FEATURE | Equinor leads development of battery-powered platform supply vessel
A partnership led by Norwegian energy company Equinor has commenced development of a platform supply vessel (PSV) powered by batteries to ensure emission-free operations, particularly in the North Sea.
Under the Plug-In Electric Zero-Emission Offshore-Ship (PIEZO) project, Norwegian shipbuilder Vard has developed a concept design for a PSV that will use batteries as the primary energy source and that will be capable of offshore charging. Other partners on the project include Norwegian private research organisation SINTEF, the Research Council of Norway, battery manufacturer Corvus Energy, and vessel operator Solstad Offshore.
The goal is to introduce an 82-metre-long PSV that will operate almost entirely on batteries while transporting cargo to offshore production facilities off the coast of Norway. Compared to existing conventionally-powered PSVs, the battery-powered PSV will generate 80 per cent fewer CO2 emissions each year thanks to a 16MWh energy storage system. Analyses of various battery capacities led to the selection of the 16MWh option as the one providing the optimal level of fuel savings.
The project partners expect the first vessel to be in operation in less than three years if everything goes according to plan. For Equinor, another expectation is to have vessels developed through the PIEZO concept to form a quarter of all Norwegian-operated PSVs, thus yielding total CO2 emissions reductions of around 300,000 tonnes annually.
Projections aided by simulated operational conditions
PIEZO also encompassed the development of precise digital simulations of energy systems, which then led to the creation of a digital simulation twin that behaves identically to an existing PSV in the Solstad fleet. The simulation is verified by operational data collected over two years, and the subsequent analysis and studies helped identify optimal battery power requirements and other capabilities that the new PSV needed to possess. Henrik Burvang, Research and Innovation manager at Vard Design, said such simulations allowed Vard to get a full overview of the energy flow in the vessel even before construction begins.
Corvus Energy, via Corvus Norway, supported the project with models to ensure accurate simulation models for the dimensioning of battery packs, life cycle analysis, and battery arrangements.
A 3D parametric hull form model was created along with allotted spaces for batteries and cargo tanks. CFD analyses were also conducted to determine the level of resistance. A system simulation then collected details on the hull form model and a typical mission profile that included transits, dynamic positioning, and cargo operations over a projected year, also taking into account other variables such as simulated weather and sea conditions in the Troll gas field off the western Norwegian coast.
The partners studied more than 364 simulated voyages that used 50 different configurations of the vessel design as well as various speed settings and projected hotel loads.
Hull optimisation and other key aspects
The propulsion is not the only aspect that will benefit from significant improvement under the PIEZO project. Thomas Olsvik, Vard Design Vice President for Conceptual Design, said development also involved optimising the hull form to reduce resistance, as one of the objectives was to reduce energy consumption regardless of the fuel to be used.
As hull optimisation was an important part of the project, Vard developed a tool that makes it possible for the hull design to be optimised for the operation the customer will perform. Thomas Brathaug, Principal Naval Architect Conceptual Design at Vard Design, said the tool allows the design team and customers to immediately identify how the choices they make will affect the vessel’s energy consumption.
Olsvik added that other factors are considered besides hull optimisation in order to reduce energy consumption. These include but are not limited to interior design and other support systems.