## D

##### DAM

(hydr). A structure that detains the FLOW of water in an open CHANNEL or watercourse. POWER dams raise the level of streams or rivers to create or concentrate HEAD for power purposes.

F - barrage
S - represa
##### DAMPER

(heat). A movable plate or other device for regulating the air-FLOW and burning rate in a stove. It is often located either inside the stove or in the FLUE pipe.

F - registre
##### DARRIEUS ROTOR WINDMILL

(wind). A VERTICAL AXIS WIND MACHINE that has long, thin, loop-shaped BLADES connected at the top and bottom of the WIND SHAFT.

F - eolienne a rotor de Darrieus
S - molino de viento de rotor Darrieus
##### DC

(elec). Abbreviation for DIRECT CURRENT.

F - CC
S - C.C.
##### DDG

(alc). Abbreviation for DISTILLER'S DRIED GRAINS. (See: DISTILLER'S GRAINS)

F - GSB
S - G.S.D.
##### DDGS

(alc). Abbreviation for DISTILLER'S DRIED GRAINS and SOLUBLES. (See: DISTILLER's GRAIN)

F - G.S.B.S.
S - G.S.D.S.

(constr) (sol). An empty area within the walls of a building in which the air remains motionless and acts as insulation. Dead air space may be included in a SOLAR COLLECTOR between the ABSORBER PLATE and the GLAZING, between glazings, and in the CASING.

F - espace d'air inerte
S - espacio de aire no renovado

(wind) (arc). A ledge supporting the CAP of a WINDMILL without the interposition of WHEELS or ROLLERS.

F - chemin dormant
S - reborde

(wind). A log or a mass of concrete or steel buried in the ground, to which GUY WIRES for supporting towers and poles are attached.

F - point fixe d'ammarage
S - macizo de anclaje
##### DECOMPOSITION

(bio) (chem). Decay of ORGANIC MATTER due to the action of BACTERIA. Also the separation of a substance into its component parts by chemical action.

F - decomposition
S - descomposicion
##### DEEP CYCLE BATTERY

(elec) (wind). A BATTERY that can be fully charged and discharged without shortening its life. They are often used with WIND GENERATORS.

F - batterie a cycle profond
S - bateria de gran ciclo
##### DEGREE DAY COOLING

(gen) (meas). A measurement used to evaluate the summer cooling requirements of a given location. Each degree that the daily temperature is above 75 [degrees] F (24 [degrees] C), one cooling degree day is counted.

F - degre-jour de refroidissement
##### DEGREE DAY HEATING

(gen) (meas). A measurement used to determine the winter heating requirements of a given location. Each degree that the daily temperature is below 65 [degrees] F (19 [degrees] C) is a heating degree day.

F - degre-jour de chauffage
##### DEHYDRATION

(gen). The removal of moisture from a substance.

F - deshydratation
S - deshidratacion
##### DENATURE

(alc). The process of adding a substance, often METHANOL, to ETHANOL to make it unfit for human consumption.

F - denaturer
S - desnaturalizar
##### DEPHLEGMATOR

(alc). (See: ALCOHOL STILL)

F - deflegmateur

(heat) (meas). The total heat loss from a building during the most severe winter conditions the building is likely to experience.

F - charge thermique nominale
S - carga de calefaccion prevista
##### DESSICANT

(gen). A substance with an affinity for water, used for drying purposes.

F - dessiccatif
S - desecante
##### DESTRUCTIVE DISTILLATION

(alc) (gen). The heating, DECOMPOSITION, and subsequent DISTILLATION of FLUIDS from ORGANIC MATTER (e.g., METHANOL production from wood).

F - distillation destructive
S - destilacion destructora
##### DETENTION TIME

(biocon) (meas). The amount of time that incoming material is retained in a BIOGAS DIGESTER.

F - temps de retention
S - periodo de detencion

(sol). Indirect, scattered sunlight, which casts no shadow. It is the opposite of DIRECT RADIATION.

F - rayonnement diffus
##### DIFFUSION

(chem). The process by which a substance of a greater CONCENTRATION mixes with a substance of a lesser concentration to produce a uniform mixture.

F - diffusion
S - difusion
##### DIGESTED SLUDGE

(biocon). The residue remaining after DIGESTION. Digested sludge contains some UNDIGESTED SOLIDS and stabilized ORGANIC MATTER.

F - boues digerees
S - sedimento digerido
##### DIGESTED SLURRY

(biocon). (See: DIGESTED SLUDGE)

F - boue digeree
S - fango digerido
##### DIGESTER

(biocon). The tank in which ANAEROBIC DIGESTION takes place.

F - digesteur
S - digestor
##### DIGESTER TANK

(bio). The reservoir area in a BIOGAS DIGESTER in which DIGESTION of ORGANIC MATTER takes place. It usually has some gas holding capacity, and provides For the collection and removal of SCUM and SLUDGE.

F - reservoir digesteur
S - tanque digestor
##### DIGESTION

(biocon). The process by which ORGANIC MATTER is decomposed by the action of ANAEROBIC BACTERIA, producing METHANE and high-grade fertilizer.

F - digestion
S - digestion
##### DILUTION RATE

(biocon) (meas). The frequency with which water is added to a BIOGAS DIGESTER.

F - taux de dilution
S - tasa de dilucion
##### DIRECT CONVERSION

(sol). The transformation of sunlight to electricity without an intervening thermodynamic cycle.

F - conversion directe
S - conversion directa
##### DIRECT CURRENT

(elec). A continuous, one-directional FLOW of electricity, such as that from a BATTERY. Commonly abbreviated as dc.

F - courant continu
S - corriente continua
##### DIRECT GAIN SYSTEM

(sol). (See: DIRECT SOLAR GAIN)

F - gain direct, systeme de
S - sistema de ganancia directa
##### DIRECT METHODS OF SOLAR HEATING

(sol). SOLAR HEATING techniques in which SOLAR RADIATION enters a building through windows and SKYLIGHTS and is trapped inside to warm a room.

F - chauffage solaire direct
S - metodos directos de calefaccion solar

(sol). Sunlight that has traveled a straight path from the sun. It is the opposite of DIFFUSED RADIATION.

F - rayonnement direct
##### DIRECT SOLAR ENERGY

(sol). ENERGY acquired From conversion of DIRECT RADIATION.

F - energie solaire directe
S - energia solar directa
##### DIRECT SOLAR GAIN

(sol). A PASSIVE SOLAR HEATING system in which SOLAR RADIATION passes through and warms a room in a dwelling before being stored in THERMAL MASS for longterm heating.

F - apport solaire direct
S - ganancia solar directa
##### DISCHARGE PIPE

(hydr) (biocon). [1] The pipe through which water exits from a WATER TURBINE. [2] The outlet for EFFLUENT from a BIOGAS DIGESTER.

