Vertical Axis Wind Turbine Update
This is a vertical axis wind turbine update and some extra data if you are interested in them. I get a lot of questions from the neighbors and when I give tours of Mezzacello. So why not just give people a proper introduction to what they are and how they work.
Why Vertical Axis?
Traditional (HAWT or horizontal axis wind turbine) wind turbines do not work so well in the city, for two reasons. 1. They need to be higher in the air where the wind current is. 2. In a city, tall things are discouraged. But a vertical axis wind turbine can work at speeds as low as 1.5m/s whereas a HAWT needs at LEAST 4m/s just to start turning.
You are never going to find that type of consistent wind in a city, besides between skyscrapers or in a very windy city. But I get a consistent 3-7m/s at Mezzacello Urban Farm and the reason is very simple. It’s traffic.
COTA busses and UPS, USPS, FedEx, Amazon, and Rush Hour Traffic make lots of wind!
Artificial Wind
It’s a simple fact: Cars, Busses, and Trucks displace air as they move through it. That air has to move somewhere, and air having a slight electromagnetic potential tends to clump together and move (we call that turbulence or wind). A VAWT is the perfect way to turn that small but consistent bit of turbulence into power.
Over the last three years (I started this during COVID19 lockdown) I have been experimenting with wind power at Mezzacello. First it was a traditional HAWT and that was atop the bioreactor (3m) in the air. A HAWT needs at least 12m (40’) to be effective. So we pivoted.
The next iteration was also atop the bioreactor. It is the place where I imagined the wind would be strongest. I lacked data. This was the second generation wind turbine design, the toroidal flower.
The toroidal wind turbine
The heavy wind turbines and their location in the center of the farm was less than ideal. I really I liked the design and the aesthetic, but they never really produced enough energy. But I am glad I at least tried them.
The current iteration is the sleeker VAWT model. I love how much more efficient they are. While they weigh the same, the sleek VAWT design turns more efficiently due to their larger surface area to wind ratio.
Location, Location, Location!
When I moved the Sleek VAWTs to the southern border of the farm I also decided to alternate their locations to see if their wind access is consistent. What I learned is that the wind is strongest directly on the alley and facing Broad Street than it is on the other side. The shed roof drives the wind away from from the edge of the turbine and up into the center of the turbine.
There is also a function of distance to efficiency to condider. The Sleek VAWTs that are now atop the Bioreactor do not turn NEARLY as often or as consistently as the broad street VAWTs do. And the furthest south VAWTs turn the most. On average they produce 40% more power than the VAWTs just to the north on the SAME shed!
Final Notes
My final note on the Sleek VAWT design is pretty simple. Place all VAWTs on the southern face of the farm. Wire them each two and two to a single charge controller and tie them into a spring loaded flywheel to store energy over time, rather than hope for consistent energy. Spend the money on good flexible easy to work with wire and reliable MC4 connectors.
You will be SHOCKED at how much wires these systems require. The further away from your charge controller you are, the more wire you will need. I strongly encourage anyone interested in installing these systems to take my Physical Electricity workshop here at Mezzacello Urban Farm. In that Saturday workshop I can teach you how to build a VAWT, mount it, wire it and tie it into a battery array. I can also show you how I have my solar arrays, AC Inverters, and Batteries tied together.
The VAWT systems are really great and simple to build, wire and install. I think the next iteration is going to be building them with 3D printers so the blades, shaft, and the electromagnetic motor case are easier to assemble and deploy. I am looking for a 3d Printing intern to help me build and design these!
