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Towards green transition of touristic islands through hybrid renewable energy systems. A case study in Tenerife, Canary Islands
Abstract
The Canary Islands are still largely dependent on expensive imported fossil fuels, are stressed by the increasing touristic impact and are extremely vulnerable to climate change due to water scarcity. Water desalinisation is an energy-demanding process and is essential to the sustainable development of these islands. The aim of this study is to explore the potential advantages of a hybrid installation, exploiting two different renewable energy sources, specifically waves and solar, to supply a large desalination plant in Tenerife. The paper ultimately provides a generally applicable procedure for the design of hybrid installations, including three steps: the assessment of available renewable energy sources, the optimal combination of these sources and finally the economic assessment. The wave and solar resources are assessed first, then the hybrid installation is conceptually designed proposing a criterion for the optimal mixing of the renewable energy sources that can be applied to other resources and other sites. The basic idea is to maximize the exploitation of the renewable power, minimizing the need of the fossil-based back-up system. The costs of the hybrid installation are finally assessed considering the sensitivity to government incentives, showing that the project parity point is reached within the lifetime of typical desalination plants (i.e. 40 years) and can be significantly more attractive in case of Feed-In-Tariffs available in other European countries.
... Achieving decarbonization goals, expanding the adoption of renewable energy sources, and taking a holistic approach to resource management are highly dependent on improving technological efficiency, with a particular emphasis on improving energy storage capacities [1][2][3][4]. This situation is especially relevant on islands that are energetically isolated [5][6][7][8], as is the case in the Canary Islands [2,4,9,10] and in Gran Canaria. The island faces a great energy challenge, which requires strategic measures to address its unique energy demands and constraints. ...
... Additionally, reliance on fuels such as fuel oil, diesel, and diesel oil exacerbates the issue, as these are less environmentally friendly and energy-efficient alternatives [24][25][26]. In 2021, 79.4% of Gran Canaria's electricity was generated using imported fossil fuels [27][28][29][30][31] , contributing to higher electricity prices and increased CO 2 emissions [2,9,23]. (c) The overarching goal is to progressively decarbonize the power generation system by integrating renewable and environmentally neutral technologies [23,28]. ...
The Canary Archipelago, in general, and the island of Gran Canaria, in particular, operate with an independent energy system (SIE), which depends largely on local power generation. Today, its energy supply comes mainly from two sources: (a) Renewable energy, accounting for 19.90%, and (b) Fossil fuel combustion in thermal power plants, contributing the remaining 80.10%. The existing energy infrastructure faces challenges due to aging technology, requiring either modernization or replacement to prevent a potential energy crisis and ensure a sustainable production cycle. A transformative step to improve the system is the completion and commissioning in 2030 of the Chira-Soria pumped hydroelectric energy storage (PHES) plant. This installation will allow water to be transported to high altitudes by pumping, to be deposited until the right time and to be turbined to generate electricity in optimal conditions. To fully understand the impact of this integration, detailed analyses of annual energy production patterns, equipment performance, and real-time demand data (collected at five-minute intervals) will be conducted. These assessments will provide insights into how the Chira-Soria PHES can be seamlessly integrated into Gran Canaria’s energy network. Furthermore, they will help identify both the strengths and limitations of this storage solution, paving the way for a more resilient and efficient energy future for the island.
... Gran Canaria's energy production depends 79.4% on imported fossil fuels for electricity generation [26,27]. In the year 2021, this has a direct impact on the increase of electricity costs and CO emissions [2,9,23]. (c) To achieve a progressive decarbonization of the generation system by incorporating more renewables or environmentally neutral systems [23,28]. ...
... The need for decarbonization, the penetration of renewable energies, and the broader vision of the management of our resources could be obtained with these technologies by improving their storage capacity [11][12][13][14][15]. Moreover, this is not different to other island energy systems [5,7,8,16], for instance in the Canary Islands [2,4,9,17,18] and specifically in Gran Canaria, which faces a fourfold challenge in the coming years: ...
Gran Canaria, due to its status as an island, has an isolated energy system (IES). This has made it dependent on itself for energy production, which is basically obtained from: (a) Wind and solar energy, which equals 19% of the total energy produced, (b) Energy obtained from the burning of fossil fuels in the energy production equipment of the existing thermal power stations, which equals 81% of the total energy produced. A solution must be found to the current production system, which is already partially obsolete and is due for renewal and/or decommissioning, in order to avoid “Energy Zero”, which means a change in the production cycle. In addition, the incorporation of a pumped hydroelectric energy storage plant “Chira-Soria” into the Gran Canaria electricity system represents another, even more important, change in the dynamics followed up to now. Basically, this plant, which is hydraulically stabilized by means of a seawater desalination plant, incorporates energy storage by storing water at high altitude to be turbined under appropriate conditions. The new situation will be analyzed with this incorporation and the option of an integrated operation in the overall energy system of Gran Canaria will be considered.
... In this classification, the transformation between mechanical and electrical energy is not considered. The additional cost of placing a PTO only moderately increases the CAPEX and OPEX of the floating breakwater, so that, globally, there is a concrete possibility to have a low LCoE (with for example a payoff period of order 10 years in [28] and 20 years in [29]). The first issue is, however, to investigate the possible locations where the system can perform satisfactorily and, therefore, to assess the power production potential under different conditions ( [30]). ...
... The additional cost of placing a PTO only moderately increases the CAPEX and OPEX of the floating breakwater, so that, globally, there is a concrete possibility to have a low LCoE (with for example a payoff period of order 10 years in [28] and 20 years in [29]). The first issue is, however, to investigate the possible locations where the system can perform satisfactorily and, therefore, to assess the power production potential under different conditions [30]. ...
This paper presents a hydrodynamic investigation carried out on the “Wave Attenuator” device, which is a new type of floating breakwater anchored with piles and equipped with a linear Power Take Off (PTO) mechanism, which is typical for wave energy converters. The device is tested in the wave flume, under regular waves, in slightly non-linear conditions. The PTO mechanism, that restrains one of the two degrees of freedom, is simulated through an actuator and a programmable logic controller with preassigned strategy. The paper presents the system identification procedure followed in the laboratory, supported by a numerical investigation essential to set up a credible control strategy aiming at maximizing the wave energy harvesting. The maximum power conversion efficiency under the optimal PTO control strategy is found: it is of order 50–70% when the incident wave frequency is lower than the resonance one, and only of order 20% for higher frequencies. This type of experimental investigation is essential to evaluate the actual efficiency limitations imposed by device geometry.
... The small scale SWRO desalination system is the main technical solution for the islands, ships and offshore engineering platforms, to obtain the fresh water [11]. Although the capacity of each desalination system is limited, the total capacity of all small scale desalination systems still accounts for a certain proportion since the quantity is considerable [12]. ...
... For the testing desalination system, there exists a feed pump to meet the operating requirement of TPP-ERD. Therefore, the SEC can be calculated by Eq. (11). Here, E total represents for the total energy consumption in one hour and Q P is the volume of permeating fresh water in one hour. ...
Energy recovery device is a crucial part for decreasing the energy consumption of membrane desalination system. To meet the energy conservation requirements in small scale desalination system, a new three-piston pump energy recovery device integrating the high pressure pump and booster pump is investigated and evaluated. The flow characteristics in pressure exchanging cylinders are investigated through the numerical method. The operating performance is experimentally evaluated in a membrane desalination system at the seawater pressure and flowrate of 5.00 MPa and 6.10 m³/h. The numerical results indicate that the continuous flow and pressure transition can be realized through the cooperation of three hydraulic pistons in operation. Both the inlet and outlet flowrates demonstrate the half-sine variation trends. The maximum deviation between simulation and experiment is 2.70%. The experimental results prove that the device can achieve the stable pressure exchanging, and the pressure and flowrate fluctuation amplitudes are 0.60 MPa and 0.60 m³/h. The energy recovery efficiency is as high as 82.03% which contributes to a specific energy consumption of 3.62 kW·h/m3 in desalination. This paper provides a new type of multi-functional energy recovery device for the membrane desalination system.
... In Xiao, Simon, and Pregger (2019) strategic implementation of longterm integrated energy transition pathways have been evaluated for two coastal metropolitan regions of eastern China. Dallavalle et al. explored the potential advantages of hybrid waves and solar installation to maximize the exploitation of renewable sources by minimizing the need of a fossil-based backup system (Dallavalle, Cipolletta, Moreno, Cozzani, & Zanuttigh, 2021). This study has been performed for the Canary Islands of Tenerife. ...
This paper argues that a fit-for-purpose model and datasets are necessary to generate transition pathways for the electricity generation sector at the subnational level. We present the methodology, data, and results focusing at a sub-national level, the state of West Bengal in India. The approach can be generalized for any region with necessary customization. By utilizing high-resolution spatio-temporal input datasets, this study proposes a power sector capacity expansion model to compute three sets of transitional scenarios and one set of the current-as-usual scenario. These scenarios consider sub-national energy carrier-resource constraints and are solved to identify the most economically cost efficient future transition pathway for the electricity sector in West Bengal. Based on the least-cost solution, computations determine the optimal energy mix, operations, investments, and emissions for alternative scenarios. The results show that integrating demand-side flexibility (DSF) as a balancing option can lead to transformative outcomes. Compared to the current capacity expansion trend (ScenCA), adopting a thermal mix renewable scenario with intraday load-shifting (ScenTMDSF) could reduce 77% of CO2 emissions by 2040. This does not necessitate early retirement of existing thermal power plants, total investment increases by 13% compared to ScenCA. Without DSF as a balancing option, an additional 26% investment is required compared to the current-as-usual scenario for 2040. Transitioning to 100% renewable energy (ScenREN) requires 30% more investment, early retirement of 5.34 GW of thermal capacity, and nearly 2.7 times more storage battery capacity. These numbers help in understanding the magnitude of the financial resource and kind of technological need for the developing countries not only from the point of view of equitable climate action from burden sharing and just transition principles but also provides practical example of need for redirecting global capital for creating global good through subnational scale actions.