F - [1] tube de decharge; [2] tuyau d'evacuation
S - tubo de descarga
##### DISTILLATE

(alc). The portion of a liquid that is removed from a solid or semisolid as a vapor and CONDENSED during the DISTILLATION process. ETHANOL is a distillate of FERMENTED MASH. (See also: SOLAR DISTILLATE)

F - distillat
##### DISTILLATION

(alc). An evaporation and recondensation process by which liquids are separated into various fractions according to their boiling points. ETHANOL is separated by distillation from MASH and water.

F - distillation
S - destilacion
##### DISTILLATION COLUMN

(alc). (See: STILL COLUMN)

F - colonne de distillation
S - columna de destilacion
##### S DRIED GRAIN

(DDG) (alc). (See: DISTILLER'S GRAIN)

F - grains secs de brasserie

(GSB)

S - grano seco de destilacion

(GSD)

##### S GRAIN

(alc). A by-product of ETHANOL production. Once ethanol has been driven from the MASH in an ALCOHOL STILL, the remaining solids are known as distiller's grain. When dried, these grains can be used as high protein animal feed. The dried distiller's grain commonly is abbreviated as DDG. (Syn: BREWER'S DRIED GRAIN)

F - grains de distillerie
S - grano de destilacion
##### S MASH

(alc). (See: SPENT MASH)

F - mout de distillateur
S - mezcla de destilacion
##### DOUBLE CHAMBER

(biocon). A type of BIOGAS DIGESTER in which the GASHOLDER is separate from the DIGESTER TANK.

F - chambre double
S - camara doble
##### DOUBLE-GLAZING

(sol). [1] A cover for a SOLAR COLLECTOR that is made from two layers of GLAZING materials. [2] Double-glass windows designed to serve as insulation for buildings.

F - [1] vitre double; [2] double vitrage
##### DOUBLE-SHUTTERED

(wind) (arc). PATENT SAILS or SPRING SAILS fitted with SHUTTERS on both sides of the WHIP.

F - double volets, a
S - doble postigo
##### DOWNCOMER

(alc) (impl). A component of an ALCOHOL STILL. When water is separated from ALCOHOL during DISTILLATION, the water falls toward the bottom of the STILL COLUMN through a pipe called a downcomer.

F - deversoir
S - tubo de descenso
##### DOWNDRAFT

(gen) (prod). [1] A type of PRODUCER GAS GENERATOR in which air and gas FLOWS from the top of the COMBUSTION ZONE down through to the bottom. [2] KILNS or other types of ovens and stoves in which CONVECTION or combustion air flows down through the device.

F - [1] tirage en bas; [2] tirage inverse
S - corriente descendiente
##### DOWNWIND

(wind). On the side opposite the WIND DIRECTION.

F - sous le vent
S - con el viento
##### DRAFT

(heat). The FLOW of air through a KILN, stove, oven, fireplace, PRODUCER GAS GENERATOR, etc. Draft affects both temperature and rate of combustion.

F - tirage
S - tiro de aire
##### DRAG

(wind). An aerodynamic force that retards the motion of lift-type ROTOR blades, or that causes BLADE motion in DRAG-TYPE WIND MACHINES.

F - trainee
S - resistencia aerodinamica
##### DRAG-TYPE SYSTEM

(wind). WIND MACHINES that are actuated by aerodynamic DRAG in a WIND STREAM (e.g., SAVONIUS ROTOR).

F - type a trainee, systeme du
S - sistema del tipo de arrastre
##### DRAG-TYPE WIND MACHINE

(wind). A WIND MACHINE that rotates by being pushed by the wind instead of by being driven by LIFT forces. This is generally a slow-moving device.

F - eolienne a trainee
S - aerogenerador del tipo de arrastre
##### DRAIN DOWN SOLAR COLLECTOR

(sol). A SOLAR COLLECTOR that will automatically drain itself to protect against freezing.

F - capteur solaire a evacuation automatique
S - colector solar con drenaje
##### DRY BIOMASS

(gen). Moisture-free BIOMASS. It is valuable because it can be conveniently stored for long periods of time. (See also: DRY ORGANIC WASTE)

F - biomasse seche
S - biomasa seca
##### DRY-BULB TEMPERATURE

(meas). The temperature of air as indicated by a standard thermometer, as contrasted with WET-BULB TEMPERATURE that depends on atmospheric humidity. This measure of AMBIENT temperature is used in designing PASSIVE SOLAR HEATING and SOLAR COOLING systems.

F - temperature au thermometre sec
S - temperatura de bola seca
##### DRY DIGESTION

(biocon). DIGESTION in which more than 10 percent of the SLURRY is solid material.

F - digestion seche
S - digestion seca
##### DRYING BED

(biocon). An area prepared for drying EFFLUENT after it hs been removed from a METHANE DIGESTER. Dried effluent can be used as fertilizer or as animal feed.

F - lit de sechage
##### DRY ORGANIC WASTE

(gen). ORGANIC WASTE that is free from moisture. This type of waste can be stored for long periods before being used as a fuel or fertilizer. (See also: DRY BIOMASS)

F - dechets organiques secs
S - desperdicios organicos secos
##### DRY SLURRY

(biocon). SLURRY that is more than 10 percent solid material.

F - boue seche
S - fango seco
##### DRY STEAM

(geo). An ENERGY source obtained when hot water boils in an underground reservoir. As the steam rises, some of it condenses on surrounding rack. The uncondensed steam that reaches the surface is called dry steam, and may be tapped and used in STEAM TURBINES.

F - vapeur seche
S - vapor seco
##### DUAL-FUEL ENGINE

(auto) (gen). A gasoline or diesel engine equipped to operate on an alternative fuel, either alternately or in combination (e.g., gasoline-BIOGAS, diesel-biogas, gasoline-WOOD GAS, diesel-wood gas).

F - moteur polycarburant
S - motor a doble combustible
##### DUNG

(bio). Manure, usually without urine. Dried dung can be burned directly as a fuel or used as a fertilizer.

F - fumier
S - estiercol
##### DUNG GAS

(biocon). (See: BIOGAS)

F - gaz de fumier
S - gas de estiercol
##### DYNAMO

(elec). A device for converting mechanical ENERGY into electrical energy by electromagnetic induction. Dynamos are often adapted to be driven by WINDMILLS. (See also: ALTERNATOR)

F - dynamo
S - dinamo
##### DYNAPOD

(gen) (impl). A pedal-operated POWER source. It is used to drive a variety of machines and devices.

F - dynapod
S - dynapod

## E

##### EARTH KILN

(heat). A relatively inefficient KILN made by mounding earth over the materials to be burned. Used in traditional CHARCOAL production.

F - meule a charbon de bois
S - horno de tierra
##### ECCENTRIC WHEEL

(gen). A wheel in which the axle is not at the center point, but slightly off-center.

