Figure 1: Visual representation of the offshore wind energy, FLASC energy storage and Hydrogen production concept.
Project team members: Oleksii Pirotti, Diane Scicluna, Robert N. Farrugia, Tonio Sant, Daniel Buhagiar and Jessica Settino
The current trend in the EU is to reduce the emissions of Carbon Dioxide into the atmosphere and develop a decarbonised economy. One of the more sustainable ways towards reaching this objective is by investing into renewable energy (RE) technologies. Given that Malta is strategically located in the middle of the Mediterranean Sea, the potential for using wind energy should not be overlooked. The offshore wind industry has been attracting a lot of attention due to the increasing prices of fossil fuels and the need for greater security in energy supply chains. But why look towards the offshore environment?
Due to the small size of the Maltese Islands and the high population density, there is limited space to install renewable energy technologies onshore. Moreover, open marine spaces offer higher wind speeds with better opportunities for power generation. Current and upcoming offshore wind projects are focusing on areas having significant wind resources and shallow sea depths, such as those found in the North Sea. Although wind resources in the Mediterranean region are lower than in the North Sea, a potential for wind generation still exists. Currently, there is only one offshore wind farm in the Mediterranean and this is located near the port of Taranto in Italy.
Early local interest in offshore wind energy in Malta came at a time when the technology consisted of seabed- mounted wind turbine foundations which were limited to sea depths of up to 30 metres. Such limits implied the nearshore sites were the only option for offshore wind farm projects. Given the deep nearshore waters surrounding the Maltese Islands, traditional bottom-fixed offshore wind technology would become very costly to implement. Since then, offshore wind turbine technology has developed floating wind turbine solutions, making it more feasible for countries having deep nearshore waters. Floating offshore foundations make it possible to exploit the wind resources available at deep offshore sites, further away from the coast. By introducing floating offshore wind turbines locally, harnessing renewable wind energy could become much more viable. Not only would this allow the introduction of a new source of renewable energy diversifying the island’s energy supply, but it would also help Malta forge ahead in reaching its renewable energy goals.
Recently, the Maltese Government published a Preliminary Market Consultation for the proposal of economic activities within Malta’s offshore Exclusive Economic Zone. This offers opportunities for diverse activities including, but not limited to the production of renewable energy from offshore resources and the production and storage of Hydrogen.
Although wind energy generation comes with significant benefits, its intermittency makes it a challenging resource to work with and to predict. Supply and demand mismatches could mean that wind generated electricity might need to be curtailed, or wasted, if the supply exceeds the demand. Likewise, any deficits due to low or no wind would have to be compensated by other means. This is where energy storage comes in. Storage is important for both on and off the grid applications which rely on a RE source for supplying electrical power. Various different storage technologies exist such as pumped hydro storage, chemical energy storage, thermal energy storage and compressed air energy storage, amongst others.
Following the decarbonisation trend is Hydrogen generation (H2), which in now seen as an important medium for long duration storage. There are already viable options to use Hydrogen, such as for road transport and aviation, for short-range and heavy-goods vehicles. Hydrogen can be produced by various means and the mode of production is usually assigned a defining colour. For example, Hydrogen produced using fossil fuels has a by-product of Carbon dioxide and is consequently dubbed “Grey” Hydrogen. “Blue” Hydrogen is also produced using fossil fuels but in this case, the Carbon Dioxide emitted is captured and stored.
“Green” Hydrogen is produced using renewable energy sources and the resulting emission is only oxygen. Green Hydrogen production would evidently be the most attractive for decarbonising our economies. Generating Hydrogen from wind power requires a number of different processes starting from reverse osmosis for seawater desalination and purification for feeding the electrolyser process. The electrolyser is used to produce Hydrogen and emits only Oxygen as a waste product. When considering the electrolysis technologies that exist today, two types of electrolysers have reached a mature commercial level - Alkaline and Polymer Electrolyte Membrane electrolysers. After electrolysis, a compressor is used to compress the Hydrogen, which would otherwise occupy a large space if left at atmospheric pressure. Compression allows the Hydrogen to be stored for onsite use or transportation to end users. The Hydrogen produced can be used in a number of different industries including the steel, chemical and transport industries. In 2021, the demand for Hydrogen reached 84.1 million tons, and this is set to increase in the future.
