Wednesday, 19 December 2012

What's wrong with fracking?

Picture from Accenture [7]

Oil and gas reserves in the North Sea are dwindling but it is claimed that there are vast reserves of shale gas under our feet which can be accessed using a new technique called fracking. In the USA fracking has transformed the oil and gas industry to the extent that production is rising and gas prices have gone down [1]. Should we go for it too or not? There are concerns about the environmental impacts of fracking and uncertainties about the size of reserves. Is gas from fracking a useful transition fuel or should we invest exclusively in renewable energy starting now. The UK government has recently allowed drilling to continue in Lancashire which had been suspended due to earthquakes. Developing a local gas production industry would be good for our energy security and good for our balance of payments - imported energy is expensive. So how bad is fracking anyway? In this post I summarise the issues.

Shale gas is natural gas (methane) which is trapped in fine grained shale rock. Conventional gas reserves have gas in porous rock below an impermeable cap - to retrieve the gas you only to drill through the cap and gas can flow out. If there isn't enough pressure in the reserve you can pump CO2 down to force more methane up (CO2 is heavier than methane which helps to ensure the methane rises to the top). However, shale is not porous so to get methane out of it you have to force cracks into the rock - this process is called fracking.

Fracking a new well takes about a week. It involves pumping a mixture of water, sand and chemicals into the rock under high pressure to fracture the rock. The sand lodges in the cracks and helps to keep them open. To fracture a decent amount of rock and get out a reasonable amount of gas you have to drill and frack sideways through the rock. A shale gas well can easily be a mile long [2].

Size of reserves

Shale rock is very variable and it is hard to know how much there is until you start drilling. Also, there is a big difference between gas-in-place (GIP) and recoverable gas. Recovery factors could be anything from 2% to 30%. Experience in the USA suggests that 10% recoverability is typical. Gas quantities are measured in trillion cubic feet (tcf). The USA gas production in 2011 was 23 tcf of which about 8 tcf was shale gas. In the UK, in 2011 we currently use around 1000 GWh/year energy in the form of gas [3] which is very roughly 3 tcf of gas.

Cuadrilla, the company which has been drilling in Lancashire, estimates GIP from its licence area at 200 tcf (trillion cubic feet). Other companies have estimated another 60 tcf or so for their areas [4]. If 10% of this is recoverable that would be 26 tcf in total or about 9 times the annual UK gas consumption. However it could easily be twice this or half.


Drilling in Lancashire was suspended in May 2011 because it triggered some small earthquakes. This is however very unusual. Permission to resume drilling has now been given, under strict conditions including staged fracking, with pauses to allow pressures to equalise. Also after each stage there will be monitoring for 24 hours and fracking must stop if there is any seismic activity of level 0.5 or higher - 0.5 being imperceptible by anyone at the surface [5].

These conditions may be too onerous to allow fracking at all [6]. They are certainly on the cautious side.

Water use

The fracking process requires lots of water: 2-8 million gallons [2] but typically 5 million gallons of water per well [7]. This is needed within the space of a week - afterwards smaller volumes are needed for drilling. Fresh water is preferred as sea water corrodes the drilling equipment. 5 million US gallons is 18 million litres which is a day's worth of normal water usage for a town of 120,000 people.

This is the water needed for one well. In the US Barnet Shale area, there were 15,000 wells drilled up to the end of 2010, at about 1 well per square km [8]. In practice fewer wells may be required with more horizontal drilling but the amount of water required to frack depends on the length of pipe, not the number of wells.

Some of this water flows back to the surface through the well head during later operations (flowback). Depending on the type of shale the fraction returned could be 10% to 75%. The flowback water is often high in salts and toxic metals, as well as the chemicals used in fracking. This water needs to be thoroughly treated before it is released to the environment. Where possible it is reused in further fracking operations.

Whether or not this water requirement is acceptable depends on the weather. Just recently we've had lots of rain but earlier in the year we did not. The Environment Agency limits water withdrawal in times of drought and fracking would have to be delayed.

Water contamination

There are two ways that fracking can contaminate water supplies. Firstly, the flow back water which comes up at the well must be captured and treated before it is released to the environment. This water can contain toxic chemicals and high concentrations of salts and metals. Normal operations should ensure the water is handled safely but spills can happen.

