In this guide:
What's the history of tidal power?
How does tidal power work?
What are the advantages of tidal power?
What are the disadvantages of tidal power?
How widely is tidal power used in the UK?
What is the future of tidal power?
You might be vaguely aware that one of the sources of renewable energy is tidal power. While it’s not as widely used as the likes of solar power, it could play a significant role in the battle against climate change as renewable energy becomes more widely used throughout the UK and the world as a whole.
The UK is in a favourable position as far as tidal power is concerned due to it being an island, and therefore able to take advantage of the tides at any point around the country. What’s the current status of tidal power in a domestic sense, and where will it go in the future?
Ancient and medieval civilisations first had the idea of using water power to operate grain mills, and the concept of using the same systems to generate electricity dates from the 19th century when electricity was first becoming widely used. Tidal power as we know it, though, was first developed in the 1960s with the construction of the Rance Tidal Power Station in the Brittany region of France. It’s still not as prevalent as it probably could be, though there are now tidal power stations across the world in locations including South Korea, Scotland, Canada, China and Northern Ireland.
There are three main methods of harnessing tidal power to create electricity.
Tidal streams are fast-moving streams of water which, due to their power, are very effective and efficient when it comes to generating electricity. Turbines are placed on the floor of the ocean to capture the power of the tidal stream. However, it’s not a simple operation because the size of the turbines can actually disrupt the flow of the stream, which is the entire point. Additionally, it can be harmful to marine life which could be caught in the turbine.
A tidal barrage plant (which is the style of the Brittany power station) is essentially a low dam that allows tidal water to flow in and out of turbines. Gates allow a tidal lagoon to be created at high tide, and it’s this water that is used to drive the turbines and create the electricity. Again, however, there can be a significant environmental impact on the surrounding area - the constant change in water levels disrupts the marine life; the saltiness of the water lowers and affects the animals and organisms that can live there; and there’s also a knock-on effect for birds and other animals that need the marine life in the area for food. Additionally, the barrage system costs much more than the other tidal power systems available.
A tidal lagoon works in a similar way to a barrage, but is much less harmful to the surrounding environment. Tidal lagoons are man-made, so they can be constructed from natural materials like rocks in a way that doesn’t affect the ecosystem. However, their energy output is lower than that of a barrage.
There are several advantages to tidal power that make it an attractive renewable energy option.
Predictability - the tides are consistent and unlikely to ever change because they’re affected by gravitational forces, unlike solar or wind power, which fluctuate depending on hours of daylight or wind strength.
Efficiency - because water is denser than air, it doesn’t take much of it to push the turbines around (as opposed to wind turbines), so tidal power plants can generate a lot of electricity even when the water isn’t moving particularly fast.
Durability - the plants and equipment needed to generate the electricity are designed to last for around 100 years, which is much longer than wind and solar farms are expected to work for.
The disadvantages of tidal power are as follows:
Environmental issues - as we’ve already noted, the impact of tidal power stream and barrage systems have a detrimental effect on the environment and ecosystem of the areas they’re constructed in, with no easy way of lessening that impact.
Construction costs - although the systems are designed to last for a century, the initial construction and installation costs are prohibitively expensive.
Limited time to generate electricity - the tides are only in a position to move the turbines for around ten hours a day, meaning that there’s a limit to the amount of electricity that can be generated each day.
Maintenance - saltwater corrodes metal over time, so regular maintenance would be required.
There are (as of February 2021) only two operational tidal power stations operating within the UK: MeyGen, on the Pentland Firth in Scotland, is operational but not fully completed, while Bluemull Sound in the Shetland Isles is also operational.
There are several proposed tidal power stations (including three in Wales) on the UK’s list of projects, but none are under construction at the time of writing.
A 2013 government report stated that the UK has the potential to generate 20% of its electricity via tidal power, but as of 2013, it was only able to generate 12% based on the facilities available.
Renewable energy proponents believe that tidal-generated energy has a much bigger part to play than it has done so far. It may be the case that further technological developments have to be made in order to make the construction part of each project more attractive than it currently is. Other countries are pressing ahead with tidal power plants and, given the UK’s ideal position in terms of access to coastline, it doesn’t seem like an option we should be discounting.
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