Greenpeace: Shale gas: What do the claims mean?

This morning shale gas explorer I-Gas told the BBC that there was a lot more gas in place under its license blocks than it previously thought. 

The news was a boost for the company’s shares . But what does it mean for those of us who aren’t shareholders?

Nobody doubts that there is a lot of oil and gas trapped in the rocks beneath the UK, the problem is the suggestion that any particular fraction if it can be gotten out. In fact this figure - the one that matters to UK consumers. 

Fims, like I-Gas, tend to suggest that you can apply a rough percentage to work out how much is 'extractable' - generally taken from experience in the US and reduced slightly to appear 'conservative'. 

But academics at Imperial have questioned the accuracy of this method which fails to take into account significant differences in politics, economics and geology of the UK and US shales.  MORE