I have just registered as a supporter of Ham Hydro’s attempts to build a power station in the weir at Teddington Lock. Having registered as a supporter, I thought I would find out about the scheme! OK. I know that’s the wrong way around, but sometimes things happen that way. But I have been really disappointed. Despite the fact that they are asking local people to buy shares in the scheme to the tune of £2.4M, they have published almost no information about the scheme!
- Here is the Energy Share page for the scheme where you can register as a supporter. It is extremely slow to load.
- Ham Hydro’s Web Page (I think)
- Ham Hydro’s Blog – big news – They have a logo!
Questions. As I have mentioned previously, our choices about energy require clear thinking and clear accounting both in terms of energy and money. So here, for example are some of the questions about this scheme to which I think Ham Hydro should already have published answers without having to be asked.
- How much electricity will this scheme generate each year?
- How will the amount generated vary between winter and summer?
- What happens if there is a drought?
- What happens if there is a flood?
- Why is this unusual form of electricity generation a sensible choice?
- Why would £10,000 spent on shares in this scheme be better for the environment than putting solar panels on your roof?
- After asking questions on the web site I have now been told that the scheme will conservatively generate 1.92 GWh of electricity per year – which corresponds to roughly around 220 kW or around 300 horsepower to give a motoring equivalent. If each unit (kWh) generated was worth £0.15 the scheme would have an income of £288,000 per year. This is just 12% of the total scheme cost.
- Teddington lock maintains an almost constant head between winter and summer, but the flow does change significantly. This pleasing web page tells me that the mean flow on the Thames at Kingston is 5.7 million cubic metres per day or 65 cubic metres per second. Applying the formula (mass of water per second x gravitational constant x height of drop) allows me to guess this corresponds to around 1200 kW possible generating power for a 2 metre head. But the scheme only draws 220 kW. So if flow fell below 1/6th of mean flow then the scheme might have to reduce generating capacity – the locks need water too! But it should be able to keep generating through a ‘normal’ summer.
- In times of drought I think the scheme would have to reduce generating output.
- In times of flood I don’t think the scheme could increase capacity to take advantage of the extra water, but the scheme would probably not be threatened physically.
- This web site claims that Archimedean Screws are fish friendly and suitable for low heads of water.
- My mate Nigel has just spent roughly £10k on solar panels for his roof and they seem to be generating around 3400 kWh per year. So if we all spent this money on solar panels then £2.4M would generate around 0.8 GWh per year. So this scheme appears to be about twice as efficient in its use of capital resources. But of course Solar PV is a much lower risk so that if only £1M was raised, the scheme would still be able to begin. [Figures updated on 20th June] Of course if we could somehow use the money to insulate people’s homes better and then get hold of some of the money these people saved then this would make the most sense of all!