Glossary

A

Absorber
The blackened surface in a solar collector that absorbs the solar radiation and converts it to thermal energy.

Absorption Machine
Refrigeration machine in which cooling of an interior space is accomplished by the evaporation of a volatile fluid, which is then absorbed in a strong solution, then desorbed under pressure by a heat source, and then recondensed at a temperature high enough that the heat of condensation can be rejected to a exterior space.

Active Solar System
A system that uses mechanical devices and an external energy source in addition to solar energy, to collect, store, and distribute thermal (heat) energy.

Aerodynamic control
The use of a propeller's design (ie shape, size, structure and material) and its properties in varying velocities of wind to act as an overspeed protection for a wind generator

Air excess
The amount of air more than the theoretical requirement to burn totally the fuel.

Altitude
The angular distance from the horizon to the sun.

Ambient
Natural condition of the environment at any given time.

Ambient temperature
The temperature of the surrounding air.

Anti-sweat heater control
It senses humid conditions and turns the heater off when it is not needed.

Average annual
The average power output in a year, measured in millions of units, ie millions of kilowatt hours.

B

Balance of systems (BOS)
The parts of the photovoltaic system other than the PV array: switches, controls, meters, power-conditioning equipment, supporting structure for the array and storage components, if any.

Battery
For off-grid systems a battery is used to provide energy storage.

Binary-Power Plant
A geothermal electricity generating plant employing a closed-loop heat exchange system in which the heat of the geothermal fluid (the "primary fluid") is transferred to a lower-boiling-point fluid (the "secondary" or "working" fluid), which is thereby vaporized and used to drive a turbine/generator set.

Bio-ethanol
Alcohol obtained from the processing of plants with high contents of starch and / or starch syrup. It could replace gasoline. Bio-ethanol could be converted in gasoline in the presence of catalysts.

Bio-diesel oil
Fuel obtained from mechanical and / or chemical processing of plants with high contents of oil (rape, soy, sun flower, cotton, etc). It could replace diesel oil.

Bio-fuel
Fuel of vegetal origin which could be used in internal combustion engines.

Bio-gas
Fuel gas obtained by anaerobic digestion of animal dejections, organic wastes, mud from municipal treatment stations.

Biomass
Bio-degradable fraction of products wastes and residues from agriculture (including vegetable and animal substances, forestry and connected industries, as well as bio-degradable fraction of industrial and municipal wastes).

Boiler
A vessel or tank where heat produced from the combustion of fuels such as natural gas, fuel oil, or coal is used to generate hot water or steam for applications ranging from building space heating to electric power production or industrial process heat.

Brine
A geothermal solution containing appreciable amounts of sodium chloride or other salts.

Bulb generators
Similar to Gravity Dam, but uses less concrete. The strength of the buttresses holds back the water.

C

Capacity Bank
An electrical device that adjusts the leading current of an applied alternating current to balance the lag of the circuit to provide a high power factor.

Cathode ray tubes (CRT)
A cathode ray tube (CRT) is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface. Most desktop computer displays make use of CRTs. The CRT in a computer display is similar to the "picture tube" in a television receiver.

Charge controller
Charge controllers are typically used in off-grid photovoltaic power systems. The primary function of a charge controller (or regulator) is to maintain the battery at the highest possible State Of Charge (SOC) and provide the user with the required quantity of electricity, while protecting the battery from deep discharge (by the loads) or extended overcharge (by the PV array).

CHP Technologies
See cogeneration

Co-firing
Method of electrical energy generation using biomass and coal in the existing plants for coal firing.

Co-generation (CHP)
Production of heat and electrical energy simultaneously, allowing an improvement in the overall efficiency of the system.

Cold Wall Effect
The chilly discomfort experienced by a person in a building as his or her body radiates heat to the cold surface of an uninsulated wall.

Collector
A device that collects solar radiation and converts it to heat.

Collector efficiency
The ratio of usable heat energy extracted from a collector to the solar energy striking the cover.

Colour rendition
It gives an idea of how colours will be seen with a lamp. A larger number indicates better reproduction of colours.

Condenser
Part of a closed refrigeration system (air conditioner or heat pump) where vapor discharged by the compressor is cooled by water or air to a point where the vapor returns to a liquid state. Condensers are usually placed outdoors because they release heat.

