Memorandum submitted by the Tyndall Centre
This report outlines both local pollution-related
and global climate-related issues that collectively raise serious
concerns about the use of shale gas in the UK. The former leaves
little doubt that in the absence of a much improved understanding
of the extraction process shale gas should not be exploited within
the UK. The later suggests a more categorical conclusion that
in an energy hungry world another fossil fuel will only lead to
additional emissions and consequently must not be exploited if
we are to meet existing climate change commitments.
- Shale gas exploitation gives rise to a range
of environmental risks and hazards that have led New York State
to impose a moratorium on hydraulic fracturing whilst it awaits
the findings of a US EPA investigation. The main issues being
considered by the EPA, and which will be equally if not more,
important in the UK, are:
- High levels of water consumption necessary for
hydraulic fracturing operations.
- Groundwater pollution following catastrophic
failure or loss of integrity of the wellbore, or if contaminants
travel from the target fracture through subsurface pathways.
- Surface pollution via leaks and spills of various
contaminants held on a site.
- Noise from drilling.
- Traffic associated with construction.
- Landscape impacts of individual sites and the
combined impact of sites across the country.
- The exploitation of shale gas will, in an energy
hungry world, lead to an increase in carbon emissions at a time
when a rapid reduction is required. There is little evidence that
shale gas has played or will play a role as a transition fuel
in the move to a low carbon economy and its development seriously
risks directing investment away from genuine low carbon technologies.
While shale gas use in the UK may not increase overall UK emissions
it must be viewed in relation to impacts on global energy use
and emissions. In this regard, if the UK Government is serious
about avoiding dangerous climate change, the only safe place for
shale gas remains in the ground.
- The extraction of shale gas is likely to release
higher levels of greenhouse gases per unit of gas produced than
does the extraction of conventional gas. These additional emissions
are relatively small compared to overall emissions associated
with combustion, however additional fugitive emissions may arise
but these cannot be quantified at this time.
1. With conventional natural gas reserves declining
globally shale gas is increasingly portrayed as a potentially
significant and beneficial new source of "unconventional
gas2. In the United States production of shale gas has expanded
from around 7.6billion cubic metres (bcm) in 1990 (or 1.4% of
total US gas supply) to around 93bcm (14.3% of total US gas supply)
in 2009 (EIA, 2010b).
2. This new availability of shale gas in the
US (and potentially elsewhere) has led to huge interest in its
potential. Arguments have been made about the impact on energy
security and the potential for shale gas could, in principle,
be used to substitute more carbon intensive fuels such as coal
in electricity generation.
3. Whether shale gas is able to provide such
benefits depends on a number of factors including: the greenhouse
gas (GHG) intensity of the novel extraction process required in
the production of shale gas: the potential impact of shale gas
exploitation on carbon emissions; and the environmental risks
and hazards associated with drilling and production. It is these
three areas that are the focus of this submission,
What are the prospects for shale gas in the UK?
4. Prospects of shale gas in the UK will depend
on the right combination of shale type, total organic content
(TOC), maturity, permeability, porosity, gas saturation and formation
fracturing and in addition, the right market conditions and economic
incentives. Shale deposits on a global level are not a new source
of gas and have been evaluated since the early 1980's and produced
with commercial viability in North America since the 1990's (Verma
et al, 2001). To assess the prospects for shale gas in the UK
it will be necessary to understand what factors have a role in
developing sustainable reservoirs internationally and indeed if
the same resources and conditions are present in the UK. Prospects
will require the right combination of "shale type, total
organic content (TOC), maturity, permeability, porosity, gas saturation
and formation fracturing" (Boyer et al, 2006). Equally important
will be the right market conditions and economic incentives for
commercial viability. Security of supply and the impact on the
environment should be an integral part of any cost-benefit analysis
and the latter will be the focus of this report.
5. The shale potential in the UK is not known
and the only way to quantify the potential of a shale gas reservoir
in terms of its producibility is to drill, core, fracture and
then test the "play". According to the British Geological
Survey (BGS, 2011), the UK has abundant shales at depth but their
distribution and gas potential is not well known. The methodologies
employed in assessing deposits such as shale gas are very different
to those currently used for conventional accumulations. Traditional
petrophysical well evaluation can only provide a limited means
of making an assessment of the accumulations (Geny, 2010) and
it is widely recognised that there is currently no way of quantifying
the potential of a shale gas reservoir in terms of its producibility
other than to drill, core, fracture and then test the "play".
