Need Electricity? Here is how to power up your house.
Jul 24, 2010 by Anthony T.
After several months of research on generating electricity from home, I
have concluded that the most economical and productive method to
start my project is to use my legs plus a ten-speed bike with a
huge alternator(automotive) mounted on a bike trainer stand. If
you are a handy person, have some basic electrical and mechanical
aptitude, and love to exercise you can easily replicate what I have
built in my house. So read on.
In this particular project that I built, I used a ten-speed bike to spin the
alternator. I built a bike stand to lift the bike, but you can buy a bike
training stand and modify it. You need to realize that an
automotive alternator needs a charged battery to operate and unlike
a PMA(Permanent Magnet) alternator for low speed windmills,
a regular alternator usually requires both high rpm and torque(horse
power) to generate electricity whereas a windmill type pma(permanent magnet
alternator) is designed to run at much lower speed with lower torque. But I
chose the automotive alternator instead of a windmill PMA type
alternator simply because the ampere an automotive alternator's output,
60A to 120A depending on model vs. 10A using a PMA, also the cost of the
automotive alternator itself at 1/4 the price. Another benefit is the
built-in regulator in automotive alternator saves me the trouble
of deploying additional external circuit device to regulate and dump
load if I go the route of a PMA alternator.
So the challenge here is obvious, high rpm and torque HP(horse power) rated on
the alternator is an issue that needs to be resolved or else no electricty can
be generated. I solved the rpm issue by using the ten speed bike wheel to
spin the flywheel of the alternator.
Handing the required high rpm:
I searched around the Internet and look for using bike to run an alternator, I
found many people use the approach of attaching the bike chain directly to the
alternator flywheel, this works fine for a low torque/low rpm PMA alternator
but for automotive alternator I don't think you can paddle the bike
fast and strong enough unless you use an engine or you are a superman. So
I chose the method of using the bike wheel to rotate the alternator flywheel
which means the size of your ten speed bike wheel to the size of the
alternator flywheel is critical here to maintain the required high rpm to
run the alternator, my short cut way of high/low gear ratio without using any
gear. For my ten speed bike, every revolution of the wheel spins the
alternator flywheel about 16 times. So to crank up a 2000 rpm rated
alternator you need to spin you bike wheel almost twice every second. Don't let
this scare you, I have tested this over and over again, the rpm is what it
takes to start the circuitry in the alternator once you achieve this you can
slow down to a more reasonable rate of spin your bike wheel at about 1 rev per
second which is not very hard.
Handling the require HP, torque
Like all voltage generators, spinning the alternator with no load is pretty
easy. If the battery is fully charged(recommended but not necessary,
see later part for detail), as you rev up your bike, you can see the
alternator generates 1.5 volt above a fully charged battery. But this is still
in a no load or light load situation. If you start to drain the voltage, you
will find it near impossible to step on your bike. It really feels like riding
a bike uphill when you start to drain the current to run your inverter and
when my legs got tired and I came to a halt.(more on inverter later). I
started this project by using a pvc pipe to replace the fly wheel, whenever I
turned on the switch to run the inverter, the alternator gets so heavy it
becomes impossible to paddle the bike, furthermore, the pvc pipe started to
grind and wore out quickly by the rubber tire.
The solution to the load and high torque issue:
I checked around the internet for increasing torque of a motor or engine(my legs
are the engine in this case) I came around several articles of attaching
weights to the flywheel. In fact, this is how tractors are general built, the
balanced weight on flywheel creates extra torque to allow the tractors to roll
over obstacles without stalling the engine. The only problem of attaching
weights to the flywheel is that they need to be balanced perfectly or it
doesn't work well. After experimenting with several configuration(I actually
tried and extended the fly wheel of the alternator), the best way to do this is
simply attach 2 piece of weight lifting plates to the alternator. The groove
between the two plates fits perfectly on my ten-speed bike back wheel. See
picture below. This method you don't need to balance the fly wheel as the
plate itself has mostly equally distrtibuted mass at all opposite ends
of clock positions.
I started with the lowest 2.5lb plates from the Sports Authority, it helps
tremendously when the inverter is turned on and the current starts to drain,
but still my legs got tired easily. So I increased the weight up to 5lb each
plate, this time it works like a charm, not only I do not feel any
additional torque needed to spin the alternator and charging the
battery while paddling the bike I can actually take a break for few
seconds like riding a real bike on the street and watch the alternator get
spinned by the centrifugal force built up by the continuous momentum from
the heavy balanced mass on the flywheel, wow, this is fun! This makes a long
ride on the bike possible.
My rough calculation shows that I need to do this at least an hour a day at home
to drastically reduce or even out my electrical bill using grid-tie
inverters. See picture below where I stacked two grid-tie inverter together in
an attempt to apin my electric meter backward.
When the late night TV Nordic Trac commercial comes up, I always imagine how the manufacturer can make the
machine better by installing a mini alternator within the rotor. Whether it's a grid-tie alternator that pushes back
electricity into your A/C line or a stand alone generator that powers up your remote log cabin, any version of it
could greatly improve the marketability of these exercise machines.
If a home exercise-generator sounds like something you want to build at home, read my detail
connection and operation guide to build one yourself.[read more..coming soon]
Solar Panel ,Wind Generator and other Alternatives
Jul 24, 2010 Anthony T.
I recently made a trip to Shanghai, China. On my way to the hotel
from the PuDong Airport, I noticed that every building has solar
heater(non-photovoltaic) on top. That is an impressive achievement for a
developing country like China. For heating water, solar power is
sufficient and economical. But for powering your house, without a government
rebate or tax credit, it takes five years at least to break even.
If you have enough capital, give my friend Craig a call, he is more
than happy to give you a quote(email him at
craig.stager@spgsolar.com )
Buying a solar system is a long term investment to part of
your house, be able to convert one time payment to monthly paments would
be more reasonable not to put a big dent in finances in the short term .
Loans are available out there for solar power system. You can download the pdf
from the National Renewal Energy Laboratory website at
www.nrel.gov - see Borrower's Guide
to Finanacing Solar Energy System [pdf].
If you are a home/building owner, you should get a professional
opinion if you want to build/remodel home or building green, go to
www.greenwren.com and get current contacts from site. My
ex-coworker Jane Jerome ,who founded Green Wren, can give you a
deeper analysis on low carbon emission footprint for your building needs.
If you have budget issue then you might want to try these
alternatives:
-
Wind Power
-
Fuel Cell Technology
The problem with wind power is that the wind just doesn't blow constantly
unless you live in a high wind area. We live close enough to the California
coast, so the wind speed is moderately sufficient when it blows to
generate electricy for couple of small light bulbs. Most of the PMA for
windmill are designed to start charging at low rpm. The more current you need
the more expensive hardware you need to invest in, you need a
generator with more powerful magnets. Permanent Magnets are expensive! In fact,
if you run a simple cost analysis on large scale windmills, most of
them may not be able to recover its
construction/maintenance cost from the generated electricity in the
entire lifetime of the windmill(if not counting government
funding/rebates/credits - running in a low wind area). So if you ask me, I only
think the types of windmill that fits in your back yard and your
roof makes sense, anything with the size of an electrical pole needs some
engineering economics cost analyses to convince me its true value.
What I would like to build next
Jul 20, 2010 Anthony T.
It would make total sense if there is a combo version of stirling engine and
wind generator working together to push the generator. Currently in the desert
of Arizona, I heard they are running some of stirling mirror to heat up the
engine that generates electricity. I like the concept but would like to add a
wind mill on top of it to keep it spining into the night after sunset. it's
still on my drawing board now. As soon as I finish the prototype you can view
the set up on my site.