| Rad |
A unit of measure of absorbed radiation. Acronym for radiation absorbed dose. One rad equals 100 ergs of radiation energy per gram of absorbing material. |
| Radiant Barrier |
A device designed to reduce or stop the flow of radiant energy. |
| Radiant Energy |
energy (heat) that is transferred by rays or waves, especially electromagnetic waves, through space or another medium. Radiation. |
| Radiation |
The flow of energy across open space via electromagnetic waves such as light. Passage of heat from one object to another without warming the air space in between. |
| Radiation |
1 The sun’s energy that comes to earth in the form of direct, diffuse, and reflected rays. 2 The transfer of heat through electromagnetic waves, without heating the air between objects. |
| Radio |
The sending or receiving of messages or effects, like sound, by means of electromagnetic waves through the air without a connecting wire. |
| Radioactive Waste |
Materials left over from making nuclear energy. Radioactive waste can damage or destroy living organisms if it is not stored safely. |
| Radiotelephone |
A two-way radio system that enables use of a regular telephone but with radio instead of wires. |
| Rankine Cycle |
The steam-Rankine cycle employing steam turbines has been the mainstay of utility thermal electric power generation for many years. The cycle, as developed over the years uses superheat, reheat and regeneration. Modern steam Rankine systems operate at a cycle top temperature of about 1,073 degrees Celsius with efficiencies of about 40 percent. |
| Raps (Remote Area Power Supply) |
A power generation system used to provide electricity to remote and rural homes, usually incorporating power generated from renewable sources such as solar panels and wind generators, as well as non-renewable sources such as petrol-powered generators. |
| Rate Of Charge |
The amount of energy per unit time that is being added to the battery. Rate of charge is commonly expressed as a ratio of the battery or cell’s rated capacity to charge duration in hours. Example: A C/20 rate on a 100 AH battery would be 5 amps, the capacity of the battery divided by 20. |
| Rate-Basing |
refers to practice by utilities of allotting funds invested in utility Research Development Demonstration and Commercialization and other programs from ratepayers, as opposed to allocating these costs to shareholders. |
| Rated Battery Capacity |
The term used by battery manufacturers to indicate the maximum amount of energy that can be withdrawn from a battery under specified discharge rate and temperature. See battery capacity. |
| Rated Battery Capacity (Ah) |
Term used by battery manufacturers to indicate the maximum amount of energy that can be withdrawn from a battery at a specified discharge rate and temperature. |
| Rated Capacity |
The manufacturer’s specification for the amount of charge that may be stored in a battery, commonly expressed in amp-hours at a specific rate of discharge. |
| Rated Module Current (A) |
The current output of a photovoltaic module measured at standard test conditions of 1,000 w/m2 and 25°C cell temperature. |
| Rated Power |
Nominal power output of an inverter, some units cannot produce rated power continuously. |
| Rated Watt |
The manufacturer’s specification for power output of a generating device. In most cases, this is not the most accurate measure to look at, since it predicts output only for ideal circumstances. |
| RDF (Refuse Derived Fuel) |
The fuel component of municipal solid waste (MSW), which is the by-product of shredding MSW to a uniform size, screening out oversized materials and isolating ferrous material in magnetic separation. The resulting RDF can be burned as a fuel source. |
| Reactive Power |
The sine of the phase angle between the current and voltage waveforms in an AC system. |
| Reactor |
A device in which a controlled nuclear chain reaction can be maintained, producing heat energy. |
| Real-Time Market |
The competitive generation market controlled and coordinated by the ISO for arranging real-time imbalance energy. |
| Real-Time Pricing |
The instantaneous pricing of electricity based on the cost of the electricity available for use at the time the electricity is demanded by the customer. |
| Rechargeable Battery |
A battery that has a reversible chemical reaction to produce electricity, allowing it to be reused many times. |
| Reclaimed Oil |
Lubricating oil that is processed to be used over again. |
| Recombination |
The action of a free electron falling back into a hole. Recombination processes are either radiative, where the energy of recombination results in the emission of a photon, or nonradiative, where the energy of recombination is given to a second electron which then relaxes back to its original energy by emitting phonons. Recombination can take place in the bulk of the semiconductor, at the surfaces, in the junction region, at defects, or between interfaces. |
| Recool |
The sensible cooling of air that has been previously heated by HVAC systems serving the same building. |
| Recovered Energy |
Reused heat or energy that otherwise would be lost. For example, a combined cycle power plant recaptures some of its own waste heat and reuses it to make extra electric power. |
| Recovery Efficiency |
(Thermal efficiency) Ia water heater, a measure of the percentage of heat from the combustion of gas which is transferred to the water as measured under specified test conditions. |
| Rectifier |
A device that converts AC current to DC current. |
| Recycling |
