Search

There is a need for increased renewable energy to meet net-zero targets and decarbonise the economy. Harnessing the predictable power of the tides with tidal stream turbines can contribute to this. Tidal energy is a nascent technology with higher costs at present. However, cost reductions have been observed with an increased deployment in other renewable energy technologies that have received financial support, and it is postulated that similar will happen with tidal energy. The first tidal stream projects have been awarded market support in the UK through the Contracts for Difference (CfD) scheme, with almost 100 MW expected to be commissioned by 2028. This work uses learning rates to investigate how much investment in ongoing market support might be needed to achieve cost reductions through subsidised deployment alongside research and innovation. Using a range of informed 'what if?' scenarios, it shows sensitivity to key inputs. The results show that the support needed is most sensitive to the learning rate, reducing it from 15% to 12.5% or 10% doubles or more than quadruples the investment required, respectively. The support is also highly dependent on the starting cost from which learning occurs, taken as the CfD Strike Price in 2025. Varying this between 156 and 220 GBP/MWh results in total investment of GBP 6.7 and 22.3 bn, respectively. Most importantly, a balance is needed between subsidising deployment to drive down costs through learning and funding innovation to maintain a high learning rate. [ABSTRACT FROM AUTHOR]

The key market drivers for marine energy are to reduce carbon emissions, and improve the security and sustainability of supply. There are other technologies that also meet these requirements, and therefore the marine energy market is dependent on the technology being cost effective, and competitive. The potential UK wave and tidal stream energy market is assessed using ETI's energy systems modelling environment (ESME) which uses a multi-vector approach including energy generation, demand, heat, transport, and infrastructure. This is used to identify scenarios where wave and tidal energy form part of the least-cost energy system for the UK by 2050, and will assess what Levelised Cost of Energy (LCOE) reductions are required to improve the commercialization rate. The results indicate that an installed capacity of 4.9 GW of wave and 2.5 GW of tidal stream could be deployed by 2050 if the LCOE is within 4.5 and 7 p/kWh for each respective technology. If there is a step reduction to the LCOE of wave energy, however, a similar capacity of 5 GW could be deployed by 2050 at a LCOE of 11 p/kWh. [ABSTRACT FROM AUTHOR]

Wave energy conversion can have a significant role in the transition to a net-zero energy system. However, cost reductions are still required for this technology to be commercially competitive. To achieve commercialisation at a reasonable expense, disruptive innovations at early stages of development need to be enabled. Thus, to explore more of the design space, design limits need to be defined. Although physical limits, such as the maximum capture width and the Budal upper bound, have been defined, more realistic limits considering the variability of the resource, device dimensions and the actual hydrodynamic behaviour of different shapes can help provide further insights. This is relevant to both technology developers and funding bodies wanting to identify potential areas for innovation. In this study, the use of multi-objective optimisation is proposed to explore these limits, by investigating the optimal relationship between average annual power production and device size. This relationship depends on resource level, mode of motion used for power extraction and hull shape. The obtained fundamental relationships fall within the existing physical limits, but provide further insights into the impact of different factors on these limits. This allows for a more direct comparison with the performance of state-of-the-art wave energy converters. • A flexible method to explore wave energy converter design limits is presented. • Design limits for power and volume are obtained with multi-objective optimisation. • The design limits are verified against the state of the art and physical limits. • The method can be used to obtain other types of fundamental relationships. • These relationships help identify areas with potential for disruptive innovation. [ABSTRACT FROM AUTHOR]

