19-11-2012, 05:19 PM
Harnessing Ocean Tidal Power
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In 1850, to run the machinery and mills of the California Gold Rush,
Lester Pelton invented the Pelton Wheel. Instead of the flat panels used
in mills on slower streams, the Pelton Wheel was a landmark design
using cups to harness the fast waters of mountain streams. Mines no
longer depended on steam engines - and their exhaustible supplies of
wood and coal - for the power needed to extract precious minerals from
hard rock.
Fast-forward to 2011. Fossil fuels have dominated the world
energy supply for nearly a century. They generate not only power but
international conflict, because of limited sources.
Alternative power sources have offered promise, with wind and
solar as the dominant alternatives. Yet these too have limitations due to
environmental fluctuations.
But now, technology development of oceanic tidal turbines enters
the mix and offers a sustainable source of socially acceptable electrical
power. Still in development, the technology is on the cusp of emerging
as a significant contributor to the global generation of electricity, and
already, the first commercial scale prototypes are undergoing testing at
sites around the globe.
Beneath the ocean waves, a new industrial boom akin to the
development of the North Sea oil and gas industry is bringing new,
secure energy supplies to a resource- and carbon-constrained world.
At the dawning of a new era of powerful technology that is able
to harvest renewable energy from the ocean’s tides, control of this
powerful motion is critical.
Like Pelton in 1850, engineers at Wichita, Twiflex Limited, and
other Altra Industrial Motion companies have adapted state-of-the-art
technologies that enable today’s emerging tidal turbines to progress in
the ongoing quest to supplant fossil fuels.
An Emerging Energy Source
A decade ago, the UK Marine Foresight Panel opined that “if
0.1% of the renewable energy available within the oceans could be
converted into electricity it would satisfy the present world demand for
energy more than five times over.”
Since then, innovators have worked out significant challenges,
which has led to the installation of several full-scale tidal turbine
prototypes off the coast of the UK to demonstrate the breakthrough
potential of this enormously promising energy source.
Tidal Turbine Design and Development
Despite the intensive effort to establish proof-ofconcept
for a wide range of innovations in tidal turbines,
a dominant technology has yet to be established. To
date, four major types of turbines have been developed in
addition to a variety of unique designs that demonstrate
different characteristics and technology.
Horizontal Axis Turbines – These devices extract
energy from moving water in much the same way as wind
turbines extract energy from moving air. They can be
open-bladed or housed within ducts to create secondary
flow effects by concentrating the flow and producing a
pressure difference.
EU Renewable Energy Initiatives
Driving the accelerating growth and capital
investment in the tidal turbine sector is the forecast that,
by 2030, 45 percent additional energy will be required to
meet the needs of the world’s population, according to the
European Ocean Energy Roadmap 2010 – 2050 produced
by the European Ocean Energy Association (EOEA).
Currently up to 67 percent of global electric consumption
is generated by fossil fuels; the continuation of which
could raise CO2 emissions by as much as 45 percent.
The World’s Largest Tidal Turbine
The Atlantis AK-1000 1 MW tidal turbine is the
largest single axis in the world. The Atlantis turbine stands
75 ft. (23m) tall with a unique twin rotor set - 59 ft. (18m)
diameter - to harness ebb and flow tides while generating 1
MW of power. These horizontal axis turbines are designed
for open ocean deployment, positioned on the sea-bed, in
the harshest environment on the planet – and they require
precise stopping power.
When international energy engineering consultant,
Prospect – a Hallin company, began its search for a very
large capacity braking system for Atlantis, it learned about
Wichita’s previous supply of a wet, multi-plate tidal turbine
brake. Wichita’s reputation for rugged-duty marine brakes
and its customized wet hydraulic braking solution gave
confidence to Prospect/Atlantis that the Wichita HBS 42-14
could provide years of trouble-free operation.