Ofgem has rejected plans by National Grid Gas Transmission (NGGT) to replace ageing gas compressors at sites in the east of England, saying they will not be required when already-planned gas turbine units are installed.
Ageing ‘Avon’ compressors, which have been used in the gas transmission network for up to 60 years, emit NOx at a level that breaches Medium Combustion Plant Directive (MPCD) rules, which require that by 1 January 2030 gas turbines between 1MW and 50MW must not exceed a NOx emissions limit of 150mg/m³.
After an options appraisal process NGGT proposed replacing the Avon engines at the
King’s Lynn compressor station and the Peterborough and Huntingdon station, at a total cost of around £200 million (in 2018/19 prices). But the regulator proposes to reject that option, because at both stations more modern gas turbine compressors can be used.
Ofgem says that at King’s Lynn newer units are already in place and can be rescheduled to manage the gas flows, while at Peterborough new units are being installed and are due to come into service by 2030.
Ofgem says if the old Avon units can take on a ‘backup’ role they will not be used for more than 500 hours per year, which is allowed under an MCPD derogation.
The Peterborough and Huntingdon compressors together carry out several key network roles, but Ofgem says NGGT can use other options, including commercial constraint management through locational balancing actions or using other compressor stations.
King’s Lynn is the sole source of compression required to facilitate the export and import of gas through the two interconnectors between Great Britain and Europe at the Bacton Terminal. Ofgem acknowledges it “has a critical role in providing security of supply for energy consumers in Great Britain” and it was used extensively last year as GB acted as a transit route to fill European gas storage after pipelines from Russia closed. But Ofgem says that year was “atypical” and should be given little weight in estimating likely future flows.
Ofgem is consulting in its decision, see details here