Information taken from http://www.energyalternatives.ca/
I have always thought that Micro-Hydro Power (if you have a creek/small river running through your property) offered reasonable payback and is environmentally pretty clean (when you don't create physical dams across your water source!). The information below gives some background and technical information. Check out the www.energyalternatives.ca site for information on purchasing equipment.
If your site has a source of running water, you simply must investigate its potential as a source of electricity.
Since water flows day and night, a micro hydro system requires far less battery storage than other technologies. Even if the stream is far away, it may still be viable.
Seasonal streams offer great performance when a hybrid water and solar system is designed. When your power requirements are the highest, in the winter, the water is usually flowing the fastest. Solar modules are most efficient when there is the most sun in the summer.
Electricity is produced from the energy in water flowing from a high level to a lower level. This change in elevation is called head and supplies the pressure, which drives the turbine. Flow is the other factor contributing to power production. It is usually limited by the size of the creek.
The amount of electricity produced is directly related to the head and flow. If the head or flow is increased the power output increases proportionally. Many micro hydro systems can utilize the existing pipe used by a gravity fed water system. A couple of sprinklers on a two-inch pipe are the equivalent of many kilowatt-hours per month of micro hydro electricity. Site considerations Many factors work together to make a successful micro hydro site.
In order to have optimal performance your equipment must neither be too big nor too small. A turbine can be up to a couple of kilometers away from where the power is being used and still be cost effective. It is far cheaper to run wire lines than it is to extend the pipe length.
Properly sized transmission lines and high voltage generators can deliver significant amounts of power a long ways away with acceptable losses and in a cost effective fashion.
A large inverter will deliver remarkable service from a small battery based system and save a lot of plumbing and water handling. On the other hand merely going a little higher up the mountain or using larger pipes can produce enough extra power to provide space heating and eliminate batteries altogether by generating AC directly.
If your site permits, you can have a large AC turbine with all the functionality of a 120/240 VAC fossil-fuel generator running 24 hours per day, but without the noise, smell, pollution and ongoing fuel and maintenance costs. While more expensive than a battery charging system, continuous outputs of 3 kW or more will heat a home for much of the year, in addition to supplying town-lifestyle appliance and lighting loads.
There is a lot more at stake, financially and otherwise in higher-powered systems. Please contact us for a reference to an AC micro hydro design professional.
Hydro systems are very site specific. If you are calling us to get a quote for your potential system, please have the head and flow information (next section) ready.
If there is no pressure gauge or pipe available, survey the site the old fashioned way. A rod is a stick that is eight feet long with each foot marked. Hold it straight up in the air at the starting point. Every place that is level with the top of the ruler is also eight feet higher than the base. Using a level, sight along to a point that is level with the top of the rod. This is also eight feet above the starting point.
Next move the rod so that you can place the bottom on the piece of ground that you marked as even with the top before. Now, every place that is level with the top of the second setting of the staff is 16 feet higher than the starting point. Repeat as necessary. Heavy brush means setting up more often. Add up your totals to get the elevation in feet.
For high head sites, over 200 feet, a sensitive altimeter can be used. Record the elevation at the bottom. Move to the top, and record the altitude again. The difference in feet is your gross head. Repeat the process and average the results for better accuracy. Because altimeters measure the difference in atmospheric pressure, choose a day when the weather is not changing rapidly. Many modern GPS receivers also offer an altimeter. The reliability of this will depend on your GPS unit and the signal strength. Again, take several readings and average them for best accuracy.
A micro hydro system typically only uses a small portion of the streams flow and has a very minor impact to the overall stream. Diverting too much of the water from a stream will cause a negative environmental impact and should be avoided.
Usually the pipe is the limiting factor in determining what flow is available. Youíd be surprised how small a stream of water even 50 gallons per minute is.
How much is enough?
In a regular house with cheap electrical rates, a household might use 700 kW/h month for basic electrical service, not including heating and cooking which can come from other sources.
Basic energy conservation practices like using compact fluorescent bulbs and the elimination of phantom loads can easily cut this total in half to 350 kW/h per month. Custom appliances, such as energy efficient refrigeration can again reduce this load considerably. You must remember that it is more economical to reduce your power consumption in the first place.
Battery charging systems generally donít provide sufficient power for heating loads, other than intermittent use. It can, however provide a home with the dozens of kilowatt-hours per month it needs for lights and music, or the few hundred kilowatt hours per month necessary for refrigeration and freezing.
Sizing your system
You can determine how much power a system will produce quite accurately when you take all the different factors into account. Exact site measurements are absolutely essential. Simply guessing your head and flow will generally leave you with disappointing results. The samples sites below are intended to give you a very rough idea of the amount of electricity available from various sites. The following page provides some formulas so that you may further calculate your siteís potential. Again, this is only intended as a rough idea. Actual site calculations involve other variables that need to be taken into account.
Hydro turbines &
generators for AC only micro hydro
systems are more efficient, so the above
power equation needs to be modified:
From the Pipe Friction Table, friction losses for 2 inch PVC pipe at 48 USGM are 2.7 feet per hundred feet.
Power generated would
be approximately 219 watts. Over 24
hours just over 5 kWh of energy would be
Copyright 2001-2003 Peter Ferlow