Consultancy firm EnAppSys says that a harsh winter would make it ‘very expensive’ to balance the market due to tight supply margins, according to its latest analysis.

The research has forecast that over the season there will be around 12 and a half hours of negative supply margins, with seven of which are predicted to fall during the National Grid’s winter period, while the other five and a half hours are expected to fall in October and March – the ‘shoulder’ months.

The firm also predicted that there will be 85 hours of supply margins less than 2GW, over half of which will come during the shoulder months.

This data is in stark contrast to their calculation of last year which predicted a margin above 2GW throughout the whole of the 2015/16 winter, barring just two hours when it averaged 1,500MW.

The research data was gathered by taking the availability figures of last year and modifying them to account for the opening and closing of plants in 2016, and then matching them against the demand profile of 2015.

Ferrybridge and Longannet are among the plants lost in the last year, both of which closed down in March, while Eggborough has also exited the market but still has a ‘supplemental balance reserve (SBR) contract.

Meanwhile, Engie has also confirmed that the Rugeley plant will be shut down later in the month.

On the other side of the coin, two new plants have opened. The Keadby CCGT plant reopened in November last year after being ‘mothballed’ for some time.

The Carrington Combined Cycle Gas Turbine (CCGT) plant will also open over the summer and is currently being commissioned.

EnAppSys says that the negative supply margins will not result in blackouts as they do not factor in the potential 2GW of smaller plants that may be available through the Short Term Operating Reserve.