HYDROKINETIC POWER DEFINITIONS
There are two types of hydrokinetic power, current-based and
wave-based. Each is described below.
CURRENT-BASED HYDROKINETIC POWER
Currents in hydrokinetic canals use a variety of technologies
to generate zero-emissions, renewable energy from water currents.
These currents typically occur at a variety of application points:
• River currents (river power known as in-stream, free-flow,
open river or run-of-river projects);
• Tidal currents (by-directional tidal power);
• Ocean currents (uni-ocean power); and
• Currents and irrigation canals and other manmade conduits.
Energy is generated from the water currents by a variety of technologies,
including:
• Horizontal axis turbines (with no ducts, single ducts and dual
ducts);
• Vertical axis turbines (with no ducts, single ducts and dual
ducts); and
• Helical turbines of both the vertical and horizontal variety
(with no ducts, single ducts and dual ducts)
As the water current passes through the turbine (rotor fan),
the turbine will rotate on a shaft that is connected to the generator.
WAVE-BASED HYDROKINETIC POWER
Wave-based hydrokinetic power also uses a variety of technologies
to generate zero-emissions, renewable power from wave action.
Energy is generated in a variety of ways depending on the technology.
Wave buoys generate electricity by riding on the motion of the
wave crest and wave trough. This up and down motion can drive
water pumps, solenoids, hydraulic systems and electric generators.
ENERGY DEFINITIONS
Availability Factor - expressed as a percent,
the number of hours a unit is available to operate in a year divided
by the total number of hours in a year. The availability factor
is greater than, or equal to, the capacity factor.
Capital Cost - The cost of field development
and plant construction and the equipment required for power plant
operations.
Capacity Factor - Expressed as a percent, the
number of hours a unit operates in a year divided by the total
number of hours in a year. Example: There are 8,766 hours in a
year. If the unit is operational 6,500 hours in a year, then its
capacity factor is 74.15% = (6,500/8,766) = 0.7415.
Cold Start - A black start process restores
a power plant to operation without relying on external energy
sources and allows the generation system to quickly go from zero
generation to full generation.
Duct - A nozzle that either converges or diverges.
Head - The total height of a column of water.
The product of the water's weight and a usable difference in elevation
gives a measurement of the potential energy possessed by water.
Impeller - Another name for the turbine fan.
Impoundment - Water that is prevented from flowing
by a natural or man-made feature.
Kilowatt (kW) – 1,000 Watts
Kilowatt-hour (kWh) - A kilowatt-hour (kWh)
is equal to the energy of 1,000 watts working for one hour. The
amount of electricity a power plant generates or a customer uses
over a period of time is measured in kilowatt-hours (kWh).
Megawatt (MW) – 1,000 kW
Megawatt Hour (MWh) - One thousand kilowatt-hours
or 1 million watt-hours.
Rotor - Another name for the turbine fan.
Slack tide - The time period at the change from
high tide to low tide (i.e., when the incoming tide stops and
reverses direction or where the outgoing tide stops and begins
to come in towards the land). The slack tide period is the period
during which no appreciable tidal current flows in a body of water.
Tailrace - The tailrace is the area immediately
downstream (in front of the dam) of a hydroelectric project where
the water re-enters the river. The tailrace can be used to generate
additional electricity with hydrokinetic turbines.
Turbine - A machine for generating rotary mechanical
power from the energy of a stream of fluid (such as water, steam
or hot gas). Turbines convert the kinetic energy of fluids to
mechanical energy through the principles of impulse and reaction,
or a mixture of the two.
Watt (W) - The unit of electrical power equal
to one ampere under a pressure of one volt. A Watt is equal to
1/746 horsepower.
|
