We have many visitors who have come to visit the Stockport Hydro Scheme. These include local people who simply wish to know how the scheme works right through to other community groups who are looking into setting up similar projects in their own area. Below is a selection of frequently asked questions covering technical aspects of the scheme, how it is performing right through to what the environmental impact has been.
Has the scheme performed as well as predicted?
There are two parts to this, the maximum output of our two turbines was originally forecast to be 68kw. Unfortunately the maximum we have ever seen is 51kw. Whilst at first this seems very disappointing as there is a large difference it does not seem to have affected our overall yearly output too badly. We think this is because the turbines are actually performing much better than expected during periods of low river levels and so are making up the shortfall. It is too early to know for sure as we will need many years of data to work out what our average yearly output actually is. However in our first full twelve months of operation which included the very dry summer of 2013 we managed to achieve an output of 180,000kwh, against our original target of 220,000 kwh per year. As we only received 80% of the rainfall which we would expect in an average year we are delighted with this result. It gives us a hope that we are on track to achieve our target output in the long term as the variability in river levels even themselves out over the years.
Who set up the project?
Steve Walsh from h2ope identified Otterspool weir as an ideal site for a hydro scheme. He then approached the relevant authorities for approval and set in motion the process of creating a community group to take ownership and run the scheme. We have heard some accusations of corruption however the fact that Stockport Council and local politicians were in favour of the scheme and supported it had nothing to do with it going ahead! No one has made any personal direct or indirect financial gain from the scheme, everyone involved have given a huge amount of their time and energy for free, the only reward they have taken from it is the satisfaction of working on a project they believe strongly in.
You have used a lot of concrete and steel doesn’t this means you’re actually causing more harm than good?
There is sometimes confusion as to whether renewable energy schemes take more energy to build and operate than they will generate. This is not true, using the example of wind turbines studies have shown they will produce 20 to 25 times more energy than they take to construct and maintain over their lifetimes. These figures are based on older turbines and it is expected the current and next generation of wind turbines will perform far better than this due to constant improvments in the technology. Although we do not have accurate data for our type of hydro scheme yet we do have students working on such studies for us and the New Mills Torrs site. We are confident that Stockport Hydro will easily produce many times more energy than it took to build. From an environmental point of view concrete is one of the most harmful building materials. However it was the only viable option for our site and even if it is not maintained the site should be usable for at least 100 years. With occasional maintenance there is no reason why the site can’t be used for an indefinite period of time. We have a free source of fuel and an ideal location, the machinery will last 40 years or more and there is no reason why it can’t be replaced and improved upon in the future. A spin off benefit of our project is that because we are community owned and run we also act as a fantastic educational resource for the local community. We aim to make people aware of their energy use and encourage them to take actions to limit their impact on the environment. This will help inspire similar renewable energy schemes plus even more importantely energy conservation both in the local area and nationwide.
Do hydro schemes harm fish stocks or the environment?
We have had some concern from local anglers that the construction and operation of the hydro scheme will damage local fish stocks. Whilst it is true the construction of the scheme has blocked access for fisherman to a very small stretch of the river we are confident the scheme is not causing any harm to the local environment.
At all times, the system ensures that the water depth over the weir is at least 6cm. This protects wildlife and the river ecosystem. Water flow is also maintained down the stepped fish pass (between the fence and the screws), which will enable small fish to swim up the river for the first time since the weir was built.Other enhancements for wildlife include four bat nesting boxes and a mammal pass (a wooden ladder and bridge upstream of the intake) to allow mammals such as voles, otters and badgers access to the river.
This video shows the Environment Agency conducting fish and debris tests on an operational Archimedes Screw in Devon.