The massive mill in the background with some useful bits in the foreground…
Back in June we started on a very interesting project, having been commissioned by the arts organisation In-Situ, to design, build and install an energy generating waterwheel which ran off rainwater in a big (predominantly empty) mill up in Brierfield, Lancashire. It was especially fun as we got to explore the massive mill’s empty rooms for components to use for the project.
First up we had to work out which roof to harvest the rain from we we set up a few IBC’s being fed from different downpipes and left them for a couple of weeks to see which ones filled up the most. This involved a fair bit of clambering around on roofs clearing mud out of guttering and spraying expanding foam to fill gaps in our feeds.
Angle grinding downpipe 1
Feeing off downpipe 1
Downpipe 1 into IBC
Inspecting downpipe 2
Downpipe 2 with a hole!
Here is a video our host Paul made of downpipe 2.
We did set up a third downpipe experiment but didn’t take any photos…
In the end we went for downpipe 2. Next we had to source four nice looking IBCs to act as a reservoir for the rainwater:
‘IBC World’
Four IBCs plumbed and in position
The generator itself was the next challenge. We had three options:
- Use a water pump as a generator similar to this
- Use a fan/something that water would turn and build a custom alternator to go with it
- Use a fan/something that water would turn and attach it to an off the shelf alternator
Option one would have been the most elegant, and we did find a couple in the mill, but the amount of flow they needed to be effective was more than our system could deliver so this was not an option. In the end we found a fan that was a good size and decided it would be more efficient (in both time and money) to use it to belt drive a scooter motor rather than build a custom alternator. We also found a good sized enclosure for the fan. These “squirrel cage” air conditioning fans are incredibly similar to a crossflow hydro turbine so it was just a case of making a nozzle to jet the water at a correct angle and we had a fairly simple recycled hydro setup!
Existing water pump we decided not to use
The fan
Fan & enclosure
Finally we needed to mount everything and attach the feed from the IBC’s
From behind
From the front
Water outlet
What does it do?
The system as we set it up for an In-Situ event had the waterwheel powering a sound-art installation and some lights which illuminated the IBCs in the third floor windows and the windows of the clock-tower which the penstock pipe ran down. We will be going back to build and install a bigger electrical system with some batteries so they can use the power for other applications.
What does it generate?
The wheel, when the flow is full, generates around 50W of electricity which is roughly 50% efficiency for the available resource – not bad!
Taking the average annual rainfall and the size of the roof, and doing maths, you can calculate the amount of energy it could generate over a year. It would be the equivalent of 7W continuous power which is 60,000Wh, or 60kWh – not much! This is limited by the rain and the roof, not the generator, and demonstrates that hydro generation from rainwater harvesting really isn’t a viable source of energy – even when your rooftop is a massive factory it’s still not really worth it!
Here is a video our parters In-Situ made of the art installation:
rain sheds light from Helmut Lemke on Vimeo.
While we were there we also fixed the big old clock which was fun:
