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Power and Energy Directly from Water
buoys installed which collectively generate 1.5 MW of electricity. The
power wave station is located 2.5 miles off the Oregon coast and is connected to the electric grid by an underwater cable. The construction of this
power station is completed [33,79,80,101].
2. Underwater turbines (Figure 13.8b) use water currents to spin underwater
blades and generate electricity. These technologies depend on the unconstrained currents found in rivers, tidal areas, or the open ocean. Vedant
Powers’ Roosevelt Island Tidal Energy project (approved by the FERC in
January 2012) installed 30 three-blade hydrokinetic generators on the bottom of New York City’s East River to produce about 1.0 MW electricity.
With some initial ups and downs, the project is now completed with blades
made out of fiberglass and plastic [33,98–100].
3. Tidal power harnesses the water flowing between low and high tides, turning a turbine to generate power. There are only 40 sites known in the world
that have the required difference in water levels between the tides needed
to produce electricity. Alaska has a significant potential for hydrokinetic
development in both rivers and tidal basins. Most inland communities in
Alaska are situated along navigable waterways that could host hydrokinetic
installations, and Alaska, with 90% of the total US tidal energy resources,
is a home of some of the best tidal energy resources in the world.
In 2008, 5-kW, and, in 2009, 100-kW turbines were installed in Yukon
River by New Energy Corporation. The New Energy Corp. EnCurrent
machine with 5, 10, 25, 125, and 250 kW capabilities were also developed
[33,94,100,102]. The water flow in Alaskan rivers is, however, season dependent, dropping of in winter compared to summer. This can create some challenging issues on constant power supply.
4. A company called Hydro Green Energy [102] is developing hydrokinetic power
turbine arrays that are composed of truly modular, interchangeable, zero-head,
current-based turbines. Hydro Green Energy’s dual-duct, axial-flow, interchangeable hydrokinetic array of current-driven turbines operate in river (instream, free-flow, open-river, or hydrokinetic run of river), ocean (ocean power),
and tidal settings (tidal power). The capacity of the Hydro Green Energy design
is 98 kW per unit (at 3.5 m/s) with a rotor diameter of 12 ft.
Due to a surface suspension system, there are inherent operational maintenance and safety advantages of this device. An on-board gantry allows
for raising and lowering of individual generating units in the hydrokinetic
turbine array. The floating raft provides a platform for operation and maintenance activities. In general, the current-based hydrokinetic energy device
provides the following advantages [102]:
a. High capacity factor (approx. 90%), maximum net energy, and highly
predictable base load power for in-stream river and ocean current applications; peak power generation in tidal energy applications.
b. Large projects consist of robust and simple metal construction. Small
projects consist of reinforced plastic construction. It utilizes conventional moving systems and the installation is simple and safe using
existing marine vessels.
Power and Energy Directly from Water
buoys installed which collectively generate 1.5 MW of electricity. The
power wave station is located 2.5 miles off the Oregon coast and is connected to the electric grid by an underwater cable. The construction of this
power station is completed [33,79,80,101].
2. Underwater turbines (Figure 13.8b) use water currents to spin underwater
blades and generate electricity. These technologies depend on the unconstrained currents found in rivers, tidal areas, or the open ocean. Vedant
Powers’ Roosevelt Island Tidal Energy project (approved by the FERC in
January 2012) installed 30 three-blade hydrokinetic generators on the bottom of New York City’s East River to produce about 1.0 MW electricity.
With some initial ups and downs, the project is now completed with blades
made out of fiberglass and plastic [33,98–100].
3. Tidal power harnesses the water flowing between low and high tides, turning a turbine to generate power. There are only 40 sites known in the world
that have the required difference in water levels between the tides needed
to produce electricity. Alaska has a significant potential for hydrokinetic
development in both rivers and tidal basins. Most inland communities in
Alaska are situated along navigable waterways that could host hydrokinetic
installations, and Alaska, with 90% of the total US tidal energy resources,
is a home of some of the best tidal energy resources in the world.
In 2008, 5-kW, and, in 2009, 100-kW turbines were installed in Yukon
River by New Energy Corporation. The New Energy Corp. EnCurrent
machine with 5, 10, 25, 125, and 250 kW capabilities were also developed
[33,94,100,102]. The water flow in Alaskan rivers is, however, season dependent, dropping of in winter compared to summer. This can create some challenging issues on constant power supply.
4. A company called Hydro Green Energy [102] is developing hydrokinetic power
turbine arrays that are composed of truly modular, interchangeable, zero-head,
current-based turbines. Hydro Green Energy’s dual-duct, axial-flow, interchangeable hydrokinetic array of current-driven turbines operate in river (instream, free-flow, open-river, or hydrokinetic run of river), ocean (ocean power),
and tidal settings (tidal power). The capacity of the Hydro Green Energy design
is 98 kW per unit (at 3.5 m/s) with a rotor diameter of 12 ft.
Due to a surface suspension system, there are inherent operational maintenance and safety advantages of this device. An on-board gantry allows
for raising and lowering of individual generating units in the hydrokinetic
turbine array. The floating raft provides a platform for operation and maintenance activities. In general, the current-based hydrokinetic energy device
provides the following advantages [102]:
a. High capacity factor (approx. 90%), maximum net energy, and highly
predictable base load power for in-stream river and ocean current applications; peak power generation in tidal energy applications.
b. Large projects consist of robust and simple metal construction. Small
projects consist of reinforced plastic construction. It utilizes conventional moving systems and the installation is simple and safe using
existing marine vessels.