Use, Operation and Maintenance of Renewable Energy Systems

Wind is an attractive source of renewable energy, and its use has become increasingly important over the last decades all around the world. After this explosion of installations of wind farms, an important concern has arisen concerning several topics in which the goals are to keep the value of the assets of the wind farms and to guarantee long life cycles. The continuous monitoring of the life of the wind turbines and a correct application of maintenance plan contribute to achieving these goals. This chapter first reviews the main principles supporting different strategies of maintenance, later a framework is presented integrating different aspects of the lives of the wind turbine, and finally some methods for the detection of abnormal behavior in wind turbines and for failure risk evaluation are presented applied to some real cases.

As in any power plant, a solar power plant in operation requires maintenance. Also, as the solar power plant becomes older, operation and maintenance (O&M) becomes more and more important for improving or keeping the performance of the plant. Another aspect to be taken into account is that usually the solar power plants are in remote locations with unreliable communication infrastructure [1]. Most of the remote monitoring systems need an Internet connection, and in the absence of a reliable connection, there could be problems of lack of data logging for long periods of time [6]. This makes it very difficult to diagnose and rectify problems in a timely manner. System O&M is a broad area and is the continuing focus of several industry/government/national laboratory working groups. These groups will better define the issues and develop consensus O&M approaches over the next few years. This chapter reviews the main principles of solar generation from a perspective of O&M of these plants.

There is some confusion between “biogas” and “producer gas”, “syngas”, “pyrolysis gas” and similar gaseous products obtained from biological or organic materials by thermal processes. (1) Biogas (a mixture of methane (CH₄—natural gas) and carbon dioxide (CO₂), also known as marsh gas) is obtained from moist organic material by microbial processes, in fact it is so natural it occurs in our own stomachs as well as in other animal’s digestive systems (particularly ruminants like cattle), marshes, mud, the Arctic Tundra and even volcanoes—anywhere air is absent. (2) Thermal processes can also be used to gasify combustible material in reduced oxygen, resulting in a mixture of gases that often includes carbon monoxide (CO)—a very toxic gas. Gasification is better applied to dry materials like wood and was used in World War Two, when petrol was rationed, to power vehicles by fitting a “gasifier” to the car/truck to make “producer gas”. In this chapter, we will look briefly at the long history of biogas, take an overview of the microbial process, cover some of the different types of digesters and look at building, starting and operating a simple type of digester, including fault finding.

This chapter elaborates the different concepts of biogas technology understood in the Danish context. It emphasizes how energy from production of biogas is distributed, either as biogas to regional combined heat and power plants (CHP) or as district heating (DH) to small-scale local networks. The chapter provides an overview of the political situation and a historical outline of the development of the Danish biogas sector; it also presents the biogas process and operational aspects (e.g., the production of biogas, use of manure, and industrial waste as gas boosters). Advantages of biogas technology are emphasized: its capacity as a renewable energy and GHG-avoiding technology, and as a waste processing and environmental technology. It is argued that biogas can provide a future platform for the use of household waste and other types of organic materials (gas boosters) to enhance gas yield, as is the case of biomass from nature conservation, straw, deep litter, etc. Further, the chapter discusses whether or not biogas technology can create new job opportunities in rural areas that lack development. Economic results from operating centralized biogas plants in Denmark now also stress the importance of developing new gas boosters to support a further development of the biogas sector. The chapter ends with a discussion of new trends in biogas production, for example, how new organizational models can be designed as well as how the use of alternative boosters—like blue biomass—can be applied. Finally, biogas is discussed in the global and European contexts and emphasis is given to the need for digesting organic waste in combination with manure to provide valuable nutrients to farmland and also for enhancing the energy services provided by the biogas technology.

Owners of wind parks often outsource operation and maintenance (O&M) of their assets. This chapter addresses the fundamental negotiating issues of wind turbine O&M contracts. We develop a conceptual mathematical framework to support the analysis and design of O&M contracts. The framework is used to investigate mechanisms through which incentives perceived by O&M contractors can be aligned with the objectives of wind park owners in both the short and the long terms. This alignment ensures that the negotiated contracts are part of a general strategy for maximizing the value extracted from wind turbines over their lifetime.

Wind power generation has become a significant component of the generation portfolio in a number of power systems worldwide. Moreover, the development of wind generation will be continued as the implementation of policies aimed at fighting the climate change requires the increase of use of renewable energy sources in power generation. Grid integration is a major issue that affects the massive development of wind generation. This chapter discusses how generator technology affects grid integration of wind generation. Wind generators based on squirrel cage and doubly fed induction machines and multi-pole synchronous machines will be reviewed. The performance with respect to stability, load-frequency and reactive power–voltage control is discussed.

