Carbon capture and storage remains a nascent technology: no one has yet proved that an integrated process can work on a commercial scale. But the US, Canada, Australia, the European Union and others have pledged billions of dollars to back demonstration projects. This suggests commercial deployment could be possible around 2020.Even so, any transition to carbon-free generation will take decades. Low-carbon technologies are generally more expensive than fossil-fuel plants: some, such as offshore wind, are a lot more expensive. And with wind, power generation will not be constantly available. Britain, which is backing Europe's fastest expansion of wind power, is building into its plans for 2030 a huge margin of spare generation capacity which can be used when there is no wind.