As we search for ways to reduce our reliance on fossil fuels, some are looking to a largely untapped source of renewable energy, tidal power. On the global scale, there is an estimated capacity of around 100 gigawatts available for tidal energy harvesting, enough to power 80 million homes. This form of energy has almost unlimited potential and may solve typical criticisms of renewables regarding their intermittency, with tidal energy being highly predictable and reliable, based on the earth’s orbit around the sun and clockwork reliability of the tides.
Today, flowing water in various forms accounts for about 16% of all electricity generation around the world. According to the International Hydropower Association the total installed capacity in 2023 was circa 1408 gigawatts, generating more than 4,300 terawatt hours of electricity. This power mainly comes from hydroelectric dams on large river systems which have developed into significant engineering projects, however at a heavy financial cost. This typically goes alongside environmental impacts up and downstream and green house gas emissions from their construction.
To date, there has been a distinct lack of success in harnessing the vast quantity of energy available in the earth’s oceans. Wave and tidal projects also suffer from high costs and limited availability of suitable sites, hampering progress towards large scale implementation. This may now finally be changing, due to new materials and underwater turbine technologies giving access to a wider range of geographical locations, making the availability of tidal power greater than previously considered and at a more competitive cost and smaller environmental impact.
As part of this, the world’s most powerful tidal turbine has been launched off the coast of East Scotland by Orbital Marine Power with a view to capitalising on this opportunity. This is called the Orbital O2 2MW tidal turbine and is the product of 15 years of continuous development from the Orkney based company. As pointed out by Andrew Scott, chief executive of Orbital, this location is ideal for testing and developing tidal technologies due to experiencing some of the strongest currents in the world. The O2 turbine has a generating capacity of 2 Megawatts, enough to power about 2000 homes. It consists of a 680-tonne floating hull, measuring 72 meters, around the same size as a jumbo jet. Attached to the sides of the hull are two 18-meter-long pivoting arms, each supporting a 20-meter rotor, all held to the seabed via a four-point mooring system of chains, each capable of suspending 50 double decker buses. Electricity is then transferred from the turbine via a dynamic cable to the seabed through a static cable to the local onshore electricity network. Crucially, the rotor support arms can be lifted out of the water, making the turbine towable using relatively small and inexpensive tugboats, minimizing the complication and cost of maintenance and repair.
Like any renewable generation source, tidal cannot solve everything on its own but turbines such as this could play an important role in complementing wind and solar installations as part of an overall strategy to help the UK reach net zero. Eighty percent of materials are UK sourced, providing a boost to local employment through the long-term operation of the turbines, creating an opportunity to become a world leader in tidal technology and significantly boost the UK’s green recovery. Coupled with the UK government’s pledge to invest £20 million per year across the UK in tidal energy, this is an exciting example of innovation in the renewables industry, bringing us one step closer to delivering a success story that will provide both environmental benefits through the generation of renewable energy and UK-wide supply chain benefits.
References:
- 2020 Hydropower Status Report – sector trends and insights
- https://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-57991351
- https://www.gov.uk/government/news/uk-government-announces-huge-investment-into-scottish-tidal-power
- https://orbitalmarine.com/o2/
Imagery : Orbital Marine
Author: John Bennett