Islanding can strengthen Sweden’s energy security

So-called island mode operation, whereby buildings or entire electricity systems can function independently, is not just a future scenario; the technology is available today. For example, Ludvika municipality secures the electricity supply for its critical infrastructure through green energy production and storage.

The Swedish electricity grid is facing two major challenges. The first is the ever-increasing demand from an industry and transport sector in transition. The second challenge, which is perhaps even more pressing, is the disruption caused by extreme weather, cyberattacks and geopolitical instability. In order to increase its supply capacity and become more resilient, the electricity grid can benefit greatly from island operation.

'In the event of a crisis or war, our electricity grid is likely to be affected. If the grid fails completely, not everyone will be able to receive assistance immediately. Instead, we need solutions to restart critical societal functions,' says Sara Skärhem, a senior project manager specialising in total defence at RISE.

How island operation mode works

Island operation means that a building or electrical system can function independently and be disconnected from the mains electricity supply. An island consists of a means of generating energy (such as hydroelectric power, solar panels or wind power) and a means of storing energy (such as batteries, hydrogen or thermal storage). The control system acts as the brain of the system, disconnecting the island from the grid and initiating island operation in the event of grid disturbances.

‘Given the developments we are seeing in the energy sector and the types of energy that will be available, it is likely that the energy islands of the future will be complex,’ says Jenny Holgersson, a senior project manager and researcher specialising in the city’s energy transition at RISE. She continues:

There are advantages to having a variety of energy generation units that support one another within the system. Furthermore, just like society at large, energy islands are becoming increasingly interconnected. This is an important aspect to investigate going forward, to avoid situations where island operation is disrupted before activation.

RISE is studying the cybersecurity of the energy island in Ludvika

The Krafttanken facility in central Ludvika is a prime example of an island operation. It houses a transformer box the size of a shipping container which is equipped with an energy storage system, an inverter, a transformer and a control system. The energy storage system consists of a battery that is charged using fossil-free energy from solar, wind and hydro sources. In the event of a power cut, the Power Tank will supply the municipality’s critical functions with electricity.

‘When we first got in touch with Ludvika, it was to study the security aspects of the energy storage facility, specifically its cybersecurity. We’ve examined the equipment at both component and system levels to see how these can be managed, says Sara Skärhem, continuing:

We have chosen to study Krafttanken because it is a well-defined and mature case study. However, what we learn about security risks and potential adversaries can be applied to the entire energy system.

Various forms of energy are required in order to supply a local organisation with electricity and other supplies.

Island operations form part of the total defence

Grums Municipality has also made preparations for off-grid operation in the form of a large battery storage facility. This facility is currently used commercially in the electricity grid’s balancing market, whereby the batteries store energy when production is high and prices are low, and supply energy when consumption and prices are high. The plan is for the facility to supply power to municipal safety hubs, such as schools, nurseries and sports halls, in the event of a grid failure. These safety hubs will provide people with the opportunity to keep warm, receive information and cook food. Krafttanken in Ludvika also serves this purpose.

RISE has collaborated with Grums Municipality to examine how their battery storage facility could be adapted for off-grid operation. The project has also explored the possibility of integrating renewable energy sources.

Grums Municipality's plan to use existing battery storage facilities for off-grid power supply is in line with Sweden’s rebuilding of its total defence capabilities and the EU’s requirements for resilience in the energy system. As well as enabling hospitals and other critical societal functions to continue operating in the event of a crisis or war, connected safety hubs can serve as strategic nodes for information sharing.

Our security situation has deteriorated significantly and our power grids are under threat. In order to supply a local organisation with electricity and essential supplies, you need energy in various forms. In that case, it is advantageous to be able to run the energy supply in stand-alone mode,' notes Jenny Holgersson.

Contingency and total defence aspects of the energy system

'There is a great deal of expertise in energy systems at RISE, and it is becoming second nature for us to incorporate contingency planning and total defence aspects into our work with the energy sector. The sector needs to continue improving its preparedness by raising the level of knowledge among all those involved, practising various crisis scenarios, and collaborating with public and private actors. RISE is ready to launch more pilot projects and build on the experiences from Ludvika and Grums,' says Sara Skärhem.

Which areas could use island mode?

In theory, a local electricity system that can operate independently when necessary can be powered by many types of energy source. These include hydroelectric power, battery storage, solar panels and wind power, for example. In practice, facilities that can control and stabilise the electricity grid in real time are best suited to this purpose. Hydropower and batteries are particularly important as they can quickly adjust production or consumption to keep the frequency stable.

Solar and wind power can also be included, but as these are weather-dependent and more difficult to control, they almost always need to be combined with other sources. This means that energy islands are usually built around a combination of several energy sources, rather than a single plant.

Could island mode areas become targets?

In theory, areas using island mode could be targeted by adversaries. However, the whole point is to make the electricity system as a whole less vulnerable by spreading production and storage out rather than relying on a few large hubs, as is the case today. While more smaller, localised systems may be easier to knock out individually, it is harder to knock them all out at once.