Physics and technology – Technology – Energy Technology
Since the discovery of fire, techniques for producing and consuming energy have been growing more efficient and complex. Early sources of energy included the sun, wood, and water power. During the industrial revolution, coal and electricity were added, followed by nuclear energy in the 1950s.
Today, the dwindling of fossil fuel reserves is spurring the development of new technology that uses renewable energy sources. The main uses of energy include heating, transportation, producing electricity, and operating machinery.
Physics and technology – Technology – Energy Production, transport, and storage
A modern communications-based society with high mobility depends upon universally available energy. A wide range of technology is used to fulfill this demand.
Energy can be present in a multitude of forms. For example, it can be stored chemically in gasoline and then made available for use through the process of combustion. A pendulum already set in motion has kinetic energy, while a tensed spring has potential energy. Electricity is considered one of the most useful forms of energy, since it can be transported efficiently and is used for a wide variety of applications.
Energy production and use From the perspective of physics, all technological devices that produce or use energy can be viewed as energy transformers. Energy production refers to the process of converting energy from a natural resource, such as coal, into a form that can be easily used by the general public, such as electricity.
The resulting energy can then be employed for a particular application, such as to start up and run a computer.
Transporting energy
Energy must be transported to make it available where it is most needed. To transport electricity, copper cables in the form of high-tension wires are used. When electricity flows through a conductor (in this case a wire), the resistance of the conductor leads to a loss in energy.
The wire itself “uses” electricity by converting some of the electrical energy to heat. Therefore, in order to minimize these losses, energy is transformed into a different state. Low voltage electricity is converted to a higher voltage and lower current, so that power can be efficiently transported to the desired destination.
Energy loss during transformation
In whichever form energy is being transported, the second law of thermodynamics states that energy transformations usually involve a loss of some of the energy. For instance, kinetic energy can be transported using gears, belts, or chains.
However, at the same time a portion of the kinetic energy is converted through friction into unwanted heat energy. Radiation energy is lost through dissipation; even a pendulum releases energy in the form of heat as it is slowed by friction and air resistance.
Energy storage
Apart from making transportation easier, storing energy can also be useful for other reasons, such as saving energy for use whenever and wherever it is needed. Electricity can be stored electrochemically in batteries or dry cells, or as a charge within a capacitor.
Transformation into and back from other forms of energy offers a multitude of additional possibilities. For example, if energy is used to lift water with a pump, the result is stored potential energy in the form of increased water pressure.
DRY CELLS AND BATTERIES
Dry cells and batteries store chemical energy. The once popular low-performing nickel-cadmium batteries are now widely banned for environmental reasons. High-performance lithium-ion batteries power laptops and cell phones are powerful mobile energy storage units.
Because they are economically and environmentally friendly, rechargeable batteries are popular. They must be recharged with special devices, or they can overload, catch fire, or even explode.