Question 3.3.6

Reporting negative values for available capacity due to overbooking.

(available capacity = (technical capacity) – (contracted capacity).

Should available capacity, in case of overbookings, be reported with a negative value, or should overbooked capacities not be taken into account?

The contracted capacity, which is reported within fundamental data reporting, is the sum of the sold firm and interruptible capacities. But to calculate the available capacity, we expect that the contracted capacity (used in the calculation) is purely the firm capacity, since the available capacity shows “only” the firm available capacities that will definitely be available to the market. It makes no sense from our perspective to publish available interruptible capacity because this may change very often with regard to the usage of the storage facility and because it depends on the decisions taken by SSOs and their willingness to risk interruption.

In that case, a negative value of the available capacities could only appear if the firm capacities are oversold. Please confirm.

Answer: In the Agency’s view the stakeholder is describing two possible options:

Option 1 - Available interruptible capacity is NOT offered by the SSO to the market in which case the following calculation applies: Contracted capacity = sold firm + sold interruptible capacity Available capacity = technical capacity – contracted (only sold firm) capacity In this case the available capacity cannot be negative. It can be ≥ 0.

Option 2 - Available interruptible capacity is offered by the SSO to the market in which case the following calculation applies:: Contracted capacity = sold firm + sold interruptible capacity Available capacity = technical capacity – contracted (sold firm + sold interruptible) capacity. In this case the available capacity can be negative. It can be ≤ 0.