F - roue excentrique
S - rueda excentrica
##### ECONOMIZER

(heat). A HEAT EXCHANGER that recovers heat from FLUE gases and uses it to heat feedwater or combustion air.

F - economiseur
##### EFFECTIVENESS

(heat) (meas). The ratio of actual heat transfer in a HEAT EXCHANGER to the maximum possible heat transfer.

F - efficacite
S - eficacia
##### EFFICIENCY

(gen). The ratio of the ENERGY output to the energy input. Efficiency is usually expressed as a percentage.

F - rendement
S - eficiencia
##### EFFLUENT

(biocon). [1] SLURRY that has been removed from a BIOGAS PLANT. [2] Liquid sewage after having passed through any stage in its purification.

F - effluent
S - efluente
##### EMISSIVITY

(sol). The ratio of RADIANT ENERGY emitted by a body to that emitted by a perfect BLACKBODY. A perfect blackbody has an emissivity of one; a perfect REFLECTOR, an emissivity of zero.

F - emissivite
##### EMITTANCE

(sol) (meas). A rating of the ability of a material to give off heat as RADIANT ENERGY.

F - emittance
S - emitancia
##### ENERGY

(gen). The capacity of a body to do work; POWER in action.

F - energie
S - energia
##### ENERGY CAPABILITY OF AN ELECTRICITY-PRODUCING DEVICE

(gen) (meas). The maximum amount of electricity that an electricity-producing device may produce under the best conditions during a given period. ENERGY capability is determined by the mechanical EFFICIENCY of the device.

F - capacite energetique d'un dispositif produisant du courant
##### ENERGY CONSERVATION

(gen). Practices and measures that increase the EFFICIENCY with which ENERGY is used or produced.

F - conservation de l'energie
S - conservacion de energia
##### ENERGY CONSUMPTION

(gen). The amount of ENERGY consumed in the form in which it is obtained by the user. This term excludes electrical generation and distribution losses. It also is called net energy consumption.

F - consommation d'energie
S - consumo de energia
##### ENERGY CONVERSION

(gen). The act of changing ENERGY from one form to another (e.g., WIND ENERGY to mechanical energy).

Mechanical -> Electrical
Wind Generator 40%
Water Turbine 68-93%
Steam Power Plant 40%
Mechanical -> Mechanical
Windmill 20-30%
Waterwheel 70-85%
Solar -> Thermal
Flat Collector 40-60%
Concentrator 80-90%
Chemical -> Thermal
Wood Combustion Burner 85% maximum
Chemical -> Electrical
Battery 80%

(Storage)

Chemical -> Chemical
Biogas Digester 40-60%
F - conversion de l'energie
S - conversion de energia
##### ENERGY PATTERN FACTOR

(wind). The ratio of the available ENERGY in all of the winds in a particular location over a certain period of time to the energy that would be available if the WIND SPEED over that period of time were constant at the mean wind speed over that period of time.

F - coefficient de diagramme energetique
S - factor energetico del viento
##### ENERGY PRODUCTS

(gen). Fuels that can be used to produce ENERGY. Also, the by-products that result when fuels are produced.

F - combustibles energetiques
S - productos energeticos
##### ENERGY STORAGE

(gen) (meas). The ability to convert ENERGY into other forms, such as heat or a chemical reaction, so that it can be retrieved for later use. Also the development, design, construction, and operation of devices for storing energy until needed. The technology includes devices such as batteries, pumped storage for hydroelectric generation and compressed gas.

F - stockage de l'energie
S - almacenamiento de energia
RENEWABLE ENERGY STORAGE
 Storage Medium Storage Efficiency (%) Major Loss Characteristics Cost* Complexity** SOLAR (Heat) Water 75-90 Leaks (thermal & physical) 2 1 Earth varies Leaks (thermal) 1 1 Rock 60-80 Leaks (thermal) 2 2 Salt Hydrates 75-95 Material Breakdown 3 3 WIND/WATER (Mechanical) Pumped Water 50-70 Evaporation, Friction 1 2 Compressed Air 40-50 Leaks, Friction 2 2 WIND/WATER (Electrical) Battery 70-85 Internal Discharge 3 3 METHANE Tank Leaks 1 2 Tank (compressed) 50-60 3 3 ALCOHOL Tank Leaks, Evaporation 1 1 * Relative Cost 1 = Negligible 2 = Intermediate ** Degree of Mechanical Complexity 3 = Considerable
##### ENHANCEMENT

(sol). Increasing the amount of sunlight transmitted through the GLAZING in a SOLAR COLLECTOR through the use of a REFLECTOR.

F - renforcement
S - intensificacion
##### ENZYMATIC HYDROLYSIS

(alc). The use of ENZYMES to convert STARCH into simple sugars. This is a stage in the production of ETHANOL.

F - saccharification enzymatique
S - hidrolisis enzimica
##### ENZYMES

(chem) (alc). Organic substances that are produced in the cells of living organisms, and which cause specific chemical changes. Enzymes are produced by BACTERIA or FUNGI and are used in the liquefication and SACCHARIFICATION steps of ALCOHOL production.

F - enzymes
S - enzimas
##### EOLIAN

(wind). Of, relating to, formed by, or deposited by the wind or air currents. (Syn: Aeolian)

F - eolien, eolienne
S - eolico
##### EQUINOX

(sol). Either of two times of year when the sun passes over the celestial equator and when the length of day and night are almost equal.

F - equinoxe
S - equinoccio
##### ETHANOL

(alc). A Flammable organic compound (C[H.sub.3]C[H.sub.2]OH) formed during sugar FERMENTATION. It is also called ethyl alcohol, GRAIN ALCOHOL, or simply ALCOHOL.

F - ethanol
S - etanol
##### ETHYL ALCOHOL

(alc). (See: ETHANOL)

F - alcool ethylique
S - alcohol etilico
##### EUTECTIC SALTS

(heat). Heat storing salts that melt at a relatively low temperature. They absorb large quantities of heat when they do melt. Heat is released when the salts freeze.

F - eutectiques
S - sales eutecticos
##### EVACUATED TUBE COLLECTOR

(sol). A SOLAR COLLECTOR that uses a vacuum to insulate the ABSORBER PLATE. This COLLECTOR is highly EFFICIENT but very expensive.

F - capteur a tube vide
S - colector con tubo vaciado
##### EVAPORATIVE COOLING

(refrig). The exchange of heat from air to a water spray or wet surface through a reversible THERMODYNAMIC process. Air passing through the water is cooled as the water evaporates. The process can be reversed by condensing the vapor on a cool surface.

F - refroidissement par evaporation
S - enfriamiento evaporante
##### EXCESS AIR

(heat). Air that passes through a COMBUSTION ZONE in excess of the quantity theoretically required for complete combustion.

