Injection into the Gas Grid

Injection into the Gas Grid Print E-mail


Biogas can be upgraded to biomethane and injected into a gas grid.  This can be the national high pressure gas transmission grid or a local low pressure gas distribution network.  To be used in the gas grid in the UK biogas needs to cleaned of impurities, dried and upgraded to a higher methane content (c. 95%) so that it resembles the qualities of natural gas. This approach is already being used in many countries including Germany, France, Austria and the USA. 

A report by National Grid suggested that, with the right support and incentives, renewable gas could meet a significant proportion of UK residential gas demand.  This included both gas produced by AD and by the thermochemical gasification of waste.  A paper by National Grid also highlights the opportunities for renewable heat from the gas grid with biogas and gasification of organic waste.  

DECC have produced a guide to biomethane production and injection into the gas network that outlines the major legal, technical and regulatory requirements. In addition, OFGEM have produced a factsheet providing basic information on how to get connected and issues arising from biomethane injection.

Injecting biomethane into the grid has several advantages:

  • biomethane injection is supported under the Renewable Heat Incentive (RHI)
  • provides a far more flexible fuel than biogas
  • biomethane has a higher energy density than biogas
  • ensures energy that is captured in the biogas is used efficiently
  • can be cheaper for the AD plant operator to install a gas grid connection than an electricity connection.

However, there are currently many barriers to grid injection, both practical and financial:

  • no UK standard for biomethane
  • upgrading adds substantially to the cost and energy requirement
  • upgrading can reduce carbon savings
  • no incentive for grid operators to accept biomethane
  • AD plants may be some distance form the gas distribution network.

A project by National Grid and United Utilities plans to inject biogas from sewage sludge digestion into the grid.  The plant should provide a better indication of the true financial cost of grid injection and indicate how National Grid could support such projects in the future. 

To read more about the strengths and weaknesses of upgrading biogas, as well as how to meet UK gas grid quality standards, see this report from BIS.

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