Preface Energy is acting as wheels for the national economic development and its progress. Rapid industrialization, infrastructural growth, population increase and our expanding economy have stressed the need to acquire additional sources of energy. However, conventional energy reserves are finite in shape and will only be available for a limited period and with steadily increasing price. The fossil fuels use is also linked to environmental problems particularly global warming and climate change. The challenges of the present energy scene offer us a window of opportunity in the form of renewable energy sources to reduce dependency on fossil fuels by expanding and diversifying our energy supply mix and shifting the development part towards sustainability as well as environmental and social responsibility. To achieve this objective, the knowledge of basics and fundamentals of renewable energy technology is essential. In this context, this book presents a systematic collection of all aspects of renewable energy resources & devices. This book is a ready reference material for students from a wide variety of engineering and science backgrounds wish to study the engineering aspects of renewable energy engineering. Number of examples has been included in the text for better understanding of matter. The contents of book include seven major aspects of non- conventional energy sources such as solar energy, solar thermal energy technology and devices, solar photovoltaic technology, biomass production, utilization and management, gasification technology, wind energy and other renewable energy sources such as geothermal, ocean energy etc. This book has been divided into seventeen chapters which cover wide spectrum of renewable energy engineering. Most of the information presented in this book reflects a basis to acquire the understanding of the renewable energy sources. In this book, all fundamentals, design, present state of art of technology and future prospective are illustrated through graphs, figures, tables, flowchart, equations etc. to make subject clear and useful.

1.1 General Renewable technologies are considered to be clean sources of energy. The optimal use of these resources minimize environmental impacts, produce minimum secondary wastes, and are sustainable based on current and future economic and social needs. Sustainable development requires methods and tools to measure and compare human activities’ and its environmental impacts for various products. Renewable energy sources (RES), which include biomass, hydropower, geothermal, solar, wind, and marine energies, supply 14% of the world’s total energy demand. Renewable resources refer to primary, domestic, and clean or inexhaustible energy resources. Large-scale hydropower energy supplies 20 % of the global electricity need. Wind power in coastal and other windy regions is a promising source of energy. Renewable energy resources can make a decisive contribution to the economic, social and sustainable development of rural regions in developing countries, yet the consumption of fossil fuels is dramatically increasing along with improvements in the quality of life, the industrialization of developing nations, and the increase of the world’s population. It has long been recognized that excessive consumption of fossil fuel leads not only to a diminishing fossil fuel reserves more quickly, but also has a significant adverse impact on the environment. Such impacts result in increased health risks and the threat of global climate change. Changes to improve environmental conditions are becoming more politically acceptable globally, especially in developed countries. Society is slowly moving towards seeking more sustainable production methods, minimizing waste, reducing air pollution from vehicles, generating distributed energy, conserving of native forests, and reducing greenhouse gas emissions. Increasing consumption of fossil fuel to meet out current energy demands, however, has sounded alarms over regarding potential energy crisis. This has generated a resurgence of interest in promoting renewable alternatives to meet the developing world’s growing energy needs. Excessive use of fossil fuels has caused global warming from carbon dioxide emissions, therefore, promoting renewable forms of clean energy is eagerly required. To monitor the level of these greenhouse gas emissions, an agreement that has fulfills the objectives of the Kyoto Protocol was create with overall pollution prevention targets.