F - exces d'air
S - aire excesivo

(sol) (meas). The amount of SOLAR RADIATION that would strike a surface if that surface were outside the Earth's atmosphere. (See also: CLEARNESS INDEX)

F - rayonnement solaire extraterrestre

## F

##### F

(meas). Abbreviation for FAHRENHEIT.

F - F
S - F
##### FAHRENHEIT

(meas). The temperature scale in which water freezes at 32 oF and boils at 212 oF. Temperatures of the Fahrenheit scale can be converted to equivalent temperatures on the CELSIUS or Centigrade scale by first subtracting 32 degrees from the Fahrenheit temperature, then multiplying the result by 5/9 according to the formula: ${\displaystyle (F-32)*5/9=C}$.

F - Fahrenheit
S - Fahrenheit
##### FALL WIND

(wind). A strong, cold, downhill wind.

F - vent catabatique
S - racha de viento
##### FANTAIL

(wind) (arc). A small, secondary ROTOR set at a right angle to the main ROTOR of a WINDMILL to provide the motive POWER to turn the CAP to face the wind.

F - gouvernail
S - timon
##### FARM WINDMILL

(wind). A multi-BLADED WINDMILL that is based on an Early American design and is used primarily for water pumping.

F - eolienne de ferme
S - molino de viento rural
##### FEATHER

(wind). Turning the SAILS or the ROTOR of a WIND MACHINE out of the wind to protect the device from damage from high WIND VELOCITIES.

F - mettre en drapeau
S - poner en bandolera
##### FEATHERING MECHANISM

(wind) (impl). A mechanism on a WINDMILL that automatically turns the BLADES out of the wind when winds are too strong. This slows the windmill, protecting it from damage in high winds.

F - mecanisme de mise en drapeau
S - mecanismo de puesta en bandolera
##### FEED

(gen). See: FEEDSTOCK)

F - alimentation
S - alimento
##### FEEDSTOCK

(gen). The raw ORGANIC MATTER, such as grain, fruit, DUNG, or other BIOMASS, used as the INFLUENT in the FERMENTATION or DIGESTION processes.

F - charge d'alimentation
S - materia prima organica
##### FENESTRATION

(sol). An opening in a building that admits light and/or air.

F - fenestration
S - ventanaje
##### FERMENT

(biocon). A transformation or DECOMPOSITION of ORGANIC MATTER by the catalytic effect of ENZYMATIC action. To cause or undergo the action of FERMENTATION.

F - fermenter
S - fermentar
##### FERMENTABLE SUGAR

(alc). (See: MONOSACCHARIDE)

F - sucre fermentable
S - azucar fermentable
##### FERMENTATION

(alc) (chem). [1] A biological sequence of ENZYMATIC reactions that convert sugars to carbon dioxide and ALCOHOL in the absence of FREE OXYGEN. The term generally refers to metabolism in the absence of oxygen. [2] The process by which YEAST changes sugar to ALCOHOL in the absence of air. [3] The process of chemical change in ORGANIC MATTER brought about by living organisms.

F - fermentation
S - fermentacion
##### FERMENTATION PERIOD

(gen) (meas). The length of time required for a substance to FERMENT.

F - duree de fermentation
S - periodo de fermentacion
##### FERMENTATION TANK

(alc). The container in which FERMENTATION takes place in an ETHANOL production operation.

F - cuve de fermentation
S - tanque de fermentacion
##### FERMENTER

(gen). (See: FERMENTATION TANK)

F - fermenteur
##### FETCH AREA

(wind). The geographic area over which the wind passes shortly before reaching a WIND MACHINE. It is considered in the selection of a site for a wind-powered device.

F - portee du vent
S - extension expuesta
##### FIRE BACK

(constr). A metal plate set in a CHIMNEY to control the back DRAFT of flames.

F - contre-feu
S - respaldo refractario
##### FIREBOX

(gen). The area in a stove, oven, or PRODUCER GAS GENERATOR in which combustion occurs.

F - chambre de combustion
S - caja refractaria
##### FIRE BRICK

(constr). A type of brick with a high melting point that is used to line FLUES, CHIMNEYS, furnaces, and fireplaces.

F - brique refractaire
##### FIXED-DOME DIGESTER

(biocon). A BIOGAS DIGESTER in which the gasholder is an integral part of the digester, rather than a FLOATING GAS CAP. This type of digester is usually used to produce fertilizer. METHANE is considered a by-product.

F - digesteur a dome fixe
S - digestor de sombrerete fijo
##### FLAT BLACK PAINT

(sol). A nonglossy black paint with a relatively high ABSORPTANCE.

F - peinture noire mate
S - pintura negra uniforme
##### FLAT-PLATE SOLAR COLLECTOR

(sol). A device that uses an ABSORBER PLATE to COLLECT SOLAR RADIATION without assistance of devices to concentrate the sun's rays.

F - capteur solaire a panneau plan
S - colector solar de placa lisa
##### FLOAT

(hydr). The BUCKET of a WATER WHEEL.

F - aube
S - paleta [1]
##### FLOATING GAS CAP

(biocon). A lid over a BIOGAS DIGESTER that rises or falls with the production of METHANE.

F - cloche a gaz flottante
S - sombrerete movible
##### FLOW

(gen). The volume of a substance passing a point per unit time (e.g., meters per second, gallons per hour, etc.)

F - debit
S - flujo
##### FLOW DESIGN

(hydr) (meas). The FLOW rate at which a TURBINE is designed to operate.

F - debit nominal
S - diseno de flujo
##### FLUE

(const). A passageway in a CHIMNEY that vents gases produced during combustion. The flue opening can be regulated to control the DRAFT in the oven or stove, thus changing the rate of combustion.

F - carneau
S - conducto de humos
##### FLUE GAS DRYING

(heat). THERMAL drying using gases in a FLUE as the source of heat.

F - sechage au gaz de carneau
S - secado por gases del conducto
##### FLUID

(gen). Any substance that FLOWS, such as a liquid or gas. Fluids differ from solids in that they cannot resist changes in their shape when acted upon by a force.

F - fluide
S - fluido
##### FLUIDIZED BED GASSIFIER

(prod). A type of PRODUCER GAS GENERATOR in which air FLOWS upward through a bed of suitably-sized fuel particles fast enough to buoy the particles and give them an appearance of great agitation. The fuel particles generally are small. This type of combustion reduces the sulphur-dioxide emissions when coal is burned.

F - gazogene a lit fluidise
##### FLUME

(hydr). [1] A HEAD RACE in the form of a trough or CHANNEL that carries water to a WATER WHEEL. [2] A waterway, usually made of wood and often supported on a trestle, that conveys water to be used for POWER, transportation, etc.

