Renewable Energy Dictionary


Alternative Fuels: A popular term for “non-conventional” transportation fuels derived from natural gas 
Alternator: A generator producing alternating current by the rotation of its rotor, and which is powered by a primary mover.
BioDiesel Refers to a diesel-equivalent, processed fuel derived from biological
(propane, compressed natural gas, methanol, etc.) or biomass materials (ethanol, methanol).
sources (such as), vegetable-oils which can be used in unmodified
diesel-engined vehicles.
Biomass Energy Energy from the burning of agricultural, forestry, and other organic
material (including landfill gas, digester gas, and municipal solid waste)
Calorie: The unit used to measure heat energy in the metric system. A calorie (small c) is the amount of energy it takes to raise the temperature of one gram of water by one degree Celsius. A Calorie (large C) is the amount of energy it takes to raise the temperature of one kilogram of water by one degree Celsius. The energy content of food is expressed in Calories.
Carbon Footprint A representation of the effect human activities have on the climate in
terms of the total amount of greenhouse gases produced (measured in
units of carbon dioxide).
Carbon Dioxide (CO2): Carbon dioxide is produced when fossil fuels are burned. It is also a naturally occurring gas that is taken up by plants. CO2 contributes to theGreenhouse Effect.
Carbon Tax A tax on energy sources which emit carbon dioxide into the
atmosphere. It is an example of a pollution tax.
Conductors: Materials that electrons travel through freely. The best Conductors are metals such as copper which are used to make the wires that conduct Electric Current from generation facilities to consumers. Water, people, animals, trees and the ground can also beConductors.
CFC’s: Chloro-Fluoro-Carbons, chemicals that are circulated in air conditioners and refrigerators to transfer heat from one location (usually inside a room or container) to another (usually the outdoors). CFC’s were used in aerosol cans but this is now illegal in the United States because they contribute to the Greenhouse Effect.
CFL Compact Fluorescent Lamp – relatively efficient lightbulbs, using about
25% of the power of incandescent lightbulbs, for the same light output.
It typically screws into a standard light socket.
Co-generation The simultaneous production by means of a single source of useful
energy (usually electricity) and heat (eg process steam) than can then
be recovered for use as additional energy.
Climate change A statistically significant difference noted either in the mean state of the
climate or in its variability persisting for an extended period of time.
Presently, climate change is thought to be caused by human activity,
the most prominent being the generation of energy.
DME The National Department of Minerals and Energy in South Africa.
Efficiency: The amount of useful Work done by a given amount of Energy. An efficient light bulb uses most of its energy to produce light, not heat. An efficient car goes many miles on one gallon. An efficient refrigerator uses less electricity to keep food just as cool. An efficient power plant produces more electricity from the coal or oil it burns or wind, sun and water it harnesses and creates less heat and pollution in the process.
Electric Current: The movement of electrons through a material. Electric Current is measured in units of Amps. See also Conductors and Resistors.
Electricity Grid The electricity supply line system.
Emissions: The gases and airborne particles produced during Combustion.
Energy: A measure of the ability to do work. E.g. energy is required to lift a
bucket of water 10 metres, and a certain amount of energy is required
to keep a light bulb alight for 1 hour. Basic unit of measurement is the Joule (J).
Energy Audit: A process whereby the energy use profile of an entity is determined i.e.
amounts of energy used, types of energy used etc.
Energy Efficiency: Using less energy to achieve the same objective, e.g. an energy
efficient air conditioner uses less energy to achieve the same cooling.
Energy Conservation: Measures to avoid the use of energy services.
ESCO: Energy Services Company. A company that specializes in energy
efficiency measures under a contractual arrangement in which the
company shares the value of energy savings with the customer.
Fluorescent Lights: These bulbs produce very little heat while giving off light. Lights that make a phosphor glow. The inside surface of fluorescent bulbs is coated with a special white material called a phosphor. Electric Current is used to energize the atoms in the phosphor so they give off light. Compare with Incandescent Lights.
Fuel Efficiency: The amount of useful Work done when a given amount of fuel is burned. A Fuel Efficient car travels more miles on one gallon of gas than a conventional car.
Fossil Fuel: A fuel such as coal, oil, natural gas, produced from the decomposition
of ancient plants and animals.
Gasification: The process in which a solid fuel is converted into a gas; also known as pyrolitic distillation or pyrolysis. Production of a clean fuel gas makes a wide variety of power options available.
Generator: A device that uses mechanical Energy to create electrical Energy.
Geothermal Energy: Energy produced by the internal heat of the earth; geothermal heat sources include: hydrothermal convective systems; pressurized water reservoirs; hot dry rocks; manual gradients; and magma. Geothermal energy can be used directly for heating or to produce electric power.
Geothermal Heat Pump: A type of heat pump that uses the ground, ground water, or ponds as a heat source and heat sink, rather than outside air. Ground or water temperatures are more constant and are warmer in winter and cooler in summer than air temperatures. Geothermal heat pumps operate more efficiently than “conventional” or “air source” heat pumps.
Gigawatt (GW): A unit of power equal to 1 billion Watts; 1 million kilowatts, or 1,000 Megawatts.
Global Warming: An overall rise in the global temperature presently thought to be faster
than the natural rate, due to human activity (see Climate Change).
Gigajoules: A gigajoule (GJ) is 1,000,000,000 joules. It is a unit of energy.
Greenhouse Effect: What happens when Energy from the sun gets trapped in the atmosphere. Gases like Carbon Dioxide and CFC‘s prevent solar Energy reflected by the earth from escaping into space. In houses or cars, glass or plastic traps heat from the sun, resulting in a small scale Greenhouse Effect.
Greenhouse Gases: Those gases, such as water vapor, carbon dioxide, tropospheric ozone, methane, and low level ozone that are transparent to solar radiation, but opaque to long wave radiation, and which contribute to the greenhouse effect.
Horizontal-Axis Wind Turbines (HAWT): Turbines in which the axis of the rotor’s rotation is parallel to the wind stream and the ground.
Hybrid Renewable Energy System: A renewable energy system that includes two different types of renewable energy technologies that produce the same type of energy; for e.g., a wind turbine and a solar photovoltaic array combined to meet a power demand.
Hydropower: Energy derived at a variety of scales from water pressure, especially the

