Reply #31: While waves conitnue to break waves the energy output won't continually be 100% peak power.

[Statistical]

There is variability to waves, just like there is variability to wind. Most windfarms are built in areas where wind blows the overwhelming majority of the time but despite that capacity factor in the 20%-30% range is common. Even wind is blowing it won't produce 100% peak power each time. Even if they did time for maintenance, and repairs reduces capacity factor.

Granted it is only a single data point but this wave farm achieves a 20% capacity factor (150KW average annual output over 750KW peak power)

http://en.wikipedia.org/wiki/Agu%C3%A7adoura_Wave_Park

---------------------
Developed by the Scottish company Pelamis Wave Power, the Pelamis machine is made up of connected sections which flex and bend relative to one another as waves run along the structure. This motion is resisted by hydraulic rams which pump high pressure oil through hydraulic motors which in turn drive electrical generators. The three machines which made up the Aguçadoura Wave Park were each rated at a peak output of 750kW, giving an installed peak capacity of 2.25MW, enough to meet the average electricity demand of more than 1,500 Portuguese homes.<5> The average output from a Pelamis machine will depend on the wave resource in a particular area. The higher the resource the higher the average output. According to information on the Pelamis web site it appears that the average power output for a Pelamis wave machine is about 150kW. <6>
--------------------

For the sake of argument lets assume this system has 50% higher capacity factor - 0.30
150kW peak * 0.30 capacity factor * 24 hours * 365 = 394 MWh of annual production.

Total US electrical demand is roughly 4,400 TWh. Thats 4,400,000 GWh or 4,400,000,000 MWh
4,400,000,000 MWh / 394 MWh per unit = ~ 11.2 million units.

To supply 20% of electical demand would be 11.2 * 0.2 = 2,240,000 units.