... The Canary Islands (Spain) experience a similar situation due to the overexploitation of its aquifer due to the intensification of agriculture, the increase in population, and the development of tourism [24]. The Canary Islands are characterised by extreme aridity since rainfall is scarce and irregular, which has led to an increase in the use of desalination plants to supply the population [25,26]. ...
Water is an essential element for agricultural sustainability. In volcanic islands, freshwater sources are limited, challenging the local farming water supply. Rainfall dependence in the Galapagos Islands limits continuous agriculture, and despite using natural water sources, their irrigation quality is little known. This study aimed to carry out a control–diagnosis of irrigation water quality of the natural sources of the four agrarian islands of the Galapagos, considering water quality parameters for the proposal of sustainability strategies in the water and agricultural context. The workflow included (i) freshwater supply situation diagnosis, (ii) physicochemical parameters measurement and hydrochemical characterisation, and (iii) irrigation analysis and sustainability strategies configuration. Results indicated that of the 34 sources analysed, 55.88% are suitable for irrigation and are located in San Cristobal and Santa Cruz. The remaining 44.12% showed problems with parameters such as faecal coliforms, salinity, metals, carbonates, BOD5, and COD above the national permitted limits. Six strategies for water and agricultural sustainability are proposed, including periodic water monitoring, academy–government–community projects, community water board creation, water sowing and harvesting systems, effective management of effluent, and agricultural strengthening. The study guides comprehensive hydric management initiatives to benefit agrarian development and food security, aligning with SDGs 2 and 6.
... In Tenerife, complete financial cost recovery for desalination and water reuse could compromise its development (CIATF 2018), as it is still necessary to invest in the improvement of these facilities to reach a good quality of water with the least impact to the environment (Dallavalle et al. 2021). El Hierro, La Gomera and La Palma show very low financial cost recovery, due to the fact that a low percentage of the demanded water is billed to users, and information from private services is not always up to date or available (CIALP 2018). ...
Article 9 of the Water Framework Directive (WFD) introduces cost recovery as an instrument aligned with the 'polluter pays' principle, aiming to contribute to the overall well-being of water bodies. In this regard, this research focuses on application of the cost recovery method in the context of the Canary Islands (Spain). The study provides a comprehensive description and analysis of the methodology established for the second cycle of planning (2015–2021) in the Canary Islands, offering a comparative assessment of results for each island. We employ a Stochastic Frontier Model, which allows us to assess the efficiency of different water production techniques. The results should be of great interest to public decision makers in the field of water management to minimize cost, allocate resources efficiently or review water tariffs. The findings underscore substantial variations in cost recovery across islands, emphasizing the need for enhanced water infrastructure methods and data acquisition. Future research needs to extend the years on cost recovery to incorporate economies of scale and type of ownership.
... We used El Hierro Island, 1350 km from the Europe mainland, as a case study, irradiance data, wind speed, and demand for the 2021 year [50]. The ERA5 reanalysis hourly solar radiation and wind speed data were downloaded from Ref. [51]. ...
The power supply from solar and wind generators is not only inherently variable but also prone to failure due to rare-weather related events, i.e., hailstorms, icing. Current system sizing strategies often consider system reliability or resilience but rarely consider them simultaneously. Here, we proposed a sizing approach for an off-grid power system to supply a minimum power threshold (L th) during power disruption events. The L th concept ensures blackout avoidance and enough dispatchable stored energy during power outages. We developed several scenarios with 4-to 24-hour simulated outage events occurring multiple times per year. After sizing a system, designs are tested by simulating the systems' operation based on data containing stochastic outage events. The resulting lost load is recorded to assess system reliability and resilience. Results showed that, regardless of outage frequency, total annual stochastic outage durations up to 32 h did not affect the optimal capacities of system components while ensuring the same reliability level. However, system capacities increased by up to 90% when the annual outage duration increased to 144 h. Meanwhile, introducing a minimum power threshold, Lth = 0.97, further increased the renewables generation and storage capacity up to 50% and 7%, respectively. Systems' resilience tests showed an 80% chance of a system designed with the Lth approach to withstand the prolonged stochastic power disruptions, while this value is only 25% for the systems designed using the conventional approach.
... All abound in the need for decarbonization [1], [2] [3], [4] [5], [6] [7], in the need to increase the penetration of renewable energies, in the need for a broader vision of the management of our resources with better management of our technologies. The Canary electricity systems face challenges of environmental, economic, and social sustainability, largely dependent on imported fossil fuels for electricity generation [8]- [10]; this leads to an increase in the cost of electricity and CO2 emissions; a reduction can be made using more renewable energy sources [11]- [13]. ...
... Ocean Thermal Energy Conversion (OTEC) and seawater air-conditioning have significant potential and are successfully supplying energy in Hawaii and Tahiti [39]. Wave energy could also contribute in the future [40,41]. ...
Many archipelagos rely on imports of diesel to produce most of the electricity they consume. That results in a high price for electricity and risk of fuel spills. Currently, many islands worldwide are facing the challenge of integrating local renewable energy sources into their electricity grids. This work conducts a review of energy transition for islands and then focuses on three case studies: Galápagos, Noronha and Príncipe. It was found that the demand for energy at these locations will continue to grow at a high rate, pushed by the growth of tourism and population. In the three cases, large PV solar projects are planned for the coming years and should supply a large share of that demand. PV solar stands out as the most economically viable option for generating electricity, with a LCOE much lower than diesel (between 44% and 80% lower). Galápagos and Noronha are installing battery storage facilities to integrate the supply of energy from renewable sources. In addition, they are fostering energy efficiency and the progressive adoption of electric vehicles. Príncipe is at a much earlier stage: the grid needs substantial investment and plans for electric mobility are still incipient. Based on this research, it is strongly recommended to (1) incentivize energy efficiency, (2) provide training in the area of renewable energy to local workers, and (3) provide incentives to the residential and commercial sectors, particularly hotels, to foster contribution to the energy supply through the installation of PV solar and solar hot water heating on rooftops.
... This study uses El Hierro, one of the Canary Islands, as the study area. This island in the Atlantic Ocean is about 1350 km from mainland Europe [41,42]. To align with Europe Islands' clean energy initiatives, the Spanish government aims to entirely replace the fossil fuel sources of these islands by 2050 through the gradual increase of RE penetration [36]. ...
It remains a significant technical and economic challenge to fully power large-scale grids with intermittent renewable energy (RE). Meanwhile, due to the rapid decrease in the cost of RE power generation technologies in recent years, the number of real-world implementations and studies dedicated to the optimal capacity sizing of renewable off-grid systems has increased. However, a common approach in the literature is to rely on typical single-year meteorological and demand data. A negative effect of this assumption is that it does not consider the RE inter-annual variability, which might cause blackouts or oversizing the system and large curtailments. This study employs 43 years of hourly solar, wind, and demand data, coupled with different microgrid configurations, to evaluate the impact of diverse simulation periods on the total system cost, optimal RE mix, and system reliability. Our findings indicate that extended simulation periods considerably increased renewable energy systems (RES) reliability and that the resulting configurations can be up to 94% more robust than those obtained using a single year of data. Additionally, the optimal energy storage requirements increased when considering longer simulation periods, indicating that short simulation periods could underestimate energy storage capacities in off-grid systems. The overestimations or underestimations resulting from optimizations based on single-year data directly affect the long-term sustainability, reliability, and cost-effectiveness of the RES.
... Yue et al. [14] combined energy from the wind, solar, wave, and biomass resources to form an energy system on an island, simulated the best possible blending of renewable energy sources using the EnergyPLAN model, and concluded that the electricity export is financially viable when the island power system is linked to the outside world. There are also case studies of introducing renewable energy in some specific islands, e.g., Tsushima Island, Japan [15], Galapagos islands [16], and Tenerife, Canary Islands [17]. ...
... Padrón et al. (2019) also successfully planned desalination with a capacity of up to 50 m 3 daily integrated with photovoltaic (PV) and wind turbine (WT) systems in the Canary Islands. Recently, Dallavalle et al. (2021) projected a hybrid renewable energy system including waves and solar to supply a large desalination plant in Tenerife. In an interesting study, Tafavogh and Zahedi (2021) introduced and constructed a novel and eco-friendly HRES based on geothermal, biomass, solar, hydro, and wind to supply power and freshwater in Bandar Abas, Iran. ...
Using hybrid renewable energy technology is an efficient method for greenhouse gas mitigation caused by fossil fuel combustion. However, these renewable microgrids are not free from environmental damages, especially during the lifetime of hybrid renewable energy systems (HRES). The main objective of this study is to assess the environmental impacts of three optimized HRES for the Sea Water Reverse Osmosis Desalination (SWROD) plant. An objective optimization was developed using the division algorithm, and the environmental impacts of the optimized HRES were investigated by the life cycle assessment approach. The results showed that producing 1 m³ freshwater by an optimal size SWROD integrated with wind turbine/battery is responsible for 3.56E − 07 disability-adjusted life year (DALY). It is significantly less than 1 m³ freshwater production by an optimal size SWROD integrated with solar PV/battery (5.88E − 07 DALY) and solar PV/wind turbine/battery (5.13E − 07 DALY) energy systems. Moreover, 1 m³ freshwater by a SWROD integrated with proposed microgrids in this study led to a damage of 0.089 to 0.193 potentially disappeared fraction of species (PDF)*m²*yr to ecosystem quality. It also results in an emission of 0.143 to 0.339 kg CO2 eq per 1 m³ freshwater. Furthermore, resources for 1 m³ freshwater production by a SWROD are calculated at 2.77 to 4.806 MJ primary. Freshwater production by an optimal size SWROD integrated with solar wind/battery compared with solar PV/battery and solar PV/wind turbine/battery had less damage to ecosystem quality, climate, and resources. The results showed reductions of 91.23% in human health, 73.51% in an ecosystem quality, 92.43% in climate change, and 90.08% in resources for producing 1 m³ of freshwater using SWROD integrated with wind turbine/battery bank compared to fossil-based desalination. Finally, the result showed that solving the optimization problem using the division algorithm compared to other algorithms leads to less environmental damage in freshwater production.
