Malta is surrounded by substantial territorial waters with immense resources to harness offshore renewable energy, primarily solar and wind energy.
The deployment of wind turbines and photovoltaic panels in local waters is however challenged by the complex bathymetry and deep seas that characterize the Mediterranean region. Furthermore, Maltese waters, including coastal areas, are also unsheltered and exposed to the rough waves that batter the shorelines in storms, such as the Gregale. This makes the deployment of renewables such as floating solar photovoltaics risky. Such challenges also constrain the expansion of other maritime sector activities such as Malta鈥檚 aquaculture sector and yacht marinas.
Co-locating different economic activities within the same marine space is essential for the sustainable growth of a blue economy. Co-location enables more efficient use of marine space and cost reduction opportunities through shared infrastructure, as for example in the case of anchors and electrical connections to the onshore electricity distribution network.
A team of researchers from the University of Malta and its spin-off company FLASC B.V. have been evaluating the feasibility of deploying offshore floating breakwaters in deep waters on a scale that can provide sufficient storage to address the intermittency from offshore wind and solar farms, while providing a sheltered area large enough to accommodate a floating solar farm with a capacity of at least 80 Megawatts, multiple aquaculture cages and yacht berthing facilities.
The research project, FORTRESS (A Floating OffshoRe BreakwaTer for Supporting Marine Renewable Energy around ISlandS), is funded by The Energy and Water Agency. It is developing a novel and modular hybrid floating breakwater concept that integrates hydro-pneumatic energy storage using compressed air in a subsea environment, offering a more environmentally sustainable and safer alternative to lithium-ion battery storage.
In the proposed design, the cylindrical pressure vessels used for storing compressed air are assembled onto the floating breakwater in a way to boost wave attenuation. The proof of concept has been successfully demonstrated through extensive numerical hydrodynamic simulations using industry-standard maritime engineering software. Wave tank testing on scaled models has also been performed to validate the computer model outcomes.
A techno-economic feasibility study assessed the viability for deploying multiple floating breakwater modules to create a large sheltered water area in Malta for a multi-use marine park in a sea depth of 200 metres. While the hybrid breakwater technology being developed is technically effective in providing shelter to maritime structures in rough weather, the multiple revenue streams from providing energy storage services and renting out the sheltered marine space to operators of floating solar plants, aquaculture cages and yacht berthing facilities were still found to be insufficient to justify the investment in the technology.
This is primarily due to the high costs of the catenary mooring system required to support the breakwaters at the large sea depths. The study revealed the importance of subsidies to render investment in deep offshore breakwaters feasible. These subsidies are well justified considering other positive socio-economic impacts brought about through the investments in the long term.
For example, the deployment of breakwaters helps to mitigate coastal erosion, increase luxury yacht arrivals and improves safety of beaches for the tourism sector. These spill over benefits should not be underestimated, taking also into account that the maritime and tourism sectors alone respectively account for 13% and 30% of Malta鈥檚 GDP.
Further information about the FORTRESS project can be made available by contacting by email.
Project FORTRESS is financed by the Energy and Water Agency under the National Strategy for Research and Innovation in Energy and Water (2021-2030).
