What is tidal power, why is it important and when will we see more of it?

Photo by Michael Olsen on Unsplash

A tidal power explainer

Tidal power takes advantage of the regular movement of tides in areas where either the current is strong or the tidal range (the difference between high and low tides) is significant. Take a look at this map to see all the global tidal hotspots:

Global tidal ranges ©2015 NASA | Source: Researchgate

Tidal technologies

Whether you’re looking to take advantage of the tidal range or tidal currents, there’s a technology already in operation or being developed as a pilot project. Here’s a quick overview of the most common forms.

Tidal barrages

Proposed Derby Tidal Energy Project, Australia | Source: ABC News

Tidal lagoons

Projects like the Swansea Bay lagoon are being developed to overcome the environmental impact of barrages.

Swansea Bay tidal lagoon plan | Source: reNews

Tidal stream generators

In places where water is squeezed between two landmasses and the seafloor conditions are right, the force of water can be harnessed by freestanding bidirectional turbines sitting on the seabed in the direction of the current flow.

The world’s largest single-rotor tidal turbine, SAE’s AR2000 | Source: Power Technology

Floating barrages

The final technology I’ll mention in this post is the most adaptable, designed to emulate an outboard motor boat’s rotor blades and could be deployed in a huge range of waterways.

Turbines like outboard motors | Source: CTV News

Why is tidal power so important?

Apart from developing some awesome turbine technology, what’s so great about tidal power? Don’t we have enough renewables already with wind and solar?

As predictable as the tides

Firstly, it’s the regularity of tides that makes this form of renewable energy so attractive. Tides move in an extremely predictable pattern, unaffected by what’s going on above the water. Whereas wind and solar power generation are intermittent, underwater turbines can make use of the 4 tidal differentials a day to provide a constant pattern of power to the grid. This presents a real opportunity to replace baseload power currently provided by fossil fuels.

As old as time

Longevity is the next factor in tidal power’s favour. Solar panels and wind turbines have an expected lifespan of 25 years; gas-powered turbines wear out at around 30 years; the average nuclear plant lasts for 40 years and coal-fired units top this list at an average of 45 years.

Cheap at twice the price

Finally, the levelized cost of energy (LCOE) for tidal power plants, compared to their fossil-fuel counterparts, is really low: $40/MWh compared to $124/MWh for US combustion turbines. So while the upfront cost of these projects is high, the payback period is so long it more than makes up for this.

Tidal power is awesome. Why aren’t we using more of it?

So, let me get this straight. We have a cheap form of predictable energy that can replace fossil-fueled baseload power generation and last over a century.

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Amy Streator Wilson

Interested in everything and everyone… yet hiking, travel, mountains, space, sustainability and the power of compromise really float my boat