Condensing boiler
A condensing boiler is a high efficiency modern boiler that incorporates an extra heat exchanger so that the hot exhaust gases lose much of their energy to pre-heat the water in the boiler system. When working at peak efficiency, the water vapour produced in the combustion process condenses back into liquid form releasing the latent heat of vaporisation. A side effect is that this water, known as condensate, which is usually acidic, has to be piped away to a drain or soakaway.

Condenser Coil
The device in an air conditioner or heat pump through which the refrigerant is circulated and releases heat to the surroundings when a fan blows outside air over the coils. This will return the hot vapor that entered the coil into a hot liquid upon exiting the coil.

Conduction
The flow of heat through a solid material from hotter to colder areas.

Conductivity
A measure of the ability of a material to permit conduction of heat flow through it.

Constant frequency
a regular and consistent number of alternations per second of an alternating current (standard is 60/minute)

Control and monitoring for RES
Equipments and components to supervise the operation of RES hybrid system, to diagnose the faults and to measure the time evolution of meteorological and operating parameters.

Convection
The flow of heat in a fluid due to hotter material rising and cooler material sinking.

Crust
Earth's outer layer of rock. Also called the lithosphere.

D

Dam
A structure built across a river to raise water for storage purposes.

Diffuse solar radiation
Indirect sunlight that is scattered from air molecules, dust and water vapor.

Direct solar radiation
Solar radiation that comes straight from the sun, casting shadows on a clear day.

Diesel generators:
Generators which are used in standby power systems when large battery banks are to be avoided because of size or cost or weight. Usually, if more than a half-day of support is required, a generator is the answer.

Direct Use
Use of geothermal heat without first converting it to electricity, such as for space heating and cooling, food preparation, industrial processes, etc.

Distribution
The low voltage supply of electricity to individual consumers.

District Heating
A type of direct use in which a utility system supplies multiple users with hot water or steam from a central plant or well field.

Drain back system
The solar heat transfer fluid automatically drains into a tank by gravity. Drain back systems are available in one or two tank configurations. A heat exchanger is necessary, because the city inlet pressure would prevent draining.

Drilling
Boring into the Earth to access geothermal resources, usually with oil and gas drilling equipment that has been modified to meet geothermal requirements.

Dry Steam
Very hot steam that doesn't occur with liquid.

E

Economizer
Heat exchanger for recovering heat from flue gases for heating water.

Electric arc furnace
Electric arc furnaces are large, welded-steel cylindrical vessels equipped with a removable roof through which carbon electrodes are inserted. The electrodes are energized by three-phase alternating current, creating arcs that melt the metallic charge material. Additional heat is generated by the electrical resistance of the metal to the current between the arc paths.

Electronic connection equipment or electronic ballast
They stabilize light emission and assure a correct ignition and performance of lamps, thus increasing their lifespan.

Evaporative condenser
High efficient condenser that uses a wetted filter to cool ambient air increasing its ability to expel heat.

Evaporative Cooler
Evaporative Coolers are refrigeration devices that use the outside air's heat to evaporate water that is held by pads inside the cooler. The heat is drawn out of the air through this process and the cooled air is blown into the home by the cooler's fan.

Evaporator Coil
The inner coil in a heat pump that, during the cooling mode, absorbs heat from the inside air and boils the liquid refrigerant to a vapor, which cools the house.

F

Fan Coil
A heat exchanger coil in which a fluid such as water is circulated and a fan blows air over the coil to distribute heat or cool air to the different rooms.

Flash Steam
Steam produced when the pressure on a geothermal liquid is reduced. Also called flashing.

Flat plate collector
A solar collection device in which sunlight is converted into heat on a plane surface without the aid of reflecting surfaces to concentrate the rays.

Flow
volume of water, expressed as cubic meters per second, passing a point in a given amount of time

Forebay
Discharge point into lower reservoir/loch.

Francis turbine
Reaction turbine with two sets of curved vanes. The outer guide vanes direct the water unto the inner runner, which is free to rotate. Water is fed into this turbine through a large spiral casing to ensuring a smooth, continuous flow of water. Used at moderate head locations.

Flue gas
The gas resulting from the combustion of a fuel that is emitted to the flue.

Flue gas Analyser
It is used to measure the efficiency of a boiler. It supplies the concentration of O₂, CO₂, CO and the temperature of the exhaust gases.

