Headlines about fracking (including on these pages) are usually nothing if not sensationalist.
Something about the notion of lots of gas trapped in rocks - and the word "fracking" - seems to lead even the most cautious sub to take a long sip of the metaphorical kool-aid.
But Saturday's headline in The Times "Britain has shale gas for 1,500 years, but bills won't be lower" was truly an extreme example of its kind.
100 years?
What the story actually suggests is that we might have enough gas for a little over 100 years - assuming all goes according to the best laid plans (see our calculations here).
The article cites sources for a new analysis by the British Geological Survey (BGS) that the UK has between 1,300 and 1,700tcf of shale gas.
The most excellent Carbon Brief have done some investigative work and found out how The Times came to their startling number:
We weren't quite sure how this was worked out, so we decided to have another go at the calculation. The Energy Savings Trust told us that the average gas-heated home in the UK consumes approximately 47,000 cubic feet of gas. There are 26.4 million households in the UK.
So if we make two (rather large, and clearly inaccurate) assumptions that the number of households in the UK and the amount of gas they consume don't change over the next fifteen centuries, then just over 1800 trillion cubic feet of gas would be needed to heat all the UK's home with gas for 1500 years.
There is, however, more wrong with that calculation than just lazy assumptions about gas use.
There is a difference between the resource and the reserve - the amount we can actually get out.
The Times claims we could recover 16-20% of the available reserve. Let's be optimistic and call it 20% of 1700 - that'd be 340 tcf.
So how many years is that?
According to BP, in 2011 we used about 2.847 tcf of gas (note, this is more than we get from North Sea production, because we import gas).
So if you divide 340 by 2.847 you get... um 119 years.
Ten years?
Still - that'd be a pretty big upgrade and rests on some highly variable assumptions.
To begin with, gas demand fell sharply in 2011 due to a price spike following the Fukushima disaster and Japanese Tsunami.
UK demand in 2010 was around 3.2trn cubic feet and as coal power plants come offline to be replaced by gas, you'd expect that demand to increase.
But the key thing is the scale of extraction the article envisages.
Cuadrilla's latest analysis of the Bowland shale, provided to Poyry, suggests that by 2035 they will be able to produce around 0.7trn cubic feet from that area based on a reserve of around 200trn cubic feet - or around 30tcf of extractable gas.
They are the most advanced, so you'd expect other firms to reach peak production well into the 2030s and 40s, around the time the UK is meant to be going almost completely carbon free.
But even that claim is considered extremely optimistic by the Energy Contract Company, and indeed the US government. Both estimates - reported in the FT - suggested total UK extractable shale would be between 20 and 40 tcf with a mere 2-4 in Cuadrilla's patch. Enough to last us a decade or two.
And here is the problem.
There has been almost no work outside Lancashire and, thanks to a drilling ban, very little even there.
In Poland the ratio of available to extractable shale in Exxon's patch appeared to be roughly 0%.
As the BGS's own Professor Bradshaw put it, until we extract the gas "we simply do not know" how much gas there is.
What we can say though, is that nobody has yet provided any evidence to suggest we have enough to last 1,500 years.
