Just as high-tech windmills tap the power of wind to generate electricity, a new water-mill technology promises to efficiently tap the flow of water in rivers, streams, and tidal basins. It could be a new source of clean, renewable, and unobtrusive energy.
The quest for clean, renewable energy has resulted in a number of interesting technologies. One of the newest is now being tested; it's called Instream Energy Generation Technology or free flow hydro power. It’s a technology that promises to tap energy wherever there is a river, stream, canal, or any place where water flows.
What is Instream Energy Generation Technology?
Instream Energy Generation Technology or IEGT places turbines in rivers, manmade channels, tidal waters, or ocean currents. These turbines use the flow of water to turn them, thus generating electricity for the power grid on nearby land. In effect, IEGT is like planting windmills in the water and is environmentally friendly.
Types of Turbines
There are several types of turbines available, depending on the characteristic of the water site and other needs. The axial flow rotor turbine consists of a concentric hub with radial blades, resembling a wind mill. Either a built in electrical generator or a hydraulic pump which turns an electrical generator on land provides the electricity.
The open center fan turbine consists of two donut shape turbines which rotate in the opposite direction of the current. This in turn runs a hydraulic pump that in turn drives a standard electrical generator.
A helical turbine resembles a strange sculpture with hydrofoil sections that keep the turbine oriented to the flow of the water. The leader edge of the blades turns in the direction of the water.
The cycloidic turbine resembles a paddle wheel, where the flow of the water turns the wheel with lift and drag being optimized.
Lift or Flutter Vanes looks like a huge Venetian blind. Hydroplane blades are caused to oscillate by the flowing water, thus generating electricity.
Advantages of IEGT Power
IEGT clearly provides electricity from a renewable resource, in this case water flow, without recourse to burning any type of fuel. Unlike standard hydroelectricity, IEGT does not involve the construction of a large infrastructure, the damming of rivers or streams, or the diversion of any water ways. IEGT can, however, be used in existing water systems controlled by dams or other structures.
Besides the generation of power, IEGT can be used for other water projects. These include desalination, the creation of potable water, and the extraction of hydrogen from water for use in fuel cells.
IEGT is claimed by its proponents to have little or no impact on the environment. The turbine blades rotate slowly enough and are space apart far enough so that migrating fish will not be affected. Environmental groups such as Riverkeeper in New York dispute this, claiming that scientific evidence is not yet available to support the conclusion of no environmental impact.
The East River Project
A company called Verdant Power is testing an IEGT system in the East River, between Manhattan and Roosevelt Island. The first phase, which consisted of a single axial flow rotor turbine, with ten foot diameter rotors, anchored in concrete attached to the river bed. The turbine was not only able to capture the energy from the natural flow of the river, but from tidal currents which can reach 4 knots. The single turbine was able to generate up to 16 kilowatts of power.
As a result of this first phase of the East River Project, Verdant Power is preparing to deploy six single axial flow turbines, with five meter diameter rotors, in the tidal basin of the East River. This system, when installed, will actually generate electricity for the New York power grid. Eventually, Verdant plans to deploy several hundred turbines, generating 5 to 10 megawatts, providing power for New York City.
Other Projects
Verdant is also testing other turbine technologies in the US Navy David Taylor Model Basin in Carderock, Maryland. The basin, located close to the company’s corporate headquarters, permits rapid prototyping, fluid dynamic studies, and model testing.
Verdant is planning a one megawatt system using the helical turbine in the Merrimack River in Massachusetts. If successful, the system can be replicated in other rivers and streams in the state.
The Tennessee Valley Authority has asked Verdant to evaluate the feasibility of deploying IEGT plants in the waterways within the TVA’s domain. Characteristics such as water flow rate, water depth, river bottom topography, as well as proximity to power grid connections have to be determined before the economic feasibility of such projects can be ascertained.
The company is also evaluating the possibility of projects in aqueducts in California and tidal basins in the United Kingdom.
A Norwegian Company called Hammerfest Strøm is developing IEGT type technology to be deployed in tidal basins and other water ways in Norway. A British company called Marine Current Turbines has just completed a pilot project off Lynmouth in Devon that has generated 300 kilowatts of power. The next phase will be a system generating one megawatt, followed by a full commercial system generating ten megawatts of electricity. MCT is looking at other, similar projects in North America, South East Asia, Australia, and New Zealand.
A pilot project called the Snail, under the auspices of Robert Gordon University in Scotland, is being prepared to capture the tidal energies in Eynhallow Sound in Orkney. It is expected that similar devices would be commercially useful in the sea lochs in Western Scotland as well as channels between the Orkney and Shetland islands.
The Future of IEGT
The concept of planning turbines on the beds of rivers, streams, and tidal basins seems to be an excellent addition to the mix of energy technologies that will eventually free the world from dependence on fossil fuels, which cause pollution and are often found in politically unstable parts of the world. Of course more research and development will be needed to establish the economic viability of the technology, as well as to allay the concerns of some groups about potential environmental impacts. If the technology is seen to be viable, then a time may come when the waterways of the world will become a source of clean, renewable, and unobtrusive energy.