As I walk through the Somerset countryside with a friend or a grandson, whenever a river comes into view one of us will remark, ‘Look at all that energy going to waste!’ writes Henry Haslam.
In 1300, there were more than 10,000 water mills in the south of England.
Only a few such mills are still in use.
At other sites, the water wheel has gone but the weir and millstream remain. For the most part, our rivers represent wasted energy.
There are exceptions.
Various modern technologies are available that have been used in rivers large and small, in fast-flowing upland rivers and streams as well as in lowland rivers.
A local example operated for several years recently on the River Otter, just north of Tipton St John in Devon.
It made use of an old weir and millstream, but instead of the old mill wheels it used an Archimedes screw to generate electricity, which was used to power Tipton Mill; any surplus was sold to the grid.
Since rivers are found all over the country, generators can be installed close to the point of use.
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Offshore wind turbines tend to be a long way from where their electricity is needed, and there have been problems recently with the inadequacy of the grid that transmits their electricity output to where it is needed.
I sometimes hear it said that rivers are too dependent on the weather, and they dry up in a drought.
This argument may carry weight for schemes that involve damming the river and making use of the total flow.
Recent schemes, however, only use a small proportion of the flow and it is very rare for British rivers of any size to dry up totally.
Indeed, rivers are much less dependent on the weather than wind or solar.
They have an advantage over nuclear in that their generators can be switched on and off at short notice, so they can respond to rapid changes in the balance between supply and demand.
River power represents an under-used opportunity.
In Taunton, we have two weirs, at French Weir and Firepool.
They both have considerable flow – and were still flowing this year after several weeks of drought.
Why don’t we channel off some of their water and use it to generate electricity?
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