Power Source

The Calder and its tributaries have long been used as a source of power. It seems strange that today we are trying to introduce sustainable energy sources, when for centuries water power ran all the local industries. Perhaps its is unfortunate that the mills moved to burning coal, rather than developing more efficient use of the waterwheels.

The Pennine rivers provide an excellent source of power. They tumble steeply down from the plateau and have cut out steepside valleys. In the Calder basin high rainfall and a largely impermeable geology ensure that there are lots of tributary streams entering the main rivers. Thus throughout Kirklees and Calderdale there are many sites suited to water power generation. Further east sites are more closely associated with the main rivers.

The process of generating water power is quite simple and the West Yorkshire mills all operated to much the same principle. Above the mill water is diverted from the river along a channel known as the 'mill race'. This water is then stored behind a dam immediately next to the mill buildings. The mill race does not drop as rapidly as the river itself and so the mill pond stores water at an artificially high level. When released from the mill pond via a sluice gate, the energy in the falling water is captured by the water wheel. This spins under the pressure of the falling water, driving a series of belts and gears, which in turn power the machinery. The water then escapes to continue its journey downstream. A modern water wheel might convert this energy directly to electricity through use of a turbine. Of course the option of Hydro Electric Power (HEP) was not open to the nineteenth century mill owners. It might, however, be revived as an attractive option for small scale energy production in the future.

On larger rivers with a more gentle gradient, wiers are used to build up the head of water. These are walls built across the river channel. The river flows over the weir but is artificially deepened so that water can be diverted to the mill race.