Earth Notes: A Visit to Reading Hydro by TTK Energy Group (2023)

We were met and looked after by Anne Wheldon and David Whipple: many thanks!

Time and People

The Reading Hydro scheme arose out of ideas from Transition Town Reading Energy Group in 2013. As of 2017 the project was transferred to Reading Hydro CBS Limited. A CBS (Community Benefit Society) exists for community benefit, rather than the benefit of members.

In total it took from the 2014 concept until 2021 commissioning and going live. The scheme should have a 40-year life: clearly a marathon rather than a sprint!

Reading Hydro has taken a lot of committed and skilled volunteer effort to get this far, from planning to cable heaving, and will continue to do so for operations, education and visits such as ours, and more.

There are currently seven hydro schemes on the Thames: three community (including this one), three private, and one royal.

Grid

One interesting feature of Reading Hydro is its electricity network connection. Reading Hydro ran a cable under the river to Thames Lido, which buys most of the generated energy. This semi-merchant model is possibly the simplest, not depending strongly on the whims of government policy.

The proposed Ham Hydro scheme on the Thames at Teddington Weir failed because the Feed-in-Tariff that it would have relied on evaporated by the time that obstructive legal action finished.

Another fragile element of the Ham Hydro scheme was that near neighbours were convinced that it would have been too noisy, though in fact it would likely have reduced weir noise overall. The Reading scheme is not loud compared to its weir, though there is a slight 'thump' as each screw turns. The nearest occupied properties are further away from the Reading scheme than would have been the case for Ham Hydro, which probably helps.

Generation

The estimated average yearly generation of Reading Hydro is 320MWh. (The plant is in total rated at 46kW electrical output across the two turbines.) For comparison, a typical UK domestic PV microgeneration system will produce about 4MWh per year, so that is about 80 homes' worth. Indeed Reading Hydro claims that this is also the consumption of about 90 homes. Over its 40-year life this scheme is projected to save about 5,600 tonnes of CO2.

While the hydro scheme does not generate all the time due to varying river levels amongst other factors, it does not go off at night, and is not strongly correlated with the UK's other major renewables source, ie wind. This anti-correlation with sun and wind is very useful for the grid, to help ensure electricity production is there whenever needed.

Fish Pass

Reading Hydro is not all and only about the electricity generation. The scheme includes an additional natural fish pass on View Island, emerging next to the turbine channels but with faster flow to attract fish and eels. This new pass includes resting and spawning grounds, and is less steep than the existing pass in the weir.

See more information, including real-time data, at the comprehensive Reading Hydro CBS site.