Wind Power and Hydropower

		Total generating capacity of a facility (e.g., a wind farm or hydropower plant). Expressed in watts (W).		Kilo, mega, tera? Power vs energy
	A hydropower plant with 4 generating units of 50 MW each has an installed capacity of 200 MW.   A wind farm with 100 wind turbines of 2 MW each has an installed capacity of 200 MW.
		This doesn’t mean that the wind farm or the hydropower plant always generates 200 MW. What it does mean is that if all the wind turbines or all the generating units were working to capacity at a given moment, the facility’s output would be 200 MW.		Some interesting figures

		The capacity that can be made available with a predetermined level of reliability. It’s very important for an electric utility to be able to count on firm capacity, because electricity must be produced just when the customer needs it.
	The capacity of a hydropower plant can easily be guaranteed, because the quantity of water sent through the turbines can be controlled at all times. A hydropower plant with an installed capacity of 200 MW has a firm capacity of nearly 200 MW, since generating units seldom break down.   With a wind farm, there is no guarantee that the wind will blow when energy is needed. That is why Hydro-Québec has planned for reserves of 35 MW of hydropower for every 100MW of wind power.

		This is the power generated by a facility (e.g., a wind farm or hydropower plant) multiplied by the number of hours during which that power is delivered. For example, a hydropower plant or wind farm that generates 200 MW for one hour steady produces 200 MWh (megawatthours) or 200,000 kWh (kilowatthours) of energy.
		However, no generating facility can operate at maximum capacity all the time, since allowances have to be made for maintenance, equipment failure and energy source availability. To determine a facility’s real energy output, you need to consider its annual load factor, that is, the ratio between its actual energy output in a given year and the energy that would have been produced had the facility been operated continuously at maximum capacity throughout the year. This ratio is generally expressed as a percentage.		Some interesting figures
	A hydropower plant with an installed capacity of 200 MW and a load factor of 65% (average load factor for Hydro-Québec's generating fleet) has an annual energy output of 1,140,000 MWh or 1.14 terawatthours (TWh).   A wind farm with an installed capacity of 200 MW and a load factor of 30% (estimated average for all wind farms currently in operation) has an average annual energy output of 525,000 MWh or 0.525 terawatthours (TWh).