Emissions from Photovoltaic Life Cycles

A new report has found that thin-film cadmium telluride solar cells have the lowest life-cycle emissions primarily because they consume the least amount of energy during the module production of the four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride (CdTe).

The study, published in the Environmental Science & Technology journal, based on PV production data of 2004–2006, presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions of the four types of PV systems considered. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system.

They found that thin-film cadmium-telluride solar cells had the best life-cycle profile. Even though the process emitted  heavy metal cadmium, it still had a lower overall level of “harmful air emissions” than the other PV technologies in the study.

The report stated that "Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electrity from photovoltaics displaces electricity from the grid."

The fact that Cd-Te technology was found to have the lowest emissions profile is interesting, but the main point, to me, is that all technologies had low emissions profiles, that are insignificant when compared to the emissions of the fossil fuel technologies that they replace. While I do not find it suprising that all solar PV systems have a low emissions profile, I find it suprising that the authors did not include thin-film silicon or copper indium gallium selenide (CIGS) cells in their study.  I assume the overall results would have been the similar, but it woud have given a fairer comparison to the technologies now in use.  One problem with scientific research is that it takes so much time to do the study and get it published that by that time the information is made public it is sometimes outdated.

Comments

[Paul F. Dietz]

The CdTe information would be more interesting if tellurium weren't such a constraint. It's not a common element.

[bigTom]

Paul: Even with tellurium rare, thin film is pretty thin -the amount needed per unit is very small. Do you have any numbers on what production level would run into the tellurium constraint?
The other PV area, not mentioned is concentrating PV. This is likely harder to estimate as the photovoltaic part is less important than the balance of system.

[Kit P]

Assuming “performance ratio of 0.8 and lifetime of 30 years”

For Case 3 (US grid) we find about 50 gCO2eq/kwh.

The assumptions are mostly likely valid for the Springerville Generating Station with a capacity factor of 19%: http://www.greenwatts.com/pages/SolarOutput.asp

That is assuming some weather even does not destroy them. On the other hand, if properly maintained Springerville Generating Station might last for 60 years.

Now look what happens when idiots like Google installs PV in the wrong place for the purposes of green washing: http://www.google.com/corporate/solarpanels/home

If the capacity factor is 5% instead of an expected 20%: 200 gCO2eq/kwh.

Now if the panels work for less than 5 years which is mostly the case: 1200 gCO2eq/kwh.

I think you have to go to China to find a coal plant that is worse.

[Paul F. Dietz]

World production of tellurium in 2007 was 135 metric tons, so Te production (secondary production from copper refining; there are no Te mines) would become limiting if annual module production were in the tens of gigawatts (peak) range. This tells me that CdTe could be profitable and production greatly expanded before Te constraints were hit, but it will have trouble serving as a dominant supplier of world energy demand.

At its current price Te contributes negligibly to the cost of the PV modules, so its price could rise considerably before curtailing CdTe PV technology. Perhaps this would encourage production from other sources that are currently uneconomical.

[disdaniel]

Thanks. I find this information very useful. The EROI of solar is steadily improving. And as more solar comes online, it appears that the CO2 life cycle emmisions from solar will only fall.

[poetryman69]

Energy Independence Now!

No more Oil Wars!

Stop funding the terrorists!

Drill in Anwar.

Build more nuclear power plants

Use More coal.

Use more natural gas

Turn trash into energy

Double the efficiency of windmills and solar cells.

If France can do nuclear power so can we.

If Brazil can do biomass/ethanol power so can we.

If Australia can do LNG power so can we.

Domestically produced energy will end recession and spur the economy.

[Kit P]

“If Australia can do LNG power so can we.”

The US has been importing LNG since the energy crisis of the 70s. Importing LNG is a measure of our departure from energy independence. The goal should be to reduce the amount of LNG imported.

“If France can do nuclear power so can we.”

When it comes to making electricity with nuclear power, there is the US and everyone one else. France is a little country that has used up its coal resources. Many years ago, it had a choice between importing coal from the US or nuclear technology from the US. France has since evolved that technology and is now marketing it back to the US.

