GoingGreenFAQ.com

Residential Wind Power Basics

Throughout history human civilizations have been harnessing the energy of the wind. It was a major advancement that opened us up to sea travel, exploration, and international trade. It was also a handy tool on farms in the creation of windmills. Wind power has been taken to the next level in the modern age and is now being used for electrical generation.

Wind power systems work well in locations with wind speeds in excess of 7 mph. This wind should be available on a frequent basis. Wind turbines are somewhat of a specialty, however, since they can be used only in locations with constant patterns of winds. These patterns are often related to mountain Chinooks, coastal climates, and locations in the Great Plains under the influences of the jet stream.

Wind turbines are coupled to electrical generators, where either AC or DC could be used. If the wind power will be stored in a battery bank, then it makes sense to go with a DC generator right away. Wind turbines can be tied to the electrical grid, which in many cases means a heavy duty DC to AC inverter installation.

Most wind turbines on the market rotate about their horizontal axis. They take on the wind power and spin much like the propeller of a plane. A wide variety of sizes can be purchased between the ranges of a kilowatt and a megawatt, and for a multitude of applications. These designs should have a mechanism to make sure they are always oriented correctly with the wind.

A much less common wind turbine design exists that rotates on its vertical axis. They are designed to be compact and easy to install, as on the roof of a shop, barn, or house. The blades are encased in a housing, with an opening for the wind to come through. The wind, then, pushes on the blades much like a water wheel. Historically the performance from these designs has not been that good. We are working on some new designs for improved performance, but presently the availability of vertical axis wind turbines is very limited.

Mathematically speaking, the amount of wind power we generate is proportional to the wind velocity cubed. And so once can imagine the difference between a 15 mph and 7 mph wind source can be huge. When installing our wind turbine systems, we should try and keep them at the highest elevation that is possible. This reduces the effects of trees, structures, and other land based obstructions on wind velocity.

This cubic relationship between wind power and wind speed is nice, but there is such a thing as too much wind. When we get into heavier gusts and storm like conditions, then the aerodynamic stresses can become too great. Therefore, we must protect our systems from overload and overspeed in some way. This could mean decommissioning the units when we’ve exceed our load regulating capabilities, and orienting them to the least stress position.

By now, most of us know whether we have a good supply of wind. Some field measurements or a quick check at the local weather station can tell us our average speeds. If you like the idea of energy independence, and have ample supply of wind, then a wind power system is absolutely right for you.

Wind, historically, is one of our oldest sources of energy. If you have this valuable resource, then a wind power system is well within your capability. The benefits of energy independence are many. You will have to size your wind turbine and put some thought into the installation. But once in place, just kick back and let the energy pile up in your battery banks, and best of all its clean and its free.

Walter Hull is a mechanical engineer with expertise in natural power production. Walter continues to develop off grid power generation systems that use wind power and solar power.