Conversion of tidal energy into electricity, USA

Using tidal energy to generate electricity

Author: Pacific Northwest National Laboratory

Verdant Power's mission is to help build sustainable communities by producing clean power and water from this new renewable energy source. The Company's underwater turbines convert the kinetic energy from the water currents of oceans, tides, rivers, and canals into electrical and mechanical power. This clean power will be produced near where electricity and clean water are most needed - where people live. The mechanical energy can be used to pump water for irrigation purposes.

The electricity generation from tides is similar to the hydroelectric generation we looked at in the hydro energy tutorials. The difference this time is that the water flows in and out of the turbines in both directions instead of in just one forward direction.

Tidal energy, just like hydro energy, transforms water in motion into clean energy. The motion of the tidal water, driven by gravity, contains large amounts of kinetic energy in the form of strong tidal currents called tidal streams.

The daily ebbing and flowing, back and forth of the ocean tides along a coastline and into and out of small inlets, bays, or coastal basins, is little different from the water flowing down a river or stream.

The sea water's movement is harnessed similarly using waterwheels and turbines to that used to generate hydroelectricity. But because the sea water can flow in both directions in a tidal energy system, it can generate power when the water is flowing in and also when it is ebbing out.

Tidal energy is a clean, renewable, sustainable resource that is underutilized and represents a significant opportunity to meet growing global energy needs, both now and in the future. Water is hundreds of times denser than air, which makes tidal energy more potent than wind. It is more efficient than wind or solar energy due to its relative density. It produces no greenhouse gases or other waste, making it an attractive renewable energy source to pursue.

Also beneficial is the relative predictability and reliability of continuous tides, especially compared to other renewable energy sources like wind and solar, which are affected by the variability and uncertainty of atmospheric forcing. Low and high tide cycles are easy to predict and rarely experience unexpected changes.

To realize the benefits of tidal energy on a commercial scale, it will be necessary for researchers to identify new technologies and methods that significantly lower installation and maintenance costs, reduce environmental effects, and increase the suitability of more locations. A few tidal projects are in operation; however, the industry is growing slowly due to barriers to entry and a lack of supply chain.

Source: https://www.pnnl.gov/explainer-articles/tidal-energy