F - [1] coursier; [2] canal d'amenee
S - canaleta
##### FLYWHEEL

(gen) (impl). A rotating element attached to the shaft of a machine to maintain uniform angular velocity and revolutions per minute.

F - volant
S - volante
##### FOCUSING COLLECTOR

(sol). A type of SOLAR COLLECTOR that focuses the sun's rays on a sinqle point.

F - capteur a concentration [2]
S - colector enfocante
##### FOLD-UP REFLECTOR

(sol). A portable type of folding mirror used in SOLAR COOKERS to reflect sunlight.

F - reflecteur pliant
S - reflector plegable
##### FOOT-POUND

(gen) (meas). The amount of ENERGY required to lift one pound of a substance one foot.

F - pied-livre
S - libra-pie
##### FORCED CONVECTION

(heat). The use of a pump or blower to control the FLOW of heat into a heated FLUID (e.g. circulating warm air in a room or dwelling with a pump or blower).

F - convection forcee
##### FOSSIL FUELS

(fos). Nonrenewable, naturally-occurring fuels from ORGANIC MATTER. These include coal, crude oil, and natural gas.

F - combustibles fossiles
S - combustibles fosiles
##### FRACTIONATING COLUMN

(alc). A vertical tube or column attached to an ALCOHOL STILL that is usually filled with packing or intersected with plates. An internal REFLUX results in a separation between the high and low boiling fractions inside the column. Those with the lowest boiling point DISTILL out. (See also: DISTILLATION COLUMN)

F - colonne de fractionnement
S - columna de fraccionar
##### FRANCIS TURBINE

(hydr). A WATER TURBINE that operates on a low or medium HEAD and is often installed in large HYDROELECTRIC plants. Water enters the turbine radially and leaves axially.

F - turbine de Francis
S - turbina Francis
##### FREE OXYGEN

(bio). Oxygen in the atmosphere, which can be extracted at no cost. Conversely, oxygen extracted at a cost would cause the substance from which the oxygen molecules were taken to DECOMPOSE.

F - oxygene libre
S - oxigeno libre
##### FRESNEL COLLECTOR

(sol). A type of SOLAR COLLECTOR consisting of a concentric series of rings with reflecting surfaces. These rings focus SOLAR RADIATION onto an ABSORBER PLATE.

F - capteur a lentille de Fresnel
S - colector Fresnel
##### FRESNEL LENS

(sol). A type of lens built up from a number of narrow concentric segments. It is used in SOLAR CONCENTRATORS.

F - lentille de Fresnel
S - lente de Fresnel
##### FRICTION

(gen). Surface resistance to relative motion, which slows down movement and causes heat.

F - frottement
S - friccion

(hydr). HEAD or ENERGY lost due to FRICTION created by the contact between a moving stream of water and the conduit through which it is moving. In pipes, the friction head is also caused by bends in the pipelines, changes in the pipe diameter, valves, and couplings.

F - perte frictionnelle
S - perdida de carga por rozamiento
##### FRUCTOSE]](alc)

(chem). A FERMENTABLE sugar commonly found in fruit. Fructose can be used as a FEEDSTOCK in ETHANOL production.

F - fructose
S - fructosa
##### FUEL EFFICIENCY

(heat) (meas). The ratio of heat produced by a fuel for doing work to the available heat of the fuel. Fuel EFFICIENCY is determined by the nonheat-forming materials in the fuel and the nonwork-producing heat that is developed by the fuel.

F - rendement du combustible
S - eficiencia del combustible
##### FUELWOOD

(heat). Any type of wood that can be used to fuel a fire.

F - bois de chauffe
S - lena
##### FULL SAIL

(wind) (arc). A COMMON SAIL with the cloth fully spread.

F - aile deployee
##### FUNGUS

(bio). One of numerous plants in the division of Thallophyta characterized by a lack of chlorophyll, including YEAST, molds, and mushrooms. Fungi do not require FREE OXYGEN to survive. (Plural: fungi)

F - champignon
S - hongo
##### FURLING

(wind). Rollinq up and tying back SAILS of a WINDMILL to keep the ROTOR from turning.

F - ferlage
S - aferramiento
##### FURLING SPEED

(wind). (See: CUT-OUT SPEED)

F - vitesse de ferlage

## G

##### GASAHOL

(alc). A gasoline substitute or supplement derived from 10 percent ETHANOL and 90 percent unleaded gasoline. (Syn: gasohol)

F - carburol
S - gasohol
##### GAS CAP

(biocon). (See: GASHOLDER)

F - cloche a gaz
S - tapa de gas
##### GAS DIGESTION

(biocon). The second stage of BIOGAS generation, during which METHANE ([CH.sub.4]) is produced.

F - digestion de gaz
S - digestion de gas
##### GASHOLDER

(biocon). (1) A container for holding the BIOGAS produced in a DIGESTER. The size of the holder depends on the rates of gas production and gas use. (See also: FLOATING GAS CAP)

F - gazometre
S - gasometro
##### GASIFICATION

(prod). The conversion of wood or coal to COMBUSTIBLE GAS without leaving a combustible residue.

F - gazeification
S - gasificacion
##### GASIFIER

(prod). A special type of furnace in which the air supply to the COMBUSTION ZONE is carefully metered. This promotes the production of COMBUSTIBLE GASES as wood or coal are burned.

F - gazogene
##### GAS PRODUCTION RATE

(biocon) (meas). The quantity of METHANE generated per unit of time. It generally is expressed as cubic feet/day or cubic meters/day. The figure should be quoted under standard conditions of temperature and pressure.

F - taux de production du gaz
S - tasa de produccion de gas
##### GAS SCRUBBER

(gen). (See: SCRUBBING)

F - epurateur de gaz
S - lavagases
##### GAS STORAGE CAPACITY

(biocon). The maximum amount of METHANE that a BIOGAS DIGESTER is able to store. The amount generally is expressed in cubic feet or cubic meters.

F - capacite de stockage de gaz
S - capacidad de almacenamiento de gas
##### GAS TURBINE

(auto). An ALTERNATIVE COMBUSTION ENGINE in which a gas, under pressure or formed by combustion, is directed against the BLADES of a TURBINE. The ENERGY in the expanding gas is thereby converted into useful mechanical energy.

F - turbine a gaz
S - turbina de gas
##### GEAR RATIO

(gen) (meas). The number of revolutions required of one gear to turn another gear, which generally is of a different size.

F - demultiplication
S - relacion de los engranajes
##### GENERATOR

(elec) (impl). A device that converts mechanical ENERGY into electrical energy.

F - generateur
##### GENGAS

(prod). (See: PRODUCER GAS)

F - gaz pauvre de gazogene
S - gengas
##### GEOPRESSURED RESERVOIR

(geo). A GEOTHERMAL RESERVOIR consisting of porous sands that contain water or BRINE at high temperatures and pressure.

