Archive for the ‘Home Alternative Energy’ Category

Home Wind Power


2009
02.05

The main component of a home wind power system is the wind turbine. The main determining factor in power output is the diameter of the blades or roter on the turbine. The other parts of the system are the tower, wiring, batteries, charge control, and invertor. If you are using wind in conjunction with solar or hydro, then you can utilize the same battery bank and invertor (you will need a separate charge controler). While towers should be at least 30 feet high, higher is better. In fact, there’s 40% more wind at 100 feet elevation than there is at ground level.

Most home wind power systems use towers that are supported with guy wires. These are assembled at ground level and then tilted up into position. These types of towers can often be assembled with no more than two people.

When selecting a wind turbine, make sure you know the unit’s power curve. This refers to the optimum wind-speed range. For example, many systems produce optimum electric output in a range of 20-30 mph. If the average wind on your site is outside that range, then you’ll want to make sure you get a system designed accordingly. To determine average wind speed, you can do that manually, by setting up an anemometer and recording results for at least three months. You can also purchase a system to calculate the average for you.

Typcial cost for a wind generator system starts at about $3,200.00 if you’re willing to do the installation yourself.

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Pelton Turbine – Part II


2009
02.04

Today we’ll pick up our discussion of hydroelectric generator systems where we left off in our last post. Let’s discuss the power output to be expected from a water source. To determine that, we first need to know the flow rate and the head (difference in elevation over which the water will travel in a pipe to get to the turbine. The most efficient type of wheel – the pelton turbine – will require a minimum head of about 20 feet (at least 50 feet is better). You can still generate electricity with less head, but you’ll need to turn to a reaction or propellor type of turbine, and you will see less power output. To determine the head, simply measure the difference in elevation from the pipe intake to the location where the turbine will be mounted. The flow rate can be determined quite simply with the use of a bucket and a stop watch. Simply measure the amount of water delivered per minute.

Now to determine how much power the water source will produce, use this equation:

Net Head (in feet) X Flow (gallons per minute) / 10 = Power (Watts)

Keep in mind that “net” head means we have to account for friction loss in the pipe using a friction loos flow chart. The larger the pipe, the less friction loss.

So if we have 50 feet of net head and 100 gallons per minute, the expected power output woud be 500 watts, or 1/2 Kilowatt.

The cost for a domestic micro hydro system (including hydrogenerator, charge control, batteries, and inverter) can be anywhere from $4,000 – $6,500.00 depending on the type of components you select. This does not include pipe which would vary from site to site.

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Pelton Turbine


2009
02.03

While solar power offers tremendous advantages over non-sustainable energy, it’s hard to beat hydroelectric generator systems. If you have a good source of water and some difference in elevation, then hydro electric may be right for you. With a year around water source, one advantage of micro hydro power is that it is generated all the time – not just when the sun is out. Another plus for hydro is that it can be less expensive than setting up a solar system. There is a downside, however, and that is that micro hydro systems do have moving parts, which means periodic maintainance and/or breakdown.

We use the word “micro” to designate small, domestic power generator systems. Micro hydro turbines are readily available from alternative energy retailers. When it comes to water turbines, the Pelton Turbine is considered superior for it’s efficiency. A simple system involves delivering water downhill through a pipe to the the pelton turbine which is attached to an alternator that charges a battery bank. Systems can be extremely simple and yet very effective. For example, many simply use PVC pipe and a truck alternators attached to the turbine. You do need sufficient drop in elevation from the water source to the turbine, as well as ample flow of water.

Keep in mind that the pelton turbine is not necessarily the best in all circumstances. If the water source has plenty of volume but not as much drop in elevation, then a propellor or reaction type turbine will work better.

In our next post we’ll discuss the amount of drop that is needed for a typical domestic hydro electric generator system as well as sources for turbines and other equipment.

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