Seasoned weather watchers cannot have failed to notice the recent heavy rain over the last few weeks.  River watchers will have also noticed the River Thames rushing under Reading Bridge towards Caversham Weir and onwards to Sonning and ultimately London and out to sea,   As you can see from the graph below the river flow has increased significantly since 18th December.

So how has this affected power generation at Reading Hydro?  Surely more water or faster moving water is a good thing to generate more power?  Well it’s not quite as simple as that.  As the rains fell across the Thames catchment the flow in the headwaters started to rise as the ground became saturated and the excess drained into the river and its tributaries.  Up and down the river lock keepers started opening their weirs to allow the water to drain through more easily and reduce the risk of localised flooding.

As a result the ‘head’ of water at Reading Hydro (difference in height between the river level upstream and downstream) started to reduce..  You can see this quite clearly in the graph above.  Our turbines turn due to the weight of water falling through the two screws from the upstream to the downstream.  When the head reduces the weight of water has less height to fall and consequently the power reduces.  Below 1m head the power loss decreases rapidly and even a few centimetres loss can see a drop of several kWs of power.

As you can see in the graph below the generation has declined greatly since the 20th December.   During this time our amazing Clearance team worked nearly every day to keep the screens clear and the water flowing through our turbines.  Of course the heavy rain washed a lot of debris down the river, some of which ended up on our screens particularly on the 21 December and over the Christmas and New Year breaks.  You can see the difference clearing the screens makes as the power generation jumps up, but then gradually declines as more debris builds up.

Sadly in the early hours of Sunday morning the increasing river flow and high downstream level reduced our head to below 0.5m at which point Turbine 2 shutdown while Turbine 1 was only generating 2kW.  The decision was taken to shutdown the system until levels improve and the all-important head rises to a sustained level.  With the weather forecast set to become drier for the next few days we are crossing our fingers that the river levels will change in our favour.

As part of efforts to raise climate change awareness as the intergovernmental COP27 meeting starts in Egypt this week, a leading environmental charity has recognised Reading Hydro as an ‘outstanding example’ of how community action can help combat the challenges of the climate crisis. Carbon Copy, the organisation behind the Running Out of Time Relay linking COP host cities Glasgow and Sharm El-Sheikh in the world’s longest continuous relay, identified 27 local projects which ‘formed the backbone’ of the relay route to celebrate and highlight how community action can make a real difference to global challenges like carbon emissions, including Reading Hydro via its Turbine House on Caversham Weir, Reading, UK

As an organisation, Reading Hydro is proud to have been part of this historic endeavor linking two crucial global summits on tackling climate change, as well having the collective efforts of our volunteers and investors being recognised in such an incredible way. We hope our local project can be an inspiration to others (and those at COP27) in how to turn good ideas and warm words into a positive and clean energy reality.

The full press release is here

Great news – today (23rd October) the Environment Agency gave us permission to generate again, and both turbines were re-started just after noon!
The river flow at Thames Bridge had continued to run at about 5 cumecs (cubic meters per second) overnight, but surged above 10 cumecs by noon because of the heavy rain.
River conditions are still not stable, and we may have to shut down one or both turbines at short notice. But it’s so good to see them turning again.

We’re still working hard behind the scenes, maintaining the hydro equipment, developing our education programme, giving presentations to various groups, improving our internal processes. And we’d still welcome more volunteers – do look on our volunteers page for the roles we’d like to fill.

You will have noticed if you regularly walk past our turbines that they haven’t been turning for quite some time If you look at the power generation page on our website you will see that Reading Hydro hasn’t generated any electricity since 1st July.  You can also see from the river conditions data on our website that the Environment Agency river flow sensor at Reading Bridge currently reads just over 3 cubic metres per second (m3/s). This is less than 10% of the average river flow.  At this very low flow rate, the Environment Agency cannot allow Reading Hydro to use water to generate electricity, because they must prioritise providing water to the fish passes and the weir gates.

We knew that in some summers there would be periods of no electricity generation because of low river flow rates. This was taken into account in the estimate of average annual generation, and resulting income, in our business plan.  But the shortage of water this year is extreme. 2022 has, to date, been the driest year in England since 1976: the Thames region has experienced the driest July since 1911, and we are now officially in a drought.

