This work is focused on the analysis of the wave resource and its exploitation by means of a proposed 12 MW wave plant in Northwestern Spain. For this purpose, a total of four current technologies of wave conversion are analysed at three different sites located at different water depths, which correspond to one of the European areas with the greatest wave energy resource and where its electric production is still underdeveloped. To carry out the research, the wave data recorded at an offshore buoy near the area and the power matrices of the four selected wave energy technologies are used. The offshore wave conditions—representing 95% of the total energy of an average year—are propagated through spectral numerical modelling towards the coast. On the basis of the results, two of the four selected technologies forming the 12 MW power plants and one of the three considered points emerge as the ones allowing the greatest energy production and, at the same time, having a minimum area of occupation which, in turn, is crucial to reducing the visual impact. Finally, this research discusses the energy supply capacity of the proposed plants to satisfy the energy consumption required by nearby communities.
Coastal and Offshore Energy
The marine environment is increasingly pressured from human activities, such as offshore renewable energy developments. Offshore wind farms may pose direct risks to seabirds at protected breeding sites. However, changes in food availability may influence foraging behaviour and habitat use during the breeding season or between years. Consequently, seabird–wind farm interactions, and risks posed to populations, may vary over longer time scales, but this has seldom been quantified. We used GPS-telemetry to study the movements of 25 lesser black-backed gulls from the Alde–Ore Special Protection Area (SPA), UK between 2010 and 2012, while birds were associated with their breeding colony. Variation in movements away from the colony, offshore, and in operational, consented and proposed Offshore Wind Farm Areas (“OWFAs”) was investigated: (1) between years and (2) across the breeding season, addressing: (3) sex-specific, (4) individual and (5) diurnal/nocturnal differences. The extent of overlaps with OWFAs varied between years, being greatest in 2010 (7/10 birds showing connectivity; area overlap: 6.2 ± 7.1%; time budget overlap: 4.6 ± 6.2%) and least in 2012. Marine habitats close to the colony were used before breeding. Birds spent little time offshore as incubation commenced, but offshore usage again peaked during the early chick-rearing period, corresponding with use of OWFAs. Individuals differed in their seasonal interactions with OWFAs between years, and males used OWFAs significantly more than females later in the breeding season. This study demonstrates the importance of tracking animals over longer periods, without which impact assessments may incorrectly estimate the magnitude of risks posed to protected populations.
Being highly dependent of imported fossil fuels for its electricity generation, Thailand has an ambitious target for the integration of renewable energy in its electricity portfolio. This paper presents the offshore wind resource map of the Gulf of Thailand, with the objective of identifying the potential areas for grid connected offshore wind power development. A coupled numerical mesoscale atmospheric model and a microscale wind flow model, along with long-term global reanalysis climate data, are used to generate high resolution (200 m) wind resource maps at heights of 40 m, 80 m, 100 m, and 120 m above sea level. The offshore wind resource maps are validated using measured wind speeds obtained from 28 meteorological towers installed along the coast of the Gulf of Thailand. The site selection of potential areas for offshore wind power development is assessed with a multi-criteria decision making analysis. Specifically to the Bay of Bangkok, results show that a technical power potential in the order of 3000 MW could be developed to generate an annual energy production estimated in the order of 6 TWh/year. For the whole Gulf of Thailand, a technical power potential estimated at 7000 MW could generate in the order of 15 TWh/year.
The cost-effective utilization of wave energy is still a major engineering challenge. Shoreline locations for Wave Energy Converters (WECs) offer lower wave energy densities when compared with offshore locations, but give significant advantages from the points of view of construction, maintenance and grid connection.
This article provides a first analysis on the viability of a very low-head hydropower plant, in which waves accumulate water into a shoreline reservoir created by a steep detached ramp. The system is particularly suitable for micro-tidal environments such as the Mediterranean Sea and has the additional advantage of protecting shorelines, seawalls and coastal assets from wave action.
Physical model tests, conducted with regular waves, have been used to get a preliminary estimate of the average water flux overtopping the ramp in a sea state; a novel low-head hydropower machine, developed at Southampton University, has been considered for the conversion of the hydraulic energy into electricity.
The site of Porto Alabe, located along the West coast of Sardinia (Italy), has been chosen as a first case study. Based on the inshore wave climate, the layout of the ramp has been designed as a tradeoff between the needs of maximizing the energy production, providing the coastal area with an adequate protection and making the plant a desirable investment to either private or public players. The results are interesting both from a technical and an economic point of views and encourage a further deepening on the response of this kind of WEC.
Assessments of global wave power have been receiving increasing attention currently; however, a characterization of the global resources that holistically consider the different temporal scales that influence wave climate (monthly and seasonal, interannual and long-term) is still lacking. Moreover, the debate around the global figure of available resource is still widely open. This study provides a new global wave power assessment using a dataset that covers the period from 1948 to 2008, which was corrected using altimetry data and validated with buoys in terms of wave power. This study characterizes the mean wave power globally as well as its monthly and seasonal variability. Furthermore, it provides a link with the most relevant climate indices globally. The effect of the interannual variability is especially noteworthy for the Northern Hemisphere, where the seasonality is strongest. Additionally, we detect decadal long-term changes and determine that natural variability could explain a few of the differences found between decades. Lastly, we provide an assessment of the global theoretical wave power that covers the last six decades, compare approaches and estimates, and discuss factors of discrepancy. The global offshore wave power is estimated at 32,000 TW h/yr, which is reduced to 16,000 TW h/yr when considering the direction of the energy. The historical average change is 580 TW h/decade. Our results indicate that the global natural variability could be a more relevant factor in the lifetime of wave farms than the historical long-term changes in wave energy.