2.1 Introduction The name thermodynamics stems from the Greek words therme (heat) and dynamis (power), which is most descriptive of the early efforts to convert heat into power. It may be defined as the science that deals with the relations among heat, work and properties of a system. Today, thermodynamics is broadly interpreted to include all aspects of energy and energy transformations, including power generation, refrigeration, and relationships among the properties of matter. It is viewed as the science of energy, and thermal engineering is concerned with making the best use of available energy resources. Thermodynamics basically entails four laws or axioms known as Zeroth, First, Second and Third law of thermodynamics. The zeroth law deals with thermal equilibrium and establishes a concept of temperature. The first law pertains to the conservation of energy and introduces the concept of internal energy. The second law indicates the limit of converting heat into work and introduces the concept of entropy. The third law defines the absolute zero of entropy. The concept of energy was introduced by Newton in the field of mechanics during generalizing the hypothesis of kinetic and potential energies. Energy may be defined as the capacity to do work and it is a scalar quantity. It cannot be seen or observed. Its presence can, however, be felt by the properties of the system. There occurs a change in one or more properties of the system in case of energy transfer. The absolute value of energy of a system is difficult to measure, whereas the energy change is rather easy to calculate. Energy follows the conservation law, one of the most fundamental laws of nature, which simply states that during an interaction, energy can change its form from one form to another but the total amount of energy remains constant, that is, energy cannot be created or destroyed only form can be changed.

3.1 The Sun The Sun is a star. It is a huge, spinning, glowing sphere of hot gas. It appears so much larger and brighter than the other stars because we are so close to it. The Sun is the center of our Solar System and contains most of the mass in the Solar System. All of the planets in our Solar System, including Earth, orbit around the Sun. In sun the energy generation is a multi-step process of thermo-nuclear fusion reactions. In the thermo nuclear fusion hydrogen (four protons) combines to form helium (one helium nucleus). The mass of the helium nucleus is less than that of four hydrogen protons and mass having been lost in the reaction is converted to energy. The reaction is represented as

4.1 Introduction Heat is energy which flows due to difference in temperature. Whereas energy is stored heat. Therefore, when the heat energy transfer is completed. It is stored in the form of potential or kinetic energy, in general as internal energy. Heat as energy is measured in terms of observed changes in other forms of energy & other physical properties. A heat transfer analysis is required for estimating the size, the efficiency and cost of the equipment necessary to transfer a specified amount of heat in a given time. It is well known fact that the size of a solar collector or a heat exchanger depends not so much on the amount of heat to be transmitted but rather on the rate at which heat is to be transferred under given conditions. 4.2 Modes of Heat Transfer Heat is transferred from one body to another in three possible ways, conduction, convection, and radiation.

5.1 Introduction Energy in the form of heat is one of the main energy requirements in domestic, agricultural, industrial and commercial sector of our economy. From an enduse point of view, solar thermal energy finds its application in these areas. Solar thermal energy devices convert radiant energy of the sun into thermal energy for different productive works. In fact, solar energy consists of infrared radiation, it is characteristics of infrared radiation that whenever it falls on any object, it converts into thermal heat energy. The conversion of sun light into thermal energy is easily or conveniently achieved by means of a metallic or plastic cover, painted black with ordinary black board paint or having selected coating over it and covered with one- or double-glazing cover for transmitting solar radiation inside it. This metallic cover is known as absorber, below it either channels or pipes or passages for allowing entry of water or air are provided, through which heat energy is transferred to working medium either air or water. The absorber plate is covered with suitable thickness of insulating material on its back or sides for preventing loss of heat from the absorber plate. This complete system is enclosed in an airtight box. When exposed to solar radiations, the blackened metallic surface absorbs solar energy and converts into heat. This heat could be used for cooking of food, heating of water and air, evaporation of moisture form the grains etc. In fact, absorber works on the principle of black body, which absorbs maximum and a good absorber, is a good emitter. Hence generated heat could be utilized for different applications.