Wave energy has a large global resource and thus a great potential to contribute to low-carbon energy systems. This study quantifies the environmental impacts of a 10 MW array of 28 point-absorber wave energy converters, by means of a process-based life cycle assessment (LCA). Midpoint and Cumulative Energy Demand LCA results are presented over 19 impact categories, representing impacts encompassing human health, ecosystems and resource availability. Three scenarios are undertaken to represent the use phase of the array, identified as a particularly uncertain input, with very little long-term operation of wave energy arrays available to validate assumptions. The resultant global warming potential of the array ranges from 25.1 to 46.0 gCO2e/kWh over a 95% confidence interval, 23–43 times lower than conventional fossil fuel electricity generation. The Energy Payback Time of the array ranges between 2.6 and 5.2 years. LCA results are found to be particularly sensitive to annual energy production across all impact categories, and to assumptions associated with the frequency of marine operations over a number of categories quantifying the production of greenhouse gases. This LCA has been undertaken at an early stage in the WEC product development and will inform innovative research focused on further reducing the environmental impacts of electricity generation. • Evaluation of the environmental impacts for a 10 MW array of wave energy converters. • Inclusion of three scenarios to investigate impacts of use phase marine operations. • Monte Carlo uncertainty analysis presents results over 95% confidence intervals. • Environmental hotspots are identified to inform future design considerations. [ABSTRACT FROM AUTHOR]

Developing new wave energy technologies is risky, costly and time-consuming. The large diversity of concepts, components and evaluation criteria creates a vast design space of potentially feasible solutions. This paper aims to introduce a novel methodology for the holistic assessment of wave energy capabilities in various market applications based on sound Systems Engineering methods. The methodology provides a consistent hierarchy of performance metrics relevant to the given system of reference, design activity and development stage under consideration as a means to scrutinise wave energy requirements. Full traceability of system requirements and performance metrics is then facilitated by multi-criteria decision tools and aggregation logic, respectively. The qualitative assessment in the case studies has resulted in very different rankings of System Drivers and Stakeholders for the two market applications considered. However, the Stakeholder Requirements and Functional Requirements present a small variation in the weights for the two application markets which results in a quantitative assessment with very similar Global Merit. Finally, the performance benchmark using the Commercial Attractiveness and Technical Achievability concepts enables a more objective comparison in the utility-scale and remote generation markets and a way to concentrate innovation efforts before proceeding to the next development stage. [ABSTRACT FROM AUTHOR]

• Methodology for capital and operational indicators estimation is presented. • Introducing stochastic operation and maintenance modelling for uncertainty reduction. • Reference database for further works on floating wind farms provided. • Results shows agreement with observed values for offshore wind projects. • Comparison against previous work shows underestimation of operational costs. Floating offshore wind is rapidly gaining traction in deep water locations. As with all new technologies, to gain the confidence of developers and investors, the technical and economic feasibility of this technology must be proven and robust cost estimates are necessary. In this paper, the authors present a methodology to calculate the capital and operational indicators of a floating wind farm over its project lifetime. A set of computational models is used to reduce the uncertainties in the estimation of the technical and economical parameters. In particular, the effect of using detailed operation and maintenance models and strategies allows a better estimation of operational cost. The paper highlights the requirements and specific adjustments considered for floating offshore wind technology. The methodology is demonstrated for two case studies inspired by real floating wind installations in the United Kingdom, namely the Hywind and Kincardine projects. The related input data, gathered from publicly available sources, constitute a reference database for future studies in the floating offshore wind sector. Results are presented for the two case studies. These show that availability and energy production are in line with typical values for offshore wind projects, and highlight the substantial contribution of operational expenses to the cost of energy. Results are also compared against previous estimations for floating offshore wind projects, showing satisfactory agreement for the overall project costs but an underestimation of operation and maintenance costs in previous studies. This highlights the importance of using detailed operation and maintenance models to adequately capture operational expenses. [ABSTRACT FROM AUTHOR]

