What is energy?In physics, energy is defined as the capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, atomic, or various other forms. There are, heat and work—i.e., energy in the process of transfer from one body to another. After it has been transferred, energy is always designated according to its nature. Hence, heat transferred may become thermal energy, while work done may manifest itself in the form of mechanical energy. All forms of energy are associated with motion. For example, any given body has kinetic energy if it is in motion. A tensioned device such as a bow, spring, or water storage reservoir, though at rest, has the potential for creating motion; it contains potential energy because of its configuration. Similarly, atomic energy is potential energy because it results from the configuration of subatomic particles in the nucleus of an atom. Thermal or heat energy comes from the vibration of atoms as energy is absorbed through emitted photons from electromagnetic radiation. Energy can be converted from one form to another in various ways. Usable mechanical or electrical energy is, for instance, produced by many kinds of devices, including fuel-burning heat engines, generators, batteries, fuel cells, and magnetohydrodynamics systems. Energy can be neither created nor destroyed but can be converted from one form to another and energy and mass are different manifestations of the same thing and each can be converted to the other form in the proportion of E=mc2
Conservation of Mass and Energy LawThe Law of Conservation of Energy states that energy cannot be created or destroyed, but can change its form. The total quantity of matter and energy available in the universe is a fixed amount and never any more or less. The law of conservation of mass or matter, also known as the Lomonosov-Lavoisier law, states that the mass of substances in a closed system will remain constant, no matter what processes are acting inside the system. It is a different way of stating that though matter may change form, it can be neither created nor destroyed. The mass of the reactants must always equal the mass of the products. This law works fine for anything that is not approaching the speed of light; at high speeds, mass begins transforming to energy (for which reason, we now have the Law of Conservation of Mass and Energy). However, this means that in most situations the law of conservation of mass can be assumed valid using standard Newtonian based classical physics. However the mass–energy relation of E=mc2 states that the universal proportionality factor between equivalent amounts of energy and mass is equal to the velocity of light squared. This also serves to convert units of mass to units of energy, no matter what system of measurement units is used. This law was first formulated by Antoine Lavoisier in 1789, but Mikhail Lomonosov in 1748 had also expressed similar ideas earlier. It was the key to making chemistry into a real science instead of an offshoot of alchemy; prior to this, buoyancy of gases made it difficult to determine before and after measurements of weight. In nuclear reactions and in very large astronomical objects, this law becomes questionable. After this, the ideas of chemical elements, process of fire and oxidation, and many other basic chemical principles could be understood. One of the first conservation laws to be discovered was the conservation of mass (or matter). Suppose that you combine a very accurately weighed amount of iron (Fe) and sulfur (S) with each other. The product of that reaction is a compound known as iron sulfide or FeS. If you also weigh very accurately the amount of iron sulfide formed in that reaction, you will discover a simple relationship: The weight of the beginning materials (iron plus sulfur) is exactly equal to the weight of the product or products of the reaction (iron sulfide). This statement is one way to express the law of conservation of mass. A more formal definition of the law is that mass (or matter) cannot be created or destroyed in a chemical reaction. A similar law exists for energy. When you turn on an electric heater, electrical energy is converted to heat energy. If you measure the amount of electricity supplied to the heater and the amount of heat produced by the heater, you will find the amounts are equal. In other words, energy is conserved in the heater. It may take various forms, such as electrical energy, heat, magnetism, or kinetic energy (the energy of an object due to its motion), but the relationship is always the same: The amount of energy used to initiate a change is the same as the amount of energy detected at the end of the change. In other words, energy cannot be created or destroyed in a physical or chemical change. This statement summarizes the law of conservation of energy. At one time, scientists thought that the law of conservation of mass and the law of conservation of energy were two distinct laws. In the early part of the twentieth century, Albert Einstein (1879–1955) demonstrated that matter and energy are two forms of the same thing. He showed that matter can change into energy and that energy can change into matter. Einstein’s discovery required a restatement of the laws of conservation of mass and energy. In some instances, a tiny bit of matter can be created or destroyed in a change. The quantity is too small to be measured by ordinary