Subsea Liquid Energy Storage – The Bridge Between Oil and Energy/Hydrogen

Abstract This paper demonstrates a pioneering technology adaption for using a membrane-based subsea storage solution for oil/condensate, modified into storing clean energy storage in the form of ammonia (as a hydrogen energy carrier). The immediate application will provide an economical alternative to electrification of offshore platforms, instead of using expensive cables from shore. Storing ammonia at the seabed using innovative subsea storage technologies will dramatically reduce CO2 emissions for offshore assets. The fluid will be stored in a safe manner on the seafloor, protecting both personnel and marine life. The next step will be to include subsea ammonia storage as part of the global logistical value chain, which can power the merchant shipping fleet. Clean ammonia can be produced using renewable resources as wind or solar. It focuses on bridging the ongoing oil/condensate storage qualification, adapted into storing ammonia. The large-scale verification test scope is explained, and we show how the test is extended to also prove the concept of safe energy/ammonia storage. The ammonia storage concept is explained, and we show how this can be included as part of a low carbon future. The focus is the immediate market for providing clean power to existing or new offshore assets. The full system solution will encompass storage tanks placed nearby the platforms at safe water depths, riser systems providing fuel to the ammonia power generators, and the tank filling systems. Bridging and adapting technologies from the petroleum industry into renewables shows the importance of utilizing the technology developments and competence of the oil and gas business. The technical evaluations have shown that the oil/condensate storage can be adapted into storing energy/ammonia with minor modifications. Converting hydrogen into ammonia gives slight energy losses, but it is defended by the large economic benefits of storing ammonia versus pressure storage of hydrogen. The paper presents qualification work already completed and how to implement ammonia fuel storage for platforms. In addition, we show the test setup for a large-scale qualification provided by an original equipment manufacturer (OEM) company together with major Operators. Innovative modular design methods have shown that the concept can be included on existing offshore assets, which have limited topside space available. Adding green or blue ammonia as an alternative to power cables from shore have several benefits, and many of the connecting building blocks are falling into place. The main conclusion is how to adapt Novel technologies from the oil industry to store ammonia in a safe way on the seafloor.