section of New Yorks East River is now the test bed
for a tide-powered turbine farm that could cost $20 million
and generate up to 10 MW of electricity when completed in
2007. The project is a global first and could lead to a new,
stable and nonpolluting energy source.
of Sight. Low-rpm turbines will generate power
After testing a single 16-kW barge-mounted
turbine on the river for six weeks in 2003, Verdant Power
LLC, Arlington, Va., is now installing the first two of six
proprietary underwater turbines for an 18-month test that
could green-light a federal license for the proposed project.
The tide-powered farm would consist of up to 300 turbines
stretched along a mile-long, 270-ft wide section on the east
side of Roosevelt Island, where the current runs at a steady
4 knots. "The power from the test will go to two specific
customers on the island, a grocery store and a parking deck,"
says Dean R. Corren, Verdant director of technology development.
"This will help reduce their draw on the grid."
The 16-ft-long unducted axial flow
turbines are bolted to rock-socketed, grout-filled steel pipe
piles at an operating depth of about 8 ft below the surface
of the 30-ft to 40-ft deep river. The units will operate in
a bi-directional mode, taking advantage of the rivers
ebb and flow. Each turbine has three slow-turning composite
blades to form a rotor 16-ft in diameter. Because the blades
turn at a leisurely 36 rpm, engineers did not feel a need
to design cages to protect aquatic life or to fend off river
The turbines can convert kinetic
hydro energy into power ranging from 25 kW to 250 kW, depending
on turbine size and current. Verdant plans on using 36-kW
units in the East River. Kinetic energy is converted to mechanical
power in a nacelle within the turbine. Cables bring power
to shore and tie it into the grid at a Roosevelt Island substation.
"There is a similar unit offshore
in the U.K. but this is a global first to place a field of
turbines producing distributed electricity," says Trey
Taylor, Verdant president. The prototype turbines are being
assembled by Zak Inc, Troy, N.Y., and installed by locally
based MVN Associates.
Halfway through the performance
test company and state officials should have enough information
to decide if the project is feasible. "Nine months out
well file for a Federal Energy Regulatory Commission
license," says Taylor. "Once we get the license
we will start the build-out, which will take about a year
to complete. We still need to work out fish migration, security
and navigation issues."
Taylor notes that tide-powered,
or in-stream, kinetic hydro turbines are more advantageous
than wind or solar powered turbines because placement can
be made anywhere there is predictable natural or man-made
water flow. More could be built in tidal estuaries and
in rivers near cities and in man-made channels such as irrigation
canals that could help meet our energy needs, he says.
Verdant is also working on a scaled-down turbine for use in
California irrigation canals. The firm has contacted several
irrigation districts and is looking for a partner to start
a pilot project. It could use three-ft rotors on 10-kW
units, says Taylor. There are 11,000 miles of
canals and aqueducts in California and were investigating
speed, depth and accessibility.
The East River surface testing
cost about $1.5 million, one-third of which was partially
underwritten by the New York State Energy Research and Development
Authority. NYSERDA is Verdants research partner in New
York and will help with the "six pack" test funding
by contributing another $500,000. "Were looking
at all different sources of renewable energy for state needs,"
says Joseph H. Sayer, NYSERDA senior project manager. "Tide-powered
turbines seem not to have a major environmental impact, are
quiet with no visibility impairment and New York City is an
energy load center in need of new generation, so this could
Sayer notes New York state is estimated
to have 1,000 MW of potential in-stream kinetic hydropower
available. "Hopefully developers will be inclined to
work at other sites besides the East River," he says.