force or pressure of falling water used to power a water wheel, turbine, and so on.

Incandescent Lights: Light bulbs that use Energy from moving electrons to heat a wire until it glows.
Joule: A metric unit of energy or work; the energy produced by a force of one Newton operating through a distance of one meter; 1 Joule per second equals 1 Watt or 0.737 foot-pounds; 1 Btu equals 1,055 Joules.
Joule’s Law: The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature.
Kilowatt: A unit of electrical Power equal to 1,000 Watts
Kilowatt-hour (kWh): A unit of electrical Energy equal to the amount of Energyconsumed by electrical appliances that use one Kilowatt for a period of one hour. The cost of electrical Energy is expressed in terms of $/kWh.
Lithium-Sulfur Battery: A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight.
Median Wind Speed: The wind speed with 50 percent probability of occurring.
Megawatt: A unit of electrical Power equal to 1,000,000 Watts.
Methane: A colorless, odorless, tasteless gas composed of one molecule of Carbon and four of hydrogen, which is highly flammable. It is the main constituent of “natural gas” that is formed naturally by methanogenic, anaerobic bacteria or can be manufactured, and which is used as a fuel and for manufacturing chemicals.
Methanol (CH3OH; Methyl alcohol or wood alcohol): A clear, colorless, very mobile liquid that is flammable and poisonous; used as a fuel and fuel additive, and to produce chemicals.
Municipal Waste: As defined in the Energy Security Act (P.L. 96-294; 1980) as “any organic matter, including sewage, sewage sludge, and industrial or commercial waste, and mixtures of such matter and inorganic refuse from any publicly or privately operated municipal waste collection or similar disposal system, or from similar waste flows (other than such flows which constitute agricultural wastes or residues, or wood wastes or residues from wood harvesting activities or production of forest products).”
Municipal Solid Waste (MSW): Waste material from households and businesses in a community that is not regulated as hazardous.
Municipal Waste to Energy Project (or Plant): A facility that produces fuel or energy from municipal solid waste.
Nacelle: The cover for the gear box, drive train, generator, and other components of a wind turbine.
Natural Gas: A mixture of hydrocarbon compounds and small quantities of various

non-hydrocarbons, widely used as a fuel throughout the industrialized
world; it exists in the gaseous phase or in solution with crude oil in natural
underground reservoirs.