6.1. Introduction Solar crop drying has been demonstrated to be cost effective and an effective alternative to traditional and mechanical drying systems, especially in location with god sunshine during the harvest season. Considerable energy savings can be made with open sun drying since the source of energy is free and sustainable. However, this method of drying is extremely weather dependent and has the problems of contamination, infestation, microbial attacks, etc., thus affecting the product quality. Additionally, the drying time required for a given commodity can be quite long and results in post-harvest losses. Solar drying of agricultural products in enclosed structures by natural convection is an attractive way of reducing post harvest losses and low quality of dried products associated with traditional sun-drying methods. The crop is vulnerable to damage due to hostile weather conditions. The crop is also susceptible to re-absorption of moisture, if it is kept on the ground during periods of no sun, which reduces its quality. This type of problem can be solved by solar dryer. Many dryers have been developed and used to dry agricultural product in order to improve shelf life .Most of these either use expensive sources of energy such as electricity or combination of solar energy and some other form of energy which is not cost effective and dependent on regular supply of fuel. Principally, drying requires temperature for removing moisture from product, air flow rate to remove moisture from drying chamber and optimum relative humidity within the drying chamber to allow fast drying. These all three requirements for drying can easily be achieved from solar energy. Solar drying is one of the direct applications of solar heat, which involves removal of moisture from the products through the application of solar energy. The removal of moisture requires only low temperature heating, which can be met easily by absorbing solar energy by the surface. This increases the temperature of the air inside the dryer. The moisture produced from the drying product is usually carried out along with the exhaust air. The characteristic of solar energy is good for the drying at low temperature i.e. high flow rates with low temperature rise. The intermittent nature of solar radiation can not affect the drying performance at low temperature. Further, solar energy is available at the site of use and saves transportation cost.

7.1 Introduction A greenhouse is quasi-permanent structure, covered with a transparent or translucent material, ranging from simple homemade designs to sophisticated pre-g\fabricated structures, wherein the environment could be modified suitable for propagation or growing of plants. Materials used to construct a greenhouse frame may be wood, bamboo and steel or even aluminum. Covering can be glass or various rigid or flexible plastic materials. Depending on the covering material, different terminology have been used in the context of greenhouse structures as mentioned below: Glasshouse: A greenhouse with glass as the covering material is called glasshouse Polyhouse: It is a greenhouse with polyethylene as the covering material.

8.1 Introduction Solar energy can be directly converted into electrical energy. Energy conversion devices which are used to convert sun light into electricity by use of the photovoltaic effect are called solar cells. The advantages of solar cells are: 1.They are reliable, convenient and durable. 2.It is green, sustainable and pollution free technology. 3.Directly solar radiation can be converted into electricity (conversion of global solar light by flat plate photovoltaic). 4.Maintenance cost is quite low therefore suitable even in isolated and remote area, since no moving parts are involved. 5.Solar cells are quite compatible with almost all environments, respond instantaneously with solar radiation. 6.Considerable expected lifetime i.e. 20 years or even more.

9.1 Introduction Basically, for heating or cooling the space using solar energy, the solar energy is to be collected, stored and distributed properly in the space to be heated or removed from the space to be cooled. There are two basic approaches for solar houses, there are: (a)Active solar house technology (b)Passive solar house technology In active approach, the solar energy is collected and stored in some separate solar energy collector and then energy is distributed in the space where heating is to be done using electrically operated pumps and fans coupled with radiator etc. The storage of solar energy in active solar house may be in the form of storage as sensible heat or storage as latent heat or chemical heat storage. As per requirement of heating the size of solar collector and storage system be decided. Generally, the active concepts of solar houses are used for heating purpose. Active concept can also be used for space cooling applications. Solar vapor compression and absorption system can be used for this purpose, essentially, this includes incorporation of solar heat collectors, thermal storage system, auxiliary heat supply system (to compensate intermittent nature of sun energy) and control systems. Further, there are three ways of solar space heating i.e. solar air systems, solar liquid systems and solar heat pump systems.

