Cyriel de Jong has completely rewritten his chapter on gas storage pricing and hedging, which provides an excellent description of the best-practice trading and valuation strategies for gas storage.
Journal of Natural Gas Science and Engineering: Gas storage review article
Various approaches have been suggested for the valuation of gas storage. Of those approaches, the most general ones are based on Monte Carlo price simulations. These approaches allow the evaluation of different market trading strategies and different assumptions about the underlying price process.