Nuclear Energy: Energy released by radioactive decay, through a nuclear reaction, or in
the course of fission or fusion of atomic nuclei.
Panemone: A drag-type wind machine that can react to wind from any direction.
Passive Solar Heater: A solar water or space-heating system in which solar energy is collected, and/or moved by natural convection without using pumps or fans. Passive systems are typically integral collector/storage (ICS; or batch collectors) or thermosyphon systems. The major advantage of these systems is that they do not use controls, pumps, sensors, or other mechanical parts, so little or no maintenance is required over the lifetime of the system.
Pellets: Solid fuels made from primarily wood sawdust that is compacted under high pressure to form small (about the size of rabbit feed) pellets for use in a pellet stove.
Pelton Turbine: A type of impulse hydropower turbine where water passes through nozzles and strikes cups arranged on the periphery of a runner, or wheel, which causes the runner to rotate, producing mechanical energy. The runner is fixed on a shaft, and the rotational motion of the turbine is transmitted by the shaft to a generator. Generally used for high head, low flow applications.
Penstock: A component of a hydropower plant; a pipe that delivers water to the turbine.
Phase: Alternating current is carried by conductors and a ground to residential, commercial, or industrial consumers. The waveform of the phase power appears as a single continuous sine wave at the system frequency whose amplitude is the rated voltage of the power.
Photobiological Hydrogen Production: A hydrogen production process that process uses algae. Under certain conditions, the pigments in certain types of algae absorb solar energy. An enzyme in the cell acts as a catalyst to split water molecules. Some of the bacteria produces hydrogen after they grow on a substrate.
Photovoltaic Device: A solid-state electrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the characteristics of the light source and the materials in and design of the device. Solar photovoltaic devices are made of various semi-conductor materials including silicon, cadmium sulfide, cadmium telluride, and gallium arsenide, and in single crystalline, multi-crystalline, or amorphous forms.
Renewable Energy: Energy which can be replenished at the same rate it is used.
Solar Energy: Electromagnetic energy transmitted from the sun (solar radiation). The amount that reaches the earth is equal to one billionth of total solar energy generated, or the equivalent of about 420 trillion kilowatt-hours.
Solar Radiation: All the constituents that make up the total electromagnetic radiation
emitted by the sun.
Solar Thermal Parabolic Dishes: A solar thermal technology that uses a modular mirror system that approximates a parabola and incorporates two-axis tracking to focus the sunlight onto receivers located at the focal point of each dish. The mirror system typically is made from a number of mirror facets, either glass or polymer mirror, or can consist of a single stretched membrane using a polymer mirror. The concentrated sunlight may be used directly by a Stirling, Rankine, or Brayton cycle heat engine at the focal point of the receiver or to heat a working fluid that is piped to a central engine. The primary applications include remote electrification, water pumping, and grid-connected generation.
Sustainability: An attempt to provide the best outcomes for the human and natural
environments both now and into the indefinite future.
Thermoelectric Conversion: The conversion of heat into electricity by the use of thermocouples.
Thermophotovoltaic Cell: A device where sunlight concentrated onto a absorber heats it to a high temperature, and the thermal radiation emitted by the absorber is used as the energy source for a photovoltaic cell that is designed to maximize conversion efficiency at the wavelength of the thermal radiation.
Thermosyphon (Solar) Systems: Thermosyphon systems use a separate storage tank located above the collector. Liquid warmed in the collector rises naturally above the collector, where it is kept until it is needed. The liquid can be either water or a glycol solution. If the fluid is water, freeze protection is provided by electric heat. If the fluid is glycol, the heat from the glycol is transferred to water in the storage tank.
Tidal Power: The power available from the rise and fall of ocean tides. A tidal power plant works on the principal of a dam or barrage that captures water in a basin at the peak of a tidal flow, then directs the water through a hydroelectric turbine as the tide ebbs.
Thermal Energy: The energy developed through the use of heat energy.
Tracking Solar Array: A solar energy array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one axis where the array tracks the sun east to west and (2) two-axis tracking where the array points directly at the sun at all times. Tracking arrays use both the direct and diffuse sunlight. Two-axis tracking arrays capture the maximum possible daily energy.
Turbine: A rotary engine that is turned using the Energy in a moving gas or fluid such as water, wind or steam. Turbines are usually made with a series of curved vanes on a central rotating spindle.
Volt: A unit used to measure the pressure that is available to move electrons. Voltage is like water pressure. Flashlight batteries store electrons at 1.5 Volts, car batteries at 12 Volts. The electricity available from wall outlets has a pressure of 120 Volts behind it.
Watt: A unit used to measure electric Power. The Power rating of an electrical device inWatts expresses the amount of energy the device consumes in one second. Watts are equal to Volts times Amperes.
Wave Power: Energy generated by the oceans’s wave currents, especially windgenerated
Wind Energy: The energy contained in the movement of air masses; in human energy
use traditionally captured by means of the sails of a ship or the vanes of
a windmill, and currently by mechanical blades similar to airplace propellers.
Wind Turbine: A term used for a wind energy conversion device that produces electricity; typically having one, two, or three blades.
Woodgas – a flammable gas produced by burning or heating wood or other biomas in an oxygen starved environment. This gas comprises methane, hydrogen, Co2, Co and nitrogen. Such gas can used in internal combustion engines of generators, boats and cars. Expect up to 1/3rd power loss.

Yaw: The rotation of a horizontal axis wind turbine around its tower or vertical axis.
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