... Grid, PV, DG, and batterybased system is considered a feasible system that meets an average critical load demand of 329 kW h/day. A wave-and solar-based renewable energy system is presented in Dallavalle et al. (2021) to supply power to a large desalination plant located in the Canary Islands. The combination of two RES is providing 2 MW of electricity to the desalinization plant. ...
The study analyzed the techno-economic feasibility of a village in the Indian state of Assam and designs a framework for a rural hybrid energy system. Through an extensive resource evaluation, techno-economic feasibility analysis and system size optimization are carried out using HOMER Pro software. Batteries are being used as a form of energy storage in the community power system, which is based on solar PV and micro-hydro as its principal energy sources. Macro-economic variables and resource variations have been considered in sensitivity analysis to ensure the robustness and commercial viability of the proposed hybrid energy systems. A reliable and economical design can provide 279861 kWh of electricity for the village at a modest cost of energy (COE) of $0.0953/kWh using 118 kW of solar power, 11 kW of hydropower, and 261 kWh of battery storage. Furthermore, solar energy systems account for about 62.5 percent, while micro-hydro turbines account for 37.5 percent. In addition, the suggested system does not pollute the local environment caused by carbon emissions. Most importantly, this hybrid energy system is capable of providing 24/7 continuous electricity to the site under consideration.
... The techno-economic feasibility and optimal sizing of wind-PV HRESs in different application scenarios have generated widespread research interest. The widely-distributed application scenarios of HRESs include remote island [16], Arctic residential community [17], tropical village [18], nature disaster area [19], tourism island [20], agriculture & irrigation area [21], off-grid telecommunication station [22], highrise residential building [23], desalination plant [24], university campus [25], etc. Moreover, various energy storage technologies such as batteries, pumped hydro storage, compressed air energy storage, thermal energy storage, hydrogen storage and several hybrid energy storage systems have been applied in HRES [26]. ...
To promote the large-scale deployment and grid integration of renewable-based power system, this paper investigates the province-level techno-economic feasibility of wind-photovoltaic-battery hybrid renewable energy system (HRES) for baseload supply application around China. Firstly, the power generation cost and grid parity potential of province-level standalone wind and photovoltaic power plants are assessed. Then, the optimal sizing of province-level HRESs aims to minimize the net present cost and meet the reliability constraint for baseload supply, which is solved by teaching and learning-based optimization. Finally, the techno-economic comparison between different system configurations, the correlation between HRES cost-effectiveness and resource potential as well as resources complementarity, and the grid parity potential of HRES for baseload supply are quantitatively analyzed. The results reveal that: (i) 84.4% of regions in China can achieve solar photovoltaic plant-side grid parity in 2022, while only 15.6% of regions can achieve wind power plant-side grid parity; (ii) HRESs in all regions are technically feasible but not cost-effective for baseload supply; (iii) wind-photovoltaic-battery HRES is the optimal configuration for most regions, indicating that the wind-solar hybridization is more reliable and cost-effective than standalone power plants; (iv) the economic performance of HRES depends mainly on the wind-solar joint resource potentials and the supply-demand relative deviation; (v) investment cost reduction and utilization of energy curtailment are promising to help HRES achieve plant-side grid parity for baseload supply. The findings of this paper can help policy-makers and investors optimally determine the national pathway of renewable energy transition.
... Greek islands in general are suitable for the installation and operation of wind farms, due to their very high wind potential. Today, more and more studies serve the energy supply for islands in the world [5][6][7][8][9]. ...
The lack of fresh water and energy independence in remote islands leads to the investigation of Hybrid Systems (HS). In this paper, the implementation of wind energy for meeting energy, water, and electromobility demands on a Greek island is examined. The stochastic nature of wind potential leads to the introduction of energy storage units. Energy storage can be achieved through the HS, which utilizes the rich wind potential of the island of Kos, stores excess energy through pumping to an upper reservoir, and produces hydropower in order to cover the energy deficit. The HS in this study consists of a wind farm with a total capacity of 9.4 MW, which is composed of 4 wind turbines of 2.35 MW, two desalination units with a total capacity of 2275 m3/day a 10 kW power pump for pumping the desalinated water to the drinking water reservoir with a capacity of 180000 m3. It also consists of a hydro turbine of 5 m3/s and an upper reservoir with a capacity of 400000 m3 at a height of 176 m above the hydroelectric station. The first operated scenario aims to meet the energy and water needs of Pyli (3500 inhabitants). The second scenario aims to cover the electromobility and water needs of 20000 inhabitants, which is equivalent to the entire city of Kos. The simulation models operate with hourly meteorological and demand data for the period 2016-2020, results about CO2 emissions, before and after the integration of the HS are presented, and a cost-benefit analysis is performed for the first scenario.
... Under a certain stress level, large deformation or even grain breakage could be generated in calcareous sand, posing a major threat to the structural integrity of geotechnical constructions [4][5][6][7]. In recent years, large-scale offshore wind turbines [8,9], subsea energy mining platforms [10,11], and artificial reefs [12,13] have all been erected, and their safety must be ensured completely. ...
The strength and deformation properties of maritime geotechnical structures made primarily of calcareous sand are critical for project safety. The geogrid reinforcement is developed as a promising approach to improve the mechanical properties of calcareous sand. This study investigates the mechanical property of biomodified geogrid via a microbially induced calcite precipitation (MICP) process to improve the effectiveness of geogrid for reinforcement of calcareous sand. A series of unconsolidated undrained triaxial experiments were conducted to evaluate the mechanical property and deformation behaviors of biomodified geogrid and reinforced calcareous sand (BGRCS), taking into consideration the impacts of the geogrid layer, times of biotreatment, and confining pressure. Compared to the untreated geogrid, the strength of the BGRCS is distinctly changed due to the increase roughness, and the deviatoric stress-strain curves are evidently hardening. Strength and pseudocohesive force can be further enhanced by raising the geogrid layer of the reinforced specimens, while internal friction angle also increases the amplitude of variation with the times of biotreatment. The geogrid, times of biotreatment, and confining pressure are all intimately related to the strength and the deformation of the reinforced specimens. The interactions of geogrid ribs and calcareous sand particles are analyzed and friction using scanning electron microscope tests that could provide a reference for revealing the mechanical mechanism of BGRCS.
... Under a certain stress level, large deformation or even grain breakage could be generated in calcareous sand, posing a major threat to the structural integrity of geotechnical constructions (Lv et al., 2019(Lv et al., , 2020Rezvani et al., 2021). In recent years, large-scale offshore wind turbines (Trojnar, 2019;Yang et al., 2018), subsea energy mining platforms (Dallavalle et al., 2021;Depellegrin et al., 2019), and artificial reefs (Kim et al., 2021) have all been erected in recent years, and their safety must be ensured completely. ...
The strength and deformation properties of maritime geotechnical structures made primarily of calcareous sand are critical for project safety, and geogrid reinforcement is a promising new approach. A series of consolidated drained triaxial experiments were conducted to evaluate the mechanical property and deformation behaviors of geogrid reinforced calcareous sand (GRCS), taking into consideration the impacts of the geogrid layer, relative density, particle size, and confining pressure. In comparison to the unreinforced calcareous sand, the strength of the GRCS is greatly enhanced, and the deviatoric stress-strain curves are altered from slightly softening to hardening, as well as the suppressed shearing dilatancy. The geogrid, relative compactness, particle size, and confining pressure are all intimately related to the volume changes and shearing dilatancy of reinforced specimens, but particle crushing is mostly impacted by the confining pressure. The interactions of geogrid ribs and calcareous sand particles are summarized as two types of constraint and friction using scanning electron microscope tests to establish a simplified calculation method of horizontal and vertical equivalent additional stresses that could provide a reference for revealing the mechanical mechanism of GRCS.
Tilos, a Greek island in the Mediterranean Sea, hosts a pioneering hybrid energy system combining an 800-kW wind turbine and a 160-kWp photovoltaic (PV) field. The predominance of wind power makes the energy production of the island almost constant during the year, while the consumption peaks in summer in correspondence with the tourist season. If the island wants to achieve complete self-sufficiency, seasonal storage becomes compulsory. This study makes use of measured production data over 1 year to understand the best combination of renewable energy generation and storage to match energy production with consumption. A stochastic optimization based on a differential evolution algorithm is carried out to showcase the configuration that minimizes the levelized cost of required energy (LCORE) in different scenarios. System performance is simulated by progressively increasing the size of the storage devices, including a combination of Lithium-ion batteries and power-to-gas-to-power (P2G2P) technologies, and the PV field. An in-depth market review of current and forecasted prices for RES and ESS components supports the economic analysis, including three time horizons (current and projections to 2030 and 2050) to account for the expected drop in component prices. Currently, the hybrid storage system combining BESS and P2G2P is more cost-effective (264 €/MWh) than a BESS-only system (320 €/MWh). In the mid-term (2030), the expected price drop in batteries will shift the optimal solution towards this technology, but the LCORE reached by the hybrid storage (174 €/MWh) will still be more economical than BESS-only (200 €/MWh). In the long term (2050) the expected price drop in hydrogen technologies will push again the economic convenience of P2G2P and further reduce the LCORE (132.4 €/MWh).
