Using a Car Alternator for Your Wind Turbine

For today's wind turbine enthusiast, the core of the turbine is the alternator itself. This component is often the most difficult to construct, and therefore the easiest to decide to purchase. The problem comes when you want to actually utilize the power from your alternator.

Typically car alternators are made to run from about 800 RPM to 7000 RPM or more. Typical wind turbine installations don't reach high into the hundreds of RPM. To bridge this gap, you need to use a pulley or gear system to step the rpm up. But remember, as you go to a higher RPM, the torque you produce goes down. From engineering parlance:

power = torque (times) speed

The power generated at any given time is constant, and the torque si not easily modified, so all you can change is the speed. Using a reduction pulley or gear reduction system is the way to do this. There will be some losses in such a system however and you need to be aware of this. Ideally, you should think about building your own alternator rather than using one from a car. Remember, always use the right tool for the job.

Solar Energy Panels – Thermal or Electric?

Use of solar energy on a small scale is happening on two fronts: solar thermal and solar electric. Traditional solar panels are solar electric; they generate electricity from the sun. Solar thermal panels are used to heat water or air which is in turn used as hot water or to heat spaces. These systems take advantage of the average 1400 Watts per square meter of solar energy that the Earth receives.

The major advantage of using thermal solar energy panels to heat water is that there are fewer energy conversions in the system. Each conversion of energy from thermal to electric and back to thermal creates a loss. If a solar electric system were used to heat water for home use, losses can be very high. But utilizing the thermal energy from the sun to directly heat water means that there are fewer losses and higher efficiency. This means that less water needs to be heated by the solar energy panel.

For all other uses, solar electric energy panels are the most useful. The energy that they generate can be stored in a battery bank and used later when it is needed. This is especially useful because the amount of power that a solar panel can generate during the day is relatively constant, however at night there is no power generated. Storing this energy means that solar energy panels can be used to power your home even when the sun isn’t shining.

All solar energy panels are most efficient when they are pointed directly at the sun. Most panels are fixed to a roof or other portion of the structure which means that the sun strikes them at different angles throughout the day. When space permits, mounting the panels on a freestanding structure with a sun tracker is the most efficient; however even this doesn’t guarantee that the panels will provide full rated power all day. The amount of energy that reaches the surface of the Earth from the Sun is greatly affected by the amount of atmosphere between the sun and the point on the surface.

When the Sun is low in the sky, there is significantly more atmosphere between the Sun and your solar energy panel. This means that the amount of energy generated will be lower than full rated power all day. This doesn’t mean that they aren’t useful, but it must be taken into account when planning any renewable energy system. Since most renewable energy systems utilizing solar energy panels will have some degree of intermittent power generation, a method to store this energy is required.

Solar electric panels will have their energy stored in a battery bank, and solar thermal panels will most likely still require a hot water holding tank of some sort. An electric or gas element may still be required to maintain temperature in the tank, but this will require much less energy than heating up cool water. This is the major benefit found when using solar thermal panels; reduction in electricity use is a major concern in any renewable energy system.

DIY Solar and Wind Resources

There are many DIY Solar and Wind resources online. If you start with our FREE Report on renewable energy use at home, you'll have a great idea about how to get started.

From there, you may want to check out Earth4Energy or Home Made Energy. Both of these eBooks have valuable information on how to build your own solar electric panels and wind turbines for LESS than $200.

If you are interested in more types of renewable energy tech, the FREE report you'll find at Home Energy Focus is probably the place to start.

Product Review - The Renewable Energy Handbook

Over at Amazon, they've got a wealth of information on building your own solar and wind power systems. One such book is The Renewable Energy Handbook: A Guide to Rural Energy Independence, Off-Grid and Sustainable Living. Here is their description:

As oil prices continue to rise, many people are starting to think about how to unhook from the electricity grid. The Renewable Energy Handbook focuses completely on off-grid, sustainable living and rural energy independence.

Author/engineer William H. Kemp, who is a leading expert in small- and mid-scale renewable energy technologies, designed and built his own off-grid home. The result is a house that has all the standard “middle-class” creature comforts while using less than five times the total fossil-fuel energy of the average North American house.

The Renewable Energy Handbook focuses on the unique requirements of off-grid living and contains chapters on energy conservation; heating and cooling; backup power; domestic water heating; wireless communications; photovoltaic, wind, and microhydro energy generation; battery selection; and inverters.

Since its release in 2003, The Renewable Energy Handbook has been a top-selling technology book and is recognized as the best book in its field.

The book is augmented with hundreds of illustrations, line drawings, photographs, and appendices.

This book is a must-have for anyone serious about powering their home from renewable energy. Most of all, if you intend to convert to off-grid or semi-autonomous power systems this book is for you!

More on Storage

Alright, so you've got a solar panel or wind turbine built, now what do you do with all of this power you're generating? You can't always use it right away, and sometimes you're generating it in the middle of the night when you're not using much power at all.

Most solar systems use a battery bank to store energy over short periods of time, until it can be used. For many home renewable energy systems, this is probably the best option. The storage system in this case consists of three different parts:

1. The Charge Controller

Because your renewable energy source doesn't always provide the same amount of power to the batteries, connecting it to them directly would be disastrous. For this reason, a charge controller is used to charge your batteries, and keep them at the right level.

