With successful tidal range schemes established in France, South Korea, and various projects being pursued in the UK, including frontrunner Swansea Bay Tidal Lagoon, is it time for Australia to embark on its own tidal range energy future?
Australia is endowed with a diverse range of conventional and renewable energy resources. As the effects of our reliance on fossil fuels increases to be felt on a global scale there is an ever greater push towards the use of alternative and more sustainable sources of energy.
Given the high tidal ranges experienced along the northwest, north and northeast coasts of Australia, tidal range energy can be a key component of a broader shift towards renewables.
The north coast of Australia, namely parts of Western Australia, Queensland and the Northern Territory, experiences tides of up to around 10 metres. This is up there with some of the largest tides in the world. Yet Australia’s potentially vast tidal energy resource remains largely untapped.
Tidal range generation works by using the tides to create a head difference of water across a barrage and then using this to drive turbines, which in turn drive electricity generators. A typical facility consists of an embankment, used to retain the body of water from which energy is generated, a series of sluice gates, which allow the more rapid equalisation of water levels over the embankment, and a powerhouse structure, which contains the turbines.
In its simplest form, tidal range generation works by allowing water to flow freely into the basin through the sluice gates as the tide rises.
At high tide, the sluice gates are closed and water is held in the basin. As the tide ebbs a head difference is created across the barrage and the trapped water is realised through turbines which convert the power of water to shaft rotation to drive electricity generators. And the process repeats. A more advanced implementation of this is to generate electricity on the ebb and flood tides.
Picking the right site
Choosing suitable sites for tidal range projects is critical in developing commercial projects. Generally speaking, locations need to provide a high tidal range (not less than say 5 metres), a relatively shallow seabed and an area large enough to store the volume of water needed for energy generation.
The particular characteristics of a site will dictate the engineering design and construction. This includes location and access, geology, topography, prevailing weather conditions, environmental considerations, and distance to the grid. These factors and others influence capital costs and finance and ultimately the viability of a scheme.
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Wider benefits for the community
Tidal range projects also provide opportunity for a wealth of wider potential socio-economic benefits, not only jobs but also creation of amenities (such as boating lagoons) and the opportunity to incorporate or upgrade often much-needed infrastructure, such as coastal defences. These wider benefits must be considered in the appraisal of schemes.
Areas subject to semidiurnal tides experience roughly two high tides and low tides a day. Therefore, single schemes in isolation provide intermittent energy as generation is largely dependent on the phasing of the tide. On a wider scale, we could take advantage of the phasing of tides around the coast to provide a smoother energy supply by using a number of generation facilities at different locations. There is also the potential to couple tidal range generation with hydro storage schemes to help provide energy when it is needed.
One of the biggest challenges for Australia is its size. Locations of high tide are generally away from large population centres and the distances can be huge. So how do we get the energy to where it’s needed?
Adapting existing infrastructure
Australia is the world’s largest exporter of LNG, having seen significant investment in this area over the last 20 or so years. There are currently seven operating LNG export facilities, three more under construction, and further projects under consideration. However, this is resulting in upward pressure on domestic market prices.
Securing energy for future generations
An effective part of the distribution solution would be to convert tidally-generated energy to compressed hydrogen and leverage existing infrastructure, such as that originally created for LNG, to move the product to where it is needed. This could go beyond supply to the national market and enable Australia to become an exporter of renewable energy in the form of compressed hydrogen.
So, can tidal range be a step on the way to providing clean and secure energy for future generations and to Australia becoming a leading renewable energy exporter?
I would love to hear your thoughts on the opportunities for tidal range energy in Australia. Contact me on LinkedIn.