10.1 Introduction Winds are the motion of air around the Earth. This movement in air is caused by the uneven heating of the planet’s surface by the sun. The idea of using wind as a form of power is not new. The traditional applications of wind were primarily as sources of kinetic energy for rural, agricultural and a limited number of industrial uses such as pumping water and grinding grain. Presently wind energy can be used for two major applications, such as wind mills for pumping water for drinking as well as for irrigation purposes and second application is as aero-generator for electricity generation for domestic and industrial uses. In addition to this, presently wind energy battery charger are also available, which can store energy for lights, radio communication, hospital equipment and to power various emergencyrelated equipment. The wind energy has an enormous resource, but the problems of utilizing the winds are many and varied. Wind energy is very diffuse in nature and local topographical features significantly alter the prevailing winds, thus leading to the extremely site specific nature of wind energy. Scientists have estimated that as much as 10% of the world’s electricity could be prepared by wind generators by the middle of 21 century. India has estimated wind power potential of 40,000 MW. India now, ranks fourth in the world in wind power generation. The world’s largest wind farms are in California (USA), where wind turbines can generate power up to about 1120 MW. The first wind mill used as source of electric power was built in Denmark in 1890.

11.1 General Biogas is generated through a process of anaerobic digestion of organic materials. The materials normally used are human and animal waste, crop residues, agro-industrial waste and other biomass in a combination with water. Biogas production technology contributes in following ways: (a)It provides a better and cheaper fuel for cooking, lighting and for power generation. (b)It produces good quality, enriched manure to improve soil fertility. (c)It provides and effective and convenient ways for sanitary disposal of human excreta, improving the hygienic conditions. (d)It generates social benefits such as reducing burden on forest for meeting cooking fuel by cutting of tree for fuelwood, reduction in the drudgery of women and children etc. (e)As a smokeless domestic fuel, it reduces the incidence of eye and lung disease. (f)It also helps in generation of productive employment. The biogas technology is primarily based on fermentation of cellulosic rich organic matter under anaerobic conditions. The methane producing bacteria become more active after the creation of anaerobic conditions, thus, the gas produced become rich in methane & carbon dioxide, beside traces of hydrogen sulphide, ammonia, oxygen, water vapour etc. depending on the feed material and other conditions. For burning of gas, it is necessary that methane contents should be more than 50 per cent. The complete knowledge of process of methane production including its chemistry, physiology, bio-chemistry, micro-biology and bacteriology has been studied over years in many parts of the world. The culture and isolation of microbes under various environmental conditions have been successfully experimented to improve rate of reaction. The conditions, under which cattle dung, organic wastes, bushes, weeds etc. will produce methane, can be understood through chemistry of fermentation.

12.1 General The term “biomass” generally refers to renewable organic matter generated by plants through photosynthesis. Materials having organic combustible matter is also referred under biomass. Biomass is an important fuel source in our overall energy scenario. Biomass is produced through chemical storage of solar energy in plants and other organic matter as a result of photosynthesis. During this process conversion of solar energy in sugar and starch, which are energy rich compounds takes place. The chemical reaction of photosynthesis can be written as: 6CO2 + 6H2 O + sun light → C6 H12 O6 + 6O2 + 636kcal It indicates that the storage of 636 kcal is associated with the transfer of 72 gm carbon into organic matter. Biomass can be directly utilized as fuel or can be converted through different routes into useful forms of fuel. In fact, biomass is a source of five useful agents, which start with `F’ like Food, Fodder, Fuel, Fiber and Fertilizer. Further, biomass has many advantages like.

13.1 Introduction Geothermal energy is the nature-based heat generated from within the earth. Underneath the earth’s relatively thin crust, temperature range from 1000 to 4000°C & in some areas, pressures exceed 138 MPa is available. Geothermal energy is most likely generated from radioactive thorium, potassium and uranium dispersed evenly throughout the earth’s interior which produce heat as part of the decaying process. This process generates enough heating, keep the core of the earth at temperature approaching 400°C. Composed primarily of molten nickel & iron, the core is thought to be surrounded by a layer of molten rock, the mantle at approximately 100°C. Nine major crustal plates float on the mantle & currents in the mantle cause the plates to drift, colliding in some areas and diverting in others. When two continental plates converge a complex series of chemicals in the form of molten magna rises in the earth’s crust and depending upon its magnitude, it may break the crust and reach at the earth surface. Volcano, hot spring, geysers & fumaroles are natural geothermal resources near the surface and perhaps where economic drilling operations can tap their heat and pressure.

