Wind Energy: With Your Help, It Could Save Our Planet
By Mary Jones
With millions of gallons of oil spewing into our Gulf coast, polluting our seashores and choking our coastal wetlands, there is no better time than now to consider–and act on–alternative fuel sources.
Harnessing the wind can go a long way to moving us off our dependency of oil.
But what does that mean, exactly? And can wind energy be done efficiently?
Yes, it can: if realistic goals are set, and true incentives put behind commerce and and communities getting behind this most natural, and most plentiful, of all resources.
HOW THE EARTH MAKES WIND
Wind is a result from the uneven heating of the Earth by the sun and the fact that temperatures are always trying to reach an equilibrium (heat is obviously moving to a cooler area). With the rising price of energy and the damage to the environment from fossil fuels, it is starting to be equitable to harvest this renewable resource.
The benefits of wind energy are that it is virtually free (once you buy the equipment) and there’s no pollution. The disadvantages include the fact it isn’t a consistent source (the speed varies and many times it is insufficient to produce electricity) and it typically requires about one acre of land.
How Wind Energy Works
The volume of power that is available varies by wind speed. The amount available is named it’s power density and it’s measured in watts per square meter. For that reason, the U.S. Department of Energy has separated wind energy into classes from 1 to 7. The standard wind speed for class 1 is 9.8 mph or less while the average for a class 7 is 21.1 or even more. For effective power production, class 2 winds (11.5 mph average speed) are often required.
Normally, wind speeds increase as you get higher above the Earth. Because of this, the typical wind mill is installed on a tower no less than 30 feet above obstructions. That there are two basic different kinds of towers used for residential wind power systems (free standing and guyed). Free standing towers are self supporting and are usually heavier meaning they take special equipment (cranes) to place them. Guyed towers are supported on a concrete base and anchored by wires for support. They typically are not as heavy and most manufacturer’s produce tilt down models which may be easily raised and lowered for maintenance.
The kinetic (moving energy) from the winds is harnessed by a device termed as turbine. This turbine consists of airfoils (blades) that capture the power of the wind and use it to turn the shaft of an alternator (like you have on a car only bigger).
There are two basic kinds of blades (drag style and lifting style). We all have seen pictures of old windmills with the large flat blades which are an example of the drag style of airfoil. Lifting style blades are twisted rather than flat and resemble the propellor of a small airplane.
A turbine is classified as to whether it is designed to be installed with the rotor in a vertical or horizontal position and whether the wind strikes the blades or the tower first. A vertical turbine typically requires less land for it’s installation and is a much better option for the more urban areas worldwide. An upwind turbine is created for the wind to impact the airfoils before it does the tower.
These units ordinarily have a tail on the turbine which is needed to maintain the unit pointed into the wind. A downwind turbine does not require a tail as the wind acting on the blades tends to keep it oriented properly.
These turbine systems would be damaged if they were to be allowed to turn at excessive speeds. Therefore, units must have automatic over-speed governing systems. Some systems use electrical braking systems although some use mechanical type brakes.
The output electricity from the alternator is sent to a controller which conditions it for use in the home. Using residential wind power systems requires the home to either remain tied to the utility grid or store electricity in a battery for use when the wind does not blow sufficiently.
When the home is linked with the grid, the surplus electricity that is made by the residential wind power system can be sold to the utility company to lower or even eliminate your utility bill. During times with not enough wind, the home is supplied power from the utility company.
The Price of Wind Energy
Small residential wind power turbines can be an attractive alternative, or addition, to those facility. Unlike PV’s, which stay at basically a similar cost per watt independent of array size, wind turbines get more affordable with increasing system size. At the 50 watt size level, for example, a small residential power wind generator would cost about $8.00/watt compared to approximately $6.00/watt for a PV module.
That’s why, all things being equal, Photo voltaic is cheaper for very small loads. As the system size gets larger, however, this “rule-of-thumb” reverses itself.
At 300 watts the turbine costs are down to $2.50/watt, while the PV costs are still at $6.00/watt. For a 1,500 watt wind system, the cost is down to $2.00/watt; and at 10,000 watts, the cost of a wind generator (excluding electronics) is down to $1.50/watt.
Now, that’s one way to save our planet — and our bank accounts.
Mary Jones writes about residential wind generators at her website ResidentialWindTurbines.com. Her personal hobby blog focuses entirely on suggestions to reduce CO2 and lower energy costs using alternative power sources.
HOW YOU CAN HELP:
Educate yourself, and others. Start by reading these papers:
American Clean Energy Security Act (ACES): An analysis by the Pew Climate Center.
Green Recovery: This report, from the Center for American Progress and the Political Economy Research Institute, suggests ways in which we can create 2 million good jobs through a green recovery.
Renewing America: This report, from Environment America, details how we can jump-start our economy through investments in clean energy.
There are more Environment America green recovery reports here.