| Haboob |
A squall of billowing dust that blows across the
Syrian Desert when a monsoon collides with dry air currents above
it. |
| Halogen Lamp |
A special type of incandescent globe made of quartz
glass and a tungsten filament, enabling it to run at a much higher
temperature than a conventional incandescent globe. Efficiency is
better than a normal incandescent, but not as good as a
fluorescent light. |
| Harmattan |
A very hot wind with dangerous cross-currents that
blows southwest from central Africa and across the Sudan,
typically December through February. It is often preceded by “the
smokes,” clouds of stinging, red dust. |
| Harmonic Content |
Frequencies in the output waveform in addition to the
primary frequency (usually 50 or 60 Hz.) Energy in these harmonics
is lost and can cause undue heating of the load. |
| H-Coal Process |
A means of making coal cleaner so it will produce less
ash and less sulfur emissions. |
| Head |
The difference in elevation between two parts of a
liquid-based system. In hydro power, the difference between a
source of water and the location at which the water from that
source may be used (synonym vertical drop). With pumps, the
vertical distance the pump must move the water. |
| Headrace |
A flume or channel that feeds water into a hydro
turbine. |
| Health Spa |
an establishment (often commercial) which is visited
by guests seeking therapy and relaxation; many center around hot
mineral springs or use hot water from geothermal wells. |
| Heat Balance |
The outdoor temperature at which a building's internal
heat gain (from people, lights and machines) is equal to the heat
loss through windows, roof and walls. |
| Heat Capacity |
The amount of heat necessary to raise the temperature
of a given mass one degree. Heat capacity may be calculated by
multiplying the mass by the specific heat. |
| Heat Engine |
An engine that converts heat to mechanical energy. |
| Heat Exchanger |
a device in which heat is transferred by conduction
through a metal barrier from a hotter liquid or gas, to warm a
cooler liquid or gas on the other side of the metal barrier. Types
of heat exchangers include "shell and tube," and "plate." |
| Heat Gain |
an increase in the amount of heat contained in a
space, resulting from direct solar radiation, heat flow through
walls, windows, and other building surfaces, and the heat given
off by people, lights, equipment, and other sources. |
| Heat Loss |
A decrease in the amount of heat contained in a space,
resulting from heat flow through walls, windows, roof and other
building surfaces and from exfiltration of warm air. |
| Heat Pump |
A device typically used for heating and cooling of
buildings by drawing from or dissipating into the ambient
temperature of air or water. When cooling, a heat pump works like
a refrigerator. When heating, it also works like a fridge, except
the heat produced is used to heat a space. |
| Heat Rate |
A number that tells how efficient a fuel-burning power
plant is. The heat rate equals the Btu content of the fuel input
divided by the kilowatt-hours of power output. |
| Heat Sink |
A medium or container to which heat flows. Thermal
mass walls and floors in a passive solar home act as a heat sink
during the day. |
| Heat Storm |
Heat storms occur when temperatures exceed 100
degrees Fahrenheit over a large area for three days in a row.
Normal hot temperatures cause electricity demand to increase
during the peak summertime hours of 4 to 7 p.m. when air
conditioners are straining to overcome the heat. If a hot spell
extends to three days or more, however, nighttime temperatures do
not cool down, and the thermal mass in homes and buildings retains
the heat from previous days. This heat build-up causes air
conditioners to turn on earlier and to stay on later in the day.