The process of converting into new products materials that are no longer useful as they were originally designed. |
| Refiner |
means any person who owns, operates, or controls the operations of one or more refineries. |
| Refinery |
A facility that separates crude oil into varied oil products. The refinery uses progressive temperature changes to separate by vaporizing the chemical components of crude oil that have different boiling points. These are distilled into usable products such as gasoline, fuel oil, lubricants and kerosene. |
| Reformulated Gasoline (RFG) |
A cleaner-burning gasoline that has had its compositions and/or characteristics altered to reduce vehicular emissions of pollutants. |
| Refrigerant |
A fluid such as freon that is used in cooling devices to absorb heat from surrounding air or liquids as it evaporates. |
| Regulation |
The service provided by generating units equipped and operating with automatic generation controls that enables the units to respond to the ISO’s direct digital control signals to match real-time demand and resources, consistent with establsihed operating criteria. |
| Regulator |
A device that prevents overcharging of batteries by controlling the charge cycle, and usually adjustable to conform to specific battery needs. Regulators do not step the voltage down, but control the rate of charge so the battery stays at a specified voltage. Also called CHARGE CONTROLLER. |
| Regulatory Must-Run Generation |
Utilities will be allowed to generate electricity when hydro resources are spilled for fish releases, irrigation, and agricultural purposes, and to generate power that is required by federal or state laws, regulations, or jurisdictional authorities. Such requirements include hydrological flow requirements, irrigation and water supply, solid-waste generation, or other generation contracts in effect on December 20, 1995. |
| Reheat |
The heating of air that has been previously cooled either by mechanical refrigeration or economizer cooling systems. |
| Reid Vapor Pressure (RVP) |
a standard measurement of a liquid’s vapor pressure in pounds per square inch at 100 degrees Fahrenheit. It is an indication of the propensity of the liquid to evaporate. |
| Reliability |
Electric system reliability has two components– adequacy and security. Adequacy is the ability of the electric system to supply the aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to withstand sudden disturbances such as electric short circuits or unanticipated loss of system facilities. |
| Reliability Must Run Unit |
In return for payment, the ISO may call upon the owner of a generating unit to run the unit when required for grid reliability. |
| Remote Site |
A site with no electrical utility grid connection. |
| Remote Systems |
See stand-alone systems. |
| Renewable Energy |
Energy derived from resources that are regenerative or that cannot be depleted. Types of renewable energy resources include wind, solar, biomass, geothermal, and moving water. |
| Renewable Resource |
a resource that can be used continuously without being used up (because it regenerates itself within a useful amount of |
| Renewable Resources |
Renewable energy resources are naturally replenishable, but flow-limited. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Some (such as geothermal and biomass) may be stock-limited in that stocks are depleted by use, but on a time scale of decades, or perhaps centuries, they can probably be replenished. Renewable energy resources include: biomass, hydro, geothermal, solar and wind. In the future they could also include the use of ocean thermal, wave, and tidal action technologies. Utility renewable resource applications include bulk electricity generation, on-site electricity generation, distributed electricity generation, non-grid-connected generation, and demand-reduction (energy efficiency) technologies. |
| Reregulation |
The design and implementation of regulatory practices to be applied to the remaining regulated entities after restructuring of the vertically-integrated electric utility. The remaining regulated entities would be those that continue to exhibit characteristics of a natural monopoly, where imperfections in the market prevent the realization of more competitive results, and where, in light of other policy considerations, competitive results are unsatisfactory in one or more respects. Reregulation could employ the same or different regulatory practices as those used before restructuring. |
| Reserve |
The extra generating capability that an electric utility needs, above and beyond the highest demand level it is required to supply to meet its users¼ needs. |
| Reserve Capacity |
The amount of generating capacity a central power system must maintain to meet peak loads. |
| Reserve Generating Capacity |
The amount of power that can be produced at a given point in time by generating units that are kept available in case of special need. This capacity may be used when unusually high power demand occurs, or when other generating units are off-line for maintenance, repair or refueling. |
| Reserve Margin |
The differences between the dependable capacity of a utility’s system and the anticipated peak load for a specified period. |
| Residential Building |
means any hotel, motel, apartment house, lodging house, single and dwelling, or other residential building which is heated or mechanically cooled. |
| Residue |
any organic matter left as residue, such as agricultural and forestry residue, including, but not limited to, conifer thinnings, dead and dying trees, commercial hardwood, noncommercial hardwoods and softwoods, chaparral, burn, mill, agricultural field, and industrial residues, and manure. |