The operators of the new US nukes are still in high school. They will join the US Navy, be trained and then operate the 100+ navy propulsion reactors. After spending a few years keeping the sea lanes open, they will come home and work in nuke power plants in the US or do other things.

[J.C., Sr.]

I should like to add to poetryman69's comment from Gov. Janet Napolitan's statement "I see no reason why Arizona shouldn't be the Persion Gulf of Solar Power."

[Alex]

I remember reading back in November that the aim of the new PV technology (film CdTe) is to drastically reduce the cost of PV installation thus making it the most attractive RES. I also understand especially from the reviews of this article that comments tend to get off the point and wildly generalize;(nuclear-world affairs ect), or get into mind boggling research on CO2 emissions during production. Hell guys - Let the tech run!!!
You'll collect much more accurate data then.

[Al Fin]

Solar CO2 emissions? That is getting a bit obsessive, old chaps. I can understand looking at pollutants and disposal problems coming from PV manufacture. But CO2?

Bending over, focused on minutia of CO2 emissions from sun, solar, geothermal, with butts in the air waiting to be kicked by the real problems. Yep, that sounds about right.

North Korea has very low CO2 emissions. Perhaps some of you would like to live there?

[5 years? What are you taking about?]

bigTom,

Panels will not die in 5 years. All panel manufacturers warranty their panels for between 20-30 years. How can they do this? because, they just don't break. The power fade is very small, around 20% over 30 years. Panels must meet a impact test of 1" hail traveling at 52 MPH. The DOT sign installs at the side of the road with little or no maintenance have been in place for 2 decades. In fact PV systems do not need maintenance.

As for google. It was far from green washing. They did it because it was economical, and their power reliability is a critical business need

[Kit P]

5-year, give bigTom a break, I wrote that post. You may want to cut me some slack and consider for the moment your reading skills are not up to par. I wrote, “if properly maintained Springerville Generating Station might last for 60 years.”

So clearly I understand how long solar PV can last. I will be happy to explain the various root causes of solar systems not working.

[Scott_T]

I always wondered why the first couple batches of panels the factory makes aren't strapped to the roof to power the manufacturing of more panels?

[Kit P]

Scott, the short answer is PV do not make very much electricity.

Putting solar panels on roofs is not a very good idea if your goal is to maximize the amount of electricity produced and therefore provide the lowest rate of life cycle ghg emissions. Most manufacturing facilities are located where there is cheap coal produced power and a skilled work force. The roof is in the wrong place.

The second reason is if the manufacture of solar panels put them on the roof someone like me would ask a reasonable question like how much electricity do they produce. The answer would be very bad for business.

One of the responses to my assertion that PV panels are nothing more than scrape is that the manufacture will stand behind them for 30 years. Read the fine print. If you pay to take them down, put them in the original shipping container, and pay the shipping they will test them for you. Yes, properly installed, properly located PV will make electricity.

[Clee]

Sharp makes photovoltaic panels. They put 5.2 MW of PV on their Kameyama Mie LCD plant. Don't know why they put it on an LCD plant rather than one of their PV plants.

[Kit P]

Ouch!!! Check my math Clee but that works out to about a 1% capacity factor based on info that Clee provided and this below:

“The Kameyama Plant generates one-third of its annual electricity, 12,000kW, using liquefied natural gas (LNG), and utilizes generated waste heat for air-conditioning, hot-water and steam.”

and

“Together with the 200 modules on the walls of the co-generation building, about 48,000 kWh is generated a year.”

For those of you who demand that their big TV is made in an environmental manner, the solar generated electricity used by Sharp has a higher ghg rate than my West Virgina coal generated electricity.

[Clee]

It's annoying that I can't find an article that mentions both the peak rating and the annual kWhs generated. There are two or three Sharp plants at Kameyama. I believe the 5 MW PV is Plant 2, completed in 2006. The 48,000 kWh/year figure looks like it might be about Plant 1, completed in 2004, but it's not really clear.

[Clee]

Found an article that said they had 60kW of PV before building Plant 2. So 48,000 kWh/year from a 60 kW system is 9% capacity factor. Not great, but considering they used walls and not just rooftops, I didn't expect it to be 20%.

