Walking on a tight rope

“When the snows fall and the white winds blow, the lone wolf dies, but the pack survives.”

Just as Ned Stark explained the importance of resilience during winter in Game of Thrones, the functioning and continued stability of the modern electric grid similarly depend on principles of preparedness and adaptability. It is the most complex house of cards the humanity has ever built. It forever lives on the proverbial tight rope, balancing over the darkness that a grid failure would mean. This balancing act means that there must always be equal amount of production and consumption. The electric grid is extremely complicated, but at the end of the day it comes down to this simple balance. If the balance is lost, the grid fails and the lights go dark.

It surprises me how this simple fact is not well understood among the general public. In most parts of the Western world, we have had stable and reliable electricity for so long, that we have learnt to expect that it just always works, without realizing that we are always only few failures away from total chaos. And with failures, I mean system level failures, not someone snapping the cable down the road from your house. In fact, I could not even remember when we last had a major grid level blackout in Finland. And there is a good reason for that – the last one happened before I was born, in 1974. Sure, there has been local interruptions since, but nothing that would require the entire grid to be restored from a blackout state.

Grid frequency serves as a real-time measure of the balance between electricity generation and consumption. Ideally, the grid maintains a steady 50 Hz in Europe and Asia, and 60 Hz in the Americas. If demand exceeds supply, frequency drops; if supply exceeds demand, it rises. The grid operators’ primary task is to manage the frequency fluctuations within strict, safe limits (typically 49.9-50.1 Hz in Europe). In Finland, the grid operator Fingrid provides the real-time frequency on their website:

Source: Fingrid

The grid is designed to tolerate some fluctuations, and the grid operators maintain reserves to manage supply issues, such as power plant failures or interruptions in the main transmission lines. In Finland, the design philosophy has been that the grid must be able to tolerate, at any time, the dropout of the single largest production unit, the nuclear power plant OL3. The nameplate capacity of the OL3 is 1600 MW, and it represents about 14% of the generation capacity in Finland.

If (and when) that dropout happens, the grid operator has approximately 5 seconds to react and activate additional supply. During those 5 seconds the inertia of the grid will resist the change in frequency and will hold the grid up while the Fast Frequency Reserve (FFR) is activated. The more the frequency drops (i.e. the more unstable the grid becomes) the less time you have.

Source: Fingrid

Essentially, we are perpetually just 5 seconds from a blackout; however, it is encouraging that we have managed to keep the grid stable for more than 50 years, so there is still hope.

The electric grid faces new challenges from the evolving patterns of how we use and produce electricity. With the expanse of renewable energy, we have certainly introduced new grid level problems. Renewable energy is (mostly) dependant on weather and time of day. In other words, it is unreliable from the grid’s perspective and can not adapt to changing levels of electricity consumption. Some say that this alone is the reason we should not use renewable energy sources, or at least not in any significant scale. I disagree.

The way things are going, the consumption side of things will face equally massive changes with the ever increasing electrification of vehicles and how we heat our houses.

Going back to my Game of Thrones quote in the beginning – what we actually need to do, is to develop an electric grid that can tolerate and thrive in this new reality. In the same manner as “The lone wolf dies, but the pack survives” the electric grid of the future will work the best, when it consists of components that can intelligently support each other from production and consumption to storage. This will include predictable and stable production, like nuclear, which is not dependent on weather or time of the day, as well as industrial scale storage solutions which will support renewable energy sources.