The actual energy transition calls for the highest ever engagement of institutions and private sectors in the adoption of renewable energy systems in order to decarbonize all production chains. The high potential of renewable energy sources (RESs) in several locations worldwide is looked at as an important opportunity to both limit the energy supply issues and shift towards a greener society. On the other hand, it is also accompanied by the issues of resource variability, forecasting need and difficult management of the energy surpluses. The contemporary exploitation of multiple RESs in a hybrid renewable energy system (HRES) is a strategic initiative aimed at reducing the energy supply risk in a specific location, while decarbonizing the power generation facilities that satisfy specific energy requests. By means of systems optimally designed that valorize the RESs site-specific features and time trends, it is possible to comply with the identified energy demands while obtaining increased reliability. This contribution introduces an approach for the preliminary design of HRESs which is capable of accounting for the specific geographical constraints and the energy requests to be fulfilled. The approach is simulation-based, thus analyses the performance of all the possible combinations of renewable energy conversion technologies in terms of supply reliability and assesses their sustainability profile through key indicators. The application of the method is exemplified through a case study located on the island of Crete, Greece, for the valorization of the combined exploitation of offshore wind and wave energy. The most sustainable designs of the HRES in the site foresee the installation of 12 offshore wind turbines and maximum 10 wave energy converters for an overall system potentiality higher than 110 MW.
Small-scale seawater desalination system with energy recovery devices is the mainstream technical solution to cope with fresh water issue and tight power supply in the exploitation of islands. Aiming at the complex working conditions, the adaptability of piston type high pressure pump integrated with energy recovery device (HPP-ERD) is investigated through the numerical simulation and all-year-round island desalination. The numerical results indicate that the consecutive flowrate regulation, broad pressure sustainability and uniform temperature distribution are realized in HPP-ERD within the flowrate of 5.30 m³/h, the pressure of 5.50 MPa, and the temperature of 25 °C. The experimental results prove that HPP-ERD exhibits excellent stability and adaptability at the starting stage and stopping stage, and achieves stable operation in the pressure range between 3.00 MPa and 5.50 MPa. The all-year-round operation demonstrates that HPP-ERD can adapt to the seawater temperature ranging from 0.85 °C to 25.69 °C and the humidity between 63% and 85%. The total internal leakage maintains nearly constant at 0.19 m³/h which contributes to the annual specific energy consumption (SEC) of 3.80 kWh/m³. This investigation provides researchers and engineers with the application references of HPP-ERD in island desalination system.
The Canary Islands power systems face environmental, economic, and social sustainability challenges. They heavily rely on imported fossil fuel for electricity generation; this leads to an increase in the Cost of Electricity (COE) and CO2 emission; a reduction can be made by utilizing more renewable energy sources (RES). This paper presents a comprehensive techno-economic assessment of increasing the RES utilization in Tenerife and Gran Canaria. Results illustrate that the least-cost RES penetration in each island exceeds 60% compared to 18.8% and 15.5% today. This implies a potential 58% reduction in CO2 emission intensity. The additional RES integration decreases the COE by 23.0% and 25.3% in Tenerife and Gran Canaria, respectively. The impact of imposing CO2 emission penalties is explored, results show a slight increase in the optimal RES capacity. Electrical Interconnection between both islands is also investigated, it is found to increase the optimal aggregate RES penetration beyond 70%, reduce COE by 30.3% and lower CO2 emission by 70%, compared to the current situation. Finally, the results obtained can support decision-makers to establish policies to help transform the energy system in islands into a more sustainable and reliable system using RES, energy storage, and energy exchange between islands.
This paper analyzes the adoption of an off-grid hybrid renewable energy system (HRES) for a high-rise building owned by a public institution in Nigeria. The analysis is based on the comparison between the use of a single criterion and multiple criteria in the selection of the most feasible energy system. The proposed HRES comprises of a wind turbine, diesel generator, photovoltaic (PV), and battery storage system. Hybrid optimization of multiple energy resources (HOMER) software was used to design the HRES for a case study (based on a single criterion-total net present cost), while Evaluation Based on Distance from Average Solution (EDAS) method was used to evaluate the effect of choosing an optimal system based on multiple criteria. Based on the simulations conducted with HOMER, eight feasible HRES (ES1-ES8) were identified. When the feasible HRES were ranked based on total (NPC), the optimal configuration comprises 70 kW PV modules, 20 kW diesel generating set, 40 kW converter, and 70, 3000 Ah batteries. The results obtained from the optimization process were subjected to a multi-criteria analysis based on sustainability principles. The ranking of the first two systems (ES1 and ES2) returned by single criterion (total NPC) remained the same, while changes were observed in the ranks of the remaining systems (ES3–ES8). This modular feasibility study shows that it would be economical to power the entire university using HRES. It is expected that this study would help the university communities and other stakeholders make informed decision during the planning stage of similar projects.
Worldwide, the emerging trend of hybrid renewable energy sources integration in modern power systems is increasing due to privileged prices and clean electricity supply. However, the optimal planning of rural hybrid systems is a challenging and complex task, especially when different alternatives and sustainability aspects are considered. This paper develops an integrated decision-making approach for the optimal planning of a 100% renewable energy supply system comprising solar, wind, hydro, and biomass sources in a rural area located in Pakistan. An hourly-based design optimization analysis of twelve on/off-grid electrification alternatives is performed. The optimization model simultaneously addresses five sustainability criteria related to economy, reliability, ecology, society, and topography aspects. Furthermore, a novel hybrid decision-making model has developed to identify the unique best configuration with on-grid and off-grid options. The proposed model combines fuzzy analytic hierarchy process, multi-objective optimization based on ratio analysis technique for order of preference by similarity to an ideal solution, and evaluation based on distance from average solution methods. The results reveal that the solar-hydro-biomass battery with a life cycle cost of 10.9 M. Both scenarios have a negligible capacity shortage of 0.09%. Ecologically, the optimal off-grid system produces only 408.37 kg/yr of CO2 due to the significant energy share of solar and hydro sources (99.3%). The optimal on-grid system produced the minimum CO2 with 29,177.89 kg/yr compared to other alternatives. Also, employing the optimal on/off-grid designs require land area and jobs of 96.6 m², 14 jobs, and 118 m², 15 jobs, respectively. Overall, the developed approach with the presented case study offers a valuable benchmark and guidelines for investors and stakeholders to create realistic investment plans for the energy industry looking to push efficient inducements to encourage the high dissemination of renewables.
The present study (2021) compares the levelized cost of electricity (LCOE) of renewable energy technologies for electricity generation with conventional power plants. The future cost ratio between the different power generation technologies is also compared for the years 2030 and 2040. The focus is on the LCOE of photovoltaic (PV), wind power plants (WPP) and bioenergy plants in Germany. For the first time, PV battery systems are included in the study, as they represent a growing segment of the German power system market. As a reference, the development of the LCOE for newly built conventional power plants (lignite, hard coal, combined cycle gas turbines (CCGT), gas turbine) is also examined.
Study can also be downloaded here: https://www.ise.fraunhofer.de/en/publications/studies/cost-of-electricity.html
The widespread use of renewable energy sources and the growing concern about climate change, together with Spain's exceptional weather and solar radiation conditions, have led to an increase in the use of photovoltaics for energy production in the country. Solar power generation has been tightly regulated, although the legal framework has changed frequently over the years. When assessing the potential financial performance of any business venture, legal as well as financial aspects must be considered, but a critical factor is the discount rate used, which must reflect the company's capital cost. Other factors are the period of interest, the firm's activity, market risk, and the level of debt of firms in the sector. The main objective of this study is thus to estimate the discount rate for companies using photovoltaics to produce solar power. We calculate it by employing two financial techniques: capital asset pricing model and historical return analysis. We then evaluate the investment in a photovoltaic plant with a capacity of 5000 kW located in eastern Spain, assuming it started its activity in different years which coincide with changes in the regulatory framework. The results show the relevance of the initial outlay costs for the profitability of photovoltaic power plants.
Population growth has increased in the last two centuries. In the driest countries, water supply alternatives are scarce, and desalination is an alternative to guarantee water supply. The question is what conditions must be met by the new desalination plants to achieve the objectives of sustainability. The present study is an analysis of the social, economic, and environmental variables that are critical in the development of desalination plants: technology used, energy sources, correction of the generated environmental impacts, and the most appropriate contractual model for its development. These attributes justify at the time of writing why reverse osmosis is the safest and most efficient technology among those available and those that are under investigation. It is proposed to incorporate renewable energy production sources, although it is still necessary to continue depending on the significant contribution of the traditional energy sources. The need will also be demonstrated to adopt corrective measures to mitigate against the impact produced on the environment by energy production and to implement monitoring plans to confirm the validity of these corrective measures. Finally, turnkey contracts are proposed because osmosis technology is complex, although technology should be justified by means of a decision support system. One of the determining factors is proposed in this present analysis.
The widespread use of renewable energy sources and the growing concern about climate change, together with Spain’s exceptional weather and solar radiation conditions, have led to an increase in the use of photovoltaics for energy production in the country. Solar power generation has been tightly regulated, although the legal framework has changed frequently over the years. When assessing the potential financial performance of any business venture, legal as well as financial aspects must be considered, but a critical factor is the discount rate used, which must reflect the company’s capital cost. Other factors are the period of interest, the firm’s activity, market risk, and the level of debt of firms in the sector. The main objective of this study is thus to estimate the discount rate for companies using photovoltaics to produce solar power. We calculate it by employing two financial techniques: capital asset pricing model and historical return analysis. We then evaluate the investment in a photovoltaic plant with a capacity of 5000 kW located in eastern Spain, assuming it started its activity in different years which coincide with changes in the regulatory framework. The results show the relevance of the initial outlay costs for the profitability of photovoltaic power plants.
