We incorporated REN Armazenagem on September 26, 2006 using assets acquired from the Galp Group, which include the gas stations, the lock stations and three underground storage caverns with a (estimated) capacity of 47, 53 and 52 million m3 respectively. Two of the gas storage caverns of which are operating and one which is under construction with an expected completion in the second quarter of 2008. Subject to Ministry authorization, we have the right to build and acquire additional natural gas caverns for the expansion of the system. REN Armazenagem holds these assets and rights. Our underground storage concession awarded as public services includes:

• The underground storage in the gas caverns and the extraction, treatment and delivery of natural gas to the national gas transmission network.
• The construction, operation, maintenance and expansion of the facilities and infrastructure related to the storage of natural gas.

Currently, the two operational gas caverns have a combined storage capacity of 1,185 TWhrs.

The control station has two alternative natural gas engine-driven compressors with an injection capacity of 110,000 cubic meters per hour and gas dehydration facilities for extraction with a capacity of 300,000 cubic meters per hour. It also serves two other gas caverns at the site that are not owned by REN Armazenagem.

The gas caverns are constructed by leaching salt out of naturally occurring salt caverns at more than 1,000 metres deep. Fresh or salt water is pumped through a cavern and absorbs the salt, leaving a gas pocket where the salt is dissolved. The cavern undergoes a leakage test after the leaching phase and an inner pipe string is lowered into the cavern to remove as much brine as possible. Finally, a subsurface safety valve is installed at a depth of approximately 50 meters in order to prevent unintentional gas flow out of the cavern.