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Portsdown Hill Injection Hub


The Portsdown Hill facility is the UK's first purpose built gas injection hub, designed to provide all year round grid access to remote biomethane producers.


Injection Hub Concept:

The Injection Hub concept developed by SGN Commercial Services, was for a large volume centralised facility to serve multiple remote bio-methane production sites that are unable to inject gas locally due to unsuitable local capacity.



At full capacity, the site will supply low carbon energy to meet the annual heat demand for up to approximately 27,000 customers in the local Havant and Portsmouth areas. The biomethane entry facility at Portsdown Hill is the largest connection or ‘green gas’ source entering a Gas Distribution Network (GDN) within the country, and the only network entry point not requiring enrichment by the addition of propane.

The Portsdown Hill facility was designed and built with four operational stanchions with one in reserve for maintenance, however the site can accommodate five tankers simultaneously downloading at 1200m³ per hour.



SGN’s Portsdown Hill ‘Gas Injection Facility’ was designed to inject compressed biomethane into a gas transportation and distribution network, blending the biomethane with natural gas without the further need to add propane for Calorific Value (CV) enrichment.


Unlocking Potential:

There are circa 100 sites throughout the UK producing biomethane in this way and most benefit from close proximity to a gas pipeline and injection can take place adjacent to the point of manufacture. A further 500 gas producing sites in the UK have been identified as having the potential to contribute to the gas network but are constrained by their location.


Technical Challenges:

The transport of gas is by trailers and its technology was already well established and tested pre-2012 with methane trailers operating at pressures of around 250 bar. However, it was the injection facility that presented the technical challenge as this was a new concept to the gas industry. Traditionally, gas networks within the UK operate up to pressures of 100 bar so innovative safety systems and downloading equipment were developed and added to the gas network at this entry point to ensure the extension of the gas network could operate safely up to 250 bar.



There are several benefits associated with a Injection Hub model compared with direct injection via a conventional ‘biomethane-to-grid’ model:

  • No enrichment needed – no propane to meet the target CV – cost saving (typically 4% of volume injected to grid is propane)
  • Reduction in flaring, due to:
    • Storage availability
    • Increased stability over gas quality (propane addition / control is the single largest gas quality excursion event)
    • Low gas demand within network (Portsdown Hill is a high-volume site)
    • Increased resilience – multiple streams (one dedicated exclusively for maintenance) provide redundancy
  • Open access – supporting multiple customers
  • Connection ready – facility is fully operational
  • Reduced costs – sharing of expensive equipment and maintenance cost, redundancy included
  • Technical risk reduced – site maintained by network operators