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Introduction
The
Pedley Wheel is a working example of how, linked to modem technology,
water wheels can have a new and useful role to play. It is
the result of nine years' development and trial at Pedley Wood,
resulting in the present machine. This produces primarily AC electricity,
but also mechanical power from low-head, low-flow site conditions
at a high level of efficiency. It serves as a prototype for similar
installations in Third World communities. Design and construction
are deliberately simple to encourage local manufacture and installation
at competitive costs.
Micro hydropower is an
acknowledged solution for rural electrification needs, both practically
and environmentally. In mountainous areas, small turbines are cheap
and effective. In low-head and low-flow conditions, these turbines
are significantly less satisfactory and the case for a waterwheel-driven
generator is attractive because of:
- simple, reliable
technology and components
- capable largely of
local manufacture and assembly
- a broad efficiency
band through a wide range of flow conditions
- no trash problems
- provides AC electricity
and mechanical power to encourage local industry.
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Pedley
Wheel Trust
Pedley Wheel
Trust is a small, private, registered charity established
in 1990 to encourage awareness of environmental problems.
It also raises funds and promotes the installation of
Pedley Wheel generators for rural communities in the
developing world.
Funding
Funding is from private
internal resources with some external help for specific projects.
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History
The first
Pedley Wheel was established at Pedley Wood, Cheshire,
England in 1991. It was built to demonstrate in a graphic
way how renewable energy in the form of water power
could be used to generate electricity. The 8' diameter
wooden wheel was connected to a Ferguson tractor back
axle and gearbox to increase axle speed from 12 rpm
to 1500 rpm - sufficient to drive a DC truck alternator.
The result was several hundred watts and a massive technical
learning curve, which has led to the present wheel and
its installation as an efficient electricity generator
- particularly suitable for use in developing world
rural villages and increasingly in suitable European
locations to meet renewable energy demands.
In summary,
the inital wooden Pedley Wheel, after several million
revolutions and six years' continuous running, was replaced
by the present steel wheel, which offers a more robust,
efficient and simple engineering solution. Old plain
phosphor-bronze bearings wore out and were replaced
by modem self-aligning roller bearings. The advantages
of applying modem industrial technology were emerging
and incorporated.
The biggest problem of
all, and that which virtually committed the "water wheel"
to the scrap heap one hundred years ago, was gearing.
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Development
To convert the low speed/high
torque characteristics to the high speed requirements of modem industrial
applications - particularly electricity generation - was an engineering
nightmare. With minimum gearing requirements of 100:1, chains, belts,
ropes etc were all unsatisfactory solutions. However, the modem
integral geared electric induction motor offers the ideal partnership.
Rugged, mass produced, relatively inexpensive and available worldwide,
it enables the water wheel - itself highly efficient as a prime
mover - to convert its renewable energy into electrical power at
240 volts AC, thus suiting most domestic and light industrial requirements,
whilst allowing cheap and easy transmission.
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Pedley
Wheel Statistics
Pedley
Wheel is the water wheel currently installed and operating
at Pedley Wood, in Sri Lanka and increasingly in the
UK.
- Diameter
2-6m
- Wheel
Speed 6-16 rpm
- Generator
Speed 1600 rpm
- Water
flow: 50-500 litres/second
- Power
output approx. 0.5 kW-20 kW.
- Efficiencies:
Water wheel 82%, Generator 90%, Gearbox 97%
- Electrical
power derived from theoretical maximum (water to wire):
approx 65%
Contact
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