2. Exertion of vigor or power: "I have this project which is requiring a great deal of time and energy."
3. Vitality and intensity of expression; forcefulness of expression; such as, a speech delivered with energy and emotion.
4. Usable heat or power.
5. A source of usable power; such as, petroleum or coal.
6. In physics, the capacity to do work; the property of a system that diminishes when the system does work on any other system, by an amount equal to the work so done; potential energy.
Forms of energy include heat, light, sound, electricity, and chemical energy. Energy and work are measured in the same units—foot-pounds, joules, ergs, or some other, depending on the system of measurement being used. When a force acts on a body, the work performed (and the energy expended) is the product of the force and the distance over which it is exerted.
First recorded in 1599, from Middle French energie, from Late Latin energia, which was from Greek energeia, "efficiency, activity, operation" came from energos, "active, working" from en-, "at" + ergon, "work". Used by Aristotle with a sense of "force of expression"; the broader meaning of "power" was first recorded in English in 1665. To energize; that is, "rouse to activity" is from 1753; energetic of people, institutions, etc., is from 1796. The term energy crisis was first recorded in 1970.
Such a system can substitute for furnaces, air conditioners, etc. within the district's individual buildings.
2. The energy constituent in a circuit because of its position in relation to a magnetic field.
3. The energy of electric charges or currents because of their positions in an electric field.
4. The integral with respect to time of the instantaneous power input or power output of a circuit or appliance.
The basic unit is the watthour.
By definition, power is the rate at which energy is transformed or is made available and is measured in watthours.
From an economic viewpoint, the most important of all electrical measurements is the measurement of energy. The watthour meter in various forms can be found in nearly every home, factory, highway billboard, and other locations where electrical energy is being purchased.
Metering, installation and wiring have been governed by national, industrial, and local codes for so many years that, at least in the United States, a particular type of installation is nearly identical everywhere in the country.
Measurement of energy is almost always with a "fixed-installation metering". This provides safety because of the grounding of the meter enclosure and ease of reading as a result of a proper location and mounting.
Tamper-proof housing, which are also weatherproof where necessary, are typical structures that normally insure the integrity of the electric meter readings.
2. The energy inherent in a circuit because of its position in relation to a magnetic field.
2. Energy which is possessed by electric charges because of their positions in an electrostatic field.
2. The energy required to release an electron from its atomic or molecular orbital.
2. A quantum-mechanical concept for energy levels of electrons around the nucleus.
Electron energies are functions of each particular atomic species.
The study of the distribution of energy that is lost by scattered electrons when a substance is bombarded with monochromatic electrons.
2. A technique for studying atoms, solids, or molecules in which a substance is bombarded with monochromatic electrons, and the energies of scattered electrons are measured to determine the distribution of energy loss.2. A graph of the energy of a diatomic (two atoms) molecule in a given electronic state as a function of the distance between the nuclei of the atoms.
2. The potential energy that a collection of electric charges have as indicated by their positions as they relate to each other.
2. The direct conversion of electric energy into heat energy, as in an electric heater.
The main systems are the Steam (Rankine) Cycle and the Gas Turbine (Brayton Cycle).
- Steam (Rankine) Cycle is an ideal thermodynamic cycle that consists of four processes:
- Heat transfer to the system at constant pressure.
- An expansion at constant entropy.
- A constant-pressure heat transfer from the system.
- A compression at constant entropy; used as a standard of efficiency.
- Gas Turbine (Brayton) Cycle, an ideal gas cycle used as a standard for the actual performance of a simple gas turbine, consisting of four processes:
- A reversible adiabatic (no heat transfer) compression at constant entropy.
- A heat transfer at constant pressure up to the maximum temperature.
- An adiabatic expansion at constant entropy back to the original pressure.
- A heat transfer at constant pressure back to the original volume and entropy.
- Entropy in thermodynamics is a measure of the disorder or randomness of a closed system; more entropy means less energy is available for doing work.
The total entropy of an isolated system cannot decrease when the system undergoes a change; it can remain constant for reversible processes, and will increase for irreversible ones.
Geothermal energy is produced by tapping the Earth's internal heat. At present, the only available technologies to do this are those that extract heat from hydrothermal convection systems, where water or steam transfer the heat from the deeper part of the Earth to the areas where the energy can be tapped.
The amount of pollutants found in geothermal vary from area to area but may contain arsenic, boron, selenium, lead, cadmium, and fluorides. They also may contain hydrogen sulphide, mercury, ammonia, radon, carbon dioxide, and methane.
Getting the Earth's Heat
Geothermal power plants, which tap hot subterranean water or steam, are high on the lists of at least thirty states in the U.S. which are requiring utility companies to generate some portion of their electricity from such renewable sources.
Most utilities have not pursued geothermal energy primarily because up-front costs, including exploratory drilling, can be expensive since geothermal taps deep reservoirs, not groundwater, which collects much closer to the surface.