We’ll keep you posted as conditions change.

You may have noticed if you have walked past our turbines or looked at the live data feed on our website that we have only been running one of the two turbines for half of May.  This is because we have had a bearing failure on Turbine 2 (Sophie), the one furthest away from the View Island bank.

We have an automatic condition monitoring system fitted to the turbines and, early on 13^th May, we received a Red alert alarm for the bearing that supports the top end of the Archimedes Screw.  Spaans Babcock, who made and installed the turbines, came straight to site, and told us that we needed to shut that turbine down.  The bearings should last 10-15 years so the failure was not expected.  Spaans had to order some spare parts, and then arranged to come and replace the bearing, under warranty, starting on 30^th May.  The turbine started running again on 1^st June. 

In order to replace the bearing we had to remove the water from the outlet channel of Turbine 2, which we had not done before.  This was achieved by lowering wooden planks – stoplogs – into the grooves at the end of the channel and sealing the wooden wall this made with a tarpaulin. Once this was done we were able to pump the water out of the channel.  After Spaans had completed their work we carefully removed the stoplogs, allowing water back into the channel.

Although both turbines are now running again the water level in the River Thames is now low which means that we are not always able to generate full power.  The Environment Agency requires Reading Hydro to shut down when the river levels are below an agreed ‘set level’ to make sure there is enough water for navigation.  When the upstream level gets close to the set level, power generation is reduced.

This aerial photo was taken in August 1928 and shows Caversham Weir and View Island towards the bottom of the image.

A large house can be seen on View Island along with gardens and another smaller property.

On the Reading side of the Thames, what is now Thames Lido is visible in Kings Meadow. This was built in 1902 as the Ladies Swimming Bath; the Men’s Swimming Bath (now demolished) is slightly closer to the town centre and when built in 1879 was the largest pool in the South at 79m x 24m. Reading Bridge was a relatively recent addition, having been built in 1923.

Given the shadow lengths, this October 1955 photo would have been taken in the late afternoon, facing the opposite direction to the earlier photo. Some aspects are very similar – there is still an extensive collection of railway sidings near Reading Station and the two open air pools are still visible. However, the Men’s Pool was disused by this point and the site was sold the following year for development as offices and workshops.

On View Island both structures have been demolished and there is a new footbridge between Hills Meadow and View Island, although this has now gone.

Great news! Reading Hydro’s turbines have both been running full-time since 22nd November (apart from short periods of scheduled maintenance on Saturday mornings).

You can see this for yourself on the Performance data pages of our website. The main page gives a snapshot of all the data – the current power generation of each turbine/generator, the water levels, and the turbine house environmental conditions. There are then links to more detailed pages on Power generation, Water levels, and the Environmental conditions. These have graphs that show historical data for some values. You can look at the performance over different time periods, and for one or both turbines.

It’s thanks to Reading Hydro’s fantastic Digital team that we have these pages. Live data is needed by our operations and maintenance O&M team and the Environment Agency to keep a check on how the hydro plant is working. But equally important, we want it to be available for anyone to see. 

The team collects raw data from the turbine house control system, and processes it into the website display format. There have been teething problems including checking sensor calibrations, so we aren’t displaying water flow because we’re not yet satisfied with these measurements.

The Digital team is constantly improving the data display to make it easier to read, and more accessible for people with visual impairment. Our website usage stats show that (not surprisingly!) the data pages are the most popular ones on our website, and many people view them from mobile phones. So the processing has been changed to make the data display update more quickly, and look better on mobile browsers. 

For anyone interested in the technology behind this, it is documented on our github page.

Thanks to all the Reading Hydro Digital team – Arabela, Mark, Stuart, Bapu and in particular Lynda for the website work.

Why do we need an Uninterruptible Power Supply (UPS) in the turbine house? Don’t we have enough electricity there?

The reason is to make sure that our monitoring systems keep working, even if something happens to shut down the turbines. In fact, that’s when the monitoring is most important, so that we can see what happened, and access the controls to rectify the problem if it can be resolved remotely.

We now have this critical equipment on the UPS. We hope it’s never needed, but we are ready if it is.