Ocean space multi-use is a significant blue economy trend. Being able to share space with other operations would help Floating Wind Farms offshore wind grow more quickly. However, the majority of technologies are not multi-use suitable. In the third piece of a series, we discuss how W2Power’s excellent multi-use capabilities provide possible economic and environmental advantages.
Key benefits of Enerocean’s W2Power floating wind solution and how it offers an alluring path to cost-effective offshore wind expansions were outlined in two earlier articles1, 2. All floating wind systems tested at sea are compared in a recent review paper3 for their current conditions. With our TRL 6 prototype, W2Power qualified in 2019, and Enerocean is currently constructing a full-size demonstrator in a port, which will signify TRL 7.
Two design factors for floating wind were emphasized by the review’s authors: stability and cost effectiveness. In this essay, we highlight the potential for economic upside provided by W2Power’s multi-use, emphasizing that it has accomplished its design objectives on both fundamental fronts.
We suggest adding the concept of multi-use to the list of design factors. Developers, investors, and all other stakeholders might benefit from this while the maritime habitat is protected. The importance of multi-use capabilities will increase as marine spatial planning (MSP) assumes a larger role. Thus, the ability to adapt to, or even assist, alternative uses of the marine space could start to stand out as a characteristic of successful technology. The multi-use applications for W2Power are summarized in Fig. 1, which was designed with multi-use in mind from the start.
Energy Versatility
A better capacity factor and fewer times of low production can result from the use of an additional renewable energy source when producing electricity. The cost-effectiveness of photovoltaics is what sparks interest in floating solar because solar resources at sea are unrelated to wind. According to design studies, the W2Power of today is capable of producing 350–375 kW of PV electricity.
Compared to standalone floating solar, the floater’s ability to support the PV panels, cabling, and electronics decreases capital cost (CapEx), while reduced seawater corrosion lowers operational expenditure (OpEx). The same cable, grid connection point, and substation can be used to export the PV electricity, or special PV inverters can be kept on board for use.
In the majority of deep waters, ocean swell, which has only a slight correlation with local winds, dominates wave resources. As a result, wave power generated by a hybrid wind/wave platform can be more valuable on the market. Utilizing wave energy has also been a primary area of research and development (R&D) using our unique wave energy converters, which was another initial design objective for W2Power4. The WEC arrays’ near-symmetric structure makes wave energy extraction essentially omnidirectional, and the platform’s size enables the required wave capture length.
According to engineering studies for various sites, W2Power may produce up to 3 MW from waves in addition to its existing industry-leading power rating of 20 MW from wind under the best wave circumstances. It would be the most potent wave energy generator ever created if it were realized. Due to the platform’s ability to support and maintain the WECs’ station, as well as control and export power, it would also be the most cost-effective wave energy technology (see Figure 2).
With W2Power, the benefits of multiple uses include power conditioning and export. An appealing idea is to install an on-board substation. Traditional offshore substations need specialized fixed support, which alternative semi-submersible or spar-based floaters lack in terms of both carrying capacity and space. Enerocean design studies on a compact, adaptable modular substation type that is now for sale5 indicate that it might be mounted on the bow column without significantly strengthening the floater. Notably, this would enable the W2Power/substation unit to produce wind energy continuously.
Beyond Energy Production, Multiple Uses
Multi-use can involve additional maritime operations in addition to providing electricity to strengthen the business case. These consist of seawater desalination and energy storage. Recent years have seen a rise in interest in the electrolysis-based creation of “green” hydrogen. The advantages of using any “Power-to-X” technologies offshore rely on the extra expenses and dangers associated with operating at sea. The difficulty of the problem increases with the complexity of the offshore process.
A compressed air-based energy storage method that is ideally suited for offshore use has been developed by Enerocean. The fact that our floater design can sustain very large commercial fish cages makes employing W2Power as a platform for offshore mariculture particularly appealing, according to our research.
Fish, shellfish, mollusks, and algae are grown for human consumption using mariculture. Eight times bigger than offshore wind, the worldwide aquaculture market (including freshwater) was $289.6 billion in 2022 and is expected to reach $420 billion by 2030.6 To increase production and lessen its negative effects on the environment, the sector is looking for innovative technology. Going offshore is one trend that allows for more production without adding to pollution.7 However, the lack of solutions that can resist the most extreme environments has been the gaping hole up to this point.
Enerocean has developed proprietary technology that significantly reduces the cost of securing very big fish cages to the floater. In R&D that was financed by the EU and in which Enerocean participated, numerous multi-use cases were methodically explored.In tank experiments, 8 W2Power carrying a fish cage was developed to TRL 4; more recently, open-sea studies brought it to TRL 6 (Fig. 3). This is the first instance in which a floating wind platform has successfully tested a fish cage that is fully operational at sea.
The internal cage mooring (ICM) and cage insertion and removal (CIR) unique technologies for regulating the fish cage were supported by sea tests of the underlying physics and technical principles. Due to IP protection, these are not depicted in Fig. 3. Long stretches of time spent in waves with equivalent loads much above the design parameters of any free-floating fish cage were included in the six weeks at sea. Modern mooring line load monitoring cells on the ICM produced loads that were well within the design envelope of the system.
Any effects of the fish cage on the stability of the floater are probably minimal at full scale. These findings demonstrate that the W2Power platform offers the fish cage outstanding stability and support. By relocating to offshore seas, mariculture businesses can significantly cut down on expenses and dangers.
Cost-Benefit Analysis for Many Uses
A “synergy equation” was used to reflect the increased costs of integrated vs separate installations at sea in a methodology for evaluating multi-use floating wind systems.9 Based on improved versions of this, detailed business cases for a previous W2Power (12 MW) design with a commercial extremely large fish cage were designed and thoroughly examined.
Conservative adjustments were made to the stacking density, fish growing cycles, and growth rates from industry sources. Results for one significant commercial species and one newly discovered species show that gross earnings from the sale of fish may be equal to or even higher than those from the sale of power, while the additional capital expenditures to fit the fish cage on W2Power were within the error range of 5–10%.
Meeting the demands of investors in the power and aquaculture sectors, as well as balancing the safe operation of fish farms with offshore wind’s “not-normally-manned” character, are two clear problems for the future. These, however, are probably resolved because of the economic gain.
Summary
In conclusion, this article demonstrates how W2Power’s exceptional cost efficiency may be made even more competitive by realizing appealing multi-use, and it also provides additional insight into how using a scaled prototype at sea can be helpful as a platform for real-world innovation.