F - reservoir sous geopression
S - tanque de presion geotermica
##### GEOTHERMAL

(geo). Of or relating to the heat of the Earth's interior.

F - geothermique
S - geotermico
##### GEOTHERMAL FIELD

(geo). A geographical region with known GEOTHERMAL POWER sources that might be tapped to produce ENERGY.

F - zone geothermique
S - zona geotermica
##### GEOTHERMAL POWER

(geo). ENERGY obtained from GEOTHERMAL sources. Geothermal power is tapped in three ways: by using hot water, steam, or DRY STEAM. Each may be used to drive a TURBINE.

F - energie geothermique
S - energia geotermica
##### GEOTHERMAL RESERVOIR

(geo). A water reserve created near a HOT DRY ROCK RESERVOIR to develop a potential GEOTHERMAL POWER site.

F - reservoir geothermique
S - tanque geotermico
##### GEOTHERMAL STEAM

(geo). Steam drawn from sources within the Earth.

F - vapeur geothermique
S - vapor geotermico
##### GEYSER

(geo). Natural steam or hot water spouts in active GEOTHERMAL regions.

F - geyser
S - geiser
##### GIN POLE

(wind). A long board or pipe used to improve the leverage in lifting a TOWER for a WINDMILL.

F - fleche de levage
S - mastil grua
##### GLAZING

(impl) (sol). A transparent sheet that admits sunlight to a SOLAR COLLECTOR and then inhibits the escape of heat. Commonly used glazing materials include ACETATE, acrylic, fiber-reinforced plastics, and glass.

F - vitrification

F - rayonnement global
##### GLUCOSE

(chem) (alc). The most common sugar, which is derived from STARCH during the ETHANOL production process.

F - glucose
S - glucosa
##### GOBAR GAS

(biocon). (See: BIOGAS)

F - bio-gaz
S - gas gobar
##### GOVERNOR

(gen) (impl). A device that regulates the speed of an engine or other device under varying conditions of load and pressure. Also a device for regulating the FLOW or pressure of a FLUID passing through a device.

F - regulateur
##### GRAIN ALCOHOL

(alc). ETHANOL made from grain by DISTILLATION.

F - alcool de grains
S - alcohol de granos
##### GRAM CALORIE

(gen). The amount of ENERGY required to raise one gram of water one degree CELSIUS.

F - calorie [2]
S - caloria-gramo
##### GRAMLAXMI GAS

(biocon). (See: BIOGAS)

F - bio-gaz
S - gas gramlaxmi
##### GRATE

(impl) (heat). A frame of metal bars that holds fuel above the floor of a firebox. It usually is used in a boiler, GASIFIER, fireplace, or stove.

F - grille
S - parilla
##### GRAVITY CONVECTION]] heat).

(See: NATURAL CONVECTION)

F - convection par pesanteur
##### GUIDE VANES

(hydr) (impl). Surfaces that direct water to the appropriate parts of TURBINE BLADES or BUCKETS so as to increase POWER output.

F - aubes directrices
S - alabe director
##### GUSSET

(constr) (wind). A triangular metal brace for reinforcing a corner or angle. It is commonly used in TOWER construction.

F - gousset
S - esquinero
##### GUST

(wind). A sudden, brief increase in WIND VELOCITY that is then followed by calmer air.

F - rafale
S - rafaga
##### GUYED TOWER

(impl) (wind). A WINDMILL TOWER that is supported by GUY WIRES.

F - pylone haubanne
##### GUY WIRE

(wind) (impl). A cable that stabilizes a structure and keeps it in position. For example, wires attached to a WINDMILL TOWER so that it cannot move or shake from the force of the wind.

F - hauban
S - retenida de alambre

## H

##### HARNESS

(ani). The gear or tackle, other than a YOKE, used on draft animals to pull a vehicle or drive an implement. It differs from a yoke, which joins together draft animals.

F - harnais
S - arnes

(hydr) (meas). [1] The vertical distance from the point where water enters an intake to the point where the water leaves a HYDROPOWER device. It is generally measured in feet or meters. The product of the head times the FLOW is a measurement of potential POWER. [2] The vertical distance a liquid must be pumped from its source to its point of use or storage.

F - chute d'eau [1]-[2]
S - altura

(sol). The pipe that runs across the top of an ABSORBER PLATE to gather or distribute HEAT TRANSFER FLUID from or to the grid pipes that run across the absorber surface. Some headers run along the bottom of the absorber plate.

F - entree-sortie
S - tubo colector

(hydr). A CANAL or conduit that feeds water into a mill, WATER WHEEL, or TURBINE.

F - bief d'amont

(hydr). The water upstream of a DAM or a HYDROPOWER plant.

F - eau d'amont
S - aguas arriba
##### HEAT CAPACITY

(heat) (meas). The amount of heat required to raise by one degree the temperature of a unit mass of a substance.

F - capacite thermique
##### HEAT ENERGY

(heat). ENERGY in the form of heat.

F - energie thermique
S - energia calorifica
##### HEAT EXCHANGER

(heat) (impl). A device, such as a coiled copper tube immersed in a tank of water which is used to transfer heat from one FLUID to another through a separating wall. A CONDENSER is one type of heat exchanger.

F - echangeur de chaleur
##### HEAT GAIN

(heat). The increase of heat in a space resulting from DIRECT RADIATION and from the heat given off by such other sources as THERMAL MASS, a stove, a fireplace, humans, or animals.

F - apport de chaleur
S - ganancia calorifica
##### HEATING VALUE

(heat) (meas). The amount of heat produced by the complete combustion of a specific amount of fuel. This is a measure of FUEL EFFICIENCY.

F - pouvoir calorifique
S - valor calorifico
##### HEAT LOSS

(heat). An unwanted decrease in the amount of heat contained in a space. Heat is usually lost through CONVECTION.

F - perte de chaleur
S - perdida calorifica
##### HEAT PUMP

(heat) (impl). A mechanical device that transfers heat from a heat source to a HEAT SINK. This process causes the source to cool and the sink to become warmer.

F - pompe a chaleur
S - bomba calorifica
##### HEAT RATE TRANSFER COEFFICIENT

(heat) (meas). The rate at which heat is transferred per hour, per unit surface, per degree of temperature difference.

F - coefficient de transmission de chaleur
S - coeficiente de transferencia del consumo calorifico
##### HEAT-REFLECTIVE GLASS

(sol). A type of glass designed to reflect SOLAR RADIATION.

F - verre a pouvoir reflechissant thermique
S - vidrio reflector de calor
##### HEAT SINK

(sol). A body that is capable of accepting and storing heat. It therefore may also act as a heat source.

F - puits de chaleur
S - sumidor de calor
##### HEAT TAX

(heat). Referring to the HEAT ENERGY that becomes unavailable for further use whenever ENERGY is converted from one form to another.

