Build Your Own Homemade Wind Generator

Marshall’s story really began after the Price family built
their lakeside residence nearly 18 years ago. The constant
breeze blowing off the water served as an ever-present
reminder that free energy was going begging . . . but it
wasn’t until Mr. Price started collecting information on
wind machines, and ran across “a little red book on
homemade energy” (THE MOTHER EARTH NEWS Handbook of
Homemade Power), that he finally found the answer to
the problem that had been keeping him from building his own
plant: the need for information concerning the design and
fabrication of the all-important wooden blades. Once he’d
uncovered that technique, the rest, for the most part, was
a matter of locating junkyard parts and fitting them
together so they’d be compatible with one another and with
the nature of the lakeside breezes to create his low-cost homemade wind generator.

“One thing about the wind here,” he told us, “it’s darned
unpredictable. It can be blowing nicely at a steady 18
miles per hour, and then all of a sudden it whips up to 30
knots without so much as a how do you do. On top of that,
it changes direction just as erratically . . . and that can
play the devil with your equipment. A 12 foot rotor spinning at
200 RPM or so has tremendous inertia, and doesn’t take
easily to being reoriented.”

It was critical, then, that Marshall Price plan for these
contingencies before beginning the construction of his
plant. He first scrounged a Delco ambulance alternator that
was capable of delivering 147 amps at about 15 volts . . .
which figures out to be over 2,000 watts in a very strong
breeze. After reconditioning this component, the
do-it-yourselfer started working on a governor system
that’d allow his three 6 foot blades to feather–that is,
pivot on their mounts–when wind speeds got
dangerously high. (When feathered, the blades are less
effective as airfoils, and thus keep the rotor’s RPM within
safe limits.)

The hub-mounted control setup Price came up with is similar
to the type Marcellus Jacobs used on his well-known wind
machines. “I’d read stories about Jacobs, and I wanted to
know how his governor worked. I finally located a copy of a
drawing from an old service manual, studied it, and then
built my own version. It acts on centrifugal force and uses
lead weights, linkages, and springs to control the blades’
pitch. I knew I wanted a top speed of about 230 RPM on the
power shaft, so I just used the trial-and-error method to
set up the governor correctly. During the winter I made a
little testing stand in the basement and mounted the hub on
it . . . then I drove the unit with a belt connected to my
walking tractor’s engine, took RPM readings off the hub
using a tachometer, and experimented with the governor
until I got it right. I’ve been using it ever since, and,
by gosh, it works!”

Of course, if it’s to generate usable electricity, the
alternator must spin a good deal faster than 230 RPM, so
Marshall set about making a gearbox that would step up the
generator’s speed considerably. To accomplish this, he just
welded a housing out of 1/4 inch plate and mounted two salvaged
Chevrolet gearsets inside. The 8.2-to-1 ratio thus created
means that for every one turn the power shaft on the hub
makes, the alternator shaft spins 8.2 times . . . or about
1,800 RPM in near-gale (36 mph) winds.

The power shaft itself was recycled from an old Datsun. “I
bought the whole car for $10, then sold the body to a
junkyard for $15. That left me with the entire drivetrain
and a profit of $5.00. I stripped out the swing
arms from the independent rear suspension, used one for the
windplant-bearings and all–and kept the other as a
spare.”

Having taken care of governing the high-speed performance
of his generator, Mr. Price had to consider control at low
RPM, as well. He used a centrifugally activated
microswitch-snitched from an electric typewriter–to
energize the alternator’s field windings when the shaft
speed reached approximately 750 RPM. Translated into wind
velocity, that means that the generator doesn’t start
charging until the breezes reach 7 or 8 mph. Below that
speed, the alternator is ineffective anyway, so there’s
little use in allowing battery power to drain into the
field circuit at such times.

Finally, to protect his equipment from the inevitable heavy
blows that occur periodically, Marshall hinged and “loaded”
the windplant’s tail frame so it could be folded parallel
to the plane of the blades when necessary. A small cable
winch mounted at the base of the tower keeps the tail
perpendicular to the rotor path under normal conditions,
making maximum use of the wind . . . but when that cable is
released, the vane swings to one side, presenting the tips,
rather than the faces, of the blades to the breeze so the
rotor can’t overspin.

This method of restraint is commonly used in upwind
machines, but in this case, Mr. Price again took a tip from
the Jacobs design and set the tail springs so they’d shut
down the windplant if the cable broke, rather than
open it to the full force of a storm. Marshall points out
that he can take advantage of his machine even in strong
winds, simply by unwinding the winch partially and allowing
his blades to face the breeze at an angle, so they’ll spill
off a good deal of wind and yet continue to turn rapidly
enough to generate power.

Handmade Redwood Blades

A knack for scrounging, coupled with the ability to
understand the potential of each junk component, aided
Price immeasurably in bringing his project to completion.
But he knew from the start that he’d have to fashion the
wooden blades from scratch.

“I went and handpicked three straight-grain redwood 2 by 8s
from the lumberyard, then cut and shaped them according to
the specifications in the homemade power book. Because
windplant blades are driven by the wind–they don’t
drive into it themselves as an aircraft propeller
does–their contour must differ from that of a
standard propeller to work correctly. After I’d formed and
sanded the wood, I protected it with fiberglass resin and
matting–coating it evenly to maintain proper balance
at speed–then roughed up the glass lightly and gave
each blade another coat.

“Now those redwood airfoils aren’t just bolted to the hub .
. . each spar coming off the governor pinions is
7/8 inch-diameter cold-rolled steel, and extends a full 20 inches into
a socket that’s been bored into the blade. Furthermore,
these internal spines are pinned through the wooden
shoulders, and I’ve also got them sandwiched on the outside
with 6 inch by 6 inch metal plates. This way, I can have my
feathering feature as a governor, and still feel
comfortable about the integrity of those redwood blades at
higher wind speeds.”

