So, you have decided on a horizontal axis wind turbine — the good, old fashioned type.
You have picked your site and now you need a tower. You have more options than Carter has liver pills. Guyed towers, monopole, lattice structures, tilting guyed, non tilting monopole . . . the list goes on and on.
So where does one start?
For homeowners, the first consideration, as always, is budget.
Generally the guyed versions are the most economical. However, they need skill to erect.
Mono-pole and lattice type towers are the most expensive due to the extra cost of manufacturing. They also require a crane to mount the turbine once they have been stood in place. The advantage of the monopole is the small footprint.
Lattice towers take up the next smallest amount of space; with the guyed towers using up the most, with their widespread anchors and cables.
Room for raising and lowering the tower is the next consideration as in the first six weeks and then in six months, maintenance is required. This involves the bolts being re-torqued and the inspection of the moving parts.
Monopoles take the least room but require a crane or picker truck and hard ground — the same applies to the lattice type. Guyed towers can be lowered but require a trained crew to perform this task.
This is where the hydraulic self-raising monopole turbine tower comes into the spotlight.
If you have access to a tractor with hydraulics, it is very easy to perform this task.
In the absence of a tractor, a hydraulic power pack can be rented from a local equipment rental shop.
The self-raising monopole tower can be raised and lowered at will without any specialized equipment or training, as safety equipment is built right into the system. Velocity check valves will prevent the tower from falling, even in the event of a hydraulic hose rupture.
The next consideration for any tower is the base.
Poured concrete gravity base or piles? This depends on the ground material at your site.
Sitting on a pile of gravel or bedrock? A concrete gravity base is you only option.
Sitting on pure clay or silt? Piles will do the job just fine.
If you have been involved in the construction of your home, you probably know what type of earth is under your feet. If not and you know the buildings contractor, you will be able to get this information from him, or possibly a neighbour who has done some digging on his site.
In the event none of these lines of information are available, then a test hole may have to be dug.
A good tractor or skid steer mounted auger can “dig up” the basic information.
The choice of towers is large, and there are important considerations to the decision, but the end result will provide a solid base for your turbine and keep it in the air for years to come.
Lorne Oja is an energy consultant, power engineer and a partner in a company that installs solar panels, wind turbines and energy control products in Central Alberta. He built his first off-grid home in 2003 and is in the planning stage for his second. His column appears every second Friday in the Advocate. Contact him at: lorne@solartechnical.ca