This research was reported back in February, but it was profiled again in a European Commission newsletter this month. It bears repeating, if only because there's a lot of misinformation going around about how the energy that goes into producing solar panels isn't much less than the lifetime energy you get out of it (claims I often hear -- surprise, surprise -- from proponents of nuclear and clean coal plants).

Researchers from Brookhaven National Laboratory and the EC's Integrated Project CrystalClear used data from 12 solar PV manufacturers to determine lifecycle emissions from four different PV technologies: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Their findings, according to the newsletter:

"The thin-film cadmium telluride technology emitted the lowest amount of harmful emissions because it uses the least energy during production. However, the differences in emissions between these PV technologies were very small in comparison to the significant emissions that could be saved by switching from conventional energy technologies to PV. The researchers suggest at least 89 per cent of air emissions associated with electricity generation could be prevented if PV replaced energy from the average European grid."

Even with the cadmium telluride approach, which produces heavy metals, it still found that this thin film process produced heavy-metal emissions that were 90 to 300 times lower compared to a coal plant fitted with the latest emission-control technologies. I should note that the cadmium telluride approach, used by First Solar, incorporates end-of-life recycling of heavy metals. Montreal-based 5N Plus, for example, is a main supplier to First Solar and places emphasis on its recycling services.

And, as processes for producing PV become more efficient, emissions will continue to fall. "Thinner films and greater efficiency are trends that will further reduce PV lifecycle emissions," the researchers concluded.

For a 2006 paper from Columbia University that looks at lifecycle emissions of a 3.5 MW multicrystalline solar PV plant in Arizona, click here.

If one looks at data from the World Nuclear Association, they'll see that solar PV is shown to emit three to 10 times the CO2 per g/kWh as nuclear. But you'll notice that the data for solar PV is several years out of date. Given much of the advances around solar PV are only a few years old, one could easily challenge the assumption of the nuclear industry. What I'd like to see as an up-to-date comparative analysis between nuclear, wind, solar, natural gas, and coal. If anyone has see one, please let me know.