Marine hydrokinetic energy refers to several developing
technologies that are in various stages of research and development, all of
which tap into the kinetic potential and movement of seawater to generate
electricity. Hydrokinetic energy is comprised of wave, tidal,
and current energy.
The untapped potential of hydrokinetic energy offshore in the U.S.
is enough to power nearly 108 million households each year. In other words,
if all of the offshore hydrokinetic energy was used, it could power 94% of
the households that currently exist in the U.S. regardless of
the loss of energy due to inefficiencies in the technology used to harness
Wave energy uses Wave Energy Converters (WECs) to harness the potential of
waves created when wind blows at the surface of the ocean. The amount of
convertible energy depends on wind speed, duration, and fetch. The idea has
been around seriously and academically since the 1970’s, and currently,
pre-commercial installed prototypes do exist. Along with tidal stream
technologies, wave energy is thought to have the highest commercial
potential. Major tech wave technology developers in the U.S. include Atargis
Energy, Columbia Power Technologies, Ecomerit Technologies, Oscilla Power
Inc., and Resolute Marine Energy.
Tidal energy captures the potential energy in the daily variation in the tides.
This energy source can be further broken down into tidal stream and tidal range.
Tidal stream captures the potential hydrokinetic energy that exists from the
horizontal ebb and flow of the tides. Tidal range captures the hydrokinetic
energy that exists from the vertical rise and fall of the water column due to
tides. Tidal stream, along with wave energy, is thought to have the highest
commercial potential. There are major tidal streams along the coastline of every
continent, giving it global viability, and has been garnering increasing interest
from commercial operators and utilities. Tidal range is the only currently
mature hydrokinetic energy source, with two existing large-scale
projects in France and South Korea. However, tidal range also has more barriers
to development, including limited potential project locations, high capital cost,
and more environmental consequences than have been demonstrated by other
alternative energy types.
Current energy taps in to the conveyor belt of global ocean currents to generate
electricity. This energy source is different from tidal range energy in that these
currents are unidirectional, whereas tidal range captures temporary movement that
can flow in two directions. Open ocean currents have the benefit of being a
constant, reliable energy source, however, it tends to have slower velocities.
If better technologies are developed that that successfully harness these slower
velocities, current energy has potential for scaled up projects globally.
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