It is understood that electricity generation from the waves and tides can be temporally and spatially offset from other, more established variable renewables, such as wind and solar. However, it is less well understood how this offsetting can impact on power system operation. A novel modelling framework has been developed to quantify the potential benefit of including higher proportions of ocean energy within large-scale electricity systems. Economic dispatch modelling is utilised to model hourly supply–demand matching for a range of sensitivity runs, adjusting the proportion of ocean energy within the generation mix. The framework is applied to a 2030 case study of the power system of Great Britain, testing installed wave or tidal stream capacities ranging from 100 MW to 10 GW. For all sensitivity runs it has been found that ocean energy increases renewable dispatch, reduces dispatch costs, reduces generation required from fossil fuels, reduces system carbon emissions, reduces price volatility, and captures higher market prices. For example, including 1 GW of wave displaces up to £137M and 128 ktCO2 over the year of dispatch modelled. Similarly, 1 GW of tidal stream displaces up to £95M and 87 ktCO2. When including 10 GW of ocean energy, dispatch costs reduce by up to 7% and carbon emissions reduce by up to 29%. This analysis has included the development and publication of open source models of the Great British power system. • Modelling framework developed to quantify power system benefits from ocean energy. • Economic dispatch modelling used to represent power system supply–demand balancing. • Hourly generation timeseries created to represent wave and tidal stream resource. • Sensitivity analyses used to vary proportion of ocean energy within power system. • GB case study quantifies economic and environmental benefits from ocean energy. [ABSTRACT FROM AUTHOR]

Variability in the predicted cost of energy of an ocean energy converter array is more substantial than for other forms of energy generation, due to the combined stochastic action of weather conditions and failures. If the variability is great enough, then this may influence future financial decisions. This paper provides the unique contribution of quantifying variability in the predicted cost of energy and introduces a framework for investigating reduction of variability through investment in components. Following review of existing methodologies for parametric analysis of ocean energy array design, the development of the DTOcean software tool is presented. DTOcean can quantify variability by simulating the design, deployment and operation of arrays with higher complexity than previous models, designing sub-systems at component level. A case study of a theoretical floating wave energy converter array is used to demonstrate that the variability in levelised cost of energy (LCOE) can be greatest for the smallest arrays and that investment in improved component reliability can reduce both the variability and most likely value of LCOE. A hypothetical study of improved electrical cables and connectors shows reductions in LCOE up to 2.51% and reductions in the variability of LCOE of over 50%; these minima occur for different combinations of components. [ABSTRACT FROM AUTHOR]

• Temporal characterisation of wave and tidal resource availability for Great Britain. • Ten metrics used to explore temporal characterisation and supply-demand matching. • Generation profiles with marine energy consistently outperform those without. • Correlation with load is not a suitable metric to establish supply-demand alignment. • Detailed discussion of potential GB power system benefits from marine energy. Wave and tidal energy have the potential to provide benefits to power systems with high proportions of stochastic renewable generation. This is particularly applicable in combination with wind and solar photovoltaics, as the offsetting of these renewable resources results in more reliable renewable generation. This study utilises ten metrics to quantify the temporal complementarity and supply-demand balancing requirements of the energy mix in Great Britain, to investigate the potential magnitude of these system benefits. Wave and tidal generation profiles are created using historical resource data and hydrodynamic models. The results show that the inclusion of wave and tidal generation creates a renewable energy mix which is more available under multiple conditions: throughout a year of operation; at times of peak demand; for multiple consecutive hourly time periods; and at times when wind and solar generation are not available. Three regional case studies also show that the inclusion of marine energy allows for improved regional supply-demand matching, reducing instances of energy shortage and excess and potentially relieving transmission congestion at particularly constrained locations within GB. Finally, the implications of these findings are discussed in terms of GB wholesale market operation, system balancing and system security. [ABSTRACT FROM AUTHOR]

The transition to low-carbon energy systems is a complex process that implies radical technological changes, greenhouse gas emission reductions, and benefits to the local economies yet, also significant investment, a need for capacity building, strengthening supply chains and supporting legal frameworks. Consequently, the choice of renewable energy technologies should be based on a comprehensive assessment addressing the different dimensions that are affected. Clean energy technologies are traditionally evaluated on the basis of their techno-economic performance. Such an approach penalises emerging energy technologies that are generally more capital-intensive given their innovation requirement and the lack of support mechanisms facilitating their industrial roll-out. In this paper, a multi-criteria evaluation framework is proposed encompassing three important broad dimensions: techno-economics, environment and socio-economics. The applicability and flexibility of the proposed evaluation framework are demonstrated on different case studies. First, the hypothetical deployment of a floating offshore wind farm both in Scotland and Portugal is evaluated. Later, the proposed framework is used to evaluate the deployments of wave energy devices in the same two locations. The results show that this multi-criteria approach provides a more holistic overview of the performance and implications of renewable energy technologies, particularly emerging ones, and can better support decision- and policy-making in the medium- and long-term. Furthermore, the framework can be used by researchers, investors, developers and/or analysts to assess energy planning alternatives. • Techno-economic performance of renewable technologies is traditionally assessed. • An alternative multi-criteria evaluation framework is proposed. • A comprehensive assessment including economics, environment and socio-economics. • The proposed framework is suitable to assess emerging offshore technologies. • Offshore technologies will be instrumental for low-carbon energy systems. [ABSTRACT FROM AUTHOR]

