By Mohammed Almoghayer, Senior Project Manager specialising in marine energy at the Offshore Renewable Energy Catapult.

Tackling climate change is not just about how we fuel the world’s big cities – we need to remember that 45% of the world’s population lives in rural and island communities. Another startling statistic is that one billion people still have no access to electricity and 85% of them are located in these rural and island locations.

I spent the last four years in Orkney studying how the archipelago, historically one of the most fuel-poor regions of Scotland, is transforming how it powers its communities. My resulting research paper, published in the energy journal Science Direct last month as part of my PhD, offers a blueprint for how tidal power could be deployed by island communities across the world in a way that will make their energy more affordable, predictable and cleaner.

The Island Factor

I chose Orkney for my research as it has achieved notable success in overcoming what is known as the ‘The Island Factor’. Energy has traditionally been expensive for small islands and archipelagos because of the diseconomies of scale in small populations, reliance upon imported fossil fuels (with the associated high transportation costs), their highly specialised economies, limited resources and fragile ecosystems.

When it comes to renewables, islands often have rich resources in terms of solar, wind and wave power. Matching supply to demand is the issue though and requires building storage to mitigate fluctuations, as well as infrastructure to deal with the more complex grid operation and network planning.

This is where tidal power offers the most promise. It can deliver appropriate baseload power directly to the grid, as first shown by Nova Innovation’s Shetland Tidal Array. It is seasonally consistent and loads no further complexity into the local grid infrastructure.

The northern Scotland islands are also the base for two world-leading tidal energy projects, EnFAIT and ELEMENT, that both look to reduce the cost of energy and accelerate tidal energy’s route to market. Using the Shetland Tidal Array, the ELEMENT project will show how artificial intelligence can slash the cost of tidal energy by an estimated 17 percent, bolstering the case for tidal energy as an important part of the world’s future energy mix.

Orkney has become Europe’s prime research site for marine energy with the establishment of the European Marine Energy Centre (EMEC) and the local community is served by Orbital Marine Power’s O2 tidal turbine, a partner under the TIGER project for building tidal capacity.

By integrating tidal power in combination with wind and wave, Orkney is transforming itself from a net energy importer to an island that is poised to be a net exporter. It is also the location of the world’s first smart grid using the new Active Network Management (ANM) approach from Scottish Hydro Electric Power Distribution (SHEPD) that has avoided the need for expensive grid upgrades to deal with renewables integration.

By adding hydrogen generation off the back of tidal turbines at the European Marine Energy Centre’s test site and community-owned wind turbines, Orkney is increasingly able to absorb the extra energy generation and become a net exporter of energy. Hydrogen is now powering heating for the local school and inter-island ferries, with exploration underway to use it for other forms of shipping, heating and aviation.

The alternative would have been reliance on imported diesel, leaving Orkney residents at the mercy of global fossil fuel prices, or the slow, costly process of increasing power cable capacity from the mainland. Wind power, meanwhile, would not be enough alone as it would still require shoring up with electricity imports.

Orkney – how it became the world’s tidal power laboratory

My research used Orkney as a test case and showed the optimal way to deploy tidal power on an island in a way that cuts energy costs and provides long-term energy security and ensures no conflicts with existing supply or with other sea users (such as local fishing, transport and commercial vessels).

The preferred strategy for tidal power outlined in my paper is to limit the capacity of tidal devices while maximising the generation time, thereby increasing the capacity factor. In layman’s terms, this is the equivalent of leaving your heating on a low setting for the full day, rather than switching on a high blast of heat for just an hour.

The approach used by each island location also needs to be tailored by selecting:

• The right device for the site. One tidal turbine design does not fit all sites but needs to be tuned for each location considering the characteristics of the tidal flow (more or less energetic)
• The best arrangement of the turbines. This means the overall placement of the array, as well as deciding the position of each turbine in an array and its tuning affect power output. A notable study being conducted under the EnFAIT project in Shetland by Nova Innovation is testing a variety of configurations using the company’s moveable turbines.
• Generation strategy. Lowering the cost of energy requires an efficient generation strategy. A higher power output requires more expensive infrastructure, which when combined with a low system capacity factor, will result in a higher energy cost.

My conclusion was that this approach can be taken as the starting point for tidal power integration by island communities across the world, offering them the chance to generate their own power and eventually begin exporting to the mainland too. We know that 50-60% of the economic value of the tidal power sector is set to remain within communities where turbines are located, alongside the job creation and supply chain opportunity that goes with that.

Tidal stream power is a growing force, and I believe it is not only a technology that can support Net Zero but can also boost the economies of island and coastal communities as well as making access to energy more equitable across the world.

Visit ORE Catapult’s Tidal Power Express hub and video library to see the UK’s leading tidal developers introduce their technologies and debate tidal’s place in our Net Zero future.