14.1 Introduction Hydro-electric power is electricity produced by the movement of fresh water from rivers and lakes. Gravity causes water to flow downwards and this downward motion of water contains kinetic energy, that can be converted into mechanical energy, and then from mechanical energy into electrical energy in hydro-electric power stations. (“Hydro” comes from the Greek word hydra, meaning water). At a good site hydro-electricity can generate very cost-effective electricity.

15.1 Introduction The oceans cover 71% of the earth’s surface and it acts a natural collector and store of solar energy. On an average day, 60 million sq. km. of tropical seas absorb an amount of solar radiation equivalent in heat content to about 245 billion barrels of oil, if this energy could be trapped, large scale renewable source becomes available especially for tropical countries. The energy available in the ocean is clean, continuous throughout the year and renewable. Renewable energy contribution to the available energy resources is very important to the country as it is presently facing an energy resources crunch. Out of the total installed capacity of approximately 370.106 GW as on March 2020, Renewable Power Plants including hydro-electric plant contribute 35.86 % of total installed capacity. However, with the present increase in demand, more attention is required to extract the renewable sources so that at least 50 to 60 % share for the total energy requirement by the renewable energy sources. There are various forms of ocean energy such as Ocean Thermal Energy Conversion (OTEC), Wave Energy, Tidal Energy, Salinity Gradient Energy, Offshore Wind Energy, Marine Currents, Marine Biomass Conversion. Among these, the first three forms are likely to be technically viable for the future. More recently Ministry of New and Renewable Energy (MNRE), Government of India hasdeclared Ocean Energy as renewable energy, and clarified to all the stakeholders that energy produced using various forms of ocean energy such as tidal, wave, ocean thermal energy conversion among others shall be considered as renewable energy. MNRE reported that, the total identified potential of tidal energy is about 8000 - 9000 MW, with about 7000 MW in the Gulf of Cambay in Gujarat, about 1200 MW in Gulf of Kutch and less than 100 MW in Sundarbans. Primary estimates of wave energy potential along Indian coast are about 5 – 15 MW/m, so that theoretical estimates are around 40 – 60 GW. Ocean Thermal Energy Conversion (OTEC) has a theoretical potential of 180,000 MW in India subject to suitable technological evolution. As of date, there is not any installed Ocean Energy capacity in India.

16.1 Fuel Cell Fuel cell is an electrochemical device that convert chemical energy of a reaction directly into electrical energy. The basic physical structure of a fuel cell consists of an electrolyte layer in contact with a porous anode and cathode on either side. A schematic representation of a fuel cell with the reactant or product gases and the ion conduction flow directions through the cell is shown in Fig. 16.1

17.1 Introduction It is well known fact that planners as well as end users have to consider any resources as technology from economic point of view. Therefore, it is important to have techno – economic analysis of each energy source option. In the feasibility study of particular energy option, three tier judgment approaches is required, which include technical feasibility, economical viability and social acceptability. Hence in the rural energy planning programme one has to considered techno socio economic analysis of an individual energy option. Since in integrated rural energy planning, locally available energy resources are used, presuming that it is socially recognized. Hence in the IREP project, the need and scope of techno economic analysis in terms of economic analysis of different technical feasible options, before between “economic” and “finical” analysis should be kept in mind. An economic analysis is needed to verify that a particular energy source will provide “net benefit” to society as a whole, before its final integration in the energy context, while a financial analysis integrated in the energy practices. In simple words, a financial analysis is concerned with goods and services, money inflow and outflows and the transfer of payments. An economic analysis also considers the social benefits and costs of goods and services which are not traded in a market.

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