Traders are concerned that German gas storage is not sufficiently refilled during summer months ready for the following winter as price discrepancies between the seasons act as a disincentive.

Typically, gas is stored during summer when demand and prices are lower to be sold later in winter when demand and prices are higher. THE is proposing a subsidy if the spread is not attractive enough for this to happen on a market price basis.

"THE has been working on a new product ... in consultation with the German economy ministry and the Bundesnetzagentur regulator which is designed as a pure filling product," said the hub on a slide posted on its website on Tuesday.

On another slide, THE said the idea was for incentives via subsidising new storage facilities. It said the supplier could receive a subsidy if new storage was injected on a day when the reference spread was lower than the offer price.

Germany's gas storage sites are currently 62.77% full, data from Gas Infrastructure Europe shows.

The head of German utility Uniper said on Wednesday incentives could be needed to ensure the storage sites are refilled.

Boosting underground storage was one of Germany's main responses to being mostly cut off from Russian pipeline gas since the war in Ukraine began in 2022. Its facilities can hold 23 billion cubic metres, equivalent to over a quarter of annual national consumption last year.

German storage operators' group INES said earlier this month storage facilities could be fully refilled for the 2025/26 season under any scenario but called for an increase in financial incentives to encourage firms to book storage.