Docstoc

Drainage mills _ wind power Decorative motifs found in Norfolk

Document Sample
Drainage mills _ wind power Decorative motifs found in Norfolk Powered By Docstoc
					Drainage mills & wind power
Decorative motifs found in Norfolk churches suggest that windmills for
grinding corn have been used in this area since the fourteenth
century. A fine example of a later style of corn mill can be found at
Sutton (TG383242). There is also another type of windmill seen in
Norfolk which were built to drain marshes. These drainage mills (or
windpumps) were erected on the Broads from the mid eighteenth
century onwards. It is likely that drainage mills were originally
designed and first used in Holland.

In the thirteenth century much of the marshland area of the Broads
could only be used for grazing during the summer months when the
area was not flooded. At this time sea levels were rising and flooding
became more frequent. Dykes were dug and embankments built to
protect the grazing marshes and later when this was no longer
sufficient, drainage mills were built. These wind powered drainage
mills pumped water from marshes into dykes which was then pumped
into the rivers. The drainage mills all comprise sails with a
mechanism to turn the sails into the wind (a fantail or tail pole) and a
mechanism to pump water (scoop wheel, plunger pump, or turbine).
The mills transfer power from the turning sails through two sets of
gears to an internal shaft. These shafts usually powered scoop
wheels which scoop up collected water from low lying dykes and
deposit it into higher level rivers which transported the water out to
sea at Great Yarmouth. Later mills were often fitted with centrifugal
pumps, known as turbines, which lifted water in a similar way to the
effect of stirring a cup of tea very quickly.

During the 1800s, 240 drainage mills were dotted throughout the
Broads, 74 of which remain today, although most are derelict. Mills at
Horsey (TG457222) and Berney Arms (TG465050) can be
investigated in depth as they are open to visitors. Around the How
Hill estate you can see three very different styles of drainage mill (a
trestle mill, a hollow post mill and the more common tower mill) each
with interesting names: Clayrack (TG369193), Turf Fen (TG369188)
and Boardman’s (TG369192). Both Clayrack and Turf Fen are named
after the land they are sited on, often mills take the name of either the
owner of the marsh or the marshman or millman who looked after
them, examples in Broadland being High’s Mill (TG457072), Hobbs’
Mill (TG347163) and Howard’s Mill (TG462072).

Clayrack is a very special drainage mill because it is one of only two
‘Hollow Post’ drainage mills left in the Broads and the only one fitted
with a scoop wheel. Most remaining drainage mills have a brick
tower. In 1981 Clayrack Mill stood 4km away from its current position
on Ranworth Marshes (TG363153). It was badly in need of
restoration but Ranworth hosts many nesting birds vulnerable to
disturbance so it had to be removed. Happily it was reconstructed in
its current How Hill location and can occasionally be seen working to
drain the marshes.

Boardman’s Mill (or Skeleton Mill) is one of only three ‘Trestle’ mills
left in the broads (the others are at Horning TG 344175 and St Olaves
TM459995). The mill was built in 1897 by a local millwright from
Ludham (TG389184) named Dan England. The trestle mills were a
later and less expensive alternative to the brick tower mills but their
largely timber construction has meant that like the hollow-post mills, few now survive.
Boardman’s mill was also originally fitted with a scoopwheel but this was later replaced by a
turbine pump. The mill stopped working in 1938 when it was blown over in a gale.

Turf Fen is a typical brick tower mill, built in 1875. This mill has a special feature in that it has
twin scoopwheels (not yet restored), with a choice of high or low gears, rather than the usual one,
to provide additional power. The mill was used to drain Reedham Marsh (TG366194) until the
marsh was no longer used for grazing cattle in the 1920s.

Due to the efficient drainage of marshes grazing became more extensive from the mid-18th
century onwards. Drained marshes contain lots of nutrients and so the grazing was very lush.
But during the nineteenth century wind powered mills were supplemented by steam powered
pumps, often working side by side. Technology continued to develop and during the first part of
the twentieth century diesel powered pumps started to replace wind powered drainage in the
Broads; although some marshes were still drained by wind power until the 1950s. Diesel
powered pumps were far more efficient at draining the marshes and peaty soil shrank as it got
drier. As a result we see many areas of grazing marsh that are lower than the water level in the
river, in the Horsey area the marshes are even lower than sea level. Today the marshes are still
drained. It is very important to be able to manipulate water levels for agriculture, reed cutting and
nature conservation. The pumps used to do this drainage are today powered by electricity.

People living in today’s society in the UK use more electrical appliances than ever before which
means that large amounts of electricity need to be generated to cope with demand. Most
electrical generation in the UK is done by burning fossil fuels which results in harmful carbon
emissions that are causing global warming. There are alternative ways of generating electricity
which do not deplete the world’s scarce supply of oil, gas and coal. There are several renewable
sources of energy which use resources that will never run out, such as hydro (water), solar (sun)
and wind power.

Generators inside wind turbines change wind energy into electrical energy. Wind is a free
source of energy and it causes much less pollution that other forms of electricity generation such
as gas, oil or coal and nuclear power. Wind farms take up very little ground space and the areas
in between the turbines can be utilised to graze animals. However, installing wind turbines can
be costly, large amounts of materials can be used during their construction and some people
consider wind turbines to be a blot on the landscape. Some residents at Martham (TG455180)
have also raised concern over the noise pollution wind turbines cause and the interference with
their television reception they have caused. Conservation organisations such as the RSPB have
raised objections to wind turbines because of the threat they pose to nesting colonies or
migrating birds.

The USA, Denmark and Germany are all big producers of wind energy. In many parts of the
world high technology wind turbines such as those at Martham are too expensive to be widely
used. Different technologies are being investigated, whereby wind turbines can be built cheaply
and easily from everyday materials, to enable developing countries to harness the wind as a
source of power.

The Broads Authority is keen to support developments for the generation of electricity from
renewable sources. At Somerton there are already two separate wind power developments. The
first is the Somerton Wind Turbine (TG468192). This turbine was built in 2000. The single
turbine stands 65 metres tall and each of it’s blades are 33m long. The energy it produces is
enough to supply 1400 homes and it provides 5% of Great Yarmouth’s electricity requirements.
The second development is Blood Hill (TG477190) which consists of 10 turbines built in 1992.
Each turbine is 30m high with blades measuring 13m. Together the 10 turbines produce
enough electricity to power 1400 homes.

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:7
posted:3/23/2011
language:English
pages:3