Introduction to wind power in new brunswick:
As the sun warms land and water, differences in their capacity to absorb and reflect the heat create air pressure differences above the different land forms. Air moves from over oceans to land (or vice versa) in response to pressure differences. We experience this movement of air as wind. The energy of moving air – wind - is harnessed using wind turbines that work something like airplane wings mounted to a rotating central hub. Air moves across the wings and causes rotation of the hub (See Figure 1.)
Figure 1. Horizontal mounted wind turbine. IPCC SRREN.
A rotating hub spins a shaft in the electric generator unit which moves coils of wire around a magnet; this movement within a magnetic field creates an electric current and the flow of electricity.
Turbines, on average, are 50-100m tall and require wind speeds of 16km/h or greater to be economically competitive. On average, a single turbine can produce about 1-5 MW (mega Watt), but large numbers are placed to form a complete wind energy facility. The facility can range in size to fit the available wind speeds, geography, and electrical demand.
- Upfront Costs – Wind facilities traditionally have high upfront costs and low operation/fuel costs (the fuel is free!). Prices of $2.5 million/MW of installed capacity are common.
- Fuel Costs – Free!
- Flexibility – Because wind speeds cannot be controlled, the amount of electricity generated from a wind facility can’t be increased or decreased as needed. When the wind blows, there is power, when it isn’t, production decreases. This is called intermittency. The typical electricity output of a single turbine is shown in Figure 2 below (in blue) as a fraction of its full rated output. The output of a group of wind plants in Germany at various locations is shown in yellow, while the output of the entire wind energy system across Germany is shown in orange. This image shows that as wind facilities are separated by geography, there can be less variability (a smoother, flatter line) in their output because the weather conditions affecting one location aren’t necessarily having an effect farther away.
Figure 2. Wind energy output of a single turbine, group of wind farms, and total german wind system as a fraction of their full possible output. http://srren.ipcc-wg3.de/report/IPCC_SRREN_Full_Report.pdf
- Capacity Factor - On average, wind facilities achieve a capacity factor of 30%. This means that, throughout the year, a wind facility produces 30% of the electricity that it could if it all turbines were spinning at full capacity.
- Environmental Impact – There are no CO2 emissions related to the fuel for wind turbines, any emitted CO2 relates to manufacture, transport, construction, and maintenance. On average, over the entire life cycle of a wind generation facility, there are typically emissions of 13 grams of CO2 per kWh (kiloWatt hour) of energy generated. A small wind turbine, at your house for example, can produce about 1kW of power. If you were to use it to generate electricity at full strength for one hour, you would have generated 1 kWh of energy (in the form of electricity). Power is expressed in Watts (or kilo watts) while energy can be expressed in kWh. Other than emissions, wind turbines have an overall low environmental impact. They don’t kill many birds or bats (especially compared to house cats or buildings with shiny glass), they produce no other pollutants, and they don’t have to use water or air to cool down their components.