As the UK aims to reduce its fossil fuel reliance in line with the British Energy Security Strategy, tidal power could meet as much as 11% of the nation’s annual electricity demand. Yet, in 2022, tidal power made up just 1.8% of the UK’s energy mix. So, what is holding back the UK’s tidal power potential, and how can technology play its part in increasing energy generation?

As one of the 195 Paris Agreement signatory countries, the UK pledged in 2015 to limit the Earth’s temperature increase to 1.5 degrees Celsius above pre-industrial levels. Despite COP28 President Sultan Al Jaber recently claiming otherwise, a key way of remaining below this threshold is to focus on phasing out fossil fuels.

Fossil fuels such as oil and coal produce a significant proportion of greenhouse gases including CO₂, which has been directly linked to the Earth’s warming. This temperature increase is leading to the destruction of coral reefs, polar habitats and significant stretches of coastline.

Yet, despite continued calls for climate action, fossil-fuel CO₂ emissions continue to climb. According to data from the Global Carbon Project, global carbon emissions caused by fossil fuels reached record levels in 2023, with a predicted high of 40.9 gigatons released — a 1.1% increase on 2022 levels. With 2023 also seeing the world’s first year-long breach of the 1.5 degrees Celsius benchmark, it is clear that these climate trends are heading in the wrong direction. So, how can tidal power play a role in limiting fossil fuel reliance?

Harnessing hydropower

As an island nation with the world’s second-strongest tides behind Canada, the UK is ideally placed to benefit from tidal power in its bid to reduce fossil fuel reliance. Surprisingly, the potential of tidal as part of the UK’s energy mix is relatively untapped, with the possibility to be increased sixfold.

The UK’s Environmental Audit Committee (EAC), a group of members of parliament (MPs) from across the political spectrum, lamented the lack of tidal power inclusion within the British Energy Security Strategy. The plan, which aims to accelerate green energy generation and reduce reliance on energy sources from abroad, only includes one mention of tidal power.

The EAC also highlighted the multiple advantages that hydropower offers. As currents are highly predictable, it is much easier to manage electricity production than with other renewable energy methods such as wind and solar. Since water is much denser than air, a tidal turbine can produce substantially more energy than a similarly sized wind turbine, even in non-ideal conditions.

Tackling tidal power issues

Although tidal projects come with potential challenges, there are measures that can be taken to minimize these drawbacks.

For example, potential installation sites are often limited by local ecosystems and the environmental impact tidal turbines could cause. However, recent research on a Northern Irish tidal project using high-precision modeling to map eel swimming patterns has shown that danger to marine life is significantly lower than first predicted. As the marine energy sector continues to develop, these kinds of technical environmental monitoring programs will ensure accurate data for the commissioning of future tidal projects.

The cost associated with water turbines has also limited tidal project development and installation. Since these turbines need to withstand harsh winds and saltwater, they come at a much higher price. However, as more systems are approved and commissioned, economies of scale will kick in, reducing costs. According to an EAC report, the price of a tidal lagoon, which places turbines around an enclosed body of water to capture energy from water movement, is akin to that of offshore wind farms once whole-life costs are included.

A further potential issue is the remote location of these tidal farms, which can make regular maintenance and repairs challenging. Fortunately, there are also opportunities to minimize this drawback. One study found that blade failure was the most common cause of tidal turbine breakdown, with most of these blade failures being attributed to design flaws.

The study found that loads were frequently underestimated during the design phase. As a result, the turbines would fail when the water was at high velocity, or during sudden changes in water flow. The recent creation of an innovative type of tidal turbine blade that eliminates adhesive joints typical in rotor blades, will help reduce the likelihood of failure in challenging tidal conditions.

Another way of protecting against excess power generated by strong currents is by including a dynamic braking resistor (DBR) in the generation and control circuit.

Power disturbances may result in a runaway condition leading to overspeed, which can eventually damage the mechanical structure due to stress in the turbine blade. The resistor acts as an electrical buffer, allowing for the safe dissipation of electricity and preventing the electrical circuit from becoming overloaded. As a result, it’ll be less prone to damage and require less frequent maintenance and repair work as a result.

With the threat of crossing the 1.5-degree temperature threshold and suffering from irreversible climate damage creeping ever closer, increasing the amount of renewables in our energy mix is crucial. By making the most of current electronic and design innovations, it is possible that renewables such as tidal power will become our new normal — and we’ll wonder what made us stick with fossil fuels for so long.