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Wind energy: From recipes to reality!

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Introducing Residential Wind Turbines

The two main types of wind turbine are Vertical axis (VAWT) and Horizontal axis wind turbines (HAWT). Vertical axis wind turbines are beautiful pieces of architecture, but at present are more like revolving sculptures, as opposed to the more efficient horizontal axis wind turbines. - See Green Favourites section, and explore the Sustainability Forum links for further information. The swept area of a VAWT is minimal compared to a HAWT, and yet the BETZ limit (limit of energy possible from a wind turbine) is continually ignored by bogus VAWT companies, who may not be clear about the real energy data.

So, no surprise then that we have opted for HAWT. HAWT should be mounted on a suitable mast that gets clean unobstructed wind from any direction. The HAWT Turbines at ‘Le Vivray’ are Hugh Piggott's 3.7 meter design. This particular design has been manufactured by 1,000s of enthusiasts all over the world, and can be put together just about anywhere. Hugh’s design is very clever: simple, minimal materials and yet incredibly strong and robust. Surely the Holy Grail of any Machine. They can stay working in even Hurricane conditions, where most other such turbines have to be stopped or lowered.

The blade design has been developed to efficiently match the PMG (permanent magnet generator) design, matching the wind/blade speed & diameter to the coil windings, and hence give carefully balanced electricity to the load. Here, the load is our batteries.

So we achieve optimal output from modest breezes to howling gales, where the clever geometry of the furling tail design (French: "mise en drapeau") pulls the blades away from the wind if it becomes excessive. - We say the turbines are "dancing”.

Materials costs for self build is about £1000, but can be a lot less if one takes time to hunt around for bargains. Hugh's self-build recipe means you carve the blades to an exact template. You make the framework. You make the coils. You cast the stators. And assemble the parts. - His "Wind Turbine Recipe Book" is a mine of information!

We have seen 3.1kW output from one of our turbines, but in general we would say that a 3.7m diameter is a 1kW Turbine, this being the average output, including completely still days - when our solar panels take over, even when it is dull! However, we do see some unscrupulous manufacturers of other designs calling our size of turbine "3kW", and Yes, they may achieve 3kW for a short time - before overheating and fatigue/stress and poor quality manufacturing take their toll!

So. If you are considering a Wind Turbine, then firstly be aware that even good quality European manufacturers have come unstuck when they have had parts manufactured in China, in cases where standard operating procedures (SOPs) and quality control may not have been observed. But don't take our word for it: join one of the Sustainability Forums and ask questions!

Our wind turbines are made from raw materials, locally sourced where possible, engineered and assembled on site, here at Le Vivray.

Our three wind turbines are 3.7m diameter design from Hugh Piggott’s book "A Wind Turbine Recipe Book" that can be found at www.scoraigwind.co.uk. They have optimal winding of the magneto coils to match wind and blade design, and a height including blades of 11m. The blades automatically tip out of the wind when the turbine reaches maximum speed (“self-furling”). The turbines give 1 to 2kW each in even very moderate winds, with max output 3.1kW.

Energy produced by the main suppliers e.g. EDF is still relatively cheap compared to the initial investment if your renewable energy -producing equipment is installed commercially: it will likely be around 15-20 years before your investment is returned. And a fact not generally understood is that the giant commercial wind turbines may take even longer, due to the materials and energy used to create them in the first place. i.e. concrete and steel foundations, service equipment and roads, metals and other materials used in manufacturing and maintenance over an estimated 20 year lifespan...

...So, could these simply constructed, mid-sized domestic wind turbines (2-6kW) really be the way forward? Well, the pay-back time for ours is around 4 years (with careful purchasing on e-bay!), and with an est 20-30 year life-span, yes, they do it for us.

Materials required to make a 3.7m blade diameter wind turbine.Wooden ply moulds (background) for casting the 2 magnet discs and the coil stator, 2 steel discs 400mm dia x 10mm thick (on floor), 32 neodymium magnets, the main bearing unit (Peugeot Boxer van rear stub axle Hub), alloy heat-sink and rectifiers, amp meter and MCB fuses, Tristar 45a charge controller, coils of resistance alloy wire for the dump loads. Coil winding equipment, coil of 1.8mm dia enamelled copper wire, Large coil drum: 100m 8mm dia galvanised wire rope for the tower lines, coils of green and red tri-phase rated 6mm2 flex cable for coming from the magneto down the tower, tower wire turnbuckles etc, steel tubes for the tower top, steel angle and steel plate for the magneto frame.

Wind Turbine 3.7m diameter.

Our own manufactured fiberglass blade moulds (exact copies of Hugh Piggott’s design) and plywood patterns for cutting the fiberglass woven cloth.

Main frame, bearing axle, and tail metal work.

Wind turbine lowered for maintenance.

One of our wind turbine magneto units being assembled: magnet disc 1 is shown. Assembly is completed with the Coil stator and magnet disc 2.

Side view of the main frame.

Demonstrating wind turbine construction methods and sustainable building techniques at a local show.

Le Vivray, 61120 Neuville sur Touques, France

Wind turbine construction