We all love renewable energy, don’t we? Well, as great as they are, they have one notable weakness: they lack the ability to create inertia into the electricity system. Inertia sounds like something only hardcore engineers can understand. Well, it is actually not that complicated.

What does inertia have to do with renewable energy?

Inertia is the force that resists change in the system. Without this force, the changes infrequency can be sudden which is not good in power systems as the frequency always needs to remain close to 50 Hz. Now, as the amount of renewable is increasing and traditional inertia-creating generators are being removed from the system, it is getting more and more difficult for transmission system operators (TSO's) to keep the frequency at a steady 50 Hz.

In Nordic countries, this change has been seen quicker than in Central Europe as the system is smaller and more vulnerable to frequency, production capacity and production mix changes. Therefore, Nordic TSO's have designed with a new frequency stabilizing product called Fast Frequency Reserve (FFR). This new product is going live in stages from the beginning of May this year and it is going to be the rocket of frequency reserve markets. By that, we mean it will be the quickest market to respond.

In this reserve markets, there are different options on how quickly the capacity must react,with the quickest option being that the capacity must have fully shut off within 0.7 seconds after a frequency deviation

With this rocket, the decrease in frequency can be stopped quicker, bringing stability into the Nordic power system.

A new challenge for demand-response aggregators

But what does this have to do with demand response?

Well, alongside energy storage such as batteries and flywheel storage, demand response is one of the best ways of supplying this new reserve service. From a system point of view, turning a consumption load off is just as effective as turning a generator or storage system, and most of the time consumption has the ability to react quicker than a generator. As well as that, seeing as the consumption loads would have been on anyway, they are the most sustainable source of this new reserve service. That is why we, as a demand response aggregator, are actively working in this area as well as other reserve markets, aggregating consumption to empower them to supply services to TSOs.

When there are enough electricity consumers being active, we can answer the challenges of low inertia in the system and make it possible to increase the use of renewable energy. We love more renewables, don’t we?

Katja Hollmén

Operations manager Sympower