When Europe started its Emissions Trading Scheme, as a follow-on from the Kyoto clean development mechanism, it was assumed that a lot of the clean energy investment would take place in Europe. What no one anticipated was that virtually all of the clean offset investments took place in the developing world.

And so to China, where according to Camco International the Jinan Iron and Steel Group Corp of China has agreed to sell about 12.3 million metric tons of emission credits generated by a project to capture and use greenhouse gases from the steelworks.

At current European spot carbon prices (the world's highest at around EUR 9.40 per ton), that's worth about $146m.

Also, take a look at the spike in the price of Camco's stock on the 12 month chart that happened at the end of October. That's because of the publication of the Stern Review of the Economics of Climate Change on 30th October - which argued that the right price for carbon was $85 a ton, a good nine times higher than it is now. Highly improbable if you ask me, but you can see why investors would be encouraged to hold stocks that are involved in carbon trading.