Another world first for Shetland’s tidal energy

Shetland is rich in renewable resources, particularly in terms of potential wind and tidal power, and there’s been another very positive development at the tidal installation in Bluemull Sound, the channel which separates the northern islands of Yell and Unst.

A year ago, we reported on Nova Innovation’s successful deployment of a third tidal turbine at that site The first Nova M100 turbine had been installed in March 2016, with a second added that August. The Bluemull Sound offshore tidal array was the first in the world to supply electricity to the grid.

The latest development at the site represents another world first, because it demonstrates how to overcome one of the well-known challenges in realising the potential of most forms of renewable energy, namely its variability. Tidal power isn’t available during the period when the tide is on the turn. We usually have plenty of wind, but wind speeds rise and fall and, even in Shetland, there are days when there’s little or no air movement. Wave power is broadly related to wind speed.

That variability creates a difficulty if the renewable energy is to be used in our electricity grid. In the absence of any way of storing renewable power, a reliable grid must be able to fill the gaps in the supply. A conventional power station such as one fuelled by gas or (in Shetland’s case) oil needs to be able to take over when the wind drops or the tide turns. The challenge is particularly acute in Shetland, which – with huge renewable resources – is not connected to the National Grid.

In the absence of that connection, the development of renewables in Shetland has been limited by the capacity of the main power station in Lerwick to respond to what can be quite sudden changes in supply from renewables. There is a very successful, privately-owned wind farm just outside the town which can supply up to 3.68MW, and several other individual wind turbines, or small groups of turbines, exist elsewhere in the islands. However, proposals greatly to expand wind energy production currently depend on smoothing out the variability in power generation, either through the installation of a cable to connect Shetland to the more accommodating national network, or the development of viable energy storage.

That’s why the latest development at Nova Innovation’s Shetland site is so significant. The company has connected its tidal energy array to battery storage developed by Tesla. The Tesla powerpack is able to store sufficient energy to fill the gap during slack tide, enabling the tidal power station to supply a consistent flow of electricity into the Shetland grid. The result is the world’s first grid-connected ‘baseload’ tidal power station.

Simon Forrest, Nova Innovation’s Chief Executive Officer, said:

“By storing the clean energy generated by the natural ebb and flow of the tide, we can control the supply of electricity to the grid to match demand. This creates a consistent source of completely predictable power from a clean, sustainable resource. Nova’s expertise in smart grid control, renewable generation and energy storage has delivered this game-changing innovation. We now look forward to expanding our services to other markets and renewable projects.”

Nova Innovation explain that linking tidal power to energy storage improves security of supply, reduces carbon emissions and helps to balance electricity supply and demand. The predictability of the tide and the six-hour generation cycle times make it the perfect partner for energy storage.

The project may be relatively small in scale, but it is clearly a game-changer. It’s no longer the case that only coal, gas, oil or nuclear can supply the steady output that’s needed for a reliable electricity grid. The potential for tidal power around Shetland – let alone around Britain – is enormous and Nova Innovation are clear that, as tidal technology is scaled up, it can displace other forms of generation.

The project has benefitted greatly from support from a number of partners, including Belgian-based ELSA, and Nova Innovation is now leading EnFAIT, a project backed by the European Union that aims to accelerate the pace of tidal energy generation and learn lessons from the Bluemull Sound installation. The Bluemull Sound installation is to be doubled in size, with plans to add another three turbines.

The project has also secured funding from the Scottish Government’s Low Carbon Infrastructure Transition Programme. The programme, supported by the European Regional Development Fund, is promoting low-carbon infrastructure projects across Scotland.

Scotland's Energy Minister, Paul Wheelhouse, said:

“Nova Innovation are a dynamic Scottish company with exciting technology and, of course, they can and should be rightly proud of having developed the world’s first tidal array at Bluemull Sound, Shetland. Now, with the support of £272,606 of Scottish Government funding, this already successful project will also allow for the deployment of additional tidal devices, expanding the generating capacity of the Nova Innovation Shetland Tidal Array.

Mr Wheelhouse sees the project as bringing benefits not only in Shetland but in other small island communities and, crucially, “we can also play a key role in helping inform the sustainable decarbonisation of energy for communities across the world.”

The project also has the support of leading environmental charities because of its impact on reducing carbon-intensive energy production. Sam Gardner, Acting Director of WWF Scotland said: “Predictable renewable power and smart storage working in harmony is the holy grail of the transition to a renewable electricity system. It’s great that the Scottish Government has backed this project and we hope it inspires politicians and others with the confidence to provide further support for ground-breaking technologies to cut climate pollution.”

The Intergovernmental Panel on Climate Change has just reiterated the need for “rapid, far-reaching and unprecedented changes in all aspects of society” if we are to limit global warming to 1.5°C. ​Clearly, the work being done by Nova Innovation in Shetland is a vital step if we are to achieve the transformation that’s required.