ELECTRIC MOTHERSHIP CONCEPT CHANGES SERVICE MODEL

Power-as a service is integral to an innovative offshore wind farm service model seeks to integrate a battery-electric mothership with pure electric crew transfer vessels with offshore electric charging

A coalition of UK based technology developers, naval architects and autonomy experts have joined forces with a Shift to develop a battery-hybrid offshore charging vessel concept. The vessel, which could be based on a converted offshore service vessel, is designed to act as mothership for up to six crew transfer vessels servicing offshore wind fields in the North Sea or elsewhere in the UK’s waters.

None of the technological elements included in the proposal, ranging from the use of offshore charging through to battery swapping, is innovative. However, the elements have not been combined with the digitalisation aspects of the proposals before, as far as Dr Peter Collinson of autonomous vessel consultancy Dendrityca knew, told The Motorship in an exclusive interview.

The project specifies 15m-long Swath crew transfer vessels. The CTV design is particularly well suited to operating in the North Sea, as its hull form is naturally heave damped, with low motions eliminating the need for gangways.

The concept is expected to connect with a battery recharging and recycling hub established at the port, and would rely on the battery-electric service vessels replacing discharged batteries with fresh batteries (using a swappable battery basis). The onshore hub would also feature a battery container charging point. “The advantage of this approach is that the offshore wind farm will be serviced by vessels potentially operating on energy generated at the windfarm, without requiring it to be converted to hydrogen or hydrogen vectors, such as ammonia”.

The design also anticipates that the larger mothership vessel will operate on electricity drawn from a designated charging point installed offshore at the wind farm.

One of the interesting aspects of the proposal was that the battery integrator in the project, Shift, proposed to offer swappable batteries for the CTVs based on a Power-as-aService (PaaS) model. As part of the this model, Shift would supply, operate and own the energy storage systems (ESS), the charging infrastructure and the service vessels using PwrSwap.

The ESS themselves would be fitted on a modular basis and provided on a subscription basis, allowing them to be easily replaced if necessary. The swappable battery system will include Shift’s liquid-cooled IP67/A60 battery cells.

The PaaS system would be supported by a digitalisation tool monitoring the operational performance of the Shift system. While the system will also help to optimise the delivery of speeds, loads and navigation routes, it will also be integral to the pay-as-you-go model.

Offshore Wind Markets

Just as one contract for fleet auxiliaries does not signify a renaissance in UK shipbuilding, there is no reason that the UK should maintain its current position as a leading developer of offshore wind power assets. Both the US and the European Union have made expanding their offshore wind generation capacity by 2035 part of their decarbonisation packets.

While the expansion of market opportunities for wind turbine installation vessels is already translating into a surge of new orders for WTIVs, the market opportunities for servicing the fixed bottom generation assets is less clear.

A related issue is connected to the servicing requirements, as licences for newer and larger fields are continuing to be awarded. “This will inevitably lead to increased demand for CTVs to service offshore wind assets in deeper waters, without beginning to take into account the expansion of offshore infrastructure this transition will generate,” Dr Peter

Other countries have applied specific regulations to their offshore assets in order to achieve specific decarbonisation outcomes. referring to Norway’s regulations to encourage the electrification of offshore oil and gas rigs in Norwegian waters, as well as proposals to force OSVs and CTVs operating in Norwegian waters to operate on alternative fuels by the second half of the 2020s

Collinson of autonomous vessel consultancy Dendrityca told The Motorship in an exclusive interview.

A separate and related development relates to the expected introduction of floating offshore wind generation capacity. This is attracting interest in East Asia, particularly where shallow coastal waters availability is limited, and might eventually open up new offshore areas for exploitation.

Commercial model

In common with other offshore assets, such as oil and gas, the initial focus of wind operators during the recent period has been on installing assets and ensuring availability rather than focusing on cost-optimisation during the performance of servicing contracts.

Collinson noted that the Zephyrus model was likely to offer significant cost savings for maintenance over the 25-year or so operational life of the assets.

“We estimate that the Zephyrus model will be up to 50 percent cheaper than a contract serviced with conventionally powered vessels,” Collinson said, adding that the majority of the savings were the result of lower fuel and opex expenditure on the vessels.

“We haven’t taken into account the additional cost savings that the Zephyrus model will produce if future regulatory changes alter the cost of conventional fuels,” he added, noting that the expected introduction of the Emissions Trading System in the EU and a future potential carbon levy could change the economics of such a model.

“Other countries have applied specific regulations to their offshore assets in order to achieve specific decarbonisation outcomes,” Collinson said, referring to Norway’s regulations to encourage the electrification of offshore oil and gas rigs in Norwegian waters, as well as proposals to force OSVs and CTVs operating in Norwegian waters to operate on alternative fuels by the second half of the 2020s.

It remains uncertain whether the UK will choose to introduce requirements for vessels servicing offshore wind farms to be zero emission or low emission.

Collinson concluded by noting that there was an opportunity to develop a wider UK supply chain, with a number of the project participants, such as AMC Ltd and MJR Power & Automation and Ad Hoc Ltd. based in the country.

8 The proposal envisages developing a swappable battery hub to supply energy to the CTVs based on a Poweras-a-Service (PaaS) model. Such hubs are expected to offer opportunities for battery recycling as a future step

8 The Zephyrus project includes UK-designed full-electric CTVs