G

Gas Turbine
A type of turbine in which combusted, pressurized gas is directed against a series of blades connected to a shaft, which forces the shaft to turn to produce mechanical energy.

Gasification
Thermodynamic process in which biomass (e.g. wood biomass) is converted in fuel. The required heat is obtained by the combustion of a part of the material considered for gasification. The resulted gas contains hydrogen, water steams, carbon oxide, methane, carbon dioxide, nitrogen, etc. Due the high contents of carbon dioxide, water steams and nitrogen, calorific power of the gas is low. For the gas utilization in internal combustion engines it have to be cleaned from impurities.

Generation component
those sub-elements of a wind system which actually contribute to producing electric power, including the generator or alternator, the tower, the rotor, the controls

Generator
A machine which produces electricity when the rotor is driven by an engine or turbine.

Generator field
the magnetic field of a generator

Geothermal
Of or relating to the Earth's interior heat.

Geothermal Energy
The Earth's interior heat made available to man by extracting it from hot water or rocks.

Geothermal Gradient
The rate of temperature increase in the Earth as a function of depth. Temperature increases an average of 1° Fahrenheit for every 75 feet in descent.

Geothermal Heat Pumps
Devices that take advantage of the relatively constant temperature of the Earth's interior, using it as a source and sink of heat for both heating and cooling. When cooling, heat is extracted from the space and dissipated into the Earth; when heating, heat is extracted from the Earth and pumped into the space.

Geyser
A spring that shoots jets of hot water and steam into the air.

Glazing
A glass, plastic or transparent/translucent covering.

Grave Fill
Grave fills are elements with a high energy storing capacity used for heating or cooling purposes in buildings; they absorb energy from the sun and warm up the air circulating through them. This hot air flows afterwards to the room that wants to be heated. Grave fills are usually situated underneath the building.

Grid
Network of transmission lines, substations, distribution lines and transformers used by central power systems

Grid-connected distributed PV system
System installed on consumers' premises usually on the demand side of the electricity meter. This includes grid-connected domestic photovoltaic power systems and other grid-connected photovoltaic power systems on commercial buildings, etc.

H

Head
The vertical distance between two water levels

Heat Capacity
A measurement of the specific heat of a material multiplied by its density. See "specific heat."

Heat Exchanger
A device for transferring thermal energy from one fluid to another.

Heat Flow
Movement of heat from within the Earth to the surface, where it is dissipated into the atmosphere, surface water, and space by radiation.

Heat pump
A mechanical device that transfers heat from a cooler medium to a hotter one. It can be used to cool a building in summer and heat it in winter. When the device is used for heating it delivers more energy than it uses, giving an apparent efficiency of over 100%.

Heating season
The period from early fall to late spring (in the northern hemisphere) during which additional heat is needed to keep a house comfortable for its occupants.

Heat source
A medium or container from which heat flows.

Heat storage
A device or medium that absorbs collected solar heat and stores it for use during periods of inclement or cold weather.

Heat transfer coefficient "U"
Coefficient that measures the insulation capacity of a certain material. It is the inverse of the thermal resistance "R". Its units are W/m²ēC and, a good insulating material needs to have low U-values.

High-Pressure Sodium Lamp
A type of High-Intensity Discharge (HID) lamp that uses sodium under high pressure as the primary light-producing element. These high efficiency lights produce a golden white color and are used for interior industrial applications, such as in warehouses and manufacturing, and for security, street, and area lighting.

Horizontal axis
a wind generator which has its axis or centre around which the rotor revolves, parallel to the earth's surface and the wind flow

Hybrid power systems
Hybrid power systems combine two or more energy devices, or two or more fuels for the same device, that when integrated, overcome limitations inherent in either.

Hydro-electricity
Electricity generated by using water to rotate a turbine, which turns a shaft that drives a generator, which in turn converts the mechanical energy into electricity.

Hydrothermal Resource
Underground systems of hot water and/or steam.

I

Induction furnace
It uses a strong magnetic field to induce an electric current in the material to be heated. The material to be heated must be an electrical conductor. The major use is for the heat treatment of metals.

Infrared radiation
Electromagnetic radiation from the sun that has wavelengths slightly longer than visible light.

Injection
The process of returning spent geothermal fluids to the subsurface. Sometimes referred to as reinjection.

Insolation
The total amount of solar radiation direct, diffused and reflected-striking a surface exposed to the sky.

