Introduction
Wind has been used for over 1,000 years to provide mechanical power. Not until recently though has the use of wind been engineered for everyday life. Whatever the desired function, there is a windmill that fits one’s need. Ranging from small household use to industrial use, there is a windmill that will get the job done. Not only can a windmill add to the scenery, it produces clean, environmentally safe electricity that is made from a reusable and free source without causing global warming. A single windmill can reduce an electric bill by more than 75%, eliminate to the ever-rising cost of electricity, and reduce dependence on foreign oil.
Which Windmill will Work Best for Me?
When determining what windmill is correct to use, there are a few things that must be consider. The biggest factor in determining the correct windmill is the average wind speed for the specific area. Average wind speed for an area can be found online, from local air field records or personally recording data over a period of time. Unless the airflow may be blocked by the local surroundings or buildings, public records are the best source of data. They offer free, reliable information that can help reduce initial costs. Wind speed will determine the overall results of the windmill. Another factor in determining a windmill is the amount of energy needed to be produced. Windmills are rated by kilowatt output and come in a vast variety of choices.
After the right size windmill has been selected, the next step is determining the height of the post and whether or not it should be connected to the local utility grid. In order to connect the windmill power source to the local grid, obtain permission from the local electric company. On a windy day when less electric is being used, the excess power will result in your meter “spinning backwards.” This means the extra power can be saved for later use or be sold to the electric company. Again, check with the local supplier to determine buy-back costs and availability.
Grid Tie-In vs. Off-Grid Windmills
Grid Connect System without Battery Back-up, also known as a Grid-Tie
With this type of system, the windmill power supply is connected to the electrical box that has already been provided to the house. The power supplied by the windmill works in correlation with the existing utility grid. This windmill system converts the alternating current produced from the windmill into direct current that can safely be used in the home or to supply the power grid. Because the frequency of the current is now independent of the wind speed and/or windmill rotation speed, it can be used in parallel with the power grid. Therefore, when there is not enough wind power, the consumer will be using utility power, and when there is enough wind, the consumer uses the windmill power supply.
Advantages: This windmill system can be use in parallel with the utility grid and always produces a safe frequency level. In the event of no wind speed, the consumer uses power supplied by the utility grid. There is nothing noticeable when switching between the two. In some states, any power that is supplied back through the meter must be compensated for by the utility company. Since there is no battery, there is less maintenance work.
Disadvantages: In the event that the utility grid shuts down, there is no power supplied from the windmill. Therefore, both systems are non-operable and there is still no power supplied to the house. In order for the windmill to still produce usable energy, a battery system needs to be installed.
Grid Connect System with Battery Back-up
This system is very similar to the grid connect system without battery back-up as described above, but with one main difference ¬ it uses a batteries for back-up. The batteries that are used for back-up can be installed in two ways: 1.) they can be charged from the utility grid and 2.) they can be charged from the energy produced by the windmill. In either case, the purpose of the batteries is to keep the windmill operational, even during a utility power outage.
Advantages: This system is running and producing power at all times. It is producing under normal conditions and when the utility grid is down. Also, as in the first type, this system has the ability to use its own power and power from the utility grid all in synchronization with one another.
Disadvantages: As with every “best” operating system, there are a few downsides to this type of windmill. Although the options to run off battery power exist, this is another added expense when calculating the initial set-up fee. Also, the cost and time involved with maintaining these batteries is much higher than the system without battery back-up.
Battery Charging, Off-Grid System
This type of system is primarily used when the consumer is too far from the utility power grid. The battery charging system is designed to store the power it produces in a batter. The battery must be specially sized to ensure accurate storage supplies. This type of windmill system is normally used in remote areas. The system is not connected to any type of utility grid and relies solely on its wind supply to power the home.
Advantages: There is no dependence to the utility companies to supply you with power. For very rural areas, the ability to have power now exists. The farm or home has no concern with power shortages and outages from the utility grid.
Disadvantages: There are two main disadvantages with a battery charging system. The first is there is not always enough energy stored in the battery to give all the power that may be needed. Once the battery runs out, the homeowner cannot rely on the utility grid to provide power. The second disadvantage is the amount of maintenance involved with keeping the battery in good condition and all levels inside the battery accurate. The costs of a new battery can become very expensive if correct care is not given.
Cost
One of the big questions that come to mind is of course the cost. The average home uses approximately 830 KWh per month. This amount can differ greatly depending on the size and lifestyle of the home in question. A southern home in which air conditioners are heavily used obviously uses more electricity then a northern home. In order to meet this demand a 5-10 kilowatt windmill system would be required.
Windmill systems cost on average $3000 -$5000 per kilowatt of electrical capacity. This equates to approximately $40,000 for a standard 10-kilowatt system. This is cheaper then your standard solar system, yet the payback period is still long. Depending on the location of the windmill, it can pay for itself in as little as 6 years, but could take as long as 30.
To promote the use of clean and renewable energy sources the government offers incentives. In order to find an incentive program in specific area, the Database of State Incentives for Renewables & Efficiency website is a great place to start.
Location
In order for the windmills to work effectively they need one thing, and that is wind. Standard residential size windmills have a cut-in speed of 7-10 miles per hour. Any wind under this speed cannot turn the blades and will not produce any electricity. In order to get a rough estimate of available wind speeds in your area, a quick search through the University of Utah’s site can be done as well as looking through local records often made available to the public. If the windmill site is located in a hilly or mountainous area, it may be wise to measure the wind speeds over a period of time to make sure it is sufficient and not sheltered in anyway.
Where to Buy
The American Wind Energy Association has compiled a great list of U.S. manufactures of windmills and wind turbine units.
References
http://www.abundantre.com/index.htm
http://www.builditsolar.com/Projects/Wind/wind.htm
http://www.awea.org/
http://www.dsireusa.org/
http://www.met.utah.edu/jhorel/html/wx/climate/windavg.html