An extensive study recently released by the Massachusetts Institute of Technology has shown that the heat available under ground is surprisingly plentiful nationwide.
More information about special Geothermal Energy sources.
2. A spectrometric technique that uses a beam of ions of high kinetic energy passing through a field-free reaction chamber from which ionic products are collected and energy analyzed.
It is a generalization of metastable ion studies in which both uni-molecular and bi-molecular reactions are investigated.
2. The energy required o remove completely the weakest bound electron from its ground state in an atom or molecule so that the resulting ion is also in its ground state.
3. Amount of energy required to remove an electron from an isolated atom or molecule.
There is an ionization potential for each successive electron removed, though that associated with removing the first (most loosely held) electron is most commonly used.
The ionization potential of an element is a measure of its ability to enter into chemical reactions requiring ion formation or donation of electrons and is related to the nature of the chemical bonding in the compounds formed by elements.
In air the value is approximately 33.73 electron volts.
2. In the larger sense, any energy source that can be ultimately traced to the action of the sun.
Solar thermal energy can be used for such applications as, space heating, air conditioning, hot water, industrial process heat, drying, distillation and desalination, and electrical power.
This waste-to-energy is possible, and convenient, when the heat generated by burning the "waste" is high enough to warrant satisfactory combustion conditions and to make enough energy available to overcome losses and auxiliary consumption.
Characteristics of waste-to-energy production
- Waste-to-energy is the offspring of the incineration of materials, which were originally introduced to sterilize and to reduce the volume of useless substances by burning it in a furnace.
- Modern waste-to-energy plants allow the export of energy, with very low environmental impact.
- The waste-to-energy plant consists of four basic sections: waste combustor, recovery boiler, flue gas treatment, and steam cycle.
- The design of the combustor varies widely with the waste characteristics: physical state (solid versus liquid), size distribution, heating value, ash and moisture content, etc.
- Municipal solid waste is typically burned on a moving grate, where it is kept 20-30 minutes until it is completely burned.
- The hot gases generated in the combustor go through the recovery boiler to generate steam, which is used directly as a heat carrier or it is sent to a steam turbine to produce power.
- Flue gases are treated by adding reactants called sorbents and by filtering the particulate matter.
- A modern, large plant, treating a half-million tons of municipal solid waste per year, can generate more than 400 million kWh per year, meeting the electricity needs of more than 150,000 families.
Waste-to-energy is the process in which municipal waste is used to generate useful energy for electricity, heat, or both.
Energy has several forms, some of which are easily convertible and can be changed to another form useful for work.
Most of the world's convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks.
Electrical energy is usually measured in kilowatt hours, while heat energy is usually measured in British thermal units (Btu).
These changes can be physical or chemical, and allow energy to be converted to another form; for example, the chemical energy of fuel is converted into heat and then into mechanical energy in an engine.
2. A measure of the electrostatic potential of the barrier.
The energy capacity of a given cell varies with temperature, rate, age, and cut-off voltage. This term is more common to system designers than it is to the battery industry where capacity usually refers to ampere-hours.
The three main applications for battery energy storage systems include spinning reserve at generating stations, load leveling at substations, and peak shaving on the customer side of the meter.
Electric energy is measured in kilowatt hours.
"Femtosecond lasers are the fastest in the world and are capable of producing energy pulses that last a millionth of a billionth of a second and can be focused into beams less than one hundredth the diameter of a human hair."
Lists of words about Energy Sources and additional information.
To make a moving car stop, all its kinetic energy must be converted into other forms by heating up the brakes, for example.
A car at the top of a hill has potential energy because of its position. It can turn its potential energy into kinetic energy by going down the slope.
The Solar Energy Technologies Program focuses on developing cost-effective solar-energy technologies that have the greatest potential to benefit the nation and the world.
Solar technologies diversify the energy supply, reduce the country's dependence on imported fuels, improve air quality, and offset greenhouse gas emissions. A growing solar industry also stimulates the economy by creating jobs in solar manufacturing and installation.
It has been proposed as a storage option to support large-scale use of photovoltaics as a means to smooth out fluctuations in power generation.
Wind energy uses the energy in the wind for practical purposes like generating electricity, charging batteries, pumping water, or grinding grain.
Turbines are perched on high towers, usually 100 feet or higher, and often placed in large groups, or "farms", to generate electricity to towns and cities.
On a much smaller scale, stand-alone turbines are sometimes used by farmers and homeowners to generate supplemental electricity.
In the past twenty years, U.S. government incentives in the form of tax credits to producers and incentives for homeowners have helped to lower the price of wind power by an estimated eighty-five percent, making it a more feasible option.
There are people who object to wind farms because of their appearance or the noise the turbines make. Wind power raises few other environmental problems except danger to birds.
There is also a problem with having a consistent generation of electricity with wind energy because of the of the unknown features of the weather. Sometimes the wind is simply non-active.