This work investigates potential cost reduction trajectories of three emerging offshore renewable energy technologies (floating offshore wind, tidal stream, and wave) with respect to meeting ambitious cost targets set out in the Strategic Energy Technology Implementation Plans (SET-Plans) for Offshore Wind and Ocean Energy. A methodology is presented which calculates target costs for current early-stage devices, starting from the 2030 SET-Plan levelised cost targets. Component-based experience curves have been applied as part of the methodology, characterised through the comparative maturity level of each technology-specific cost centre. The resultant early-stage target costs are then compared with actual costs for current devices to highlight where further cost reduction is still required. It has been found that innovation and development requirements to reach these targets vary greatly between different technologies, based on their current level of technological maturity. Future funding calls and programmes should be designed with these variables in mind to support innovative developments in offshore renewables. The method presented in this paper has been applied to publicly available cost data for emerging renewable technologies and is fully adaptable to calculate the innovation requirements for specific early-stage renewable energy devices. [ABSTRACT FROM AUTHOR]

One of the key objectives for renewable energy technologies is to reduce the environmental impact of energy generation. Floating offshore wind technologies have been developed in recent years to exploit the wind energy resource available at deep waters where bottom-fixed technologies are not economical. However, few studies exist that analyse the environmental impact of such technologies. Particularly, offshore activities such as those required for Operation and Maintenance (O&M) are not represented in detail in previous studies. The present study addresses these gaps by performing a Life Cycle Assessment using an advanced O&M model to quantify the environmental impact of a floating offshore wind farm. Different O&M philosophies – assuming towing to shore for major operations vs. performing all operations on site – and their impact are evaluated and discussed for two case studies inspired by real pilot park deployments. The results show mean Global Warming Potential (GWP) values between 25.6 and 45.2 gCO 2 eq/kWh depending on the assumed O&M strategy and vessels, with the contribution of the O&M phase to GWP ranging from 21 to 49%, and of O&M vessels from 6 to 40%. Assuming O&M strategies to be the same for fixed and floating offshore wind could result in a 20.4% underestimate of GWP, whereas the vessel choice resulted in up to 34.8% difference in the estimated GWP. An environmental impact perspective provides key insights on the choice of different designs, operation strategies and asset management, and thus should be used in the decision-making process. • Life Cycle Assessment (LCA) of two floating offshore wind case studies is performed. • An advanced O&M model is integrated in the LCA for the first time. • The impact of different O&M strategies and vessel choices on the LCA is assessed. • O&M activities contribute to 21 to 49% of the global warming potential. • O&M strategies based on bottom-fixed offshore wind underestimate the LCA impacts. [ABSTRACT FROM AUTHOR]

Current wave energy development initiatives assume that available designs have the potential for success through continuous learning and innovation-based cost reduction. However, this may not be the case, and potential winning technologies may have been overlooked. The scenario creation tool presented in this paper provides a structured method for the earliest stages of design in technology development. The core function of the scenario creation tool is to generate and rank scenarios of potential Wave Energy Converter (WEC) attributes and inform the user on the areas of the parameter space that are most likely to yield commercial success. This techno-economic tool uses a structured innovation approach to identify commercially attractive and technically achievable scenarios, with a scoring system based on their power performance and costs. This is done by leveraging performance and cost data from state-of-the-art wave energy converters and identifying theoretical limits to define thresholds. As a result, a list of scored solutions is obtained depending on resource level, wave energy converter hull shape, size, material, degree of freedom for power extraction, and efficiency. This scenario creation tool can be used to support private and public investors to inform strategy for future funding calls, and technology developers and researchers in identifying new avenues of innovation. [ABSTRACT FROM AUTHOR]

