
Seems that they have designed it so that the materials are recyclable, and in fact will take the cells back after use for recycling and reuse (==cradle to cradle? ). Thus even in this application, the lifecycle damage is relatively low.
June 20th, 2008 at 1:41 pm
Peter:
I think you misunderstood my question. If wind supplies 20%, and nuclear and hydro retain their current market shares of 20% and 6%, that still leaves fossil fuels supplying about 54% of the US electricity. Plug in hybrids are not a power source – they are at best an inefficient storage mechanism that represents an energy loss in both the charging and discharging parts of the cycle.
How do you plan to replace supply the roughly 2.4 trillion kilowatt-hours of electricity that fossil fuels like coal and natural gas will supply in your 20% wind world? How long will it take to get to 20% if we build as many windmills every year as we have for the past 3-4 years?
These are not meant as rhetorical questions, but as real questions that will need real answers.
June 20th, 2008 at 2:23 pm
Hi Rod,
“.. that still leaves fossil fuels supplying about 54% of the US electricity”
True. I’m thinking of what the next steps should be though. Where should we invest our funds in the near future to change from where we are to where we want to be. First I’d invest in the cleanest and easiest sources, such as wind. Once we get there, what do we do about the next 54% of electricity? What about going to 40% wind? Then 60% wind? I’m not sure if this will be practical or not, but we will know more when we get to 20% wind.
“Plug in hybrids are not a power source – they are at best an inefficient storage mechanism that represents an energy loss in both the charging and discharging parts of the cycle.”
True, PEVs don’t net produce power, but they do displace liquid fuels for transportation and act as a storage mechanism. PEVs allow us to tame variance in the electrical grid–a feature that helps all power producers irrelevant of type as it reduces our need to build extra power production to meet peak demand. In a world where power can be stored, even a little, more plants can run at 100% capacity–a place where most technologies become more efficient cost and production wise.
“How do you plan to replace supply the roughly 2.4 trillion kilowatt-hours of electricity that fossil fuels like coal and natural gas will supply in your 20% wind world?”
Here too, see what we find from the 20% wind experiment. Can we do 40% wind, or 100% wind next? There are barriers, but there are barriers with any technology. I don’t know, but I’m thinking of what is our next step, not the end all final solution.
“How long will it take to get to 20% if we build as many windmills every year as we have for the past 3-4 years?”
I’m not sure. It seems like it could be done pretty quickly. Investors in texas are building a ~$250 million dollar wind farm
http://www.cnn.com/2008/US/05/19/pickens.qa/
http://en.wikipedia.org/wiki/T._Boone_Pickens,_Jr.#World.27s_largest_wind_farm
This is a ~4 million kW farm by 2015. So, crudely, we would need ~500 of these farms. Seems a reasonable number in the scale of power plant building. As with any technology (nuclear included) costs tend to go down the more of them you build.
As a counter, how long would it take us to supply the 2.4 trillion kW/h of electricity if we build as many nuclear plants every year as we have built in the last 3-4 years? Something like forever based on the track record of our building nuclear plants.
June 20th, 2008 at 5:31 pm
Your emphasis on CaTe modules paints an unrealistic view of solar since they make up less than 1% of the PV market. Over 90% of modules are still manufactured with silicon and most have an energy payback of 2-5 years, which is well below their expected life of 35-40 years.
June 23rd, 2008 at 6:11 pm
Solar panel production may utilize some nasty materials, but recent developments have been significantly reducing the amount of semiconductor materials in the panels. Here is an article by Parc Research about Concentrator Photovoltaic systems (CPV) that have been developed recently.