Recent rains have reduced our generation

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.

Flow at Reading Bridge

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.

Water Levels

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.

Power Generation kW

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.

Reading Hydro highlighted at COP27

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

Generation starts again

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.

Reading Hydro & Running Out of Time Relay

With COP27 scheduled for next month, and nearly a year since COP26 in Glasgow, an extraordinary relay linking Glasgow to Sharm El-Sheik, Egypt, is being undertaken by hundreds of people across Europe and the Middle East. Known as the ‘Running Out of Time‘ (ROoT) relay, the Carbon Copy charity has brought together a community of people and projects to highlight the urgency of the climate change challenge, as well as the efforts being undertaken to try and mitigate the negative effects through positive community action.

This 7,767km relay operating 24/7 for 38 days will be passing through Reading on its journey towards Egypt, and Reading Hydro has been identified as a relay baton exchange point – we therefore invite you to support this unique effort and the teams carrying this baton towards COP27, and help deliver a message to world leaders that we can come together to tackle climate change and make a difference.

Key Info

Come support and cheer on our relay runners as they near the baton exchange point by our Turbine House. We have runners in Stages 143 & 144 of the relay, and are responsible as an organisation for getting the baton to the Turbine House on time!

If you’re joining us to support the runners, we will be cheering the team on on the other side of the river to keep the View Island pathway clear for the baton handover:

  • Date/Time: Friday 7th October, 14:40 – 15:10
  • Location: Hills Meadow pathway, by the skate ramps & opposite the Turbine House (What3Words: moral.gums.dunes)
  • Bring your best cheers and clapping with you! Our runners are expected to reach the Turbine House around 14:50

If you’d like to get more involved in the relay, there’s a couple of ways you can do this!

  • Join the stage: ROoT can host up to 25 runners per stage, so if you think you can run 6km in around 45 mins, then sign up and become part of the event!
  • Donate: You can donate and support our teams via the ROoT website – click on a runner and choose your level of donation

We’ll be posting updates of the relay on the day, so make sure you follow us on our social media to keep up with our teams!

You can also hear more about this relay from Austin, one of our runners, and Rick, Carbon Copy, in their interview with BBC Radio Berkshire.

Low flows for the River Thames at Reading is likely to continue

Coutersy of Callum Cromwell, Callum’s Night Photography

Reading Hydro volunteer Wilson Chan is a PhD student at Reading University, carrying out research on the impacts of climate change on UK water resources.  He’s applied his data modelling expertise to predict likely flow in the River Thames over the next few months. In a future blog he’ll update the data and also discuss the likely impact of climate change on the Thames flow. It’s great to have Wilson’s data modelling expertise to help us understand river flow better (even though the outlook is somewhat gloomy for the next few months….).

July 2022 has been confirmed the driest July on record for southern England.  The same month also saw a record-breaking heatwave with temperatures reaching 40°C for the first time. Precursors to the latest drought were a drier than average winter and spring 2022, and the driest winter-spring sequence since the 1970s. The flow of the River Thames at Reading has been declining since spring 2022 and high evaporation from the exceptionally hot and dry summer has exacerbated this decline. This low flow means that Reading Hydro hasn’t been able to generate electricity since June. So what is the outlook for the coming months?

To look at this, I followed the UKCEH Hydrological Outlook “Ensemble Streamflow Prediction” (ESP) technique based on historical climate to look at the likely river flows over the coming year. Details of the model and technique are in this paper, and the results are summarised in the graphs below.

The black line at the left of the upper graph is the actual flow of the Thames at Reading up to August 2022.  Each of the 56 grey lines that continue from August suggest the possible flow for the coming year, modelled by assuming that the rainfall and temperature will be identical to one of the past 56 years. The variation in weather from year to year leads to a large variation in predicted river flow, as anyone who has lived in Reading for a long time would expect. I have highlighted what would happen if we have a repeat of weather from particularly dry years (i.e. 1976, 2003 and 2011).  

It’s useful to see the wide range of plausible flow rates, but how do we know what flow is likely on a given future day?  The approach I used is to calculate the percentage of simulations falling in defined ‘bands’ of flow rate, which gives the probability that, based on past weather, the flow on a particular day next year will lie within this band, as shown in the lower graph.  Here, I’ve chosen thresholds relevant to Reading Hydro: a) 5.24 m/s, the hands-off flow below which we are never allowed to generate, b) 11.44 m/s, the minimum flow required for full generation and c) 37.9 m/s, the average flow of Thames at Reading.

The prediction isn’t very encouraging. It suggests that, without exceptionally high rainfall soon, there is a high likelihood that river flow will be below the level needed for the Reading Hydro turbines to re-start operation, until at least October 2022.

Why we are not generating

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.


The broken bearing

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 13th 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 30th May.  The turbine started running again on 1st 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.

Fitting stoplogs across the outlet channel for Turbine 2

Historic aerial photos of the Hydro site

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.

Data Pages at Reading Hydro

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.

Installation of a UPS in the Turbine House

UPS in the Turbine House

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.