The Rough operation is characterised by a number of sources of atmospheric emissions typical of offshore gas developments. Main Power generation and gas compression turbines are run on fuel gas, which is derived from the gas storage reservoir during production & standby and from injected gas during injection, whilst emergency back-up generators and firepumps are diesel driven. Combustion emissions from gas fuelled turbines include carbon dioxide, oxides of nitrogen, carbon monoxide and unburnt hydrocarbons, while the combustion of diesel on site also gives rise to emissions of sulphur dioxide. Combustion emission levels from gas turbines are linked to the amount of energy required for normal process operations as well as the efficient operation of these machines. Emissions from diesel plant are minimal due to the use of low sulphur diesel and being emergency use only.
Natural Gas (methane) emissions primarily occur from venting during normal plant operations and fugitive emissions from valves & pipe flanges etc. It should also be noted that depressurising the plant by venting to atmosphere during emergency situations is an important aspect of safe operations. Therefore, although this can be seen as a significant environmental impact it is recognised that there is no alternative, safety takes priority over the environment in this situation. Robust operating and maintenance procedures reduce the likelihood of emergency releases.