6. The success of the Bowland shale near Blackpool
will not be openly available for another four years. The first
well drilled specifically to assess shale gas in the UK by Cuadrilla
Resources, in the Bowland shale near Blackpool, is only due to
be tested in January 2011, the results of which will not be openly
available for another four years due to licensing agreements.
Further ongoing preliminary exploration of deposits with a view
to further development and known activity in the UK are summarised
in Appendix 1.
7. The onshore shale gas potential of 150bcm
stated in the DECC report could over-predict reserves due to the
Barnett shale in the US (which was used for the analogy) being
an above-average producer due to its low clay content facilitating
fracture stimulation important to the producibility of a shale
reservoir. Equally, it may underestimate the true reserves and
more shale gas accumulations may be discovered in time. Attempts
have been made at producing theoretical estimates of the shale
rock volume across the UK to provide an indicator of the potential
resources. According to the December 2010 report by BGS on behalf
of the UK Department of Energy and Climate Change (DECC, 2010a),
"the UK shale gas industry is in its infancy, and ahead
of drilling, fracture stimulation and testing there are no reliable
indicators of potential productivity". Applying some
assumptions and applying analogies with similar producing shale
gas plays in America, however, BGS estimates that UK shale gas
reserve potential could be as large as 150 billion cubic meters
(bcm). BGS acknowledge that the figure may be inaccurate due
to the Barnett shale in the US (which was used for the analogy)
being an above-average producer due to its low clay content facilitating
fracture stimulation important to the producibility of a shale
reservoir (Leonard et al, 2007). Equally, it may underestimate
the true reserves and more shale gas accumulations may be discovered
in time, as well as the techniques for making estimates developing
through experience as has happened with oil & gas reserves
in the UK since exploration began.
8. The UK onshore shale gas potential of 150bcm
would increase proven reserve levels by just over 50%. However,
at the current levels of UK consumption this represents only 2.5
years of current supply production as a standalone resource.
Taking the DECC estimates of 150 bcm and putting them into the
context of current UK gas supply (BP, 2010) provides a general
picture of the limited impact on supply that shale gas might have.
There has been a decline in conventional gas production in the
last decade in the UK, with only 59.6 BCM being produced in 2009
in comparison to 102.9 bcm in 2003. Additionally, with only a
marginal decrease in demand, this has resulted in an increase
in imports over the same period. The UK has proven gas reserves
of 290 bcm which has also declined from 910 bcm in 2003 (BP, 2010).
On a national level the DECC estimate of 150 bcm of shale gas
reserves would increase the proven reserves level by just over
50%, but at current levels of UK consumption this represents only
2.5 years of supply as a standalone resource. As the 6th largest
consumer of gas in the world, the UK has a clearly unsustainable
demand without assistance from imported supplies, or supplies
from alternative sources. Onshore shale gas would only provide
a short-term supplementary supply using current estimates of resources.
9. In terms of UK offshore potential, the costs
associated with drilling a high density of directional wells and
subsequent well stimulations would make such projects economically
unviable at current market prices. There is little coverage within
the current literature or the DECC (2010a) report discussing the
prospects for offshore shale gas in the UK, although its existence
is recognised by the DECC stating "Much larger areas are
prospective offshore for shale gas, and some of these might be
accessible by extended reach drilling" in reference to the
US. The costs associated with drilling a high density of directional
wells offshore and subsequent well stimulations would make such
projects economically unviable at current market prices. Additionally,
there could be more potential environmental impacts associated
with such exploration. However, in relation to the UK it should
be noted that over the last 10 years 99.8% of all gas production
has come from offshore wells and of the 3314 wells drilled,
only 299 of these were on land
(DECC, 2009). It is highly probable that large volumes of shale
gas exist in these generally deeper accumulations.
What are the implications of large discoveries
of shale gas around the world for UK energy and climate change
10. As efforts begin to exploit shale gas outside
of the US it is important to better understand impacts this may
have on CO2 emissions and efforts to minimise impacts
of climate change. To do this we have developed two sets of scenarios,
one for the UK and one for the World.
11. There is little to suggest that shale
gas will play a key role as a transition fuel in the move to a
low carbon economy. There is little evidence from data on
the US that shale gas is currently, or expected to, substitute,
at any significant level for coal. Projections suggest it will
continue to be used in addition to coal in order to satisfy increasing
energy demand. The importance of transitional fuels is often overstated,
for example, in the International Energy Agency Blue Map scenario
(50% reduction in global emissions by 2050), power generation
efficiency and fuel switching accounts for only 5% of required
emission reductions (IEA, 2010). If carbon emissions are to
reduce in line with the Copenhagen Accord's commitment to
2°C, urgent decarbonisation of electricity supply
is required. Given shale gas is yet to be exploited commercially
outside the US, it is unlikely to have a major role to play even
with respect to national emission reductions. If reserves
were exploited in time, shale gas would still only be a
low-carbon fuel source if allied with, as yet unproven, carbon
capture and storage technologies. If a meaningful global carbon
cap was established then the impact of a price of carbon
could facilitate some substitution of coal for shale gas
in industrialising (non-Annex 1) countries.
