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The stimulus was
provided by the need to reduce CO2 emissions, and the pledge by
the Government to produce 10% of electrical energy from
renewable resources by 2010.
At Gants Mill the new turbine was made by Valley Hydro of
Cornwall, and the electronic mains connection unit by GP
Electronics from Devon.
Left: Lowering the S-shaped penstock pipe though the floor
into the old waterwheel pit.
Below right:
Lowering the turbine. Inside is the turbine rotor, showing
the 30 blades that turn the generator. |
The plant was
installed by Hydro
Generation Ltd (now Renewables First). Installation of the new
turbine started in September 2003, and the staff of Hydro
Generation tackled with enthusiasm the variety of engineering
problems encountered.
All the pieces of the pipe work, turbine and generator were
lowered into the old wheel pit using specialised heavy lifting
gear.
Assembly of the parts required particular attention to the
stresses and weights involved, with around 2 tonnes to be
supported by RSJs slotted into the walls of the wheel pit.
Gaskets between each section were carefully compressed for the
prevention of leaks.
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Near
right: Bolting the pipes together.
Far right: The turbine lowered into position.
Below left: Diagram
of the layout of the two turbines in the old waterwheel pit,
with the original one on the right and the new one on the left.
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At the same time
electrical connections were being made, both to the
external electricity pole on the grid, and within the
mill itself. Finally the time came for the testing
and adjustment of all the working parts under operating
conditions. The installation was inspected by
engineers from the electricity board to comply with G59
regulations for connection to the grid. |
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| (Above)
Turbine and generator completed, connected by belts. |
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(Above)
Trenching for the electric cable between the generator
and the local grid. |
| At the same time
electrical connections were being made, both to the
external electricity pole on the grid, and within the
mill itself. Finally the time came for the testing
and adjustment of all the working parts under operating
conditions. The installation was inspected by
engineers from the electricity board to comply with G59
regulations for connection to the grid. |
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Above: The turbine
control panel. |
Above:
Meter connection to the local grid. |
The equipment is designed
to produce up to 12 kW of electricity in continuous
operation fed into the local grid. The unit shuts down
completely in the event of any system failure or power
cut. The automatic operation also adjusts water
flow through the turbine to maximise power output while
maintaining a reserve flow of water in the main river.
The actual output of electricity depends very much on
river flow, being naturally greater during winter than
in the summer months.
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The turbine and
generator's working life started on Friday 23 April
2004, when Adam Hart Davis visited to launch the scheme.
Visitors are able to see it as part of their tour of the
mill during opening hours.
Over the centuries the mill has been adapted to society's
changing requirements, as a corn mill, fulling mill, silk mill,
then corn mill again, and is now a fine example of a small-scale
hydropower scheme, producing electricity from a renewable
resource.
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