When you choose your charge controller, be sure that it is the right one for your system. It needs to have the proper voltage and current ratings and also enough connections for your entire system. Some charge controllers can even be connected to the grid, so that you can sell your power back to the power company and reduce your bill even further! Be careful with this feature though, sometimes these controllers will also charge your batteries from the grid when the renewable source isn't creating any power, and that will cost you money.

2. Batteries

Batteries come in many shapes, sizes and ratings. Be sure that you choose the right batteries for your application. Although you may think that car batteries are the best, they are actually some of the worst batteries for a solar power system. If you choose to use a series of them, you will be sorely disappointed because you'll be replacing them after mere months.

Most "deep cycle" batteries are not suitable either, however many DIY alternative energy systems use batteries such as golf cart or marine batteries and they last a moderate amount of time. However typically, purpose-designed batteries are best.

Absorbent glass mat batteries are the batteries of choice for indoor battery banks. They are no-maintenance and do not require venting like flooded lead-acid batteries do. They carry the electrolyte in glass mat between the plates, it is absorbed into the spaces between the glass fibers and thus can't leak out.

3. Inverter

Since many people are looking at off-grid living these days, the inverter plays an important role in this venture. Inverters come in many shapes and sizes, however there are three main types:

Square Wave Inverters
Quasi-Sine Wave Inverters and
True Sine Wave Inverters

Typically, inverters used for camping that connect to a car's cigarette lighter are square wave inverters. They are the least expensive type, but do not produce "clean" AC. A square wave is fine for certain appliances, however many newer appliances and electronics utilize timers and motors which require AC which very closely approximates a sine wave.

Quasi-sine wave inverters are the most economical choice for DIY power systems. They produce AC power which is between a square wave and a true sine wave. They come at a moderate cost, but are suitable for most applications, including computers and televisions. For very advanced and expensive applications, only a true sine wave inverter will do.

True sine wave inverters produce very clean AC power and are the best apprixmation of a true sine wave. However this accuracy comes at a cost. They are by far the most expensive inverters.

Inverters can also connect to the grid, and more than likely if your system is grid-connected, this is where you want to do it. The power company doesn't like you selling them anything but 60Hz (or 50Hz in Europe) AC power.

If you'd like more information on these and other green energy topics visit Home Energy Focus for a series of guides to DIY green power.

Phantom Loads - Not as Scary as they Sound

Did you know that when you turn off most modern electronics, they're not actually off? That's right. That off button now is more likely a "standby" button. This puts the device into a power saving mode, but doesn't turn it off. The loads these leave on your

To see how much energy your electronics are using when they're off, the P3 International P4460 Kill A Watt EZ Electricity Usage Monitor is a great place to start. If you don't want to take the Kill-A-Watt Meter from place to place, the P3 International P4320 Kill-A-Watt Power Strip can monitor the usage of many devices, and is ideal for a computer room or entertainment center.

Speaking of entertainment centers, one of the tips I have for today is putting your TV and the rest of your entertainment center on a power bar. It can be a cheap one, as long as it has an off switch. After you've turned the TV off with the remote, turn the power bar off. Sure your VCR will blink 12:00 all the time, but you'll be surprised how quickly these loads can add up and take money off of your power bill.

Turning off lights in rooms you're not in is another great way to save power. Many people are under the misconception that it takes more power to turn on a light than it does to leave it on while you leave for 5 minutes. If you get in the habit of turning the lights off when you leave a room, you'll be able to save money on your power bill. And we all know how important saving money is in today's economy. If you have a desktop computer, turning the monitor off when you leave the room is another way to save power.

Even your computer can draw power when it is "off", things like the clock and other devices may stay on and continue drawing power long after the computer is turned off.

Stay tuned for more energy-saving tips. In the mean time, check out Home Energy Focus for more green energy eBooks.

DIY Wind Turbine - The Alternator

In the last article, I discussed blade design for your wind turbine. Today I'm going to switch gears a little bit and talk about the alternator. This is the heart of the turbine and is what actually generates the power. A permanent magnet alternator will generate AC power at varying voltages and currents based on the speed that the turbine is turning.

Design of electric machinery is a very detailed topic, however there are some basic rules to follow when designing your own wind turbine alternator. First, the simplest design involves a stator (non-rotating part) which includes copper coils, sandwiched between two rotors carrying permanent magnets. As the rotors spin, the changing magnetic field induces a current in the copper coils. This is how power is generated by the wind turbine.

Generally, 3-phase AC is generated and rectified to DC in a home made wind turbine. This means that you need a minimum of 3 coils. Although in theory 2 permanent magnets on each rotor could generate power, the minimum recommended number of magnets is 4 per rotor. This keeps each coil within a magnetic field at all times and therefore generating power.

The coils are connected in either a Delta or Wye configuration. Generally the Wye configuration is preferred due to the fact that all three phases are connected to a common neutral or ground. In larger turbines, the number of coils can grow to 12 or 15 and the number of magnets per rotor can jump to as high as 16.

Once the magnets and coils have been tested, common practice is to set each rotor and stator in resin to ensure that the parts don't move relative to one another during high winds or vibration. This is another way to ensure that the efficiency of your generator does not degrade over time.

For more information on this and other DIY renewable energy topics, you can check out Earth4Energy or Home Energy Focus.