Energy resources tidal power

The choice of a renewable energy source to power a hydrogen fuel cell system will depend on the geography, climate and other resources of the location. I have chosen photovoltaics as the example power source for hydrogen production because it is available to more people than either geothermal, wind, or tidal. For a person without much technical skill, solar power is easier to implement than wind power. It is also less costly up front and not as dependent on location as the other RE power sources... 

Every continent on the planet is surrounded by a cleaner, safer, more efficient energy resource. As conventional energy supplies are depleted, means are being developed, and in some cases are in actual operation, to convert the energy found in waves, tidal currents, ocean and river currents, ocean thermal gradients, and offshore wind into usable electric power for utility-scale grids, independent power producers, and the public sector. 

In the next 20 years, hydrokinetic power drawn from the earth s oceans and rivers could account for more than 10% of the world s global electricity market (Wood, 2010). The renewable energy resources from ocean wave, tidal stream, ocean and river current and ocean thermal resources are expected to be the major growth area over the next decade (Marsh, 2009). 

A more benign approach is to extract energy from the tidal flows that occur between headlands and islands or in and out of estuaries. The power available in these tidal streams varies with the cube of the current velocity and while sea currents are typically around 3 m/sec, much lower than the minimum velocities required for wind turbines ( 7m/sec), the density of seawater is such that the output of tidal stream devices is much higher than equivalently sized wind generators. The energy flows are significant with aroimd 7.5 GW of accessible resource in Scotland alone. ... 

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