F - chaleur perdue
S - gravamen calorifico
##### HEAT TRANSFER FLUID

(sol). (See: HEAT TRANSFER MEDIUM)

F - fluide caloporteur
S - fluido de termotransferencia
##### HEAT TRANSFER MEDIUM

(sol). The FLUID that is heated in a SOLAR COLLECTOR for conducting heat to another place or substance.

F - caloporteur
S - medio de termotransferencia
##### HELICAL SAIL WINDMILL

(wind). The name for a particular type of HORIZONTAL-AXIS, SAIL ROTOR WINDMILL. It usually is used for low-lift water pumping.

F - eolienne a ailes helicoidales
S - molino con aspas helicoidales
##### HELIO-ELECTRICAL PROCESS

(sol). A process by which PHOTOVOLTAIC MODULES convert SOLAR ENERGY into electricity.

F - processus helioelectrique
S - proceso helioelectrico
##### HELIOSTAT

(sol) (impl). A solar-focusing instrument consisting of a mirror mounted on an AXIS that is moved by clockwork. The heliostat reflects sunbeams in one direction, usually to a central ABSORBER located in a TOWER.

F - heliostat
S - heliostato
##### HELIOTHERMAL

(sol). [1] A process that uses SOLAR RADIATION to produce heat. [2] A device that absorbs RADIATION on a blackened surface and converts it into heat.

F - heliothermique
S - heliotermico
##### HELIOTHERMAL PROCESS

(sol). A process by which SOLAR ENERGY is used to provide THERMAL ENERGY for space heating, space cooling, and domestic water heating.

F - processus heliothermique
S - proceso heliotermico
##### HELIOTHERMOMETER

(sol) (meas). An instrument that measures heat from the sun.

F - heliothermometre
S - heliotermometro
##### HELIOTROPIC

(sol) (impl). Turning toward light. It describes devices that TRACK the sun, following its movement across the sky.

F - heliotropique
S - heliotropico
##### HORIZONTAL AIR MILL

(wind) (arc). (See: HORIZONTAL-AXIS WINDMILL)

F - moulin a vent a arbre horizontal
S - molino de aire horizontal
##### HORIZONTAL AXIS SAIL ROTOR

(wind). A WIND MACHINE with cloth sails in which the WIND SHAFT is situated on a horizontal plane.

F - eolienne a ailes en toile sur axe horizontal
S - rotor de eje horizontal
##### HORIZONTAL AXIS WINDMILL

(wind). A WINDMILL driven by a ROTOR on a horizontal WIND SHAFT.

F - eolienne a arbre horizontal
S - molino de eje horizontal
##### HORIZONTAL WATERMILL

(hydr). A WATERMILL driven by a horizontal wheel mounted on a vertical shaft. (Syn: Greek Mill; Norse Mill)

F - moulin a eau horizontal
S - molino hidraulico horizontal
##### HORIZONTAL WATER WHEEL

(hydr). (See: HORIZONTAL WATERMILL)

F - roue hydraulique horizontale
S - rueda hidraulica horizontal
##### HORSEPOWER

(gen). A unit of POWER equal to 33,000 FOOT POUNDS per minute, 550 foot pounds per second, or 746 WATTS.

F - cheval-vapeur
S - potencia util
##### HOT DRY ROCK

(geo) A system for using GEOTHERMAL POWER. A hole is drilled and the deep rock cracked. This may be done hydraulically, as is done in conventional oil fields, or with explosives. Water is injected into the fractured rock, allowed to heat, and then withdrawn as steam for use as an ENERGY source.

F - roche chaude et seche
S - roca seca caliente
##### HOT WATER RESERVOIR

(geo). (See: GEOTHERMAL RESERVOIR)

F - reservoir d'eau chaude
S - tanque de agua caliente
##### HOUR ANGLE

(sol) (meas). The angular displacement of the sun east or west of the local meridian due to the rotation of the Earth on its AXIS at 15 [degrees] per hour (morning [+] afternoon [-]).

F - angle horaire
S - angulo hora
##### HUB EXTENSION

(wind). A piece of pipe that sticks out from the front of the hub of a ROTOR on a WINDMILL. It provides a place to attach GUY WIRES to strengthen the BLADES or SAILS.

F - rallonge de moyeu
S - extension del cubo
##### HUMIDIFIER

(gen). A mechanical means for increasing the relative humidity in an enclosed area by injecting water vapor into the air.

F - humidificateur
##### HUMUS

(biocon). Well-decomposed organic soil material consisting of the residues from plant and animal matter together with the cell substances of soil organisms and various inorganic materials.

F - humus
S - humus
##### HYBRID GENERATOR

(biocon). A two-stage BIOGAS DIGESTER design consisting of a larger batch-fed, ACID-producing, cold phase, and a smaller CONTINUOUS-FEED, METHANE-producing, heated phase. Alternatively, any digester that separates acid and methane production.

F - generateur hybride
##### HYBRID POWER SYSTEM

(gen). A system, such as one might find within a home, that derives its heating, lighting, and other ENERGY from several interconnected sources. One or more of these sources generally would come from RENEWABLE ENERGY.

F - energie heterogene, systeme d'
S - sistema de energia hibrida
##### HYBRID SOLAR ENERGY SYSTEM

(sol). A heating or cooling system that uses both ACTIVE SOLAR HEATING and PASSIVE SOLAR HEATING methods in its design. At least one of the system's significant THERMAL ENERGY FLOWS is by natural means, and at least one is by forced means.

F - energie solaire heterogene, systeme d'
S - sistema de energia solar hibrida
##### HYDRATE

(chem). A solid material resulting from the combination under pressure of a gas with water.

F - hydrate
S - hidrato
##### HYDRAULIC RAM

(hydr) (impl). A water pump that uses the ENERGY of descending water to raise a part of the water to a height greater than that of the source. It requires no other power than the energy from the descending water.

F - belier hydraulique
S - ariete hidraulico
##### HYDRAULIC RETENTION TIME

(biocon) (meas). The number of days an average volume of SLURRY remains in a BIOGAS DIGESTER.

F - duree de retention hydraulique
S - periodo de retention hidraulica
##### HYDROELECTRIC

(hydr). Relative to a system in which the potential ENERGY of falling water is harnessed by releasing it from DAMS or through a PENSTOCK downward through WATER TURBINES.

F - hydro-electrique
S - hidroelectrico
##### HYDROLOGIC CYCLE

(hydr). The cycle in which water passes through different states. It begins as atmospheric water vapor. It then becomes a liquid through precipitation. Next it flows along the ground surface, where it is useful as an energy source. Finally, it returns to its original form through evaporation and transpiration.

F - cycle hydrologique
S - ciclo hidrologico
##### HYDROLOGY

(hydr). The science of water systems on or beneath the Earth's surface.