The Chain’s Weak Link

After fabricating the blades and working out the best
method of mounting them, Marshall had only to erect a tower
and place the plant atop it. Since the source of wind is
generally from the lakeside quadrants and doesn’t suffer
interference from trees or hills, it wasn’t necessary for
Mr. Price to build a fancy lolly pivot or to rely upon
altitude to catch the best breezes. He simply sank a length
of well casing into a concrete footer, leaving about 18 feet of
the casing exposed. Then he mounted the generator and
gearbox on a frame and set that into the tower so it would
pivot on a vertical axis. Double-aught copper cables
(purchased at scrap prices from the local power company),
given plenty of slack to allow for yaw, carry generated
current to the battery bank.

Energy storage is, according to Price, the weak link in his
system. “There’s absolutely no problem at all in
making the power . . . that’s the easy part. But
decent storage-something that’s affordable and can still
take the abuse of constant charge and discharge–is
darned hard to come by.”

Marshall wanted [1] a system that would allow him to be
somewhat independent of the power companies, and [2] one
that would be working even when the wind wasn’t. As his
setup stands now, the outsized alternator generates
alternating current, which is rectified to direct current
through diodes, then stored in a mixed grill of batteries
composed of 2- and 6-volt cell blocks. That bank is wired
in a series-parallel circuit to achieve 12 volts total, and
that power is fed through a stand-alone inverter that
converts the storable DC back into AC, for use throughout
most of the house.

Mr. Price doesn’t use a voltage regulator on his system,
because the batteries–when they’re
depleted–require a good three days of steady wind to
even approach the overcharging point. In fact, he simply
uses his appliances as indicators of his storage bank’s
state of charge: “I can tell by the way the lights bum. If
they’re too bright, I know I’m getting more than 13 volts
instead of my usual 12.5, so I have to shut down the plant.
On the other hand, if the batteries are low, the picture on
my color TV gets distorted-in the upper right-hand corner,
and that tells me it’s time to crank the tail out straight
again. A few years back, we had a nine-day spell without
any appreciable breeze, and the cells were able to handle
that, so I’m not too worried about my storage capacity.”

Of course, batteries do lose their effectiveness.
But Price stresses the importance of maintaining a
cost-effective approach to these essential pieces of
equipment. He cites as an example an offer that was made to
him some time ago: “A fellow had three huge Pullman car
batteries that he wanted $3,700 for. Now if I’d invested
that amount of money at 10% interest, it would have paid my
power bill for quite a few years to come, so those Pullman
units weren’t a good buy. It’s better to get a number of
smaller batteries, pay maybe $25 apiece for them, and use
them to the bitter end. They might not last as long, but at
that price I could afford to replace them.”

A Sound Investment

Has Marshall Price’s investment–of both dollars and
time–been reasonably rewarded? Interestingly enough,
he admits that, at first, his main objective was simply to
have one wind-powered light source over his reading chair.
Then, as he made improvements in his plant and added more
lights, he boosted his storage capacity as well.
Eventually, seeing that the generator easily kept abreast
of his power usage, he installed the inverter and then tied
other appliances into the line. Today, everything in his
household is powered by the wind, save for the dishwasher,
the washing machine, and the refrigerator . . . and the
cost of operating (and enjoying) those
induction-motor-equipped conveniences usually doesn’t
exceed $20 per month.

In summary, Marshall Price is an example of someone
who–with the help of his welding and metal-shop
skills–turned several hundred dollars’ worth of
scrapyard parts into the equivalent of a
several-thousand-dollar investment . . . one that
demands little more than an annual checkup and a
battery recruiting effort every so many years. It doesn’t
take a very sharp pencil to make sense of economics like
that . . . because this Price is right!

One Step at a Time

It’s not difficult to imagine that many stand in awe of
Marshall Price for taking on such a formidable project and
seeing it through to completion. But even Mr. Price, as a
veteran tinkerer, approached his goal systematically, using
the most basic means at his disposal. If Marshall’s success
story has you itching to try your hand at a wind energy
project of your own–but you don’t know where to
begin–here are three approaches. The one you choose
will depend upon how comfortable you are with your shop
skills.

The simplest’ and least expensive project is the MOTHER EARTH NEWS Red
Baron trainer–a 70-watt wind machine which our
staffers developed as an entry-level undertaking that would
cost less than $100 to build. It’ll provide its builder
with some valuable experience and usable electric energy,
and can also serve as a monitor for a proposed wind site.
Six pages of detailed, step-by-step plans and photos are
published in the article beginning on page 96 of MOTHER EARTH NEWS N0.
92.

A more sophisticated windplant (but one that’s not much
more difficult to build) was featured in issue MOTHER EARTH NEWS NO. 93. Dubbed
the Blue Max, the 350-watt wind generator is a reliable
power producer that can be built for as little as $200. It,
like the trainer model, uses off-the-shelf plumbing
fittings as frame components, so assembly is almost a
cut-and-paste operation. Because there’s more detail work
involved with this machine, we put together a set of
construction plans (in addition to providing information in
the five-page published article). They’re available at a
cost of $10.00, plus $1.50 shipping and handling, by
writing to Blue Max, THE MOTHER EARTH NEWS PLANS, Hendersonville, NC.

Finally, if you feel confident about tackling an advanced
workshop project, Marshall Price has cooperated with
MOTHER’s staffers in producing a plans package that details
his 2,000-watt wind machine. The package costs $15.00, plus
$1.50 to cover shipping and handling, and is available from
the address above; please specify Price windplant when you
order.