Offshore wind energy has now emerged as one of the leading technologies for decarbonising the energy supply network. While wind turbines in shallow water with seabed-mounted technologies have become a mainstream technology in northern Europe, floating wind technologies targeting deep waters such as the Mediterranean are now making great strides, with multiple pilot floating farms being deployed, as for example Hywind Scotland and WindFloat Atlantic. Floating offshore solar photovoltaic technology is less mature, but is expected to advance in the years to come given the recent investment in research and development. Yet, despite the technological advances, both wind and solar energy remain intermittent resources of energy.
The University of Malta is currently undertaking a project to study the use of subsea pipelines to store energy generated from wind and solar farms offshore. The project, dubbed SAICOPES, is being funded by the Malta Council for Science and Technology, and aims to address the emerging need to invest in long duration energy storage infrastructure to be able to interconnect renewables on a large scale. The mismatch between the renewable energy supply and the actual consumer demand over lengthy periods implies that the storage technologies should be able to store energy for many hours, typically between 8 and 24 hours. Relying solely on Li-Ion batteries, currently extensively used in mobiles, laptops and electric vehicles, is unsustainable due to the short lifetime and use of crucial materials such as cobalt. Adding mechanical-based storage technologies, such as compressed air energy storage, to the technology mix will be essential for a smooth transition towards meeting the ambitions of the EU Green Deal.
Subsea pipelines are well known for transporting oil, natural gas and water across large distances, interconnecting many countries in Europe and beyond. The SAICOPES project is evaluating how countries such as Malta can leverage established offshore pipeline technology to be able to store energy in the form of compressed air. Excess energy from offshore wind or solar farms can be used to power subsea hydro-pneumatic compressors that would pressurise a network of subsea pipelines using a combination of air and water to store energy. During periods of high consumer demand, the stored compressed air is released to drive expanders and generate electricity. Researchers Charise Cutajar and Luke Aquilina from the University’s Department of Mechanical Engineering are developing comprehensive computer models to simulate the operation and efficiency of such systems.
Professor Tonio Sant who is coordinating the project commented on the important benefits of exploiting subsea pipelines for compressed air energy storage: “Apart from having a long lifetime of at least 30 years, which is at least threefold more than that of batteries, the compressed air pipelines are located offshore. This avoids the need for additional land requirements to accommodate energy storage infrastructure. Furthermore, the same pipelines can be used to interconnect different countries, say Malta and Sicily, to enhance security in the supply of renewable energy. The benefits for a densely populated island like Malta, located in the periphery of Europe, cannot be underestimated.â€
Project SAICOPES is being financed by the Malta Council for Science and Technology through the FUSION Research Excellence Programme (Project reference: REP-2023-004).
Dr Daniel Buhagiar, CEO of FLASC BV that is supporting the University team on industrialisation aspects of subsea compressed air technologies, highlighted the keen interest of oil and gas players in the offshore energy sector in such niche opportunities for diversifying present activities and contributing to the green transition.
Project SAICOPES is being financed by the Malta Council for Science and Technology through the FUSION Research Excellence Programme (Project reference: REP-2023-004).
