A Bayesian Network model to identify suitable areas for offshore wave energy farms, in the framework of ecosystem approach to marine spatial planning

Highlights

• Integrated model for suitable site identification for future wave energy farms.

• A spatially explicit model for the Spanish and Portuguese Economic Exclusive Zones.

• Technical, environmental and socioeconomic aspects have been considered.

• 17.7% of the area is suitable, accounting for 2.5 TWh∙m⁻¹ energy resource.

• Suitability maps can reduce uncertainties when authorising wave energy projects.

Abstract

The production of energy from waves is gaining attention. In its expansion strategy, technical, environmental and socioeconomic aspects should be taken into account to identify suitable areas for development of wave energy projects. In this research we provide a novel approach for suitable site identification for wave energy farms. To achieve this objective, we (i) developed a conceptual framework, considering technical, environmental and conflicts for space aspects that play a role on the development of those projects, and (ii) it was operationalized in a Bayesian Network, by building a spatially explicit model adopting the Spanish and Portuguese Economic Exclusive Zones as case study. The model results indicate that 1723 km² and 17,409 km² are highly suitable or suitable for the development of wave energy projects (i.e. low potential conflicts with other activities and low ecological risk). Suitable areas account for a total of 2.5 TWh∙m⁻¹ energy resource. These areas are placed between 82 and 111 m water depth, 18–30 km to the nearest port, 21–29 km to the nearest electrical substation onshore, with 143–170 MWh m⁻¹ mean annual energy resource and having 124–150 of good weather windows per year for construction and maintenance work. The approach proposed supports scientists, managers and industry, reducing uncertainties during the consenting process, by identifying the most relevant technical, environmental and socioeconomic factors when authorising wave energy projects. The model and the suitability maps produced can be used during site identification processes, informing Strategic Environmental Assessment and ecosystem approach to marine spatial planning.

Introduction

Renewable energy production growth and diversification are needed to mitigate climate change (Copping and Hemery, 2020) which has derived into a global ambition of achieving Affordable and Clean Energy (United Nation's Sustainable Development Goal 7) (United Nations, 2016), and marine renewable energy can contribute to achieve such objective. For example, the European Green Deal (European Commission, 2019) aims for the European Union (EU) to be climate-neutral by 2050, with a share of marine renewable energies of at least 32% of the EU's gross final consumption by 2030 (European Commission, 2020a). In addition, the marine renewable energy sector contributes to electric resilience as well as creating an opportunity to stimulate the economy (European Commission, 2021). According to Cochrane et al. (2021), by 2050, this sector has a potential range of total Gross Added Value benefit to the European economy from €59bn to €140bn.

Marine renewable energy includes the production of energy from offshore wind, tidal stream, ocean current, tidal range, wave, thermal, salinity gradients, and biomass sources (Borthwick, 2016; Dincer et al., 2018). Wind power is the most advanced technology, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future (IEA-OES, 2022; Inger et al., 2009). Most of the wave energy technological approaches, however, are at technology readiness level (TRL) 6–7, with a strong focus on R&I (European Commission, 2020c). Over the last years, a significant technology progress has been achieved thanks to the successful installation of demonstration and first-of-a-kind farms (European Commission, 2020c).

Main barriers preventing the development of wave energy converters (WECs) are: (i) the early stage of development of these technologies, (ii) the uncertainties regarding the coastal and marine impacts and the risks of wave farms (Copping et al., 2016; Copping et al., 2020b; Hanna et al., 2016), (iii) the need for a Marine (or Maritime) Spatial Planning (MSP) approach to overcome the potential competition and conflicts between wave energy sector and other marine users (O'Hagan, 2016), (iv) the fact that they have been considered uneconomical (Astariz and Iglesias, 2015), and (v) the consenting process, which is still generally regarded as a non-technological barrier caused by the complexity and the lack of dedicated legal frameworks (Apolonia et al., 2021; Simas et al., 2015). Such issues could be classified as being technological, environmental and socioeconomic barriers (apart from the administrative and authorisation aspects, which could be classified within the management aspect).

