Tubular design for underwater compressed air energy storage

Underwater compressed air energy storage (UWCAES) in deep seas is a promising scenario for energy storage. When considered at large scales, specific difficulties arise beyond the ones present when dealing with individual energy bags. After reviewing the set of requirements that a realistic large size project should meet, we propose what we think is the optimal design, the tubular bag. A particular case study is computed numerically aiming at a 1 GWh storage at 1000 m depth. Depending on the material used, lengths lie in the range of 1-15 km. Whereas scaling up is very natural, ballasting poses a challenge and some alternative is proposed. (C) 2016 Published by Elsevier Ltd.