Installed capacity
The nominal maximum electrical output of all the machines installed in the power station.

Insulation
A material with high resistance to heat flow.

Intake
Location where water enters the tunnel system.

Internal Combustion Engine
An engine where the fuel is burnt inside the engine, the best known example is a car engine. It can be used to drive an
electric generator.

Installed power
Power delivered by a photovoltaic module or a photovoltaic array, under standard test conditions.

Inverter
Device that converts direct current (d.c.) into alternating current (a.c.).

I-V curve
A graphical presentation of the current versus the voltage from a photovoltaic cell as the load is increased from the short circuit (no load) condition to the open circuit (maximum voltage) condition. The shape of the curve characterizes cell performance.

J

K

Kaplan Turbine
Propeller turbine where the flow of water is parallel to the axis of the machine, which uses blades shaped like a ships propeller to turn the shaft. Used for low head sites.

L

Landfill-gas
fuel gas obtained by anaerobic decomposition of organic fraction from urban wastes.

Level of illumination
Level of illumination is the quantity of light falling on a surface and is measured in Lux.

Light cell
Device located in a circuit that opens or closes a switch according to the received light.

Light Flux
Light flux is the quantity of light emitted by the lamp and is measured in Lumens (Lm).

Liquid Crystal display (LCD)
LCD (liquid crystal display) is the technology used for displays in notebook and other smaller computers. LCDs consume much less power than other displays because they work on the principle of blocking light rather than emitting it.

Liquid pressure amplifiers
Small refrigerant pumps that increase the system efficiency, by raising the liquid line pressure

Load
The simultaneous demand of all customers required at any specified point in an electric power system.

Low-Pressure Sodium Lamp
A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0,13 to 1,3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots.

M

Magma
Molten rock within the Earth, from which igneous rock is formed by cooling.

Mercury Vapor Lamp
A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes clear, phosphor coated, and self-ballasted lamps.

Micro Hydro Power Station
It is a Hydro Power Station with the maximum electrical output of 100 kW.

Microturbine
A microturbine is a small-scale gas turbine (30-350 kW) limited to lower temperature applications.

Mobile PV-Wind hybrid system
A hybrid system which could be packed and transported in a container. It was designed and installed at the test field of Folkecenter for Renewable Energy in Denmark.

Motion sensor
Connects and disconnects lighting in response to the presence or absence of occupants.

N

Network or grid
The total transmission and distribution system for supplying electricity to consumers.

O

Off-grid domestic PV system
System installed in households and villages that are not connected to the utility grid. See stand alone PV system.

Off-grid non-domestic photovoltaic power system
System used for a variety of applications such as water pumping, remote communications, telecommunication relays, safety and protection devices, etc. which are not connected to the utility grid. See stand alone PV system.

Open air system
Some part of the system is open to the atmosphere, or system contains fresh or changeable water.

Output
The amount of electrical energy transmitted from a power station.

P

Peak Demand
Period during the day when electricity demand is at the greatest.

Peak load
The amount of electrical power used at times of high demand (usually 5 PM - 6 PM on a winter evening).

Pellets
Fuel of high quality obtained by compression of wood biomass finely crumbled and dried at about 12% - 15%. Pellets are characterized by high caloric power (17.21 MJ/Kg) and are presented as cylinders of 68 mm diameter and 1-15 cm length. Usually are commercially available packed in plastic bags. Pellets are manufactured from wood or agricultural wastes.

Pelton turbine
Impulse type, incorporating a wheel with a series of cup-shaped buckets around the periphery. Well suited to schemes with a head over 245m.

Penstock
A pipeline down which water flows to the power station.

Permeability
The capacity of a substance (such as rock) to transmit a fluid. The degree of permeability depends on the number, size, and shape of the pores and/or fractures in the rock and their interconnections. It is measured by the time it takes a fluid of standard viscosity to move a given distance. The unit of permeability is the Darcy.

Pico Hydro Power Station
It is a Hydro Power Station with the maximum electrical output of 5 kW.

Power station
A power station which stores energy in the form of potential energy. It utilises Hydroelectric the overnight excess of baseload electricity in the country for pumping water up from the lowest to the higher reservoir. Through the day the water is released generators by reversing their direction of rotation.

Peak power
PV modules are rated by their total power output. The peak power is the amount of power output a PV modules produces at Standard test conditions (STC).