As the world continues to experience problems including a lack of seafood and high energy demands, this paper provides an assessment for integrated multi-use offshore platforms (MUPs) as a step towards exploiting open seawater in a sustainable way to harvest food and energy. The paper begins with background about MUPs, including information regarding what an MUP is and why it is used. The potential energy technologies that can be involved in an offshore platform are introduced while addressing similar applications all over the world. The paper presents the state of the art of MUP structures on the light of EU-funded programs. An MUP would have a positive impact on various marine activities such as tourism, aquaculture, transport, oil and gas and leisure. However, there are concerns about the negative impact of MUPs on the marine environment and ecosystem. Building an MUP with 100% renewable energy resources is still a challenge because a large storage capacity must be considered with a well-designed control system. However, marine bio-mass would play a vital role in reducing battery size and improving power supply reliability. Direct Current (DC) systems have never been considered for offshore platforms, but they could be a better alternative as a simpler control system that requires with lower costs, has lower distribution losses, and has an increased system efficiency, so studying the feasibility of using DC systems for MUPs is required.
Climate change conditions in the last decades have derived in a significant reduction of rivers’ levels, irregularity of rainfall and, thus, difficulties in accessing to drinkable water. This situation is especially dramatical in islanded environments, such as the Canary Islands in Spain, where these restrictions to water resources have conducted to an overexploitation of aquifers and wells, with the deterioration of the environment that this fact entails. For this reason, desalination plants have become essential, and efforts must be done to reduce their impact and costs, as the involved processes for water desalination are high energy intensive. In this research paper, an optimized size hybrid wind and solar photovoltaic power plant is proposed to feed a desalination plant under the approach of not only feed the desalination process, but also provide the power grid with clean energy, taken advantage of the surplus electricity production. This way, not only the water resources stress is mitigated (through the desalting water production), but also the grid benefits from the integration of a distributed renewable energy source (DRES). Moreover, the business model is improved as the cost of drinkable water production is reduced and the power plant owner receives extra incomes from the water sales. Optimization results for a case study in Gran Canaria island shows that, considering the power dispatch in the island, the remuneration limits for power delivery and the remuneration for provided water, the optimal DRES associated with a desalination plant providing 5600 m3/day of desalted water and a maximum annual electricity injection to the power grid of 5.88 GWh/year, an hybrid solar PV and wind generation installation with electrochemical storage is a feasible solution that makes the Levelized Cost of Electricity (LCOE) achieve a singular reduced value despite considering the additional costs of the desalination plant, although financial help must be provided to reduce the Payback Time. Keywords: Water stress, Desalination, Renewable energy, Solar photovoltaics, Wind energy, Hybrid power plant
Floating wind foundations could unlock offshore wind power generation in deeper and more remote waters. This report examines how quickly floating wind is progressing towards becoming a key contributor to the global electricity supply mix. It contains a special focus on developments in the UK and Scotland, uncovering challenges that could undermine the growth of floating wind, as well as policy recommendations to overcome these. The floating wind market is growing steadily, expanding from almost zero installed capacity in 2008 to 57 MW in 2018. Looking forward, there is an impressive pipeline of projects for future deployment. By 2030, global capacity of floating wind could be as high as 4.3 GW. Deployment of installed capacity has to date been dominated by the UK and Japan, and the vast majority of these foundations have been designed and developed by companies in Norway and Japan. New entrants, most notably the USA and France, are expected to challenge for leadership in both deployment and design. Whilst SMEs have played a central role in driving growth in the sector, multi-national energy firms are investing heavily in floating wind deployment and design. These include: (1) oil and gas majors; (2) energy utilities; and (3) Original Equipment Manufacturers (OEMs). Floating wind rated turbine capacity more than tripled and hub height almost doubled between 2008–13 and 2013–18. However, the majority of projects remain single-turbine demonstration projects, with just one array deployed. During the same period, the projects’ distance from shore has doubled to average 11km but their depth has increased by just 7%. However, at an average depth of 65m, projects are operating in waters deeper than most bottom-fixed foundations are economically capable of. The UK is the world leader in floating wind deployment, with 56% of global capacity. Retaining this future lead will, however, be likely to depend on it retaining an open trading relationship with the EU, a relationship that it has depended on heavily to deliver its two existing floating wind projects. Taking opportunities to grow the UK content of the offshore wind supply chain may help to mitigate some disruption post-Brexit. The removal of the UK’s Renewables Obligation (RO) has created a gap for long-term support of small-scale pre-commercial floating wind projects. Domestic support will become even more important, should the UK lose access to European technology demonstration funding post-Brexit.
The paper aims at investigating the interactions between a floating wave energy device (WEC) and its mooring system under a variety of wave conditions (regular and irregular, perpendicular and oblique, ordinary and extreme). The analyzed WEC is the DEXA, a wave activated body point absorber, of the type that performs better when aligned to the incident wave direction. Two typologies of mooring systems were studied: for limited depths, the spread system, with a disposition of the lines that do not constrain the yaw movements; for large depths, the catenary anchor leg mooring (CALM) system. The spread system was experimentally investigated, including a realistic power take-off system, to capture non-linear behaviors and assess device motions, power production, and forces on mooring lines. The CALM system was numerically simulated, as mooring modelling is more reliable in deep waters and allows testing of a number of different configurations, by changing the number of the mooring lines and the mooring layout. The experiments showed that a reduction of the mooring compliancy increases the power production. The numerical simulations showed that a redundancy on the number of chains allows a better distribution of the loads, with advantages on reliability and costs.
Floating offshore wind energy is an emerging technology that provides access to new wind generation sites allowing for a diversified wind supply in future low carbon electricity systems. We use a high spatial and temporal resolution power system optimisation model to explore the conditions that lead to the deployment of floating offshore wind and the effect this has on the rest of the electricity system for Great Britain in 2050. We perform a sensitivity analysis on three dimensions: total share of renewables, floating offshore costs and the impact of waves on operation. We find that all three impact the deployment of floating offshore wind energy. A clear competition between floating offshore wind and conventional offshore wind is demonstrated, with less impact on other renewable sources. It is shown that floating wind is used to provide access to greater spatial diversification. Further, access to more distant regions also affects the optimal placement of conventional offshore wind, as spatial diversification is spread between floating and bottom-mounted sites.
As non-mainland territories, the Canary Islands represent isolated electricity systems with their own peculiarities, derived mainly from their location. They are therefore subject to a special regulatory framework governing their electricity supply activities. These systems are less stable, in terms of both electrical energy generation and its transport infrastructures, because their site limitations require production to rely on a small number of plants, multiplying the problems that arise from potential grid or generator failures. This means that power generation costs in isolated groups of islands have been intrinsically higher than those on the mainland, above all in terms of fuel, given their greater dependence on fossil fuels. These costs also have a different structure, wherein variable costs prevail over fixed costs. The entry into force of Royal Decree 738/2015 defines a new method to determine the price of demand, generation, and additional costs. In addition, it creates a new virtual market for each isolated system (or subsystem), which takes into account the prices of the mainland, moving year, and generation costs. This implies a reduction in the volatility of the electricity market in these territories (lower risk) because part of the purchase price is already known. In this regard, the Canary Islands’ subsystem that has experienced the greatest increase in generation costs is the island El Hierro, since, in systems where there is a wider diversification in the generation methods, there is also a greater variation in monthly prices—that is, greater uncertainty. The aim of this study is to analyze the operation of the Canary Islands’ electricity market and the configuration of its dispatch pool. The wind-pumped hydropower station on El Hierro is described as a specific case study to illustrate the impact of the new regulatory framework.
The offshore wind energy sector in the United Kingdom (UK) has grown rapidly since the first turbine generators were installed in 2000: by 2016 there were over 1400 installed turbines with combined capacity of 5.1 GW. The sector is considered by UK Government as essential to the development of a low carbon economy and to meeting binding targets on carbon reduction and renewable energy generation. The Crown Estate, responsible for licensing development on the sea bed around the UK, has held three rounds of licensing since 2000 for wind developments. Some of the projects in the first two rounds suffered long delays due to uncertainty of project level impacts, particularly cumulative impacts. A number of key stakeholders identified a need for cumulative impact assessment (CIA) methodology to be developed that was definitive and endorsed by regulators and industry to aid unblocking barriers to delivery. This paper explores the background to the development of the guidelines and how they were ‘co-created’ with industry and regulators. We evaluate to what extent they have been used to shape and develop practice.
Abbreviations: CIA: cumulative impact assessment; EU: European Union; GW: gigawatt; MW megawatt; NERC: Natural Environment Research Council; NGO: Non Governmental Organisation; OWF: offshore wind farm; PINS: Planning Inspectorate; RED: Renewable Energy Directive; RUK: Renewables UK; SPA: Special Protection Area; TCE: The Crown Estate; TWh: terra watt hours; UK: United Kingdom.
This paper presents a short overview of the development of wave energy converters (WECs) since the 1970s where the oil crises raised the interest in renewable power generation.
The “small is beautiful” motto is dealt with and dismissed when regarding the commercial viability of utility scale WEC power plants. The potential future developmental pathway towards commercialisation of wave energy is compared to the development of the Danish wind mill sector where the first series production of 22 kW started in 1978 – four years after Prof. Stephen Salter presented his MW sized so called Duck.
