Natural gas is made up of a mixture of hydrocarbon gases and this mixture can vary widely between sources. The 'quality' of a given amount of natural gas is determined by the relative quantities of these hydrocarbon gases, and therefore also varies considerably.
In Great Britain (GB), domestic and industrial appliances are designed to operate within a certain gas quality specification range. The current gas quality standards are based on the quality of gas sourced from the UK Continental Shelf (UKCS) as this has traditionally been the primary source of supply for the GB market.
However, as a result of the natural decline in domestic gas production, GB has become increasingly reliant on imports of gas from the Continent and other world markets, and this trend is set to continue in the future. Over the next decade, gas quality specifications in continental Europe are set to become broader than those applying in GB. This could mean that in future years, any gas flowing from continental Europe to GB will not comply with GB’s quality standards, and therefore not be able to be accepted onto the GB network. This could have consequences for security of gas supply in GB.