Photovoltaic array
A mechanically integrated assembly of modules and panels together with support structure to form a d.c. power producing unit.

Photovoltaic cell
A basic photovoltaic device, which generates electricity when, exposed to a light such as the solar radiation. All photovoltaic cells produce direct current (d.c.).

Photovoltaic module
The smallest complete environmentally protected assembly of interconnected photovoltaic cells.

Photovoltaic panel
A group of modules fastened together, pre-assembled and wired, designed to serve as an installable unit in a photovoltaic array.

Photovoltaic power system
Set of interconnected elements such as photovoltaic modules, inverters that convert d.c. current of the modules into a.c. current, storage batteries and all installation and control components.

Photovoltaics
The process that produces electricity from sunlight. "Photo" refers to light and "voltaic" to voltage.

PV
Abbreviation of photovoltaic (adjective) or photovoltaics (noun).

Power Factor
The ratio of actual power being used in a circuit, expressed in watts or kilowatts, to the power that is apparently being drawn from a power source, expressed in volt-amperes or kilovolt-amperes.

Preheater
Heat exchanger for recovering heat from the flue gases for heating air.

Q

R

Radiant Floor
A type of radiant heating system where the building floor contains channels or tubes through which hot fluids such as air or water are circulated. The whole floor is evenly heated. Thus, the room heats from the bottom up. Radiant floor heating eliminates the draft and dust problems associated with forced air heating systems.

Radiation
The flow of energy via electromagnetic waves, such as visible light or infra red. Unlike conduction and convection, radiation requires no intervening medium. However, it is stopped by opaque objects such as walls or trees.

Radiant Energy
Low temperature infrared energy emissions from the sun.

Radiation
Along with convection and advection, one of the three major processes in transferring heat energy from place to place. In the radiation process, heat is transferred in the form of waves of energy. The sun transfers its heat and light energy to the earth by this process. The earth loses heat to space by this process.

Reflected radiation
Sunlight that is reflected from surrounding trees, terrain or buildings onto a surface exposed to the sky.

RES Integrated system
Renewable energy converter connected to the grid.

Reservoir
1. Water storage area created by the construction of a dam.
2. A natural underground container of liquids, such as water or steam (or, in the petroleum context, oil or gas).

Resistance furnace
Resistance furnaces use the same principle of domestic ovens. The heat produced inside the furnace is based on Joule´s law: a chamber is heated by means of electrical resistances.

Roof Ponds
Passive heating/cooling system. Enclosed water above and in immediate contact with ceiling elements, with movable insulation, which expose ponds to the winter sun for heating, and to the night sky for summer cooling.

Rotor
a complete system of blades which supplies all the force driving a wind generator

S

Salinity
A measure of the quantity or concentration of dissolved salts in water.

Selective surface
A surface that absorbs radiation of one wavelength (for example, sunlight) but emits little radiation of another wavelength (for example, infrared); used as a coating for absorber plates.

Shell Boiler
Type of boiler in which the heating gases flow inside a set of pipes, while the fluid to be heated flow outside of them.

Small hydro
the application of hydroelectric power on a commercial scale serving a small community (10 MW or less)

Smart window
is a window with glazing which has chromogenic coating.

Soft Starter
Soft starters are motor controllers applied to A.C. induction motors. They use switches to control the voltage, allowing a smooth start and reducing the overfluxing of the motor. This way, the iron losses are reduced, the motor runs cooler and more efficiently, the power factor is maintained at the most appropriate value and hence the overall efficiency of the motor is increased.

Solar constant
The solar constant is the amount of energy received at the top of the Earth's atmosphere on a surface oriented perpendicular to the Sun’s rays (at the mean distance of the Earth from the Sun). The generally accepted solar constant of 1368 W/m² is a satellite measured yearly average

Solar radiation (solar energy)
Electromagnetic radiation emitted by the sun.

Storage reservoir
An artificial loch where water is stored for long periods.

Stand-alone photovoltaic power system
Autonomous system with storage batteries (see off-grid photovoltaic power system).

Standard test conditions (STC)
The testing conditions to measure photovoltaic cells or modules nominal output power. Irradiance level is 1 000 W/m˛, with the reference air mass 1,5 solar spectral irradiance distribution and cell or module junction temperature of 25°C.