Offshore Hydrogen production has been at the forefront of the green Hydrogen production industry. Combining Hydrogen generation with offshore wind generation comes with a number of benefits, such as using the better wind resources offshore and having an endless supply of water; which is the raw material used for Hydrogen production after all. Moreover, additional benefits also include co-location, ease of supply to end-users, such as those in the maritime sector, and thus decreased costs. Instead of transmitting electrical energy through cables, Hydrogen can be transported through pipelines with significantly less losses and simpler technologies. Furthermore, the demand for Hydrogen is constantly increasing and the other current Hydrogen production techniques are not environmentally friendly.
“Hydro-pneumatic Energy Storage for Offshore Green Hydrogen Generation (HydroGenEration)” is an ongoing two-year Research and Innovation in Energy and Water project funded by The Energy and Water Agency which is seeking to investigate various technical aspects to enable the coupling of offshore wind generation and a co-located Hydrogen production plant. It is seeking to build on the experiences of an earlier project "Wind- driven offshore hydrogen production with electricity and flow stabilisation (WIND4H2)” supported through the Maritime Seed Award (MarSA) 2019 funded by Transport Malta (formerly Malta Marittima) and administered by TAKEOFF at the Knowledge Transfer Office, University of Malta. Now, in the current HydroGenEration project, the plan is to move beyond traditional systems by introducing an offshore energy storage system in conjunction with offshore wind generation and Hydrogen production processes in a Mediterranean marine context. Target future end-users could be maritime sector players such as seagoing vessels, leisure craft and other hydrogen-reliant marine transport systems.
Energy storage systems are used to capture the energy generated by the wind turbines and use it when needed to help decrease the imbalance between Hydrogen electrolyser energy demand and RE production. By using such a storage principle, the intermittent characteristics of the wind resource can be resolved. There are a number of storage technologies already present and being developed in the market. The stored electricity will help to improve the controllability of the electricity system and ensure its reliability and flexibility by smoothing out peak hours of consumption and reducing price spikes for end users. In the HydroGenEration project, the Floating Liquid-piston Accumulator using Seawater under Compression (FLASC) energy storage device is the concept of choice. FLASC was developed at the University of Malta and an important advantage is that it can be applied in an offshore environment regardless of the depth of the sea, making it an ideal option for interfacing with an offshore wind power plant and for implementation in the Mediterranean Sea. Furthermore, hazards associated with energy storage systems such as batteries are avoided. A visual representation of the project concept is shown in Figure 1.
Integration of the FLASC energy storage system into the offshore wind and hydrogen production system makes it possible to smoothen the variable wind power supplied to the Hydrogen plant thus improving operational hours for the Hydrogen-producing equipment. Power smoothening by means of integrated storage is shown in Figure 2.
Figure 2: Variable power output from a 6-Megawatt wind turbine (in Blue) in comparison with a smoothened wind power output with an integrated FLASC energy storage device (in RED).
Research is underway investigating the behaviour of the FLASC energy storage system and its contributions towards the decarbonisation of an offshore green Hydrogen production process. The HydroGenEration project team is conducting a review of current and emerging technologies’ status, looking at local prospective sites in terms of utilisation, constraints and opportunities, identifying stakeholders and conducting numerical modelling on the interactions between the different components and processes as a means of producing green hydrogen in an offshore environment for the further decarbonisation of our environment.
HydroGenEration is an ongoing two-year research project of the University of Malta and its spin out company FLASC B.V., which is based in the Netherlands. Project “Hydro-pneumatic Energy Storage for Offshore Green Hydrogen Generation – HydroGenEration” (Ref.: EWA 64/22) is financed by The Energy and Water Agency under the National Strategy for Research and Innovation in Energy and Water (2021-2030).
This project is utilising coastal wind data collected using a Light Detection and Ranging (LiDAR) system that was purchased through European Regional Development Fund for the setting up of a Solar Laboratory (ERDF 335), part-financed by the European Union.
For further information about project HydroGenEration, please contact Dr Ing. Robert N. Farrugia, via email.
Project: Hydro-pneumatic Energy Storage for Offshore Green
Hydrogen Generation – HydroGenEration - Ref.: EWA 64/22 is financed by the Energy and Water
Agency under the National Strategy for Research and Innovation in Energy and Water
(2021-2030).
