Towers

Why worry too much about the tower?

• Would you put a solar collector in the shade?

• Wind is the fuel!

• Remember, 30’ above anything w/in 500’

• Measure from the bottom of the swept area

Costs

• Turbine grabs our attention in a wind system, but . . .– The Balance of System (BOS) can easily cost

more than the turbine and– The tower can be 2-10 times as much as the

turbine

Consider the work of a workshop

• Most expect to mess with turbine most of the time,

• There is much more to do than turbine such as . . .– Tower work

• Rope work, winch work, assembly, anchors, transit work, tightening cable clamps (1-4 days)

– Electrical work• Pulling wire laying conduit diggin ditches ((1-3)

– Actual turbine work• Assemble, mount to tower (few hours – 1 day)

3 Basic Tower Types

• Tilt-up–Easy maintenance, no climbing

• Fixed, guyed–Very common, climbable

• Freestanding–Costly but attractive and climbable

Small Wind Turbine Towers

Fixed Guyed Tower

Tilt-Up Tower Self-Supporting Tower

Fixed Guyed Tower

Build on ground

Tilt-Up with crane (3) guy wire

anchors, climbing, crane

Fixed Guy Towers

• Lifted once and does not tilt down– Can have 3 guy wires

• Maintenance is done by climbing

• Come in different configurations

• Lifted in one of two ways– With gin pole, but in a

different manner– With a crane

Fixed Guy Towers

• Do not require open area of a tilt-up but still need open lanes for the guy wires

• Guy radius is 50% to 80% of tower height

• Costs are similar to tilt-up

• You have ore options for guyed towers because do not need as much open area

Tilt-Up Guyed Tower

Build on ground

Tilt-Up with winch or grip-

hoist

(4) guys wire anchors, maintenance on

ground, economical

Careful with heavy turbines and tilt up towers…

Here is the 250lb AWP freakin out the tower crew at Beech

Tilt-up towers

• All maintenance from ground

• Come in heights up to 130 feet and different sizes (to accommodate turbine size and thrust)

• All tilt-up have 4 guy wires

• 3 concrete pads with the winch attached to gin pole and 4th pad

Tilt-up Gin Pole

• Gin-pole attaches at 90° angle– Gin pole is typically 75% to 100% of the guy

radius

• Gin-pole is a lever that allows you to lift tower which pivots at bottom

• Can raise or lower with truck, tractor, winch, come-along or grip hoist– Remote location requires winch or grip hoist

Tilt-up Blues

• Big diamond shaped footprint– Clear of trees for up 150’x150’

• They can be dropped, tow vehicles can slip• For those who do not mind

climbing, a tilt-up tower can be less convenient

• Skill must be acquired for tilting towers

• Miss the beautiful vistas!

Self Supporting Towers

Build on ground

Raise with tractor or crane

No guy wires, requires climbing

or crane

Free Standing Towers

• No guy wires

• No tilting

• Modest space requirement

• Involves lots of steel and concrete so more expensive

• Higher cost of materials, labor, excavation, concrete forms, and rebar

Free Standing Towers

• 2 Basic Forms– Three-legged Eiffel style – Monopole, slender (often

very expensive and out of budget for small scale wind owners)

• Free standing tower will cost at least 1/3 to 1/5 more

Anchors

Screw-in Auger Arrowhead Rock anchors

Details

Follow manufacturer’s recommendations for

anchors

Never saddle a dead horse

Saddle, live wire

U-bolt, dead wire

Avoid sharp guy wire bends

Homebrew Towers

• Be careful.

• Engineer it properly

• Build it plenty strong

• In the end you may need an engineer’s stamp for permits so just buy a professionally designed tower.

Choosing a Tower

• Turbine manufacturer will tell you what tower size is necessary to hold your turbine

• Remember that trees grow so plan for mature tree size

• Is there space for a tilt-up?• Is someone going to climb the tower that

you know?• Ask neighbors about aesthetic concerns

Choosing a Tower

• Take time to go look at tower installations to know for yourself what you are getting into

• Don’t make your tower too short

• Most common mistake in wind system design

• If you lack experience seek professional advice