instruments, but it still amounts to something. Similarly, a small amount of energy can be created or destroyed in a change. But, the total amount of matter PLUS energy before and after a change still remains constant. This statement is now accepted as the law of conservation of mass and energy. Einstein went on to express the relationship between energy and mass as E=MC2, where E is energy, M is mass and C is the velocity of light (299.8 million meters per second) Squared or 8.98 X 1016. Because C2 is such a big number, this means a very small amount of mass can be converted into a huge amount of energy. This is why fission and fusion produce so much power from so little “fuel.” Examples of the law of conservation of mass and energy are common in everyday life. The manufacturer of an electric heater can tell consumers how much heat will be produced by a given model of heater. The amount of heat produced is determined by the amount of electrical current that goes into the heater. Similarly, the amount of gasoline that can be formed in the breakdown of petroleum can be calculated by the amount of petroleum used in the process. And the amount of nuclear energy produced by a nuclear power plant can be calculated by the amount of uranium-235 used in the plant. Calculations such as these are never quite as simple as they sound. We think of an electric light bulb, for example, as a way of changing electrical energy into light. Yet, more than 90 percent of that electricity is actually converted to heat. (Baby chicks are kept warm by the heat of light bulbs.) Still, the conservation law holds true. The total amount of energy produced in a light bulb (heat plus light) is equal to the total amount of energy put into the bulb in the form of electricity. In an automobile internal combustion engine, heat is produced by the combustion reaction of gasoline and oxygen which pushes a piston down when the mixture of oxygen and fuel rapidly expands which, in turn, is coupled to a crank shaft which turns and is coupled to the wheels. Modern gasoline engines have a maximum thermal efficiency of about 25% to 30% when used to power a car. In other words, even when the engine is operating at its point of maximum thermal efficiency, of the total heat energy released by the gasoline consumed, about 70-75% is rejected as heat without being turned into useful work, i.e. turning the crankshaft. Approximately half of this rejected heat is carried away by the exhaust gases, and half passes through the cylinder walls or cylinder head into the engine cooling system, and is passed to the atmosphere via the cooling system radiator. Some of the work generated is also lost as friction, noise, air turbulence, and work used to turn engine equipment and appliances such as water and oil pumps and the electrical generator, leaving only about 25-30% of the energy released by the fuel consumed available to move the vehicle. Today, fission, coal, natural gas and oil fired electricity plants work by heating water (or in some cases salts) to its vapor point and using that heat energy to turn an electrical generator motor.
Where does today’s energy to convert to electricity come from?
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Coal fired power plant schematic
Electricity is actually the flow or movement of electrons through a material. An electron is a sub-atomic particle. Electric generating plants typically produce electricity using magnetic induction & conduction. This happens when a large number of conductive wires are spun around inside a magnetic field, causing electrons to move in those wires thereby generating electricity.
In a generating plant, the potential energy of various types of fuels such as coal, natural gas, oil, nuclear and concentrated solar energy is converted into mechanical energy using heat energy to produce the mechanical energy. This mechanical energy is used to turn fan-like blades inside a turbine. These blades are attached to a pole-like shaft. When the blades inside the turbine begin to turn, the shaft begins to turn. This causes wires located inside a magnetic field within the generator to turn. The resulting flow of electrons is electricity. More or less electricity can be created by varying certain factors including: the type of materials used in the wire, the speed at which the turbine rotates, the size of the magnetic field, and the number of wire coils inside the magnetic field, among others.
Wires coming from the generator are used to conduct the flow of electricity out to a neighboring switchyard, where the electricity is “stepped up” or raised to a much higher voltage using transformers so that it can be sent to customers over the transmission and distribution grid.
Steam-electric plants produce electricity by using heat energy to turn water into steam. The highly pressurized steam then travels through pipes to the blades in the turbine. When the steam hits the turbine, it causes the blades to spin.
Hydroelectric generating facilities use mechanical energy from the movement of water to cause the blades in the turbine to turn.
In a steam-electric solar generating facility, heat from the sun’s rays is used to create the steam that is needed to rotate the turbine.
The generator portion of the plants is virtually the same regardless if it is driven by water at a dam, coal, oil, natural gas, nuclear, or concentrated solar.