As a result, available electricity supplies are challenged during
a higher, wider peak electricity consumption period. |
| Heat Transfer |
Heat is transferred from one substance or location to
another by three methods—radiation, convection and conduction. The
sun's rays are a good example of radiation; warm air rising is
heat movement by convection; and touching a hot iron or frying pan
with your hand is heat transfer by conduction. |
| Heating Degree Day |
A unit that measure the space heating needs during a
given period of time. |
| Heating Load |
The rate at which heat must be added to a space in
order to maintain the desired temperature within the space. |
| Heating Value |
The amount of heat produced by the complete combustion
of a given amount of fuel. |
| Heavy Water |
A type of hydrogen atom that may be used as fuel for
fusion power plants. Also called DEUTERIUM, it is found in
abundance in the seas. |
| Hedging Contracts |
Contracts which establish future prices and quantities
of electricity independent of the short-term market. Derivatives
may be used for this purpose. (See Contracts for Differences,
Forwards, Futures Market, and Options.) |
| Heliochemical |
Using solar radiation to cause chemical reactions. |
| Heliothermal |
A process that uses the sun's rays to produce heat. |
| Helm Wind |
A wind that blows down the slopes of small, smooth
hills. Helm winds are common in the British Isles. |
| Hertz |
The frequency of electrical current described in
cycles per second. |
| Hertz (Hz) |
A measure of the number of cycles or wavelengths of
electrical energy per second. The United States electricity supply
has a standard frequency of 60 hertz. |
| Heterojunction |
A region of electrical contact between two different
materials. |
| High Voltage Disconnect |
The voltage at which a charge controller will
disconnect the photovoltaic array from the batteries to prevent
overcharging. |
| High Voltage Disconnect Hysteresis |
The voltage difference between the high voltag
disconnect set point and the voltage at which the full
photovoltaic array current will be reapplied. |
| High-Sulfur Coal |
Coal whose weight is more than one percent sulfur. |
| Hms:O |
The unit of measurement of the electrical resistance
of a material to the flow of current. |
| Hole |
The vacancy where an electron would normally exist in
a solid; behaves like a positively charged particle. |
| Homojunction |
The region between an n-layer and a p-layer in a
single material, photovoltaic cell. |
| Horizontal-Axis Wind Turbines |
Turbines on which the axis of the rotor’s rotation is
parallel to the wind stream and the ground. |
| Horsepower |
A measure of the capacity to generate energy or do
work. 1 horsepower = 746 watts. |
| Horsepower (Hp) |
A unit for measuring the rate of doing work. One
horsepower equals about three-fourths of a kilowatt (745.7 watts). |
| Hot |
(Colloquial) |
| Hot Dry Rock |
A geothermal resource created when impermeable,
subsurface rock structures, typically granite rock 15,000 feet or
more below the earth's surface, are heated by geothermal energy.
The resource is being investigated as a source of energy
production. |
| Hot Spot |
A phenomenon where one or more cells within a PV module or array
act as a resistive load, resulting in local overheating or melting
of the cells. |
| Hot Springs |
a natural spring that puts out water warmer than body
temperature and therefore feels hot; may collect in pools or flow
into streams an lakes. A geothermal phenomenon. |
| HSPF (Heating Seasonal Performance Factor) |
A measure of heating efficiency for the total heating
output of a central air-conditioning heat pump. Efficiency is
derived according to federal test methods by using the total Btus
during its normal usage period for heating divided by the total
electrical energy input in watt-hours during the same period |
| Hub |
The center mount for the blades. Laser cut like
mine are hard to beat. |
| HVAC (Heating Ventilation And Air Conditioning) |
A system that provides heating, ventilation and/or
cooling within or associated with a building. |
| Hybrid System |
A PV system that includes solar PV and some other
electricity generating power source. |
| Hybrid Vehicle |
Usually a hybrid EV, a vehicle that employs a
combustion engine system together with an electric propulsion
system. Hybrid technologies expand the usable range of EVs beyond
what an all-electric-vehicle can achieve with batteries only. |
| Hydroelectric Power |
Electricity produced by falling water that turns a
turbine generator. Also referred to as HYDRO. |
| Hydroelectric Spill Generation |
Hydroelectric generation in existence prior to January
1, 1998, that has no storage capacity and that, if backed down,
would spill. This term also refers to a hydro resource that has
exceeded or has inadequate storage capacity and is spilling, even
though generators are operating at full capacity. |
| Hydroelectricity |
Electric energy made by the conversion of energy
produced from running water. |
| Hydro-Electricity |
Any electricity that is generated by the flow of
water. |
| Hydrogen Fuel Cell |
A device that converts hydrogen to DC electricity. |
| Hydrogenated Amorphous Silicon |
Amorphous silicon with a small amount of incorporated
hydrogen. The hydrogen neutralizes dangling bonds in the amorphous
silicon, allowing charge carriers to flow more freely. |
| Hydrometer |
A hydrometer is an instrument for measuring the
density of liquids in relation to the density of water. The
hydrometer is used to indicate the state of charge in lead-acid
cells by measuring the specific gravity of the electrolyte. |
| Hydronic Heating |
A system that heats a space using hot water which may
be circulated through a convection or fan coil system or through a
radiant baseboard or floor system. |
| Hydronic Heating System |
A type of heating system where water is heated in a
solar collector or boiler, and is pumped to heat exchangers or
radiators in rooms. Radiant floor systems have a grid of tubing
laid out in the floor for distributing the heat. Temperature of
the space is controlled by regulating the flow and/or temperature
of the circulating water. |
| Hydropower |
captures the energy in flowing water and uses it to
generate electricity. |
| Hydrothermal |
hydro means water and thermal means heat. Literally
hydrothermal means hot water. Steam and hot water reservoirs are
hydrothermal reservoirs. Hot dry rock resources and magma
resources are not considered to be hydrothermal resources. |
| Hydrothermal Systems |
Underground reservoirs that produce either dry steam
or a mixture of steam and water. |
| Hygas |
A process that uses water to help produce
pipeline-quality gas from coal. |