12. Without a meaningful cap on emissions
of global GHGs, the exploitation of shale gas is likely to increase
net carbon emissions. In an energy-hungry world, where GDP
growth continues to dominate political agendas and no effective
and stringent constraint on total global carbon emissions is in
place, the exploitation of an additional fossil fuel resource
will likely increase energy use and associated emissions. Possible
implications were examined through three global scenarios for
shale gas exploitation. The starting point was an estimate for
the global reserves of shale gas provided by the US National Petroleum
Council (NPC, 2007). Three scenarios were developed assuming differing
proportions of the total resource are exploited (10, 20 and 40%).
Making a further assumption that 50% of this available resource
was exploited by 2050, these scenarios give additional cumulative
emissions associated with the shale gas of 46-183GTCO2,
resulting in an additional atmospheric concentration of CO2
of 3-11ppmv by 2050. Given current growth in energy use it is
very possible that exploitation could be more rapid and that these
figures would increase accordingly. This will further reduce any
slim possibility of maintaining global temperature changes at
or below 2°C and thereby increase the risk of entering a
period of "dangerous climate change".
13. Carbon budgets should ensure that shale
gas use in the UK should not add to UK emissions, however, it
may put pressure on efforts to stick to these budgets and could
have implications for global emissions. To better understand
the potential implications of shale gas production in the UK,
four scenarios were developed. Two assumed the amount of shale
gas produced correlates with the figure provided in DECC (2010a)
- 150bcm; and two assumed an amount double this. For both the
150 and 300 bcm scenarios two different rates of extraction were
used; one based on a Hubbert type curve (a bell curve) that is
often used as an approximation for resource extraction; the other
based on the (highly uncertain) growth rates that are predicted
for the US by the EIA (eg EIA, 2010). All four scenarios see the
majority of shale gas being exploited before 2050 and the cumulative
emissions associated with the use of this shale gas ranged from
284-609 MTCO2. To give this some context this amounts
to between ~2-4.3% of the total emissions for the UK under the
UK Domestic Action budget outlined in CCC (2010). Assuming that
the carbon budget is adhered to then this should not result in
additional emissions in the UK. For example, it is possible that
UK produced shale gas could substitute for some imported gas.
However, it is also possible that extracting additional fossil
fuel resources could put pressure in efforts to adhere to our
carbon budget by reducing gas process and directing investment
away from renewable energy. It is also important to note that
in a market led global energy system where energy demand worldwide
is growing rapidly, even if shale gas were to substitute for imported
gas in the UK, leading to no rise in emissions, it is likely that
this gas would just be used elsewhere, resulting in a global increase
14. Rapid carbon reductions require major
investment in zero-carbon technologies and this could be delayed
by exploitation of shale gas. The investment required
to exploit shale gas will be substantial. In relation to reducing
carbon emissions this investment would be much more effective
if targeted at genuinely zero- (or very low) carbon technologies.
If money is invested in shale gas then there is a real
risk that this could delay the development and deployment of such
What are the risks and hazards associated with
drilling for shale gas?
15. The processes and operations involved in
the extraction of shale gas from wells are not without their human
health and environmental implications and these have risen in
prominence in the US and are now the subject of USEPA investigations.
16. When considering densely populated countries
such as the UK, potential risks and hazards of drilling shale
gas cover a wide range of environmental impacts including groundwater
pollution, surface pollution, water consumption, noise pollution,
traffic and landscape impacts. The "novel" risks
associated with hydraulic fracturing of wells are not the only
potential drawback of shale exploration, particularly when considering
relatively highly populated countries such as the UK. More "run
of the mill" impacts such as vehicle movements, landscape,
noise and water consumption may also be of significant concern
locally and more generally, especially, when one considers the
scale of development required to deliver significant supplies
to the UK.
17. To sustain production levels equivalent
to 10% of UK gas consumption in 2008 would require around 2,500-3,000
horizontal wells spread over some 140-400km2 and some
27 to 113million tonnes of water. To set the cumulative nature
of impacts in context, Table 1 provides estimates of the resources
required to deliver shale gas production at a rate of 9bcm/year
(equivalent to 10% of UK gas consumption in 2008).