Also, at least theoretically, fracking can open up new pathways for the gas and oil to seep into aquifers or even up to the surface directly, bypassing the well. In practice this is rare because the shale is normally a long way below fresh water aquifers, but it can happen. The US Geological survey has recently confirmed that fracking contaminated the Wind River aquifer in Wyoming with hydrocarbons [9]. In this case, the the drilling was directly below the aquifer [10]. High risk areas can be identified by geological survey and avoided.

Methane leakage

Methane can be released either from the well head or, rarely as in the water contamination case, through new pathways opened through the rock by fracking. Methane leakage is very serious as methane is a potent greenhouse gas. However, methane leakage is a loss of revenue for the drilling company as well as a pollutant and it is in everyone's best interest to avoid wasting the gas. A recent study by MIT of a large number of wells found leakage comparable with conventional gas drilling [11].

A blot on the landscape

Personally I think wind turbines are much prettier than gas wells. We will need thousands of either. There is also the option of putting gas wells offshore - in fact offshore reserves could be much larger than onshore. However offshore gas fracking has not been done before and there are bound to be higher costs. For example, if sea water is used instead of fresh water the drilling equipment will need to be corrosion resistant.

Picture from Accenture [7]

Wind Turbine near Swaffham in Norfork

Investment distraction

There are two reasons why it might be a good idea to invest in UK shale gas now. Firstly, even if we move over to renewable energy for most of our needs, a bit of gas for backup would not go amiss. However, under the new energy regime implemented by the recent Energy Bill (see The Energy Bill, EMR and price fixing - a toxic combination) there is little disincentive to using gas instead of wind where it is available. The price floor for carbon is still very low and there are no targets set for the carbon intensity of electricity generated. We also use a great deal of gas directly for domestic heating. Converting our heating systems to electricity is expensive and if gas is available at a reasonable price most people simply won't.

The second plausible reason is that wind and other renewable energy technologies are not yet ready for large scale rollout - if we delayed another couple of decades we could do it more cheaply. There are some developments in the pipeline now which could save costs in the future, for example floating wind turbine platforms for offshore wind, towers made with carbon fibre reinforced polymer instead of steel and even radically different designs such as robotic wings. However, there is no guarantee that these options will be developed at the scale they deserve if the energy companies are tying up their capital in gas fracking.

In my view, most of the environmental considerations against fracking are weak. However, in terms of protecting our landscape and investment in renewable energy, large scale fracking is not a good way to go.

[1] EIA Natural Gas
[2] Water’s Journey Through the Shale Gas Drilling and Production Processes in the Mid-Atlantic Region Penn State Extension
[3] Digest of UK Energy Statistics 2012
[4] The Impact of Shale Gas on Energy Markets October 2012
[5] Written Ministerial Statement by Edward Davey: Exploration for shale gas
[6] How the UK government has decided to kill frackin for shale gas (Forbes)
[7] Water and Shale gas development accenture
[8] The Basics - SHIP (Shale gas information platform)
[9] New study supports water contamination due to fracking
[10] EPA: 'Fracking' likely polluted town's water
[11] Study: 'Fugitive' methane from shale gas production less than previously thought


  1. Though fracking in the US has driven down coal use and hence US emissions as they switch to gas, it has also lowered global coal prices and hence increased global coal usage overall - emission displacement rather than reduction.
    Personally I'd prefer investment in technologies that are getting cheaper (i.e. renewables), rather than technology that shows little sign of improvement (even if the former is more expensive now).
    As you mention, the low carbon price is an issue but more important is the $500 bn per year subsidies & tax breaks given to fossil fuels which, in an ideal world, would be instead directed at renewables. e.g.:

  2. There are really a lot of talks going on regarding the effects of fracking, and people generally do go in favor of using renewable energy. However, both methods of harnessing energy resources have pros and cons that we need to know. Even if renewable energy can be easily harnessed, the problem with it is that it is not ready for wide-scale application. Most parts are expensive and a couple of energy generators can’t power up a wide city, which makes fracking a cheaper investment for the government.

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