The paper discusses the capital expenditure CAPEX and operation and maintenance costs (OPEX) for small and large WECs seen over the WEC lifetime and the resulting levelized cost of energy (LCOE) for power plant size wave energy parks. The following statement is taken from the 2014 JRC Ocean Energy Status Report [8]:
“Maintenance: small-scale devices are associated with reduced maintenance, since they are designed to operate in farms and a defect to one unit may not affect the overall array performance, hence reducing the time necessary for maintenance.”
The paper explains why this is a false statement - maintenance costs will inevitably decrease with increasing WEC size.
The paper also justifies that large WECs can obtain relatively low CAPEX and OPEX compared to small WECs, and that large WECs can be expected to match the LCOE for floating wind turbines. Combined offshore wave-wind power plants can be expected to deliver lower LCOE than pure wave or wind parks.
Offshore wind farms will play an important role in supplying the increasing energy demand while considering ecological and economic aspects. Especially floating foundations which have a great potential for offshore wind farms in water depths between 40 m up to 200 m and more, will be a major factor. The objective of this paper is to focus on the design of a TLP substructure including the anchoring in the seabed by considering the economic and ecological aspects. One main focus is on economic challenges and the approaches for reduction of the investment costs and the Levelized Cost of Energy. A second focus is on the cumulative energy demand as well on the expected CO2-emissions during the fabrication process.
Adaptation to climate change has been considered to be crucial to current societies, especially for small islands. In this paper the case of Tenerife (in the Canary Islands) is analysed. Tenerife is a small island located northwest of the African continent, in the Atlantic Ocean. Tenerife presents a high vulnerability to heatwaves and Saharan dust events as a consequence of its closeness to the Saharan desert. In fact, increasing frequency of heatwaves and Saharan dust events has been reported and could worsen in the future due to global warming. An exploration of adaptation strategies to an increase of the frequency and intensity of these phenomena is therefore needed. Different social actors have been engaged in a participatory process aiming at exploring pathways for adaptation to extreme weather events. Resilience was argued as the relevant framing to address those hazards. Four focus group sessions were carried out in order to explore key transformative elements necessary to make resilient futures for Tenerife. The results highlight the need for broader climate-based policies across all sectors to assure that the island becomes resilient to climatic and non-climatic shocks.
This paper reviews the operational flexibility and emissions of gas- and coal-fired power plants today and in the future with higher renewables. Six study cases were considered: heavy duty gas turbines in simple and combined cycle, aero-derivative gas turbines, large-scale supercritical coal power plants and small- and mid-scale sub-critical coal power plants. The most critical operational processes and pollutants associated with these plants were identified. Then, data was collected mainly from manufacturers, but also from academic research and grey literature. The data was compared and analyzed. Detailed comparisons of the power plant characteristics as well as the current and future flexibility and emissions are provided. Furthermore, a method to quantify the ability of conventional power plants to back-up renewables and the expected benefits from improved flexibility is proposed and evaluated. Results show that gas-fired power plants are not only more efficient, but also faster and generally less polluting than coal-fired power plants. However, at their respective minimum complaint load, gas plants are less flexible and produced more NOx and CO emissions than coal-fired power plants. Results also show that on average, an improvement of approximately 50% to 100% on power ramp rates, minimum power load, number of major power cycles and emissions for these plants is sought in the future to complement renewables.
Aiming towards good practice in the planning and approval of offshore wind farms suggestions are provided for the amendment of environmental impact assessment (EIA), an effective marine spatial planning and the establishment of marine compensation measure.
The investigation is focused on the situation in Germany as a frontrunner in ecological research on offshore wind energy. After 10 years of research in Germany, it is timely to offer a synopsis of the results especially regarding the successful investigations of mitigation measures. The results are based on published data collected in Germany over the last 10 years, as well as international research. The outcomes of the research were validated by interviewing experts using the Delphi method.
Key findings for good practice in impact assessment, mitigation and compensation:
1. EIAs should focus on decision-relevant subjects of protection (i.e. specific bird species and harbour porpoises).
2. There is a strong necessity for thresholds for the approval process.
3. Exclusion of OWFs in hotspots of sensitive species.
4. Application of state-of-the-art mitigation measures particularly against underwater noise to avoid damages of the hearing of porpoises.
5. The introduction of marine compensation measures is strongly suggested.
The Maldives are situated in the remote equatorial Indian Ocean, covering 900 km from north to south. The 26 coral atolls forming the archipelago are composed of sand and coral with a maximum height of about 2.30 m above the mean sea level. Periodic flooding from storm surges and the frequent freshwater scarcity are perceived by the population and the economic operators as the major environmental stresses. Moreover, the strong dependence on imported fossil fuels increases, even more, the environmental concerns. Diesel, in fact, still represents the main source of power generation, typically through privately managed small diesel sets. The real challenge for this area is to promote the environmental quality with socioeconomic growth. The present study aims to evaluate the strategic effectiveness to face these issues by wave and offshore wind energy. Resources using a 10-year hindcast dataset are here examined. The annual offshore wave power was found to range between 8.46 kW/m and 12.75 kW/m, while the 10 m and 100 m mean wind power density is respectively 0.08 kW/m² and 0.16 kW/m². Based on these results, an environmentally and socio-economically sustainable best-case scenario is constructed and two atoll islands (Malè and Magoodhoo) are specifically investigated. As a result, multifunctional structures and multi-use systems, which combine power generation, desalinization and coastal defence, are strongly recommended.
The correlation between water and energy is currently the focus of several investigations. In particular, desalination is a technological process characterized by high energy consumption; nevertheless, desalination represents the only practicable solution in several areas, where the availability of fresh water is limited but brackish water or seawater are present. These natural resources (energy and water) are essential for each other; energy system conversion needs water, and electrical energy is necessary for water treatment or transport. Several interesting aspects include the study of saline desalination as an answer to freshwater needs and the application of renewable energy (RE) devices to satisfy electrical energy requirement for the desalination process. A merge between renewable energy and desalination is beneficial in that it is a sustainable and challenging option for the future. This work investigates the possibility of using renewable energy sources to supply the desalination process. In particular, as a case study, we analyze the application of wave energy sources in the Sicilian context.
An overview of generic types of wave energy converter (WEC) is presented and their mooring requirements discussed. Mooring system configurations and components from the offshore industry suitable for WEC units are identified. Possible mooring configurations for WECs are discussed and it is argued that not only station keeping but also the overall performance characteristics of the WEC mooring should be considered in the design.
In the near future, the oceans will be subjected to a massive development of marine infrastructures, including offshore wind, tidal and wave energy farms and constructions for marine aquaculture. The development of these facilities will unavoidably exert environmental pressures on marine ecosystems. It is therefore crucial that the economic costs, the use of marine space and the environmental impacts of these activities remain within acceptable limits. Moreover, the installation of arrays of wave energy devices is still far from being economically feasible due to many combined aspects, such as immature technologies for energy conversion, local energy storage and moorings. Therefore, multi-purpose solutions combining renewable energy from the sea (wind, wave, tide), aquaculture and transportation facilities can be considered as a challenging, yet advantageous, way to boost blue growth. This would be due to the sharing of the costs of installation and using the produced energy locally to feed the different functionalities and optimizing marine spatial planning. This paper focuses on the synergies that may be produced by a multi-purpose offshore installation in a relatively calm sea, i.e., the Northern Adriatic Sea, Italy, and specifically offshore Venice. It analyzes the combination of aquaculture, energy production from wind and waves, and energy storage or transfer. Alternative solutions are evaluated based on specific criteria, including the maturity of the technology, the environmental impact, the induced risks and the costs. Based on expert judgment, the alternatives are ranked and a preliminary layout of the selected multi-purpose installation for the case study is proposed, to further allow the exploitation of the synergies among different functionalities.
The Wave Dragon is a floating wave energy converter (WEC) working by the overtopping principle. The overtopping discharge has been determined by model scale experiments in wave basins. In the present study we numerically simulate the overtopping behavior of the Wave Dragon device using a VOF based incompressible Euler/Navier-Stokes solver in the OpenFOAM framework. We present simulations of: (i) a complete sea state for different crest heights, and (ii) regular waves for different wave conditions and crest heights. The simulations compare reasonably well with the experimental data, albeit the irregular wave simulations predict a larger overtopping discharge than observed in the experiments.
During the last decades several small autonomous brackish or seawater desalination units
driven by Renewable Energy Sources (RES) have been developed within EU and non EU
projects around the world. A significant number of these units were designed, developed, and
operated by Research Centres/Universities, in collaboration with companies working in the
field of RES and Desalination, in their own premises (laboratories) in order to investigate the
reliability and performance of the technologies matching in small scale and autonomous
operation. Some systems were also developed for the supply of fresh water to remote areas,
and particularly to cover the needs of small villages or communities. Few renewable energy
desalination units were installed by RES/desalination market stakeholders as already
commercially available products.
The present work aims at analyzing the story and operation of selected RES desalination units,
representative of a larger number of systems nowadays operating all around the world. The
advantages and disadvantages of the technologies matching, problems encountered and their
solutions, costs, units performance as well as the progress of market available RES desalination
packages will be also presented.
The paper gives a review of the various projects that have been realised in throughout the years. These have all been in enclosed water bodies such as reservoirs, ponds and small lakes. The main motivation for the floating photovoltaic (PV) panels was the land premium, especially for agricultural sites were the land was more valuable for growth of the crops (in these cases, grapes because the sites were wineries). The PV panels of the existing projects are mounted on a rigid pontoon structure and vary between horizontal and tilted installations. Future concepts proposed for marine and large lacusterine sites are envisaged to incorporate laminated thin film PV, which would allow the structure to be flexible and able to yield with the oncoming waves, and submergible arrays, which would be submerged in harsh weather conditions. Interest and research has been developing in this niche field throughout the years and has currently reached the megawatt scale with even bigger plans for the future. Copyright © 2014 John Wiley & Sons, Ltd.
