• Energy Research

United Nations SDG 7 is that, by 2030, there will be an affordable, reliable and clean universal access to energy (UAE). To reach this goal, technological and social issues should be considered jointly. In this paper, the approach used by the Non-Governmental Organization “Luces Nuevas Internacional” is presented. Luces Nuevas has successfully provided basic electricity access to sparse rural communities in rural Bolivia. This paper emphasizes the methodological aspects of the approach. The key ingredient to the success is the involvement of all the stakeholders in all steps of the solution. In this way, end users feel the solution as their solution. Therefore, they are willing to use and properly maintain the devices that they buy to obtain electricity access. The case of the Tipas community shows that this approach can provide access to energy to every family that desires it. The experience shows that reaching SDG 7 requires taking into account not only the technological and economic aspects, but also the social aspects of the problem. End users involvement, from the beginning, of an electrification project is key to its success.

United Nations SDG 7 is that, by 2030, there will be an affordable, reliable and clean universal access to energy (UAE). To reach this goal, technological and social issues should be considered jointly. In this paper, the approach used by the Non-Governmental Organization “Luces Nuevas Internacional” is presented. Luces Nuevas has successfully provided basic electricity access to sparse rural communities in rural Bolivia. This paper emphasizes the methodological aspects of the approach. The key ingredient to the success is the involvement of all the stakeholders in all steps of the solution. In this way, end users feel the solution as their solution. Therefore, they are willing to use and properly maintain the devices that they buy to obtain electricity access. The case of the Tipas community shows that this approach can provide access to energy to every family that desires it. The experience shows that reaching SDG 7 requires taking into account not only the technological and economic aspects, but also the social aspects of the problem. End users involvement, from the beginning, of an electrification project is key to its success.

This study presents a new wave energy converter that operates in two phases. During the first phase, wave energy is stored, raising a mass up to a design height. During the second phase, the mass goes down. When going down, it compresses air that moves a turbine that drives an electrical generator. Because of this decoupling, generators that move much faster than seawater can be used. This allows using “off-the-shelf” electrical generators. The performance of the proposed design was evaluated via simulations. As the device operates in two phases, a different simulation model was built for each phase. The mass-rising simulation model assumes regular waves. The simulation results suggest that energy harvesting is near the theoretical maximum. Mass falling is braked by air compression. Simulations of this system showed oscillatory behavior. These oscillations are lightly damped by the drag against the walls and air. These oscillations translate into generated power. Therefore, smoothing is needed to avoid perturbing the grid. A possible solution, in the case of farms comprising dozens of these devices, is to delay the generation among individual devices. In this manner, the combined generation can be significantly smoothed.

This study presents a new wave energy converter that operates in two phases. During the first phase, wave energy is stored, raising a mass up to a design height. During the second phase, the mass goes down. When going down, it compresses air that moves a turbine that drives an electrical generator. Because of this decoupling, generators that move much faster than seawater can be used. This allows using “off-the-shelf” electrical generators. The performance of the proposed design was evaluated via simulations. As the device operates in two phases, a different simulation model was built for each phase. The mass-rising simulation model assumes regular waves. The simulation results suggest that energy harvesting is near the theoretical maximum. Mass falling is braked by air compression. Simulations of this system showed oscillatory behavior. These oscillations are lightly damped by the drag against the walls and air. These oscillations translate into generated power. Therefore, smoothing is needed to avoid perturbing the grid. A possible solution, in the case of farms comprising dozens of these devices, is to delay the generation among individual devices. In this manner, the combined generation can be significantly smoothed.

This paper analyzes the operating efficiency of a hybrid wind–hydro power plant located in El Hierro Island. This plant combines a wind farm (11.48 MW) and a pumped storage power plant (11.32 MW). It was built with the aim of supplying the island demand from renewable energy instead of using existing diesel units. The paper discusses several operational strategies and proposes an efficiency metric. Using 10 min data, the operation of this power plant has been simulated. From these simulations (more than 50,000 for a year), the operating efficiency and the percentage of demand covered from renewable energy is obtained. The difference between the worst and the best strategy is a twofold increase in efficiency. Moreover, the results of the simulations are compared with the system operational history since June 2015 (when the wind–hydro power plant started operation) until 2018. These comparisons show a reasonable agreement between simulations and operational history.

This paper analyzes the operating efficiency of a hybrid wind–hydro power plant located in El Hierro Island. This plant combines a wind farm (11.48 MW) and a pumped storage power plant (11.32 MW). It was built with the aim of supplying the island demand from renewable energy instead of using existing diesel units. The paper discusses several operational strategies and proposes an efficiency metric. Using 10 min data, the operation of this power plant has been simulated. From these simulations (more than 50,000 for a year), the operating efficiency and the percentage of demand covered from renewable energy is obtained. The difference between the worst and the best strategy is a twofold increase in efficiency. Moreover, the results of the simulations are compared with the system operational history since June 2015 (when the wind–hydro power plant started operation) until 2018. These comparisons show a reasonable agreement between simulations and operational history.

Currently, some small islands with high wind potential are trying to reduce the environmental and economic impact of fossil fuels by using renewable resources. Nevertheless, the characteristics of these renewable resources negatively affect the quality of the electrical energy, causing frequency disturbances, especially in isolated systems. In this study, the combined contribution to frequency regulation of variable speed wind turbines (VSWT) and a pump storage hydropower plant (PSHP) is analyzed. Different control strategies, using the kinetic energy stored in the VSWT, are studied: inertial, proportional, and their combination. In general, the gains of the VSWT controller for interconnected systems proposed in the literature are not adequate for isolated systems. Therefore, a methodology to adjust the controllers, based on exhaustive searches, is proposed for each of the control strategies. The control strategies and methodology have been applied to a hybrid wind–hydro power plant on El Hierro Island in the Canary archipelago. At present, in this isolated power system, frequency regulation is only provided by the PSHP and diesel generators. The improvements in the quality of frequency regulation, including the VSWT contribution, have been proven based on simulating different events related to wind speed, or variations in the power demand.