Ben Brading 6 min read

Tidal Energy | How tidal energy works and why we must utilise it!

The electricity needs of the UK continue to be met by the burning of fossil fuels. In March 2022, 36% of the country’s energy needs came from gas-fired power stations. This causes two critical problems for the UK:

Dependence on the supply of gas-producing nations, such as Russia.
Greenhouse gas emissions from gas-fired power plants.

British scientists and engineers explore different options for green energy generation to solve these problems. Let’s look at Tidal Energy, which represents a vast potential source of renewable energy given the UK’s extensive coastline.

What is tidal energy?

Tidal energy is the harnessing of tidal energy to generate electricity.

Tidal energy is not a new idea. There are examples of coastal inhabitants using tidal energy to grind grain in the middle ages. At high tide, they trapped incoming water in large storage ponds. After waiting six hours for low tide, they released the trapped water through a small channel fitted with a water wheel to capture the energy of the flowing water.

The use of tidal energy is not widespread, but research continues into this potentially unlimited source of green energy.

How does tidal energy work?

Tidal energy harnesses and converts the power of the Earth’s oceanic tides into useful energy, usually in the form of electricity.

Tidal energy comes from the gravitational interaction between the moon and the Earth. As the Earth rotates, the direction of gravitational attraction from the moon constantly moves. This gravitational force is exerted upon the ocean, causing the sea level to rise in the place of maximum attraction and to fall in the place of minimum attraction.

Tidal changes occur with complete regularity, with each 24-hour cycle containing two high tides and two low tides. The difference between high and low tide can be as much as 16 meters at the coast.

The principle of tidal energy is to extract the kinetic energy stored within the moving tidal waters to rotate turbines that generate electricity.

What are the different methods of tidal energy?

Generating electricity from tidal energy is currently achieved using two different methods:

Tidal stream generator
Tidal stream generators work in a very similar way to wind turbines. An underwater turbine is placed where the tide causes fast flowing water through a small channel. The moving water spins the underwater turbine to generate electricity.

Tidal barrage
A tidal barrage is an artificial dam used to trap water at high tide. Once the tide has ebbed, the water trapped within the barrage has gravitational potential energy. At low tide, the trapped water is released through a small channel with an electricity generating turbine.

What are the advantages of tidal energy?

The main advantages of tidal energy are that it is both renewable and green. Let’s explore both.

Tidal energy is renewable because the energy from tides is inexhaustible. The Earth will continue to rotate, and the six-hourly ebb and flow of the tides will continue indefinitely. Unlike fossil fuels we can safely harness tidal energy without it running out.

Tidal energy is green because the energy generated does not produce any greenhouse gases. If tidal energy can be harnessed to generate lots of electricity, it will go a long way to making the supply of electricity sustainable.

Your business can choose to adopt a renewable electricity supply with a green energy tariff. Compare business energy today.

What are the disadvantages of tidal energy?

The two biggest challenges to using tidal energy are cost-effectiveness and environmental impact. To contribute to the renewable fuel mix, it will be necessary to generate tidal energy at a cost comparable to wind energy and solar power. No current design has been able to achieve this cost-effectiveness at scale.

Large scale tidal energy generation causes a few environmental problems. A large tidal barrage will disrupt an entire coastal ecosystem, while the turbines used to generate the electricity may kill aquatic wildlife.

How much does it cost to generate tidal energy?

Analysis of the economics of current large-scale tidal energy projects suggests that the current cost of tidal energy per kWh is three times as much as offshore wind power generation.

However, the UK is pioneering research into tidal energy at the European Marine Energy Centre based in Orkney. It’s hoped that improving tidal power technology will make it a viable renewable energy source.

Happily, alternative forms of green electricity are getting cheaper and cheaper. Find out the cost of green electricity tariffs with AquaSwitch. Compare Business Electricity.