F - hydrologie
S - hidrologia
##### HYDROLYSIS

(alc) (chem). The chemical process that breaks complex organic molecules into simple molecules. For example, STARCH and CELLULOSE can be hydrolyzed by ACIDS or ENZYMES to produce simple sugars, which can be FERMENTED to form ETHANOL.

F - hydrolyse
S - hidrolisis
##### HYDROMETER

(impl) (meas). An instrument used to determine the density or SPECIFIC GRAVITY of FLUIDS.

F - hydrometre
S - hidrometro
##### HYDROPOWER

(hydr). POWER produced by falling water. The term is used to identify a type of electricity-generating station or any energy output in which the main mover is driven by FLOWing water.

F - puissance hydraulique
S - potencia hidraulica
##### HYDROPOWER SYSTEM

(hydr). A system in which the potential ENERGY of FLOWing water is used to create electricity or to mechanically drive machines, by impounding it behind DAMS and then diverting it through a CHANNEL to a WATER TURBINE.

F - systeme de puissance hydraulique
S - sistema de potencia hidraulica
##### HYDROXYL

(biocon). A monovalent group consisting of a hydrogen atom and an oxygen atom linked together. Most BASES contain hydroxyl groups. (See also: BASE)

F - hydroxyle
S - hidroxilo
##### HYGROMETER

(impl) (meas) (sol). A device for measuring the humidity of the air. It is used in designing SOLAR HEATING and SOLAR COOLING systems.

F - hygrometre
S - higrometro

## I

##### IMPERMEABLE DRY ROCK

(geo). Rock systems in GEOTHERMAL regions where the heat is contained almost entirely in impermeable rock.

F - roche seche impermeable
S - roca seca impermeable
##### IMPULSE TURBINE

(hydr). A TURBINE driven by high velocity JETS of water or steam that are produced by forcing the water or steam through a nozzle.

F - turbine a action
S - turbina de impulsion
##### INCIDENT ANGLE

(sol) (hydr). [1] The angle between the sun's rays and a line perpendicular (normal) to the irradiated surface. The incident angle determines both the intensity of the DIRECT RADIATION component striking the surface and the ability of the surface to reflect, transmit, or ABSORB the sun's rays. [2] In the case of HYDROPOWER devices, the angle between the water intake and a line perpendicular to the BUCKETS.

F - angle d'incidence
S - angulo incidente

(sol) (meas). The quantity of RADIANT ENERGY striking a surface per unit time and unit area.

F - rayonnement incident
##### INDIAN-TYPE DIGESTER

(biocon). A BIOGAS DIGESTER primarily designed to produce METHANE. These digesters usually have FLOATING GAS CAPS.

F - digesteur type indien
S - digestor de tipo indio
##### INDIRECT CONVERSION

(sol). The indirect use of SOLAR ENERGY from such sources as solar-produced winds, thermal currents in air and water, and wave action.

F - conversion indirecte
S - conversion indirecta
##### INDIRECT SOLAR ENERGY

(sol). A system in which SOLAR ENERGY is COLLECTED and used through mechanical means.

F - energie solaire indirecte
S - energia solar indirecta
##### INDIRECT SOLAR GAIN

(sol) . A PASSIVE SOLAR HEATING system in which heat is stored between the COLLECTING and the distributing surfaces (e.g., TROMBE WALL).

F - apport solaire indirect
S - ganancia solar indirecta
##### INDIRECT SOLAR HEATING

(sol). A method of solar heating in which SOLAR RADIATION is COLLECTED in FLAT PLATE or CONCENTRATING COLLECTORS that are mounted on a roof, a wall, or apart from a building. Pumps or fans are used to circulate HEAT TRANSFER FLUIDS through the collectors and then back to a heat storage medium.

F - chauffage solaire indirect
S - calefaccion solar indirecta
##### INDUCTION MOTOR

(elec) (wind). A common type of motor, which, when modified slightly and driven by the rotary action of a WINDMILL or TURBINE, provides ALTERNATING CURRENT (ac).

F - moteur a induction
S - motor de induccion
##### INFILTRATION

(heat). The unchecked movement of outdoor air into a building through cracks around windows and doors or in walls, roofs, and floors. Infiltration generally refers to cold air during the winter and hot air during the summer.

F - infiltration
S - infiltracion
##### INFLUENT

(biocon). BIOMASS mixed with water for use in a BIOGAS DIGESTER.

F - affluent
S - influente

(sol). Electromagnetic RADIATION from the sun or a warm body that has wavelengths longer than the red end of the visible spectrum. Infrared radiation is experienced as heat.

##### INOCULATION

(biocon). Adding a SEED of ANAEROBIC BACTERIA to a BIOGAS GENERATOR.

F - inoculation
S - inoculacion
##### INOCULUM

(biocon). A sample of partially DIGESTED SLURRY, and its associated BACTERIA, that is added at the start of DIGESTION to a BIOGAS DIGESTER. It provides sufficient micro-organisms for the digestion process to proceed at a satisfactory rate. Without this seeding, there generally is a prolonged wait before a digester begins producing gas. (Syn: seed)

F - inoculum
S - inoculum
##### INSOLATION

(sol). The rate at which ENERGY from the sun reaches the Earth's surface. Insolation generally is measured in BTU/square feet (meters)/day.

F - insolation
S - insolacion
##### INSULATED STEAM COOKER

(sol). A small, insulated cooking box in which steam acts as the heating agent. Water heated to steam by a SOLAR COLLECTOR flows into the box, condenses, and drips back into the COLLECTOR.

F - rechaud a vapeur isole
S - cocinilla aislada de vapor
##### INTEGRATED HEATING

(sol). A method of SOLAR HEATING in which SOLAR RADIATION is intercepted and absorbed by a massive exterior wall or roof pond, which usually doubles as a heat storage container. Heat flows to the rooms by CONDUCTION, or natural CONVECTION. This is a form of PASSIVE SOLAR HEATING.

F - chauffage integre
##### INTEGRATED SYSTEM

(biocon). A system in which the outputs of one activity are used as inputs in other related activities. For example, a BIOGAS system in which the EFFLUENT is used as a nutrient to enrich an aquaculture environment. In exchange, BIOMASS from the aquaculture may be used as INFLUENT to the DIGESTER.

F - systeme integre
##### INVERTER

(elec) (wind). A device that converts DIRECT CURRENT (dc) to ALTERNATING CURRENT (ac). It often is used with WIND GENERATORS.

F - onduleur
S - invertidor
##### IRRIGATION WHEEL

(hydr). (See: NORIA)

F - roue hydraulique d'irrigation
S - rueda de irrigacion
##### ISOLATED SOLAR GAIN

(sol). A PASSIVE SOLAR HEATING system in which heat is collected in one area to be used in another. (See also: SOLAR GREENHOUSE)

F - apport solaire isole