A model for the performance of generic crystalline silicon photovoltaic (PV) modules is proposed. The model represents the output power of the module as a function of module temperature and in-plane irradiance, with a number of coefficients to be determined by fitting to measured performance data from indoor or outdoor measurements. The model has been validated using data from 3 different modules characterized through extensive measurements in outdoor conditions over several seasons. The model was then applied to indoor measurement data for 18 different PV modules to investigate the variability in modeled output from different module types. It was found that for a Central European climate the modeled output of the 18 modules varies with a standard deviation (SD) of 1.22%, but that the between-module variation is higher at low irradiance (SD of 3.8%). The variability between modules of different types is thus smaller than the uncertainty normally found in the total solar irradiation per year for a given site. We conclude that the model can therefore be used for generalized estimates of PV performance with only a relatively small impact on the overall uncertainty of such estimates resulting from different module types.
Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates the device types that represent current wave energy converter (WEC) technology, particularly focusing on work being undertaken within the United Kingdom. The possible power take-off systems are identified, followed by a consideration of some of the control strategies to enhance the efficiency of point absorber-type WECs. There is a lack of convergence on the best method of extracting energy from the waves and, although previous innovation has generally focused on the concept and design of the primary interface, questions arise concerning how best to optimize the powertrain. This article concludes with some suggestions of future developments.
The existing pressures on coastal areas are prompting the off-shore transfer of economic activities such as aquaculture, transportation, tourism, energy, leading to new challenges for the sustainable use of the sea and calling for integration of different activities in the same area. This paper conceptually designs a multi-use off-shore area in a mild sea, whose purpose is the setup of an energetically self-sustained fish farm. The climate conditions for aquaculture and renewable energy production are assessed first. The features and production of the fish farm are then designed, as well as the renewable energy system offering the power support. A new dedicated tool is presented and adopted for the set-up and sizing of the electrical system required for the power stabilisation and energy supply in case the multi-use area is not grid-connected. The layout and payback time of the multi-use are finally examined, showing that wave energy systems are still far to make such installation economically competitive.
A wave energy assessment is performed in the Canary Islands, based on a 33-year hindcast, between 1979 and 2011. The third-generation wave models WAVEWATCH III and SWAN are used to study the generation of the waves in the North Atlantic basin and the transformation of the waves in the Canary Islands, respectively. The hindcast system was validated in a prior study, showing a relevant wave energy resource distribution with an average annual energy availability of 25–30 kW/m. This study intends to offer a detail description of the wave climate, combining the previous results with the new studies. The results show that the seasonal mean distribution of wave energy varies between 15 and 20 kW/m, in the spring and 25–30 kW/m, in the winter, while in the less energetic areas the seasonal average varies between 10 and 15 kW/m, in the spring, and 15–20 kW/m, in the winter. Also, the temporal variability indexes suggest that the East coast of the islands presents less variability and that the North/Northwest coast of the islands exhibits greater energy availability.
In this review, the author highlights the history, importance and emerging applications of up-conversion (UC) assisted solar cells. An attempt has been made to elucidate the fundamental physical principles that govern the energy conversion by UC materials. Details of various UC mechanisms and popular UC materials along with mathematical interpretation are also provided. The article aims to draw the attention of researchers towards recent technologies adopted to enhance solar cell/photovoltaic (PV) efficiency using UC materials. A careful review has been presented on different techniques and materials employed by researchers to optimize cell structure worldwide. This review provides a useful guide for optimization of various parameters and fabrication of UC based PV systems.
The Canary Islands are recognized as an area of particular interest to exploit and to promote the use of renewable energies as a way to reduce its energy dependence on fossil fuels and ultimately reach energy self-sufficiency and sustainability. A common major problem in mid-latitude small and remote islands is the low annual precipitation rate and the associated freshwater scarcity, leading to the installation of desalination plants powered by oil. In this context, the assessment of wave energy potential along with socioeconomic and environmental factors in a selected area at the north side of Gran Canaria Island shows that wave power availability is adequate for its exploitation and there are no sources of potential conflicts that prevent the installation of wave energy converters. In particular, the harvesting of wave energy to power existing seawater desalination plants, fully based in the use of oil, is considered as a viable, appealing and advantageous alternative over the direct injection to the electric network.
One possible contender to replace conventional reverse osmosis schemes is an energy solution where inexhaustible resources work together with a reverse osmosis plant. Based on the experience of an existing wind-powered desalination scheme run for more than 15 years by Soslaires Canarias S.L., the final objective of this paper is to propose improvements to the scheme so as to achieve a reduction in the cost of water (through restrained capital expenses) for the sake of greater feasibility and efficiency. The cost of the scheme is evaluated assuming a combined use of a reverse osmosis desalination plant and wind energy, using, for this purpose, the (exclusive) information provided by the industrial partner. Results showed that by carrying out the actions suggested in this paper, this scheme would be able to reduce its cost of water (COW) by about 0.022 EUR per cubic meter for the current LCOE of wind turbine technology in the study area (about 6 c€/kWh for the southeast of the island of Gran Canaria, Spain). This would mean that with an additional total capital investment cost of 196 000 € (from the current scheme of Soslaires Canarias S.L.), and supposing an average membrane life expectancy of 10 years for the current state-of-the-art membranes, a net present value of 74 360.95 €, a profitability index of 1.3794, and a 224.4881% internal rate of return would be achieved.
Sustainable energy is the need of the century and energy storage will play a characteristic role in integration and operation of future microgrids and smart grid networks. Energy storage can definitely aid in addressing the issues of integrating intermittent renewable power and in improving the utilization and efficiency of such hybrid systems. The need and the application areas of storage in hybrid renewable systems are explained in brief in this chapter. The chapter also entails the various types of storage systems and their probabilistic market areas. Some of the most prominent path breaking case studies for significant storage applications are also included in this chapter. The chapter concludes by identifying the technical challenges facing the deployment of storage systems globally.
The diffusion of renewable energy in the power system implies high supply variability. Lacking economically viable storage options, renewable energy integration is possible thanks to the presence of modern mid-merit fossil-based technologies, which act as back-up capacity. This paper discusses the role of modern fossil-based power generation technologies in supporting renewable energy investments. We study the deployment of these two technologies conditional on all other drivers in 26 OECD countries between 1990 and 2013. We show that moving from the first to the third quartile of the distribution of modern fossil technologies is associated with an increase in yearly renewable energy investment of between 6 and 14 kW per thousand people, on average and ceteris paribus. This is a sizeable effect, considering that average yearly renewable capacity addition in our sample are around 12 kW per thousand people. These findings are robust to different econometric specifications, various definitions of modern fossil technologies and are stronger for wind, which is more intermittent and for which the mismatch between supply and demand is more marked. Our analysis points to the substantial indirect costs of renewable energy integration and highlights the complementarity of investments in different generation technologies for a successful decarbonization process.
For small islands that are not interconnected with the mainland, the penetration of intermittent renewable energy sources (RES), e.g., wind power, in the power supply system is limited, even when there is a large potential. This is due to technical constraints of the conventional generating units and the dynamic penetration limit that is usually applied for grid stability. This problem can be tackled with energy storage, namely, pumped hydro, when the topography is suitable. In addition, when an island has few or no freshwater resources and the desalination of seawater is a necessity, excess wind power can be provided to desalination units that can produce desalinated water to be used in the pumping and hydrostation and later be supplied to the population. This study couples these two issues, using an integrated approach to power and water supply systems' planning, with the purpose of increasing the integration of intermittent RES and minimizing the electricity and water production costs. This approach is applied to the Island of S. Vicente, in Cape Verde, where the results show that the penetration of RES in an arid island can increase, while decreasing the production costs.
Freshwater scarcity and insufficient sanitation are global urgent problems, affecting billions of people. In this review paper, the process of desalination powered by wave power has been investigated as a potential sustainable solution to water shortage. The different desalination techniques suitable for this type of combined system, i.e. reverse osmosis, electrodialysis and mechanical vapor compression, have been outlined, as well as the different wave energy converters possible to power the desalination process, i.e. oscillating water columns, oscillating bodies (wave activated bodies) and overtopping systems. Some necessary considerations for this type of project are identified. The different wave power/desalination projects and how they have proceeded are presented. The most common design of a wave energy and desalination system includes a wave activated body to pressurize seawater; the seawater flows through a reverse osmosis membrane, resulting in freshwater. Some successful (freshwater producing) wave energy/desalination projects were identified: Delbuoy, the oscillating water column in Vizhinjam, CETO Freshwater, SAROS and Odyssée. It is concluded that wave power and desalination can be combined in a sustainable and autonomous system, generating freshwater from the ocean waves. However, questions regarding cost of produced water, variations in power production due to intermittency and environmental effects still remain.
The Canary Islands, as many islands and coastal regions, are characterized by no conventional energy sources (but renewable resources, mainly wind and solar), by a high population density and land scarcity. Taking into account this context, it is crucial to determine the offshore wind energy potential as a first step for the energy planning. For this purpose, a methodology adapted to islands' and coastal regions' requirements has been developed. The methodology is based on GIS (Geographical Information Systems), and takes into account technical, economic and spatial constrain. Wind turbines (bottom-fixed or floating according to the bathymetry) are placed within the resulting suitable areas, quantifying also the energy production and its cost. The economic analysis includes the calculation of the LCOE (Levelized Cost Of Energy), including integration costs, and the resulting resource cost curves. The methodology has been applied to a practical case, the Canary Islands. Results show that the electricity produced by offshore wind farms exceeds the yearly electricity demand. Moreover, the offshore wind energy cost is lower than the current electricity cost. The analysis provides further useful indicators such as percentage of suitable areas, surface covered by wind turbines, array density of turbines and marginal offshore wind energy cost.
