Gas can be extracted from ‘Gas shales’, rocks that are formed by deposits of
mud, silt, clay and organic matter. These porous rocks can have natural gas
trapped within them, and in order to extract it, the rocks must be fissured, or
fractured. These new gas resources are getting more and more interesting for
exploitation as conventional resources are getting less abundant. The European
Commission is looking at the safety and climate implications of the extraction
of these new resources in Europe.
The present report from AEA Technology analyses and discusses these estimates
for each step of electricity production from
shale gas, taking into account the direct
and indirect emissions associated with gas extraction, transportation and use,
including pre-production and production phases (excluding the exploration
What is the climate impact to be expected from shale gases production in the EU?
Some studies, which have received a lot of media attention, have concluded
that the lifecycle greenhouse gases (GHG) emissions from
shale gas may be larger than
conventional natural gas, oil, or coal when used to generate heat and viewed
over the time scale of 20 years. However the majority of studies suggest that
globally, emissions from shale gas, although slightly higher than conventional
gas, would produce significantly less (by 41% to 49%) greenhouse gases emissions
Overall, it is estimated that the potential greenhouse gas emissions that
might be associated with shale gas
exploitation in the EU are about 60-70 g CO2 per MJ of thermal energy, or
472gCO2eq per kWh of electricity generated which is slightly higher (by 4-8%)
than with conventional gas resources. It is also estimated, although with less
certainty, that the greenhouse gases emissions from shale gas exploitation in
Europe is overall slightly lower than those coming from importing conventional
gas from sources outside of Europe.
Like for conventional gas resources, the combustion of
shale gases is the main source of CO2
emissions. . However, emissions also arise from their pre-production,
production, processing and transmission stages even if overall, the importance
of the emissions at these stages is lower. The second greatest contributor to
emissions is the completion and installation of the extraction well. The
fracturing process can lead to methane
emissions when the fluid used is brought back to the surface, and such emissions
are not present in conventional gas extraction.
There are still uncertainties regarding GHG emissions in the production step.
Also, the management of waste (waste water
in particular) generated by shale gas
extraction will also influence their global GHG emissions.
Are there other impacts to be expected from shale gas exploitation in Europe?
Due to the generally higher population densities in Europe, it is argued in
the report by some that shale gas
developments might have a smaller overall land-footprint compared to the current
exploitation of shale gas underway in the United States, or to conventional gas
production in Europe as developers may be under more pressure to reduce the
impact of well developments on the landscape, although this would require
further analysis. There are however uncertainties about the level of re-use and
treatment of the wastewater generated by the extraction process.
The regulatory framework of the EU will need to be adapted in order to take
into account shale gas exploitation.
Regarding in particular the reporting of these emissions, the current EU
reporting framework, made with the UNFCCC and the IPCC, does not include any
data specific to shale gas extraction. The way the reporting is done in North
America could be used as a basis to adapt the EU reporting to the reality of
shale gas extraction.
For more information on shale gas you can
also see our highlight on the potential health and environmental risks related
to the exploitation of shale gas in Europe : http://www.greenfacts.org/en/shale-gas/