Peak supply
In order to guarantee the supply of gas to household consumers during cold periods, GTS is responsible for peak supply by virtue of the ‘Security of Supply of Gas Decree’ (‘Besluitleveringszekerheid gas’). This means that, on any given day with an average effective daily period temperature in De Bilt (NL) of lower than -9°C, GTS will deliver gas to the suppliers of household consumers, insofar as the delivered quantity of gas exceeds the maximum quantity of gas that would have been delivered on a day with an average effective daily period temperature of -9°C. The suppliers of household consumers do not have to buy this gas from their regular supplier. GTS charges the suppliers of the household consumers for the costs of the peak supply.
The full text of the regulation (only available in Dutch) is attached for your information. regulation 