RESOURCE REQUIREMENTS TO DELIVER 9BCM (10%
OF UK GAS CONSUMPTION IN 2008)
| ||Assuming No Re-fracturing
||Assuming a Single Re-fracturing on 50% of Wells (delivering an assumed 25% increase in productivity for those wells)
|Well pad area - ha||743
|Cuttings volume - m3||409,365
|Water volume - m3||26,730,000
|Fracturing chemicals volume (@2%) - m3
|Flowback water volume - m3||3,920,400
|Flowback water chemical waste content (@2%) - m3
|Total duration of surface activities pre production - days
|Total truck visits - Number||2,135,925
18. Risks and impacts of shale gas and shale gas processes
and development have been assessed as part of a study by the Tyndall
Centre for the Co-operative Group. Key risks and impacts identified
in that study are summarised below.
19. Groundwater pollution: The potential for contamination
of groundwater is a key risk associated with shale gas extraction.
A screening of the identity of 260 substances listed in a database
of fracturing fluid additives suggests that 58 of the 260 substances
have one or more properties that may give rise to concern owing
to toxic, carcinogenic, mutagenic and/or reproductive effects.
20. Groundwater pollution can occur if there is a catastrophic
failure or loss of integrity of the wellbore, or if contaminants
can travel from the target fracture through subsurface pathways.
There are a number of documented incidents in the US with principal
causes being improper construction and/or operator error. Amoung
these incidents are consequences including high levels of pollutants
(such as benzene, iron and manganese) in groundwater, and a number
of explosions resulting from accumulation of gas in groundwater.
21. Surface pollution: There are a number of potential
sources of pollution including: well cuttings and drilling mud;
chemical additives for the fracturing liquid; and flowback fluid
- the liquid containing toxic chemicals that returns to the surface
after fracturing. There numerous routes by which these potential
sources can cause pollution incidents including failure of equipment
and operator error. Unsurprisingly, a number of incidents have
been reported in the US.
22. Water consumption: Shale gas extraction requires
very significant amounts of water. To carry out all fracturing
operations on a six well pad takes between 54-174million litres
of water, which is equivalent to about 22-69 Olympic size swimming
23. Noise pollution: Given the high population density
and the likelihood that any shale gas extraction may be located
relatively close to population centres, noise pollution may be
an important consideration. Activities such as drilling mean that
each well pad requires around 500-1500days (and nights) of noisy
24. Traffic: It is estimated that the construction
of each well head would require between 4300-6500 truck visits.
This could have a local impact on roads and traffic in the locality
of shale gas well heads. Damage to roads not suited to the levels
of truck traffic associated with gas drilling has been an issue
in the US.
25. Landscape impacts: The construction of well pads
is an industrial activity and requires access roads, storage pits,
tanks, drilling equipment, trucks etc. Well pads take up around
1.5-2ha and the well pads will be spaced between 1.25-3/km2.
To produce 9bcm of gas annually in the UK over 20 years would
require 430-500 well pads and would need to cover an area of 140-400km2.
For comparison 400km2 is about equivalent to the Isle
How does the carbon footprint of shale gas compare to other
26. The key difference between the footprint for shale
gas and conventional natural gas is the extraction process.
These additional sources include: horizontal drilling; hydraulic
fracturing; the transportation of fracturing fluids; and waste
treatment of the fracturing fluids after use.
27. There is limited data available with which to estimate
the carbon impact of shale gas extraction in the UK. Using limited
data from non-peer reviewed US reports CO2 emissions
associated with shale gas extraction could account for an additional
0.14-1.63tonnes CO2/TJ of gas energy extracted.
The combination of emissions from these processes based on data
from US Shale sites and UK transportation and waste disposal provides
an estimate per well for a fracturing process of 348-438tonnes
CO2 (using data sourced from: ALL, 2008; New York State
2009; Water UK 2006; DECC, 2010b); DECC's recent report suggests
that refracturing could happen every four to five years for successful
wells. Using examples of expected total production for shale basins
in the US we estimate that, on average, the additional CO2
emissions associated with the additional extraction processes
associated with fracturing account for between 0.14-1.63tonnes
CO2/TJ of gas energy extracted assuming two fracturing
processes during the lifetime of the well (using assumptions on
production rate per well from Wagman (2006). However, it should
be noted that the estimates presented here are not based on fully
peer reviewed emissions data.