Cost reductions in nascent forms of Renewable Energy Technology (RET) are essential for them to contribute to the energy mix. Policy intervention can facilitate this cost reduction; however, this may require a significant investment from the public sector. These cost reductions fall into two broad categories: (1) incremental cost reductions through continual improvements to existing technologies, and (2) radical innovation where technologies that significantly differ from the incumbents are developed. This study presents a modelling methodology to integrate radical innovation in RET experience curve and learning investment analysis, using wave energy as an example nascent RET. This aims to quantify the potential effects of radical innovation on the learning investment, allowing the value of successful innovation to be better analysed. The study highlights the value offered by radical innovations in long-term deployment scenarios for wave energy. This suggests that high-risk R&D efforts in nascent RET sectors, even with low success rates, could still present significant expected value in offsetting future revenue support. [ABSTRACT FROM AUTHOR]

This paper presents a summary of recent progress towards the development and upscaling of an emerging class of electrostatic power take-off (PTO) systems for wave energy converters (WECs), called dielectric elastomer generators (DEGs). DEGs are electromechanical devices able to convert mechanical energy into electrical energy by exploiting the deformation of rubber-like dielectric materials. The high power density (in the order of hundreds of Watts per kilogram), good efficiency and ease of assembling, combined with the low-cost of the employed materials (a few euros per kilogram) and their intrinsic resilient/reliable response to mechanical shocks make DEGs a very promising option for the deployment of a future generation of WECs. In the last decade, some specific concepts of WECs based on DEGs have been devised and a considerable interest in the topic has been aroused in the wave energy community. Among the candidate DEG topologies for wave energy harvesting, recent studies have suggested that a specific layout, namely the axial-symmetric inflating DEG diaphragm, could be a very promising candidate for future upscaling. This paper first describes the operating principle of DEG PTOs and the effect of electro-mechanical material parameters on their energetic performance. With reference to the above-mentioned inflating DEG diaphragm topology, an overview of concepts for integration on WECs is then provided, with a special focus on advanced concepts enabling the achievement of dynamical tuning with the incoming waves. A general lumped-parameter modelling approach for the design of DEG-based WECs is proposed. Experimental activity carried out to date, i.e. dry-run laboratory tests, wave-tank tests and preliminary sea trials is reviewed, with the aim of showing the progression in the device's scale and performance. Finally, economical and technological considerations are outlined, in order to point out challenges, future research opportunities and to draft a roadmap for future research and technological transfer. • Recent advances on polymeric power take-off systems for wave energy converters called dielectric elastomer generators (DEGs). • Identification of a DEG layout suitable for oscillating water column and pressure differential wave energy converters (WECs). • General modelling framework for coupled DEG-WEC systems. • Review of experimental testing of scaled prototypes. • Roadmap and techno-economic considerations on the future development of WECs based on DEGs. [ABSTRACT FROM AUTHOR]

Of the cost centres that combine to result in Levelised Cost of Energy (LCOE), O&M costs play a significant part. Several developers have calculated component costs, demonstrating how they can become commercially competitive with other forms of renewable energy. However, there are uncertainties relating to the O&M figures that can only be reduced through lessons learned at sea. This work presents an O&M model calibrated with data from real sea experience of a wave energy device deployed at the Biscay Marine energy Platform (BiMEP): the OPERA O&M Model. Two additional case studies, utilising two other O&M calculation methodologies, are presented for comparison with the OPERA O&M Model. The second case study assumes the inexistence of an O&M model, utilising a Simplified Approach. The third case study applies DTOcean's (a design tool for ocean energy arrays) O&M module. The results illustrate the potential advantages of utilising real sea data for the calibration and development of an O&M model. The Simplified Approach was observed to overestimate LCOE when compared to the OPERA O&M Model. This work also shows that O&M models can be used for the definition of optimal maintenance plans to assist with OPEX reduction. [ABSTRACT FROM AUTHOR]