The Scottish Government and SEPA asked ClimateXChange to commission a desk-based study of the estimated greenhouse gas emissions associated with the exploration and extraction of unconventional gas in Scotland.
The study considered two major sources of unconventional gas that are currently being considered for onshore extraction in Scotland: coal bed methane and shale gas.
The study has concluded that the life-cycle greenhouse gas emissions per unit of energy from unconventional gas extraction in Scotland are likely to be equivalent to those of conventional gas extraction in Europe if best practice is followed and building on peat is avoided.
These emissions are less than LNG and gas extracted from outside of Europe. If unconventional gas disturbs peat soil, the cycle greenhouse gas emissions per unit of energy would be equivalent to natural gas from outside of Europe and LNG. The lifecycle emissions of coal bed methane are likely to be similar to the emissions from shale gas.
The study finds that the key factors influencing the lifecycle emissions of unconventional gas extraction in Scotland are:
- Methane that could escape when the borehole is being prepared for gas production, or servicing a borehole during production. These emissions will be minimised by applying Best Available Techniques to capture and use the methane, thereby preventing it from being emitted to the atmosphere;
- The impact of building associated infrastructure (such as drilling platforms, pipelines and roads) in areas with peat soil. This is because peat soil holds carbon which will be released when the soil is removed or drained when preparing the land for being built on. These emissions could be mitigated by avoiding unconventional gas exploration and development on peatland. The emissions could also be reduced by avoiding deeper areas of peat, minimising the area of land to be built upon, and maximising the number of boreholes at each well pad (i.e. using a lower number of surface installations to access a larger volume of the subsurface);
- Fugitive methane emissions that escape from valves and pipes, which are difficult to capture. The magnitude of these emissions is poorly constrained. The technology for reducing these emissions is available. Fugitive emissions could therefore be reduced by improved equipment performance and rigorous monitoring for early leak identification and intervention.
The life-cycle assessment estimates the combined quantity of greenhouse gas emissions associated with the exploration and extraction of unconventional gas in Scotland. The emissions associated with gas distribution and use was not considered in the study.
Unconventional gas is a growing industry worldwide and there is interest in developing the industry in Scotland.
Given the Scottish Government’s ambitions for a low carbon economy, it is important to understand the potential greenhouse gas emissions associated with unconventional gas, as well as the potential measures that may be taken to minimise these emissions.
To get the whole report go to SEPA/Scottish Government