Dean Thomas, son of Robert Thomas, the designer of the Wind Harvest Vertical Axis Wind Turbine is still plugging away on the design.
He’s built a 1/40-scale model of a guyed giromill. Based on published information, the optimum solidity for maximum efficiency is 16% so he’s using four blades, two on each vertical section of the rotor. This turbine is specifically designed for a niche market where winds are exceptionally good near the ground (typically between 4 and 20 meters above ground) below existing HAWT turbines along ridgelines and established windfarms. The near-ground, or “understory” resource is currently not being utilized in California.
Thomas argues that VAWTs that target near-ground resources potentially have a lower specific weight than conventional wind turbines when the tower is included. He believes pages 341-344 in my book, Wind Energy for the Rest of Us, where I compare the specific mass of VAWTs and HAWTs, should be modified because the weight of the HAWT tower is not included. For instance, for the Flowind VAWT turbine, which targeted near-ground resources, the torque mast was effectively part of the rotor and the tower, so to compare it to just the mass of the HAWT’s rotor and nacelle is an “apples to oranges” comparison.
Here’s Thomas’ table comparing a giromill to a conventional wind turbine from the 1980s.
Thomas is continuing his father’s work on VAWTs, experimenting with his own version.
