Friday, 2 August 2013

Shale in your underpants : a very personal take on fracking

part of a reply to a local resident concerned about fracking in Oxfordshire . . .

You will not be surprised to learn that the Green Party does NOT support fracking, nor even exploratory drilling that might lead to it.

Different members of the party might come to this same conclusion from a differing prioritisation of concerns. For six years (in the 1970s) I was a graduate mining engineer, working latterly as a coalface deputy in the Midlands coalfield -- which extends under Oxford.  I have had a very personal relationship with the shale measures that overlie the coal, precisely because it 'fracks' --it is friable -- it breaks, falls in lumps on your head, and turns into a mush of slippery fragments that go down the back of your neck and lodge in your underpants!  But the methane that they release was also a major hazard -- indeed, a major underground fire cause by spontaneous combustion was responsible for the permanent closure of Britain's largest remaining coal mine (Daw Mill, in Warwickshire) not so long ago.  (Something, I have to say, that would never been allowed to happen under National Coal Board management.  It was incompetence and corner-cutting).

I'm not sure what the depth of the coal measures under Oxford is.  In South Warwickshire, it's about 350 metres, and coal extraction leads to surface subsidence and small fissures that extend to the surface.  (A major problem on the coal face was that once the shale roof broke, the shale would shatter and run out of the hole like sand through an egg-timer, leaving cavernous spaces that had to be shored up with timber -- a highly dangerous operation, since the hole would be full of methane, and always liable to further collapse).  Although fracking doesn't involve the extraction of 3 metre thick strata as coal extraction does it is a new technology.  I don't know what the borehole pressures are and doubt whether there is any reliable means of monitoring how far the induced fractures extend.  It is clear from some shocking examples in the United States that the chemical/sand slurry -- and methane gas, too -- gets into aquifers.

Fracking requires multiple boreholes -- we're talking hundreds, not one or two -- and each site (which may support a dozen boreholes going in different directions I believe) will require the delivery of large quantities of toxic chemicals and the removal of toxic waste slurry.  I haven't heard how it is proposed to get the gas into the gas grid -- whether it will mean hundreds of miles of gas pipelines or compressors on site running 24 hours, and more heavy vehicles.

For myself, the priority arguments are :

that it is trying to stave off the inevitable -- we know we have to get on to renewables and the time to do that is now.  Fracking is an enormous distraction, takes our eye off the ball and (with its promise of quick profits) undermines much-needed investment in renewables technology.  It is true that in the next few years a number of our nuclear power stations will be reaching the end of their lives, leaving the Grid with a big hole in baseload supply -- so I can understand why energy ministers are concerned.  But this is absolutely not the way to do it.  They need to be ramping up the drive for renewable energy, and this is sapping that motivation.

It is unproven technology -- which in itself would not be a problem were it not for the fact that the evidence we are seeing from existing sites around the world is alarming with regard to the release of methane gas to atmosphere and pollution of aquifers -- 143 cases in the US alone.  Given that potable water is in a few years going to be an even more precious resource than oil, the risks involved are immense.  I do not believe a well borehole, once the fracking process has begun, can be reliably sealed because of hidden surface fissures.

The surface operations will not be benign.  They will involve hundreds of truck movements of toxic chemicals and slurry, gas flares night and day, construction of pipelines and a lot of leakage of methane around the site.  Methane in a concentration of 9% with oxygen is as explosive as TNT.

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