| Resistance |
Refers to how well a material conducts a flow of electrons, measured in ohms (Ω). Resistance is the property of materials to impede a flow of electrons through the material. All materials have some resistance. Those of low resistance are known as conductors, while those of high resistance are known as insulators. The unit used to measure resistance is the Ohm (Ω). |
| Resistance (Electrical) |
The ability of all conductors of electricity to resist the flow of current, turning some of it into heat. Resistance depends on the cross section of the conductor (the smaller the cross section, the greater the resistance) and its temperature (the hotter the cross section, the greater its resistance). |
| Resistance (R) |
The property of a conductor, which opposes the flow of an electric current resulting in the generation of heat in the conducting material. The measure of the resistance of a given conductor is the electromotive force needed for a unit current flow. The unit of resistance is ohms. |
| Resistance (Thermal) |
The Reciprocal Of Thermal Conductance. See R-Value. |
| Resistive Voltage Drop |
The voltage developed across a cell by the current flow through the resistance of the cell which may result from the bulk resistance of the materials in the cell and at interfaces between them. |
| Resistor |
A device with a known amount of resistance used in electrical circuits. |
| Resource Efficiency |
The use of smaller amounts of physical resources to produce the same product or service. Resource efficiency involves a concern for the use of all physical resource sand materials used in the production and use cycle, not just the energy input. |
| Rest Voltage |
The voltage of a fully charged cell or battery that is neither being charged or discharged. |
| Restructuring |
The process of changing the structure of the electric power industry from one of a guaranteed monopoly over service territories to one of open competition between power suppliers. |
| Retail Competition |
A system under which more than one electric provider can sell to retail customers, and retail customers are allowed to buy from more than one provider. (See also direct access) |
| Retail Market |
A market in which electricity and other energy services are sold directly to the end-use customer. |
| Retail Wheeling |
See Direct Access. |
| Retorting |
The heating of oil shale to get the oil out from it. |
| Reverse Bias |
Condition where the current producing capability of a PV cell is significantly less than that of other cells in its series string. This can occur when a cell is shaded, cracked, or otherwise degraded or when it is electrically poorly matched with other cells in its string. |
| Reverse Current Protection |
Any means of preventing current flow from the battery to the solar PV array (e.g. At night) that would discharge the battery. |
| RF (Radio Frequency) |
Any radiation of a frequency that may be received or radiated by radios. Common usage RF interference (RFI); refers to the interference of radio frequency radiation with the operation of devices or appliances such as radios, televisions, computers, etc. |
| Ribbon (Photovoltaic) Cells |
A type of photovoltaic device made in a continuous process of pulling material from a molten bath of photovoltaic material, such as silicon, to form a thin sheet of material. |
| Rift Zone |
long narrow fractures in the crust found along ocean floor or on land, from which lava flows out; often associated with spreading centers from which tectonic plates are diverging, such as the mid-Atlantic Ridge. |
| Ring Of Fire |
a belt of intense volcanic, geothermal and earthquake activity found all around the Pacific Rim caused by plate tectonic activity. |
| RMS |
Root mean square; defines a time averaged value of a varying sinusoidal parameter, such as AC voltage, amperage, or wattage. The square root of the average of the squares of a set of numbers. |
| Roaring Forties |
The name used especially by sailors to describe the latitudes between 40 degrees South and 50 degrees South, where the prevailing westerly winds are strong and steady. |
| Roentgen |
A unit of exposure to radiation like X-rays. |
| Roof Mount |
A PV or solar collector rack intended to be installed on a roof. For pvs, its elevation angle can be fixed or seasonally adjustable. |
| Root Mean Square (RMS) |
The square root of the average square of the instantaneous values of an ac output. For a sine wave the RMS value is 0.707 times the peak value. The equivalent value of alternating current, I, that will produce the same heating in a conductor with resistance, R, as a dc current of value I. |
| Rotational Start |
The point at which the wind is strong enough to begin turning the rotor. |
| Rotor |
A blade system which supplies all the driving force for a wind generator. |
| RPM |
Revolutions per minute, the number of times a shaft passes the same location per minute. |
| Rules Of Conduct |
Rules set in advance to delineate acceptable activities by participants, particularly participants with significant market power. |
| Runner |
The part of a hydro turbine that accepts the water and turns its energy into rotating motion. |
| Rural Electric Cooperative |
A nonprofit, customer-owned electric utility that distributes power in a rural area. |
| R-Value |
The measure of a material’s resistance to heat flow. The higher the R-value, the greater its insulating capabilities. |