It is widely acknowledged that many renewable energy technologies cannot (yet) compete with incumbent (fossil fuel) options e.g. in terms of price. Transitions literature argues that sustainable innovations can nevertheless break out of their ‘niches’ if properly shielded, nurtured and empowered. Most studies using this perspective have focused on how innovation champions engage in shielding, nurturing and empowering (SNE) activities: none have so far focused specifically on the role that policy plays in relation to these three processes. This paper therefore aims to analyze the way in which policy constrains and enables the shielding, nurturing and empowering of renewable energy innovations. To do so, it presents a qualitative review of the development of offshore wind power (OWP) in The Netherlands over the past four decades. Based on interpretation of a wide variety of written sources (academic histories, reports, policy documents, parliamentary debate transcripts, news media) and nine semi-structured interviews, it discerns six periods of relative stability in the history of Dutch offshore wind. It then analyzes the effects of various policies on the shielding, nurturing and empowering of offshore wind in these periods. The paper contributes to transitions literature (1) by providing an analysis of how policies can enable and constrain the shielding, nurturing and empowering of renewable energy innovations, and (2) by bringing together, for the first time, fragmented accounts of the surprisingly long history of Dutch offshore wind development and implementation. Both contributions are timely, given the recent reprioritization of OWP on the Dutch policy agenda.
For marine energy to be truly sustainable, its social and ecological impacts must be identified and measures by which to mitigate adverse effects established before devices are deployed in large arrays. To inform future research and encourage environmentally-sensitive developments, this review aims to identify the most significant social and ecological issues associated with wave and tidal current energy generation. Modifications to wave climates, flow patterns, and marine habitats, particularly through increased underwater noise and collision risk, are identified as key ecological issues. Social acceptance of renewable energy is found to be closely linked to the level of stakeholder involvement and the public perception of renewable energy. The review concludes with a call for a more strategic and collaborative research effort between developers, academia, and the public sector to improve environmental monitoring standards and best practices for device and array design.
Meeting the United States׳ offshore renewable-energy goals for 2030 necessitates deploying approximately 9000 wind turbines along U.S. coastlines. Because siting bottom-mounted turbines in most nearshore coastal zones is either impractical or politically difficult, turbine developers are testing floating-platform turbine technologies for deeper waters. Deepwater, floating-platform turbines have the advantages of being sited in the highest quality winds farther offshore, movable if desired, and located beyond the horizon, out of sight from shore. This paper reports on conversations with 103 coastal stakeholders at community meetings regarding development and testing of floating turbines off the coast of Maine, U.S.A. Using naturalistic field methods, this essay reports common questions and concerns of commercial lobstermen, fishermen, and coastal civic leaders. Early-stage conversations suggest that once coastal community members understand the benefits and impacts of wind farm development on their quality of life, many share specific preferences for where offshore developments could be located. Citizens׳ remarks are sophisticated, nuanced, and innovative and include robust ideas for pairing turbine siting with fishery conservation. Findings imply that when looking to site offshore turbines in public, multiple-use ocean spaces, developers, planners, and coastal communities should engage early and often in two-way conversation rather than one-way outreach.
While wind and solar have been the leading sources of renewable energy up to now, waves are increasingly being recognized as a viable source of power for coastal regions. This study analyzes integrating wave energy into the grid, in conjunction with wind and solar. The Pacific Northwest in the United States has a favorable mix of all three sources. Load and wind power series are obtained from government databases. Solar power is calculated from 12 sites over five states. Wave energy is calculated using buoy data, simulations of the ECMWF model, and power matrices for three types of wave energy converters. At the short horizons required for planning, the properties of the load and renewable energy are dissimilar. The load exhibits cycles at 24 h and seven days, seasonality and long-term trending. Solar power is dominated by the diurnal cycle and by seasonality, but also exhibits nonlinear variability due to cloud cover, atmospheric turbidity and precipitation. Wind power is dominated by large ramp events–irregular transitions between states of high and low power. Wave energy exhibits seasonal cycles and is generally smoother, although there are still some large transitions, particularly during winter months. Forecasting experiments are run over horizons of 1–4 h for the load and all three types of renewable energy. Waves are found to be more predictable than wind and solar. The forecast error at 1 h for the simulated wave farms is in the range of 5–7 percent, while the forecast errors for solar and wind are 17 and 22 percent. Geographic dispersal increases forecast accuracy. At the 1 h horizon, the forecast error for large-scale wave farms is 39–49 percent lower than at individual buoys. Grid integration costs are quantified by calculating balancing reserves. Waves show the lowest reserve costs, less than half wind and solar.
Tidal-stream energy devices currently require spring tide velocities (SV) in excess of 2.5 m/s and water depths in the range 25–50 m. The tidal-stream energy resource of the Irish Sea, a key strategic region for development, was analysed using a 3D hydrodynamic model assuming existing, and potential future technology. Three computational grid resolutions and two boundary forcing products were used within model configuration, each being extensively validated. A limited resource (annual mean of 4 TJ within a 90 km2 extent) was calculated assuming current turbine technology, with limited scope for long-term sustainability of the industry. Analysis revealed that the resource could increase seven fold if technology were developed to efficiently harvest tidal-streams 20% lower than currently required (SV > 2 m/s) and be deployed in any water depths greater than 25 m. Moreover, there is considerable misalignment between the flood and ebb current directions, which may reduce the practical resource. An average error within the assumption of rectilinear flow was calculated to be 20°, but this error reduced to ∼3° if lower velocity or deeper water sites were included. We found resource estimation is sensitive to hydrodynamic model resolution, and finer spatial resolution (<500 m) is required for regional-scale resource assessment when considering future tidal-stream energy strategies.