In addition, a prerequisite is that maritime activities included as Blue Economy sectors should be performed in a sustainable way (European Commission, 2021), being a precondition to be supported and promoted by authorities (e.g. EU Sustainable Finance Taxonomy) (Schütze and Stede, 2021). Sustainable activities¹ should make a substantial contribution to climate change mitigation or adaptation, while avoiding significant harm to the four other environmental objectives: (i) sustainable use and protection of water and marine resources, (ii) transition to a circular economy; (iii) pollution prevention control; and (iv) protection and restoration of biodiversity and ecosystems. Thus, the positive climate impact of marine renewable energy is recognised, as well as the potential for negative impacts on sensitive species and habitats (European Commission, 2020b). This calls for “win-win” solutions that deliver energy while reducing adverse impacts of human activities. Indeed, it calls for an ecosystem approach to sustainably manage human impacts on the environment (Kirkfeldt, 2019).

Environmental aspects are included as one of the main non-technological barriers for the development of wave energy sector. The limited number of experiences of operational WECs explains the fact that there are still many unknowns about the potential environmental pressures and impacts of wave farms (Copping et al., 2015; Galparsoro et al., 2021; Hutchison et al., 2021; Papathanasopoulou et al., 2015; Papathanasopoulou et al., 2014). The small number of studies so far, along with the significant variation in the design of WECs, makes it difficult to corroborate results or draw definitive conclusions about the impacts of WECs (Greaves et al., 2016; Satriawan et al., 2021; Thomson et al., 2019). Nevertheless, there is a need to anticipate the development of WEC farms by assessing the potential ecological risks, to minimise the impacts and to identify the ecosystem elements on which the focus should be (Copping et al., 2015). Moreover, marine renewable energy industries should not be considered in isolation because the significance of environmental impacts depends on the full spectra of human activities in each area (Hammar et al., 2017; Willsteed et al., 2017).

Another aspect to take into consideration is that the expansion of wave energy farms entails limitations for other uses which can create conflicts over marine space with fishing and shipping activities, among others (Alexander et al., 2013b; Kerr et al., 2014; McLachlan, 2009). The installation of WECs and offshore energy test facilities has already been questioned by local stakeholders, who have expressed their concerns, e.g., over the potential affection to waves and surfing activity (Stokes et al., 2014), on the visual impacts of the installations (Kerr et al., 2014) and associated socioeconomic consequences (Alexander et al., 2013a; McLachlan, 2009). Therefore, assessing potential conflicts and evaluating tradeoffs with existing uses (Bailey et al., 2011; McLachlan, 2009), as well as with local stakeholders (Kerr et al., 2014), is essential to guarantee the success and to maximise the economic benefit from wave energy (Kim et al., 2012).

The aforementioned considerations drive to the conclusion that the technical, environmental and socioeconomic aspects should be taken into account when identifying suitable areas for future development of marine renewable energy projects, which in turn requires the adoption of integrative management approaches. MSP provides a platform for holistic assessments and may facilitate the establishment of the marine renewable energy sector (Hammar et al., 2017). Several approaches have been proposed in the framework of MSP for the identification of suitable areas for the development of wave energy projects (Galparsoro et al., 2012). Basically, they are geo-spatial multi-criteria evaluation approaches to identify optimal locations to install a wave energy farm, while minimising potential ecological risks and conflicts with other coastal and offshore users (Azzellino et al., 2013; Bertram et al., 2020; Castro-Santos et al., 2019; Flocard et al., 2016; Galparsoro et al., 2012; Vasileiou et al., 2017). Such approaches aim to assist planners, decision-makers, industry stakeholders and investors when identifying feasible areas (Pınarbaşı et al., 2019), based on environmental (Guinda et al., 2018), technical (Guinda et al., 2018) and socioeconomic criteria (Rinaldi et al., 2016; See et al., 2012).

In this research we provide a novel approach for integrated and spatially explicit suitable site identification for future wave energy farms. Such objective required the (i) development of a conceptual framework, which could guarantee the consideration and interactions of the most relevant technical, economic, environmental and social aspects that play a role on the development of wave energy projects; and the (ii) operationalisation of the framework, by building a spatially explicit model; and finally, (iii) its implementation and testing.

Hence, the proposed objective of this approach is to support industry, scientists, and managers, in the potential future expansion of the wave energy sector. The model and the suitability maps produced can be used to inform Strategic Environmental Assessment and MSP processes, by identifying, in an early stage, the relevant environmental and socioeconomic factors that play a relevant role when authorising wave energy projects. This, in turn, can contribute to reduce uncertainties during the consenting process.