Wind Energy 101

What is a wind turbine and how does it work?

A wind turbine is a type of wind energy system which transforms the kinetic energy of the wind into electrical energy that can be harnessed for practical use.

There are two basic designs of wind turbines: vertical-axis (or “egg beater” style) and horizontal-axis (propeller style) machines. Horizontal-axis turbines are most common today.

Turbine systems include:

• A rotor – or blades – which convert the wind’s energy into rotational energy
• A nacelle (enclosure) containing a drive train, a generator, and usually a gearbox
• A tower to support the rotor and drive train
• Electronic equipment such as controls, electric cables, ground support equipment, and interconnection equipment

Wind turbine towers are mostly tubular and made of steel; the blades are made of fiberglass-reinforced polyester or wood-epoxy.

Wind turbines vary in size. The chart below shows a variety of turbine sizes and the amount of electricity they are each capable of generating:

How much electricity can one wind turbine generate?

The ability to generate electricity is measured in watts. Watts are very small units, so the terms kilowatt (kW, 1,000 watts), megawatt (MW, 1 million watts), and gigawatt (GW, 1 billion watts) are usually used to describe the capacity of generating units like wind turbines or other power plants.

The output of a wind turbine depends on the turbine's size and the wind's speed through the rotor. Wind turbines being manufactured now have power ratings ranging from 250 watts to 3 megawatts (MW). The average capacity of utility-scale turbines installed in 2008 was 1.67 MW

What may seem like a small difference in wind speed can mean a large difference in available energy and in electricity produced, leading to a large difference in the cost of the electricity generated.

How does wind energy contribute to our electricity needs?
With generating capacity at over 25,000 MW, U.S. wind power already supplies enough electricity to serve the equivalent of nearly 7 million average households.  Although wind power provided over 1.25% of the nation’s electricity in 2008, it is capable of providing 20% of the country’s energy by 2030.
Wind energy contributes to our energy security.  It’s an inexhaustible, domestic resource, and it helps reduce our dependence on imports of natural gas, oil and other fuels that play a part in global warming.

What are America’s current sources of electricity?
Coal, the largest source of emissions of the greenhouse gas carbon dioxide, is currently used to generate more than half of all the electricity in the United States.  Other sources of electricity include natural gas, oil, nuclear, and hydropower.

Does wind power offer real environmental benefits?
YES!  Wind requires no mining, drilling, water or transportation of fuel, and does not generate radioactive or other hazardous or polluting waste.  Wind power offsets other, more polluting sources of energy and is proven to reduce greenhouse gas emissions.  This is important because electricity generation is the largest source of greenhouse gases in the U.S.  When wind power projects generate electricity, fuel at other power plants is not consumed.

How does wind power benefit the economy?
Wind power supplies affordable, inexhaustible energy to the economy.  The integration of more wind power to the grid guarantees the creation of hundreds of thousands of new, high-quality jobs.  Best of all, wind powers the economy without causing pollution, generating hazardous waste, or depleting natural resources.  Wind has no “hidden costs.”  Finally, wind energy depends on a free fuel source – the wind – so it is relatively immune to inflation.