Despite being run by a private company, the project was put in motion by the government, as a way to cover 30 to 40 percent of Spain’s daily demand of natural gas for a period of up to 50 days. The objective is to cover peaks of consumption or interruptions to supply.

In theory, when the gas system required it, these facilities would be able to return gas from the storage in the same conditions as it was received through the same submarine gas pipeline.

The storage facilities used an old oil well, emptied from 1970s (in Amposta). The gas is injected 1750 m depth under the sea.

But the Castor project seems to have triggered worrying sysmic activity in the area. More than 300 earthquakes off the northern coast of Castellón have been recorded in few days of the late September 2013. The earthquakes have all been less than 4.2 degrees on the Richter scale, but have aroused concern in the population of the area (in Alcanar, Benicarló, Las Casas de Alcanar, Cervera del Maestre, Cálig, Peñíscola, San Carlos de la Rápita y Vinaroz).

Since February 2010, the Plataforma en Defensa de les Terres del Sénia denounced before the EC the Castor project because no Environmental Impact Assessment had been made to assess the environmental implications of the project.

Concerned has also raised due to 2 nuclear power stations located not very far from the earthquake epicentre.

The gas injection was halted from September 16th 2013 and the government is waiting before continuing with the gas injection.

Castor’s forecast delivery rated of 25 million cubic metres (883 million cubic feet) per day. It was thought it would contribute strategic storage and reliability of supply to industrial and domestic customers, and would compensate for a potential future supply shortfall equal to the capacity of the Maghreb pipeline or one regasification plant for over 50 days. Castor’s anticipated working gas storage capacity of 1.3 billion cubic metres (45.9 billion cubic feet) would provide a sizeable reserve for seasonal and peak demands.