Here is a summary of objections that were raised on a leaflet.

1. Hydro power is inefficient and only makes a tiny contribution.

Switching off a light will make an even tinier contribution, but it does not follow that I should not bother to do it.

Hydro it not inefficient, it extracts at least 70% of the energy in falling water (compare solar electricity at about 15% efficiency), and it supplies a significant fraction of the world's energy.

2. It would have a huge carbon footprint.

There are government figures for the carbon released by the various electricity generation technologies (you can find them at:
www.parliament.uk/documents/post/postpn_383-carbon-footprint-electricity-generation.pdf)

For the mix of fuels used in this country, it is about 500gm/kWh. However for river hydro, it is 4gm/kWh, in fact the lowest of all the technologies.

So what is the payback time (the time to recover the embodied carbon)?

Steel and concrete are not the most eco-friendly of materials, but they are the preferred materials for this sort of engineering. Steel produces 1 to 2kg/kg, depending on how it is made. Say 30 tons of steel and that's up to 60 tons of CO2. The figure for embodied carbon in concrete is about 0.17kg/kg – say 100 tons of concrete, that's 17 tons of CO2. (If you want to look it up yourself, here's a fairly detailed life cycle analysis:
www.dti.dk/carbon-footprint-of-concrete-buildings-seen-in-the-life-cycle-perspective/24513 )
So total CO2 around 80 tons.

How long to save that? We would generate about 500MWh per year average, saving abut 250 tons of CO2 per year: payback time, just 4 months! The fact is, there is a lot of energy in falling water.

Removal of trees? Like all plants they grow and die, absorbing CO2 then losing it as they decay.

3. Destruction of habitat, spoiling a quiet rural area.

This is a public park, and we opened up a view over the river. Formerly it was brambles, nettles, two unhealthy trees, and rubbish. Yes of course any construction project will cause disruption and damage, but that is short term and this is a long term project. The planning conditions require that the site is restored afterwards The fish pass, and the replanting, would have improved the habitat and created greater biodiversity.

4. Disruption caused by the contractors.

Any new development can cause short term inconvenience, which is accepted because of the long term gain. The amount of material, and therefore the number of lorry journeys, is not large and it would be spread over a few months. What the contractor is allowed to do is determined by the planning conditions, and they are framed to limit disruption.

5. Vibration, splashing, noise

Certainly no vibration in properly designed equipment, that would shorten its life. Splashing represents lost energy – it is the weir that splashes. Noise is addressed in the planning application.

6. Better to spend the money on insulating homes.

Yes, saving energy is better than generating more of it. Most houses in this country are poorly built by an inadequately trained workforce and do not deserve their certificates. So let's have a scheme which allows people to invest in insulating other peoples' buildings, and receive an acceptable return. But: nobody has found a workable business model. Tell us if you find one!

 

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