You need to know certain basic concepts and terminology related to energy for understanding energy accounting, viz., different forms of energy, the units for measuring energy and their conversion. This is what we discuss in this section.
It is not unusual to hear colleagues, friends or family members say “I’ve got no energy today” when they don’t feel up to completing an assignment, playing games or washing dishes! This everyday expression is pretty close to the scientific definition of energy, which is given below:
It is not unusual to hear colleagues, friends or family members say “I’ve got no energy today” when they don’t feel up to completing an assignment, playing games or washing dishes! This everyday expression is pretty close to the scientific definition of energy, which is given below:
ENERY IS DEFINED AS CAPACITY TO DO WORK
We use energy for everything we do in our lives – right from using our muscles to lighting up our homes, travelling to work, running machines, building houses, and so on (Fig.).
 |
| Use of Energy for Diverse Purposes |
In the power generation sector, energy is needed to run turbines that move the electric generators. For example, in thermal power plants, coal is burnt to heat water and produce steam, which, in turn, moves the turbine. In hydropower plants, the mechanical energy of water is used to move turbines. The turbine is connected to a generator that produces electricity. The electricity is transmitted to our homes and is used to run appliances that provide us light and heat. All these are different forms of energy.
Forms of Energy
Energy exists in different forms: mechanical, thermal, chemical, electrical,electromagnetic energy (e.g., light, X-rays, radio waves, etc.), sound,nuclear energy, etc. You will also come across the terms kinetic energy and potential energy (Fig.). We now explain these terms with the help of specific examples relevant to the power sector.The kinetic energy of an object is the energy possessed by it due to its motion. All material bodies in motion, for example, waves, wind, water in a stream, and the steam turning the turbine in a power plant possess kinetic energy.
Forms of Energy
Energy exists in different forms: mechanical, thermal, chemical, electrical,electromagnetic energy (e.g., light, X-rays, radio waves, etc.), sound,nuclear energy, etc. You will also come across the terms kinetic energy and potential energy (Fig.). We now explain these terms with the help of specific examples relevant to the power sector.The kinetic energy of an object is the energy possessed by it due to its motion. All material bodies in motion, for example, waves, wind, water in a stream, and the steam turning the turbine in a power plant possess kinetic energy.
 |
| Different Forms of Energy |
 |
| Examples of Different Forms of Energy |
The potential energy of an object is the energy possessed by an object due to its position or the arrangement of its parts. For example, water stored in a dam possesses potential energy; charges stored in a capacitor possess potential energy.
In Fig., the box possesses potential energy by virtue of its position at a certain height above the ground. If the rope is cut and the box falls down as shown in Fig., its potential energy is converted into its kinetic energy. In Table, we explain the different forms of energy and give examples relevant to the the power sector.
In relation to energy, you also need to understand that energy can neither be created nor destroyed. It is a law of nature that the total amount of energy in the universe remains constant.Our experience makes it seem that energy has been ‘consumed’ or ‘lost’ in a process. For example, when a battery runs out, or a gas cylinder is used up,what happens is that energy is converted or transformed from one form to another. For instance, the chemical energy of batteries is converted into electrical energy. This, in turn, gets converted into light and heat energy of the torch bulb, which is transferred to the surroundings. Thus, the chemical energy stored in the battery gets transformed to other forms of energy and is ultimately radiated into the environment. It exists there but we can no longer make use of it. We then say that it is ‘lost’ to the system of ‘torch and battery’. Let us take another example: In a hydropower plant, the potential energy of water stored in a dam is converted into the kinetic energy of falling water, which is transferred to the turbine. The kinetic energy of the turbine, in turn, is transformed into electrical energy by a generator.
When we talk about “generation” and “consumption” of energy, what we are actually describing is the conversion of one form of energy to another. In Fig., we show how energy is transformed from one form to another at various stages beginning from power generation in a thermal power plant to its transmission, distribution and a specific end-use. Notice that the chemical energy of coal gets converted through combustion into thermal energy,which is used to produce steam. The kinetic energy of steam is transferred to the turbine. The turbine is connected to a generator, which produces electricity. Depending on the end-use, electrical energy is transformed into heat, light or mechanical energy of machines and appliances You should also know the units used for measuring energy to be able to understand the discussion on energy accounting.
Units of Energy
There are many ways of measuring energy. We will talk about the ones relevant to our discussion. Most electrical appliances have a certain power rating, for example, a 60 W light bulb or a 1 kW room heater. It is, therefore, very common to measure electrical energy consumption in terms of power and time.
Power is the rate at which energy is used:
Power = Energy / Time or Energy = Power × Time
The unit of energy relevant for you at the moment is kilowatt-hour (kWh).
It is the energy consumed in one hour by an electrical equipment of 1 kW (1000 W) rating. This is one unit of electrical energy measured by the meter.
In relation to energy, you also need to understand that energy can neither be created nor destroyed. It is a law of nature that the total amount of energy in the universe remains constant.Our experience makes it seem that energy has been ‘consumed’ or ‘lost’ in a process. For example, when a battery runs out, or a gas cylinder is used up,what happens is that energy is converted or transformed from one form to another. For instance, the chemical energy of batteries is converted into electrical energy. This, in turn, gets converted into light and heat energy of the torch bulb, which is transferred to the surroundings. Thus, the chemical energy stored in the battery gets transformed to other forms of energy and is ultimately radiated into the environment. It exists there but we can no longer make use of it. We then say that it is ‘lost’ to the system of ‘torch and battery’. Let us take another example: In a hydropower plant, the potential energy of water stored in a dam is converted into the kinetic energy of falling water, which is transferred to the turbine. The kinetic energy of the turbine, in turn, is transformed into electrical energy by a generator.
When we talk about “generation” and “consumption” of energy, what we are actually describing is the conversion of one form of energy to another. In Fig., we show how energy is transformed from one form to another at various stages beginning from power generation in a thermal power plant to its transmission, distribution and a specific end-use. Notice that the chemical energy of coal gets converted through combustion into thermal energy,which is used to produce steam. The kinetic energy of steam is transferred to the turbine. The turbine is connected to a generator, which produces electricity. Depending on the end-use, electrical energy is transformed into heat, light or mechanical energy of machines and appliances You should also know the units used for measuring energy to be able to understand the discussion on energy accounting.
Units of Energy
There are many ways of measuring energy. We will talk about the ones relevant to our discussion. Most electrical appliances have a certain power rating, for example, a 60 W light bulb or a 1 kW room heater. It is, therefore, very common to measure electrical energy consumption in terms of power and time.
Power is the rate at which energy is used:
Power = Energy / Time or Energy = Power × Time
The unit of energy relevant for you at the moment is kilowatt-hour (kWh).
It is the energy consumed in one hour by an electrical equipment of 1 kW (1000 W) rating. This is one unit of electrical energy measured by the meter.
 |
| Conversion of Energy Units |
The usage of energy units varies from industry to industry and one equipment manufacturer to another. Table gives conversions of some energy units.
Before we end this section, we would like to emphasise that the term Energy Accounting applies to all forms of energy derived from various sources, e.g.,from Natural Gas, Other Fuels, Water, Sewer, Solid Waste, etc. For instance,you could keep an account of your car petrol consumption and compare it with the standard consumption to establish the maintenance practice for your car.However, in this unit we will focus on energy accounting for the electricity sector. We now introduce the concept of energy accounting.
No comments:
Post a Comment