Within-day swings in the volume gas stored in the national transmission system (NTS) are on average treble the size that they were a decade ago.
The ‘Gas Future Operability Planning’ report said power stations, interconnectors, industrial users, storage sites and entry terminals all want to be able to add and remove gas at shorter notices to quickly respond to changes in the electricity market. Distribution networks also want additional flexibility to meet their own customer requirements.
National Grid warned that a trend towards “later reconciliations of daily balancing by our more commercially responsive customers” has led to gas system stocks becoming depleted on occasions. “Longer-term capacity auctions no longer indicate a shipper’s intention to flow,” it added. “These auctions used to give us clear signals from the market that changes were required. We now have less certainty on the need to invest or take actions in advance to balance the network.”
The system operator said the growing diversity of gas supplies has led to “great variation of flow from one day to the next… Operationally we are seeing more rapid rates of change in the geographical distribution of supply and demand levels.”
The expansion of renewables in the power sector will also mean demand from combined cycle gas turbines used to balance the system will become increasingly unpredictable. “The volume of gas system stock swing attributable to CCGT operation has the scope to grow considerably into the future,” it said.
The biggest swings are likely to occur “when wind generation increases rapidly at the end of the gas day, coinciding with the reduction in total generation demand after the daily peak”. These swings could pose a “growing risk” to the gas system although they are “unlikely to cause system operability challenges” by themselves.
The report was released to coincide with the launch of a consultation by National Grid today titled ‘The Future of Gas’.
National Grid UK executive director Nicola Shaw said: “We’re in an era of unprecedented change in the energy sector. With the emergence of new technologies like energy storage and heat pumps, we need to consider the role of gas and the gas networks in a low carbon energy future.
“We need to ensure that the existing gas networks and assets help to provide customers’ needs while keeping bills down. We will be inviting views on the future of gas, and I encourage people to join the debate.”
One of the innovations which National Grid is hoping will be able to help to provide added flexibility is gas demand-side response (DSR), which will see large gas consumers receive payments to reduce their demand during times of system stress. Gas DSR was successfully trialled by the company in the summer of 2015, and the Gas Demand Side Response service became available on 1 October.
In its Future Energy Scenarios report in July, National Grid said there is a question mark over the role of gas in the UK’s future energy system. It said uncertainty – both over the direction of government policy and how events will unfold – means there is a wide array of potential outcomes. It has now developed four future scenarios specifically for gas, building on its previous work.
National Grid’s future gas scenarios:
Source: National Grid, The Future of Gas