In desalination, similarly with other industries, the cost of the final product is one of the most important criteria that define the commercial success of a specific technology. Therefore, when new projects are planned or new technologies are proposed, the analysis of the expected costs attracts a lot of attention and is compared to (perceived) costs of state-of-the-art desalination or costs of alternative fresh water supply options. This comparison only makes sense if the cost assessment methodologies are based on the same principles and use common assumptions. This paper assesses: (i) the methodologies used to calculate the water cost; (ii) the boundary conditions and (iii) the input data and assumptions. It has been found that most papers in the literature use suitable equations and boundary conditions. Also certain elements like land costs are ignored, but in most cases this is duly acknowledged and justified. However, the quality of the input data for the hardware costs, the operating costs, and the financial parameters are not always appropriate. Guidance for the methodology, data and assumptions that should be used is provided depending on the purpose for which the cost of the desalinated water is calculated.
The island of Gran Canaria offers extraordinary weather conditions for the exploitation of renewable energy. But it has also an isolated power system that is vulnerable and has low inertia. This fact limits the penetration of this energy on the network. Both wind energy and photovoltaics have an important development in the island, but both have clear disadvantages for its exploitation, due to its unstable generation curves, its lack of predictability, the fact that this type of energy can’t be generated continuously, and consequently, the problems due to its difficult management. In adition, talking about wind energy, should be noted that Gran Canaria is an ecological paradise, full of natural protected areas, and also it has a high population density. That's why the space for future energetic installations is very limited. However, the Canary Islands are surrounded by an unlimited ocean. The swell is able to supply part of the insular consumption through wave energy. This study analyze the energetic situation of Gran Canaria, the nature of its waves, and the different mechanisms and techniques for the exploitation of this energetic resource, giving an added value to those that allow to obtain quality energy to be poured into the network.
Are there important differences between reanalysis data and familiar observations and measurements? If so, what are they? This essay evaluates four possible answers that relate to: the role of inference, reliance on forecasts, the need to solve an ill-posed inverse problem, and understanding of errors and uncertainties. The last of these is argued to be most significant. The importance of characterizing uncertainties associated with results—whether those results are observations or measurements, analyses or reanalyses, or forecasts—is emphasized.
The results of a numerical assessment of the wave energy in the Iberian North and West coast are presented. The implemented system uses the WAVEWATCH III model for wave generation and swell propagation, covering the entire North Atlantic basin, and the SWAN model for wave generation and propagation in the coastal areas. WAVEWATCH III provides the wave boundary conditions for the areas simulated by SWAN, which in turn provides the boundary conditions for the high resolution areas. Although there are results available for the Portuguese west coast and Spanish northwestern coast, they use different approaches and wind forcing data, and the present paper presents a consistent approach to identify differences among the various areas, by modelling them with the same models and using the same wind forcing and parameterizations of the SWAN model. The wind fields used in both models are from Era-Interim, a global atmospheric reanalysis data set produced by the European Centre for Medium-Range Weather Forecasts and the bathymetry used in high resolution areas are from the General Bathymetric Chart of the Oceans. The model results are validated with various buoy's significant wave height, mean wave period and mean wave direction. Results are presented of the average wave power spatial distribution in the coarse SWAN domain for each month of the three years, and for the high resolution areas the spatial distribution wave energy is provided for winter and summer.
Multi-use offshore platforms (MUPs) combining renewable energy from the sea, aquaculture and
transportation facilities can be considered as a challenging way to boost blue growth and make
renewable energy (especially wave energy) environmentally and socio-economically sustainable. MUPs
allow sharing the financial and other market/non-market costs of installation and management, locally
using the produced energy for different functionalities and optimizing marine spatial planning. The
design of these solutions is a complex interdisciplinary challenge, involving scientists and technical
experts with different backgrounds.
This paper presents a new methodology for the design of a MUP based on technical, environmental,
social and economic criteria. The methodology consists of four steps: a pre-screening phase, to assess the
feasibility of different maritime uses at the site; a preliminary design of the alternative schemes based on
the identified maritime uses; a ranking phase, where the performance of the MUPs is scored by means of
expert judgment of the selected criteria; a preliminary design of the selected MUP selected.
An example application of this procedure to a site offshore the Western Sardinia coast, Mediterranean
Sea, Italy, is provided. In this site the deployment of a MUP consisting of wave energy converters, offshore
wind turbines and aquaculture is specifically investigated.
Operation and maintenance can jeopardise the financial viability of an offshore wind energy project due to the cost of downtime, repairs and, above all, the inevitable uncertainties. The variability of wave climate can impede or hinder emergency repairs when a failure occurs, and the resulting delays imply additional costs which ultimately reduce the competitiveness of offshore wind energy as an alternative to fossil fuels. Co-located wind turbines and Wave Energy Converters (WECs) are proposed in this paper as a novel solution: the reduction of the significant wave height brought about by the WECs along the periphery of the wind farm results in a milder wave climate within the farm. This reduction, also called shadow effect, enlarges weather windows for Operation & Maintenance (O&M). The objective of this paper is to investigate the increase in the accessibility time to the turbines and to optimise the layout for the co-located wind-wave farm in order to maximise this time. The investigation is carried out through a case study: Alpha Ventus, an operating offshore wind farm. To maximise the reduction of wave height in the turbine area no fewer than 15 layouts are tested using high-resolution numerical modelling, and a sensitivity analysis is conducted. The results show that, thanks to the wave energy extraction by the WECs, weather windows (access time) can increase very significantly – over 80%. This substantial effect, together with other benefits from the combination of wave and offshore wind power in a co-located farm (common electrical infrastructures, shared O&M equipment and crews, etc.) will enhance the economic viability of these marine renewables, and hence their potential to reduce our carbon footprint on the planet.
Given the significant water-energy problems associated with many remote and arid areas of the planet, most studies, projects and developments of installations for the production of fresh water using desalination technologies powered by renewable energy sources have focussed on small-scale stand-alone systems. The most commonly used energy sources have been solar photovoltaic and wind and the most widely applied desalination technology that of reverse osmosis (RO). Most of the systems use batteries as a means of mass energy storage and the RO plants normally operate at constant pressure and flow rate. This paper presents a small-scale prototype SWRO (seawater reverse osmosis) desalination plant designed to continuously adapt its energy consumption to the variable power supplied by a wind turbine (WT), dispensing with mass energy storage in batteries and proposing the use of a supercapacitor bank as a dynamic regulation system. A description is given of the tests performed to date with the SWRO desalination plant connected to the conventional grid while controlling the number of pressure vessels that are connected/disconnected to/from the system and regulating their operating pressures and flow rates (within predetermined admissible limits) to maintain a constant permeate recovery rate and adapt the energy consumption of the plant to a widely varying simulated wind energy supply. One of the most important conclusions that can be drawn from the studies undertaken is the feasibility of adapting the consumption of the prototype of the SWRO desalination plant to widely varying WT-generated power. Despite using various time interval lengths in which it was assumed that the WT output power remained constant, a perfect fit was not obtained between the theoretical WT-generated power and the power consumed by the SWRO desalination plant, nor was it possible to maintain a constant permeate recovery rate at each instant.
Faced with the challenge of meeting high water and energy demands with no conventional energy resources and a lack of potable water, the Canary Islands have been using desalination plants for nearly 50 years. The first desalination plant in Europe was installed in 1964 in Lanzarote. Today, desalination capacity in the islands stands at over 600,000 m3/d (covering 55% of water demand). Powering the plants consumes nearly 12% of total electricity demand at a cost of over 200 million Euros yearly. Though desalination continues to be the main way of meeting water demand, its major drawback is the strong dependence on conventional energy. The islands have always looked for reducing the energy consumption in desalination processes. This paper describes the relationship between energy and desalinated water and its evolution in the islands over the past 50 years, examining the trends in energy efficiency and the technological changes in the desalination systems, which also explains the predominance of reverse osmosis plants in the current scenario. A series of case studies describe various challenging desalination projects (including operating data) that have been installed in the Canary Islands.
The island of Tenerife, a UNESCO Biosphere Reserve in the Atlantic Ocean, aims to be energy self-sufficient in order to reduce its carbon footprint. To accomplish this goal it should develop the renewable sources, in particular wave and offshore wind energy. The objectives of this work are twofold; (i) to characterize the wave and offshore wind power distribution around the island and (ii) to determine which offshore area is best suited for their exploitation, taking into account the resource and other conditioning factors such as the bathymetry, distance to the coastline and ports, and offshore zoning. To carry out this research, hindcast wave and wind data obtained with numerical models are used alongside observations from meteorological stations. One area, in the vicinity of Puerto de la Cruz, is identified as having great potential for installing a hybrid floating wave-wind farm. Both resources are characterized for the area selected: the wave resource in terms of wave directions, significant wave heights and energy periods; the offshore wind resource in terms of directions and speeds in addition to the seasonality for the both resources. It is found that most of the wave resource is provided by N and NNW waves with significant wave heights between 1.5 m and 3.0 m and energy periods between 10 s and 14 s. It follows that the Wave Energy Converters deployed in the area should have maximum efficiency in those ranges. As for the offshore wind resource, most of the energy corresponds to NNE and NE winds with speeds between 9 and 14 ms–1, which should be taken into account when selecting the offshore wind turbines.
