It’s been almost a year since the Grow Heathrow wind turbine was installed, so to mark the occasion I thought it was a good time to share the process of how and why it came about. For many of us, this was our first experience building a wind turbine, but hopefully it won’t be our last.
Since Grow Heathrow is an off-grid site (meaning that it isn’t connected to the National Grid), all the energy that’s needed on-site has to be generated on-site. Shortly after the greenhouses were refurbished, we installed four 190 Watt solar panels on the roof of the southernmost greenhouse, which provided us with an abundance of clean electricity whenever the sun was out. As summer moved into autumn, our thoughts turned to winter, when there would be much less solar energy available for our solar panels to harness. We knew we had to diversify our energy sources, so we started making plans to build a wind turbine.
Having seen DIY wind turbine demonstrations at successive Climate Camps by V3 Power, and taken part in a turbine blade carving workshop run by Cambridge Greentech at the Sunrise Off Grid festival during the summer of 2011, we knew that we had the means to build a turbine of our own. All we needed to do was figure out what size we wanted it, then make sure we had enough funding to get the necessary materials. The turbine design we would be using was the one developed by High Piggott, which is based around the principle of using fairly basic materials and tools, so that anyone with a reasonable level of competence can have a go at building one. With a well equipped workshop and enough people, you can build a wind turbine without too much difficulty in a few days. Unfortunately, we were facing the prospect of building ours in a converted greenhouse, without a reliable electricity supply, in the middle of winter, and with a bunch of enthusiastic but inexperienced volunteers.
Cambridge Greentech very kindly agreed to help us with our turbine. They had organised wind turbine building workshops before, and they were able to source all the necessary materials and specialist tools for us. We decided to go for a 2.4m diameter turbine that was rated at 700 Watts, which would complement our existing 24V solar panels. A crowdfunding campaign helped us reach our funding target, and a date was pencilled into our diaries – the first week of November.
The first day of the workshop arrived – a damp and chilly November morning. Everything was as ready as it was ever going to be – we’d cleared space in the workshops, installed a brand new diesel generator, found some willing volunteers who wanted to learn how to build a wind turbine, and started building a scaffolding tower for the turbine to be installed on. The CGT van arrived, so fully loaded with equipment that the suspension was struggling to cope. After getting it all unloaded, we sat down with a mug of tea to review how the next few days were going to unfold.
Materials list: A solid block of smooth-grained pine for the turbine blades, two solid steel discs for the rotors, various lengths of steel angle and flat bar, 3 different sizes of steel pipe, 24 high strength neodymium magnets, 3 kilos of insulated copper wire, 1 kilo of resin, a hub for a caravan wheel, 16m of steel cable for guy lines, 20m of flexible 3-core cable, rectifiers with heat sinks and an enclosure, threaded bar, bolts and washers, all kinds of miscellaneous bits and pieces, and plenty of gaffer tape.
Tools list: draw blades, spoke shaves, chisels, files + rasps, cabinet scrapers, dividers, measuring tools, jigsaw, block planes, hand drills, MIG welder, grinders, stick welder, metal files, a good soldering iron, and wire cutters.
The work involved would be divided between three groups – the woodworking crew, the metalworking crew, and the electrics crew. The wood crew would spend most of their time carving the 1.8m long blades for the turbine. The metal crew would be concentrating on the turbine head, tail, and mounting poles. The electrics crew would assemble the alternator and bridge rectifier. Each crew was supervised by someone from CGT – Nikki looked after the metalwork, Pete cast an expert eye over the woodwork, and Scotty handled the electricals. So that everyone got a chance to get involved in every part of the process, the crews would change over at the end of each day.
As the days went on, the shape of the turbine started to emerge from the raw materials we’d started with. The days were short, cold and damp, but there were enough hands around to keep us all supplied with hot beverages and warming food. A lighting rig allowed us to keep working after sunset, although it was a relief for all when we downed tools at the end of each day and the noise from the generator and the grinding and welding could fall silent, at least until the next morning.
Although we’d wanted to have a finished turbine by the end of the workshop, that proved to be beyond out capability. For one reason or another, each stage of the build took longer than expected. But we had at least assembled all the components needed for our turbine, and when we turned it, which generated a voltage when turned – success! The ending of the workshop coincided with bonfire night, so we had ourselves a celebratory bonfire to wind down after a few days of intensive productivity.
Coming up in Part 2 – the final installation.