Steam Turbine
A device that converts high-pressure steam, produced in a boiler, into mechanical energy that can then be used to produce electricity by forcing blades in a cylinder to rotate and turn a generator shaft.

Storage capacity
the number of amp hours a battery bank is capable of storing.

Storage component
those sub-elements of a wind system which are used to store excess electricity

Switch clock
Clock connected to a circuit that opens/closes one or more switches according to the programmed scheduled.

T

Tap aerator
Aerators are low flow devices that mix air into the water flow and reduce water consumption.

Temperature Gradient
The rate of increase or decrease in the Earth's temperature relative to depth.

Thermal bridging
Thermal bridging appears in constructive elements when faulty surfaces or incorrect designs leave gaps in the insulation that have lower thermal resistances than adjacent areas.

Thermal conductivity "k"
Coefficient that measures the heat transfer capacity of a certain material. The units of "k" are W/mēC; the lower the value of "k", the better the insulating capacity of the material.

Thermal resistance "R"
The resistance of one square meter of the material to a one degree temperature difference. The thermal resistance is measured in m²ēC/W. A greater value of "R" means a better insulating material.

Thermostat
A device used to control temperatures; used to control the operation of heating and cooling devices by turning the device on or off when a specified temperature is reached.

Thermostatic valves
Valves installed on each radiator that allow individual adjustments, according to the local conditions or preferences.

Three-bladed
consisting of three blades

Timer
A Timer closes the lighting circuit during a certain period of time.

Trigeneration
Simultaneous generation by an energy conversion system of electricity, thermal energy and cold.

Transparent insulation
relies on compensating heat loss with solar gains and, in addition, to use these gains for space heating.

Transparent insulation materials
in contrast to opaque thermal insulation materials, have two specific properties: highly efficient thermal insulation and high transmittance for solar radiation

Trombe Wall
A wall with high thermal mass used to store solar energy passively in a building. The wall, usually concrete, stone or masonry has vents at regular intervals along the floor and just below the ceiling. The exterior south-facing side is dark in colour and fronted with glass. Air is warmed between the glass and wall and circulates by convection through the vents. It is named after Dr. Felix Trombe, one of its developers.

Transmission
The high voltage transport of electricity along power lines, carried on pylons.

Tube-type collector
A collector in which the heat transfer fluid flows through metal tubes that are fastened to the absorber plate with solder, clamps or other means (see Collector).

Turbine
Mechanical structure used in the generation of electricity; the blades of which are driven by the flow of water, rotating the turbine.

Turbine runner
The rotating element on the turbine through which water flows and thus drives the turbine round. In the case of some pumped-storage schemes the direction of rotation can be reversed to pump water uphill. In this mode of operation the runner is called an impeller.

U

V

Variable Speed Drive
A variable speed drive (VSD), also called a variable frequency drive, is a control device for squirrel cage induction motors. A VSD consists of a power converter that converts constant frequency AC power input into a variable frequency output. The output voltage and frequency is determined by the actual power needs of the motor, allowing always the best motor performances.
In a pumping system reduces noise and energy losses by controlling flow by motor speed rather than a pressure reduction valve.
Most common variable speed drives are VSP-PWM (Pulse width modulated).

Vertical axis
a wind system which has its axis of rotation perpendicular to the earth and the wind's flow

W

Water Radiator
A room heat delivery (or exchanger) component through which hot water flows, leading to an increase of the room temperature by means of natural convection.

Water tube Boiler
Type of boiler, in which the fluid to be heated flows inside a set of pipes, while the heating gases flow outside of them transferring part of their energy through the walls of the pipes.

Water turbine
The part of the power station machine which is turned by the energy of the flowing water. It drives the rotor of the generator.

Wind
Air in motion. From still (no wind) to a breeze (slight wind) to a gale (mighty wind)

Wind generators
generators which get their power from wind turning a permanent magnet around a stationary armature or visa versa.

Windmill
A traditional wind powered machine used to grind grain for flour. Often used to describe the wind pumps common in the Netherlands.

Wind turbine
A modern wind powered machine used to generate electrical energy.

Wood chips
name for crumbled wood with dimensions of 1-100 mm. Chips are resulted from the crumbling of the wood residues and remains from massive wood and other wood wastes, from wood processing, from crumbling of wood materials resulted at the buildings demolishing, wood products with expired life time, or from the crumbling of wood material resulted from energy plantations (trees and shrubs).

X

Y

Z