28. The larger the amount of natural gas that can be extracted
from a shale well, the lower the contribution the fracturing process
makes to the emissions/TJ of extracted energy. DECC's reserve
potential for the UK of 150 bcm is based on analogy with shale
gas plays of similar geology in the US. The rate of return per
well is not available for UK basins, the rate will determine the
relative carbon intensity per unit of energy extracted per well
associated with the additional emissions from fracturing etc.
29. Further emissions may arise from differences in shale
gas composition and leaking of fugitive methane emissions during
extraction. These will not be quantifiable until sites have been
drilled and levels could vary between sites. Additional differences
may occur due to the difference in the composition of gas extracted
from shale sources which may potentially require further processing
and clean up before the source is suitable for entry to the gas
distribution network. This is well dependent and it should be
noted that conventionally sourced gas will also vary in its processing
requirements. Further emissions may arise from methane leakage
during extraction; we have found no evidence to indicate whether
shale and conventional sites differ in this aspect.
30. These relatively low levels of additional emissions
suggest that there would be benefits in terms of reduced carbon
emissions if shale gas were to substitute for coal. However, rapid
carbon reductions require major investment in zero-carbon technologies
and this could be delayed by exploitation of shale gas. Combustion
of coal produces around 93tonnes CO2/TJ compared to
57tonnes CO2/TJ for gas. Clearly even with additional
emissions associated with the extraction of shale gas, the emissions
from gas would be considerably lower. The benefits increase when
the higher efficiencies of gas fired power stations compared to
coal fired power stations are considered.
ALL Consulting, 2008. Evaluating the Environmental Implications
of Hydraulic Fracturing in Shale Gas Reservoirs Authors: J.
Daniel Arthur; Brian Bohm; Bobbi Jo Coughlin, Mark Layne, ALL
Baihly, J Altman, R Malpani, R Luo, F. (2010) Shale Gas Production
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Accessed, Jan 2011
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Composite Energy (2010) http://www.composite-energy.co.uk/our-history.html
Accessed, Jan 2011
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DECC (2010a). The unconventional hydrocarbon resources of Britain's
onshore basins - shale gas. Department for Energy and Climate
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A Method for Assessing New Completion Strategies. SPE Annual
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California, U.S.A SPE 110809
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made available July 18 2007
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statement on the oil, gas and solution mining regulatory program
by the New York State Department of Environmental Conservation
Division of Mineral Resources.
Verma, S Shanthamurthy, S (2001). Shale gas-expanding India's
gas frontier? DEW Energy Journal. Vol 20 November 2001 p 43-46.
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|Cuadrilla Resources||In November 2009 planning permission for an exploratory drill site at Preese Hall Farm, Weeton, Preston Lancashire was granted by Fylde Borough Council (with no requirement for environmental assessment or application for a decision as to whether one was required). According to the planning application and other documentation, the purpose of the exploratory drill is to identify whether the formation can produce gas at economic levels and, if the results prove positive, any further development will be subject to a further planning application.
Drilling at Preese Hall was completed on 8 December 2010 and the rig is to be located a second drilling site at Grange Hill (some 15km from Preese Hall) where drilling will commence in January 2011. A full hydraulic fracturing of Preese Hall is expected to commence in January 2011.
Preparations for a third exploratory well at Anna's Road are underway and a planning permit was approved on 17 November 2010.
|Island Gas Limited||On 15 February 2010 Island Gas Limited (IGL) announced that it had identified a significant shale resource within its acreage. The reserves identified (using existing borehole logs in the locality) potentially extend over 1,195km2 with an expected average thickness of 250m. These shales are understood to be hydrocarbon bearing as they have been locally demonstrated to be the source rock for hydrocarbons in the Liverpool Bay area.
|Composite Energy||Composite Energy was initially focused solely on Coalbed Methane (CBM) but also has shale resources and conventional oil and gas within its current license portfolio and expects to add to that potential in 2010-11. Composite reports that it has identified shale potential within its licenses and is working to establish approaches to shale operations in a UK and European context (Composite Energy, 2010).
3,314 wells were drilled in total offshore, of those 402 were
in the southern North Sea, the largest contributing region of
gas in the UK. (DEC, 2009). Back
We assume the emissions from the combustion of gas from shale
sources are the same as from conventional sources. In considering
the UK, the distribution of shale gas would be the same as conventional
gas and therefore subject to the same losses. The limited verifiable
data available makes assessment of the additional extraction emissions
problematic. However, the figures above use data on expected emissions
from the Marcellus Shale in the US to determine the likely emissions
associated with the different processes. The processes included
in the assessment were: horizontal drilling; hydraulic fracturing;
the transportation of fracturing fluids; and waste treatment of
the used fracturing fluids. Back