This chapter is dedicated to introducing the control methods used in renewable energy sources. The conventional and innovative energy generation methods are explained according to their historical background in the initial section. The power electronic circuits that are widely known by most of the readers are briefly analysed in Sect. 2 where the circuit topologies and design criteria are also addressed. The control methods of power electronics used in renewable energy sources such as solar, wind, and fuel cells are comprehensively explained in the following sections. The maximum power point tracking (MPPT) that is the essential part of solar power systems is introduced by means of software and hardware. On the other hand, the required circuit topologies of current control method are explained with grid-connected and island-mode operations of a solar energy system. The rest of the chapter consists of renewable energy systems based on wind turbine and fuel cells. The wind turbine dynamics are initially introduced to create a link through the power electronics and control methods. The control methods of fixed and variable wind turbines are explained regarding to current and voltage control requirements. The fuel cell-based renewable energy systems and control methods are also explained in the last section of the chapter.

This chapter is focused on research and development of low-cost technologies for attending small and medium energetic demands. The results of such development are related to the use of hybrid systems combining different sources of renewable energy (RE). To obtain the smallest cost of a system, it is necessary to obtain the smallest cost of each one of their parts and a better control strategy integrating the operation of these parts. Besides, it is necessary to obtain the best project than it relates the best cost so much benefit in relation to installation as for operation and maintenance. In this chapter, the constituent elements of a hybrid system will be presented initially, followed by a presentation of the technological progresses of these elements. Later the control strategies will be explained to obtain the maximum efficiency of these elements and connection arrangements among them. Finally, project methodologies will be presented for the optimization of the sizing of a project of hybrid system, and they will be described through examples of their application.

Power electronics is the enabling technology for maximizing the power captured from renewable electrical generation, e.g., the wind and solar technology, and also for an efficient integration into the grid. Therefore, it is important that the power electronics are reliable and do not have too many failures during operation which otherwise will increase cost for operation, maintenance and reputation. Typically, power electronics in renewable electrical generation has to be designed for 20–30 years of operation, and in order to do that, it is crucial to know about the mission profile of the power electronics technology as well as to know how the power electronics technology is loaded in terms of temperature and other stressors relevant, to reliability. Hence, this chapter will show the basics of power electronics technology for renewable energy systems, describe the mission profile of the technology and demonstrate how the power electronics is loaded under different stressors. Further, some systematic methods to design the power electronics technology for reliability will be given and demonstrated with two cases—one is a wind power and the other is photovoltaic application.

Renewable energy sources (RES) used in small-scale distributed generation systems are a promising alternative for additional energy supply toward smarter and more sustainable cities. However, their proper integration as new infrastructures of the smart city (SMCT) requires understanding the SMCT architecture and promoting changes to the existing regulation, business models, and power grid topology and operation, constituting a new challenging energy supply paradigm. This chapter addresses the use of renewable energy systems on small scale, oriented to distributed generation (DG) for households or districts, integrated in an SMCT. In this context, the main renewable energies and companion technologies are reviewed, and their profitability investigated to highlight their current economic feasibility. A simplified architecture for SMCT development is presented, consisting of three interconnected layers, the intelligence layer, the communication layer, and the infrastructure layer. The integration and impact of distributed renewable energy generation and storage technologies in this architecture is analyzed. Special attention is paid to the grid topology for their technical and efficient integration, and to the business models for facilitating their economic integration and feasibility.

This chapter analyzes the medium-term operation of a power system in several future scenarios that differ in the level of penetration of electric vehicles (EVs) and how renewable energy sources (RES) can be safely integrated in the former. The analysis is performed for different vehicle charging strategies (namely dumb, multi-tariff, and smart). The analysis is based on results produced by an operation model of the electric power system where the charging of EVs is being considered. Vehicles are regarded as additional loads whose features depend on the mobility pattern. The operation model employed is a combination of an optimization-based planning problem used to determine the optimal day-ahead system operation and a Monte Carlo simulation to consider the stochastic events that may happen after the planning step. The Spanish electric system deemed to exist in 2020 is used as the base-case study for conducting the numerical analyses. Relationships among the share of EVs (relative to the overall number of vehicles), the amount of RES generation integrated, and relevant system performance indicators, such as operation cost, reliability measures, and RES curtailment, are derived in the case study section.