The Big Blue, the Pond, Davy Jone’s locker- whatever you call it, the ocean covers 30% of our planet’s surface. Given it’s incredible mass, the potential for sustainable energy generation through ocean power is great. Here’s what you need to know about one of the most interesting forms of hydropower.

 

What is Ocean Energy?
  • As the name suggests, ocean energy comprises all forms of renewable energy derived from the sea, including wave energy, ocean thermal energy conversion (OTEC) and most commonly, tidal energy. As the name suggests, ocean energy is the generation of energy captured from ocean’s currents based off of tidal patterns.
  • While one of the more uncommon sources today, tidal power is the oldest form of renewable energy. Evidence dates back to 900 A.D., when the ancient Romans occupied England and created water-powered mills to grind grain into flour.
  • However, tidal power has only been generated on a large scale in the last 50 years. The first modern tidal energy plant was constructed in 1966 in the area of La Rance, France in 1966, and has 240 MW installed capacity. Today, modern tidal power stations exist mainly in the United Kingdom, France, Russia, China and Canada.
How It’s Made
  • Tidal energy is essentially the harnessing of energy from the shifting ocean tides. Tidal energy generators are a common source, and are powered by large underwater turbines placed in areas with high tidal movements that capture the kinetic motion the surging ocean tides. As the tide goes in and out, the water flows through and turns different mechanisms, varying from tidal tunnels, fences or turbines, that capture power and generate electricity.
  • Tidal barrages, or dam-like structures placed over inlets where the tides are most powerful, block the water’s egress to the ocean. These are the most common mechanisms used to harness tidal energy.
Why the Tides?
  • Tides are more predictable than wind, energy and solar power and has minimal environmental effect.
  • Tidal enegery is a consistent, since tides occur 2x a day in the same pattern. Tidal power can be captured for a maximum of 10 hour cycles per day.
  • The La Rance tidal power barrage has been functioning without missing a single tide for more than 37 years.
  • Tidal power has the potential for major growth as a renewable energy source, with the possibility to generate up to 100 GW globally.
  • The largest facility is the Sihwa Lake Tidal Power Station in South Korea, with an output capacity of 254MW
  • The potential energy exploitation of tidal power is at 80% efficiency, which is comparatively high to other forms of renewable green energy sources.
While tidal energy is completely renewable, the hefty investment required to build a plant is a major prohibitive factor of expanding tidal power. According to Renewable Green Energy Power, the cost of building a tidal powered electricity station varies from 1.3million USD per MW to 1.8million USD per MW, depending on the location and technology used. However, Alstom Power, a GE acquisition, has developed low-cost and efficient tidal power technologies that tap into this consistent energy source.