[Clee]

Here's one Scott. Global Solar has just opened their new CIGS thin film solar cell factory in Tucson, Arizona. They are building a 750 kilowatt CIGS solar field next to it to supply electricity to the factory.
http://www.energystocksblog.com/2008/03/11/world’s-biggest-cigs-solar-plant-opens/

[Kit P]

“supply electricity to the factory”

More greenwashing. The solar panels may supply electricity for part of the day but no one is going to run a factory on PV. At least they are not putting them on the roof. There is hope that they are not complete idiots. Let me know Clee when they start producing electricity. At that point we can talk about performance.

[Bob Wallace]

Additionally, Scott, there's no need to install the panels on the factory roof for them to play a role in further manufacturing.

At this point in time it's just not practical to run a plant on PV alone, unless one is willing to operate only when the sun is shining. And battery storage is currently too expensive to store for the dim hours.

Manufacturing plants are going to be hooked to the grid. Hook the new PV to the grid as well and it will feed in clean power when the sun is shinning, allowing the grid operators to throttle back on more expensive sources of electricity or save hydro for when it's needed.

And if the plant is closed on weekends and holidays, then that potential electricity isn't wasted. It's fed to people who can make good use of it rather than using dirty/expensive sources.

Cute thing about electricity, you can locate the plant wherever it makes sense (think labor pool, raw materials, market, transportation links) and stick the panels where there is the most sun (think Southwest desert) and ship the power quite efficiently. Putting panels directly on the factory roof might not give one as much power as would better site selection.

[Hybrid]

I love solar power I think over the next few years it's going to be exploding even more... as performance of solar panels goes up people are going to be adopting it everywhere they can... after all it's free energy :)

Some things I'm looking forward to are more effiecient solar panels, about 5 years from now when I buy my house I want to make sure I can power the entire house and my plugin hybrid all on solar power... I'm also hoping that solar paint will finally be in customers hands... having your entire house generate so much electricity and maybe even being able to sell it back to the grid would be amazing...

BTW here is more great Solar Power information, there is quite a few amazing new solar projects being done right now... it's really great to see so much focus on alternative energy.

[Kimber Renk]

It is a known fact that electric companies do not deliver all the energy requirements you need to power each appliance in your home. Things like a hurricane, or other natural disasters, as well as inability to pay bills may contribute to a loss of electricity for a long period of time. If you want to push a better way of living and forget about bearing with the heat of the sun during a hot summer’s day or eat food coming from the can, then you should seek a better alternative to your plight.

[hosting]

Putting solar panels on roofs is not a very good idea if your goal is to maximize the amount of electricity produced.

[Potassium Chloride]

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[bill]

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[solar energy advantages]

Thanks for sharing your information with us, it is a really good read and i can't wait to read more of your stuff.I will let some friends know about it. Thanks

[Green Energy]

If we could just start making the leap to green energy, we might be able to save ourselves a few years, right? These emissions can't be as bad as we're currently producing. =\

[NFL shop]

I would like to thank you for the efforts you've made in writing this posting.

[ukrainske damer]

I try and learn something new everyday. Thanks for the information.

[Car Lease Los Angeles]

I really liked your input on this article, they have good info but I liked the points you brought up!

[Dentist Hollywood]

Well it's good to know that these solar cells consume the least amount of energy while producing these systems.

[Rug Cleaning Los Angeles]

I like your point about how all these technologies have comparatively 'low' emissions when looked at versus fossil fuel technologies.

[Air Purifier]

So true that scientific research can be outdated by the time it's published, but luckily with the internet and technology advancing as it is I hope that this will change.

[fish tv]

Do you know what the research on thin-film silicon or copper cells has shown? I'm just curious since you bring up how the authors didn't include it in the article.

[Therapist New york]

Anything that works better or gives out less emissions than fossil fuels should be a welcome change!

[seo services]

I love the Environmental Science and Technology journal, I don't read it all of the time but my friend does so I read it when I'm at his place. Good information.

[furniture stores burbank]

I hope they have made progress with this research, like you said the emissions are low compared to what's already out there.

[electrical test and tagging]

You have added this term in my vocabulary which simply means solar power. I think the people should start using this kind of power supply just before the sun runs out of its light. There's so much energy put to waste where we can ustilise such free energy source.