This chapter provide an introduction to the uses of renewable energy, followed by a description of the various types of solar collectors, such as solar thermal (ST) collectors (flat-plate, evacuated tube, compound parabolic, parabolic trough, Fresnel lens, parabolic dish collectors and central receiver tower), photovoltaic (PV) collectors, and photovoltaic thermal (PV/T) hybrid collectors, including the calculation of their efficiency. A short description of the ST system (including water heating, space heating, solar combi system, and solar DHS) and solar PV and PV/T system components is provided; their operation principle and some calculation elements are also discussed, and an energy analysis of solar space heating systems is included. A general description of geothermal energy, including its classification, in terms of thermal potential, and problems of exploitation of geothermal systems concerning heat extraction, regeneration and geothermal water treatment, is addressed. A synthesis of the primary direct (heat production for central and local heating systems and cascading systems) and indirect (power generation) uses of geothermal resources, along with recent technological advances in this field, is also included. Additionally, biomass energy is presented, encompassing biomass resources generated through photosynthesis and bioenergy technologies. The main biomass conversion processes are described, including thermal (combustion, gasification, and pyrolysis), biological (anaerobic digestion and fermentation), thermochemical (hydrothermal liquefaction and catalytic fast pyrolysis), and biochemical (enzymatic hydrolysis and gasification to biofuels) processes. A significant amount of information is provided on the valorisation of hydraulic energy, with a particular focus on water energy. This information includes the operating principle, components, and calculation of the basic parameters of hydraulic turbines for water energy conversion. In addition, the possibility of recovering excess pressure from DHSs using pumps as microturbines, converting the potential energy of thermal wastewater discharged by surface water heat pumps (SWHPs) into electricity, as well as converting the potential energy of rainwater from very tall buildings into electricity by installing Pelton microturbines at the base of the drain columns, is shown. The fundamental theoretical concepts for converting wind energy into mechanical and electrical energy are presented. After their classification, the operating principle, the main components, and some calculation elements of the basic parameters for a wind turbine are discussed. Evaluating energy losses in a variable speed conversion system is also addressed. Finally, this chapter also includes information on integrating solar thermal, geothermal, and biomass energy into DHSs, summarising the advantages and disadvantages of these energy sources.

Renewable Energy Sources

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发表日期：

2026年

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Ioan Sarbu,
Alexandru Dorca

摘要

This chapter provide an introduction to the uses of renewable energy, followed by a description of the various types of solar collectors, such as solar thermal (ST) collectors (flat-plate, evacuated tube, compound parabolic, parabolic trough, Fresnel lens, parabolic dish collectors and central receiver tower), photovoltaic (PV) collectors, and photovoltaic thermal (PV/T) hybrid collectors, including the calculation of their efficiency. A short description of the ST system (including water heating, space heating, solar combi system, and solar DHS) and solar PV and PV/T system components is provided; their operation principle and some calculation elements are also discussed, and an energy analysis of solar space heating systems is included. A general description of geothermal energy, including its classification, in terms of thermal potential, and problems of exploitation of geothermal systems concerning heat extraction, regeneration and geothermal water treatment, is addressed. A synthesis of the primary direct (heat production for central and local heating systems and cascading systems) and indirect (power generation) uses of geothermal resources, along with recent technological advances in this field, is also included. Additionally, biomass energy is presented, encompassing biomass resources generated through photosynthesis and bioenergy technologies. The main biomass conversion processes are described, including thermal (combustion, gasification, and pyrolysis), biological (anaerobic digestion and fermentation), thermochemical (hydrothermal liquefaction and catalytic fast pyrolysis), and biochemical (enzymatic hydrolysis and gasification to biofuels) processes. A significant amount of information is provided on the valorisation of hydraulic energy, with a particular focus on water energy. This information includes the operating principle, components, and calculation of the basic parameters of hydraulic turbines for water energy conversion. In addition, the possibility of recovering excess pressure from DHSs using pumps as microturbines, converting the potential energy of thermal wastewater discharged by surface water heat pumps (SWHPs) into electricity, as well as converting the potential energy of rainwater from very tall buildings into electricity by installing Pelton microturbines at the base of the drain columns, is shown. The fundamental theoretical concepts for converting wind energy into mechanical and electrical energy are presented. After their classification, the operating principle, the main components, and some calculation elements of the basic parameters for a wind turbine are discussed. Evaluating energy losses in a variable speed conversion system is also addressed. Finally, this chapter also includes information on integrating solar thermal, geothermal, and biomass energy into DHSs, summarising the advantages and disadvantages of these energy sources.