I've just written some brief notes on fracking for one of our local Parliamentary candidates. Here they are.
Global context and transition fuel
It's been argued by proponents that since burning gas produces less CO2 per unit
of energy (has a lower carbon intensity) than, for example, coal,
shifting from coal to gas will help in the transition to a low carbon
economy.
But
1) As a recent BP report indicated, there's precious little evidence
that exploiting new sources of fossil fuels reduces consumption of the
others (indeed the USA has opened up 4/5 new coal exporting terminals on
its west coast so that it can export the coal that it would otherwise
have burnt itself).
2) Natural gas is mainly methane and methane is a much more powerful
greenhouse gas than CO2 (between 20 and 40 times depending on the
timescale). This means that any leaks of methane (referred to as
fugitive emissions) can easily end up undoing any greenhouse gas savings
from its lower carbon intensity.
3) Whenever you make an investment in energy infrastructure there's an
expected working lifetime of at least 25 years. The International Energy
Agency has recently done an analysis of the expected overall emissions
from our existing global energy infrastructure (anything that converts
energy from one form to another, from car engines to power stations) and
is clear that on current plans we've got 3/4 years left of investment
as usual before the cumulative emissions from the existing
infrastructure will exceed those needed to achieve the target of a than
2C rise in global temp. Blog post locked in
4) Following on from 3), to avoid dangerous climate change we need to
leave around 60% of known fossil fuel reserves in the ground. A good
place to start would be with as yet unexploited and unconventional (in
the UK ) sources such as fracking.
Local environmental impact
A lot of opposition has centred on local pollution (e.g of water
supplies). The fracking process involves drilling deep into suitable
geological structures and then injecting high pressure water (along with
sand, to keep the fractures open, and other chemicals, to dissolve some
rock and keep everything flowing ) and there are obvious risks if the
well casing loses its integrity. If done well this should not be a
problem but experience from the USA suggests that over time even the
best managed wells can start to leak into surrounding strata and so the
long term management of wells would have to be very well controlled.
However, its possible to distinguish the methane that comes from deep
lying strata from methane of more recent biological origin by its
profile of isotopes (the same as carbon dating) and in the USA the
methane coming out of people's taps has clearly been shown to be of recent origin and therefore not the result of fracking.
Getting all materials on site means quite a lot of transport of
materials and lots of associated noise. Because you have to fracture the
rocks before you can extract the gas its not like a conventional gas
well where you drill a hole in one place and the gas simply flows to it.
Instead you're limited by how far you can drill sideways (now about 0.5
mile but originally much less) so the minimum well spacing would be at least one per mile.
University of Bristol summary of the issues
Energy policy
Fracking involves considerable investment of machinery and manpower. The present government is offering significant tax breaks for fracking
which can be compared with the support given to renewables. The
question can therefore be asked as to whether our energy security is
best served by subsidising a fossil fuel industry, and using valuable human resources there, rather than in encouraging a faster switch to renewables.
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