I’ll start with some good news, as we all need a bit of cheering up when the weather is as cold and gloomy as it has been recently: we had another excellent year for generation: after a record year in 2023 we did even better in 2024, generating just under 160 MWh. As I write we are generating flat out again, and things are looking good at least for the next couple of weeks.

As I’ve said before, what we need is steady bur not torrential rain; it can be seen from the plot below (which shows rainfall in Westerdale, at the head of the Esk catchment) that last year was wet but not exceptionally so. Torrential rain, as we got with storm Darragh, will raise the lower river level too much and by reducing the “head” – the drop from upper to lower river which drives the turbine – will reduce or even stop generation (by the way, Darragh was so wet that the water level JUST got into the turbine kiosk – only the second time this has happened since we started).

I promised in the last blog to talk a bit about maintenance. Winter is usually a busy time for the turbine to be running – it’s usually wetter than the Summer – and of course we want to run while the river is high and we can generate lots of power. However, like any complex machinery, the turbine needs some care and attention, and some of this has to be done while we are stopped, so we try to schedule the major predictable maintenance for the quieter Summer period. Some of the regular jobs, like greasing, happen all year round, but there’s a big annual service (a bit like the one a car gets) when a number of checks are done, and this is an opportunity to (for example) replace worn hydraulic hoses. Last year – because it was 10 years old – we also had to replace the high-pressure cylinder which drives the hydraulics (there’s a good explanation on the website of how the hydraulics operate the penstock which regulates flow through the turbine). Strictly speaking we didn’t have to replace it, but it needed pressure-testing, which can’t be done on-site, and the time (weeks) and cost of re-using our existing cylinder far exceeded just replacing it….frustrating.

As you may have gathered, Winter is the time to plan things which are better done in warmer drier conditions which we at least hope to get in the Summer. We are currently discussing possible repairs to the dam, and wondering how to deal with some river bank erosion. I may write more about the dam in a later blog.

We have been submitting evidence to the House of Commons Energy Security and Net Zero Select Committee for their Unlocking Community Energy at Scale inquiry Debbie and Mark made our points so well that we appear third in the list of 147 submissions – we hope that government is listening.

To finish on another happy note, we will pay off the last instalment of our loan from the North York Moors National Park Authority in March. This is a significant moment and we are planning a little celebration – maybe more about this next time.

Rory Newman, Chair of Esk Energy

Autumn is certainly upon us: the nights are drawing in, and the trees are turning. We had a fairly dry late summer, so didn’t generate much, but since then it has rained….and rained – luckily for us not as torrentially as in other places, but it certainly filled up the river, and things have been busy at the turbine as a result.

We had a very successful working party just before the weather turned – we cleared lots of overgrown vegetation, and started to try to shift a set of willows that had fallen over into the river and rooted just above the turbine intake; we felt these were causing an eddy which allowed silt and rubbish to be deposited at our intake, reducing the flow.. We only managed to move part of the set of trees – but heavy rain then half-uprooted them and left them dangling across the intake.

Just hauling failed to shift them – too heavy – but Mike Ford found an electric winch, which more or less did the job…even this could only drag the root mass partway up the bank, so we are gradually cutting pieces off as weather allows, and will eventually get it moved.

One of the features of Autumn is the beauty of the trees as the leaves change colour and fall; this is lovely, but all those leaves have to go somewhere, and many of them end up in the river, get waterlogged, and clog up our intake screen. Sometimes just stopping and starting the turbine will fix this, but often someone has to go down and clear the intake with a big rake. It keeps us fit.

Other news: Mike has organised a replacement high-pressure cylinder for our hydraulics, now installed. I’ll write some more about servicing and maintenance in a later blog….

Rory Newman, Chair of Esk Energy