Technical solutions
We are try to get more capacity out of the existing infrastructure by taking technological measures. This includes, for example, increasing the load on equipment where this can be done safely, dispensing with the failure reserve, or linking up power generated by both solar and wind to a single connection: like a kind of carpooling, but for electricity.
Taking the ‘rush hour lane’
The electricity grid is often equipped with a failure reserve. If a power cable breaks, we have a spare cable that is used in order to fix the fault on the original power cable safely and quickly. This failure reserve is also referred to as the ‘rush-hour lane’ of the energy grid. It helps us prevent or limit the duration of a service interruption in large areas by diverting energy transmission in the case of a failure or maintenance.
The step we are now taking in some areas is to use the rush-hour lane even when there is no failure. In doing so, we create additional transmission capacity, particularly for renewable energy generation by solar and wind farms. The drawback is that we do not have any ‘reserve’ capacity if a failure occurs. We have therefore made arrangements with solar and wind farms that use the rush-hour lane. In the event of a failure, we may temporarily disable their connection or temporarily (partially) reduce the available power. We call this generation management. In order do this remotely, we have developed a control box. A control box enables us to manage generation capacity (from solar and wind farms) and to temporarily slow down the production of these large electricity generators The first field tests were carried out in 2023, and we will continue developing this solution in 2024. You can read more about this solution on our website.
Cable pooling
In cable pooling, we accommodate power generated by both solar and wind on a single connection. This helps us to make better use of the electricity cable, because it is usually not windy when the sun is shining and vice versa. The total capacity of connections to power generation facilities is used only to a limited extent. The connection must nonetheless be able to cope with peak loads. At peak times, for instance if the sun is out on a windy day, cable pooling means that customers themselves reduce the output generated by the solar or wind farm to prevent an overload on the electricity cable. This solution means that we can increase the capacity utilisation of a connection, fewer connections are needed and we can accommodate more generation capacity on the grid.
In fact, cable pooling has nothing but benefits for the customer, who can be connected directly. And it benefits Stedin too. If we apply cable pooling to just 1% of our heavy-use customers (around 200), we will soon save ourselves – according to the most conservative calculations – a year’s worth of excavation work. Cable pooling therefore has great potential.
Additional capacity through cable pooling
In 2023, we realised three cable pooling projects in Zeeland: on the provincial border near Woensdrecht, in Borssele and in Koegorspolder near Terneuzen (see box). In total, this allowed us to accommodate over 80 MWp of additional power on existing connections.
Cable pooling in Koegorspolder
Cable pooling is currently being tested in the Koegorspolder in Zeeland. At this location, a wind farm has available capacity and we connected a second customer’s battery to the same cable. When it is very windy, the wind turbines generate a lot of power and it is the perfect time to buy for the battery operator, because power is cheap then. The ‘surplus’ power on the cable is then purchased locally before it puts strain on our grid. Conversely, when there’s no wind, it becomes interesting for customers with batteries to feed power into the grid, as the price is higher then. That’s because at that time there is actually capacity on the connection because the wind farm does not burden it. A win-win, therefore.
This pilot is based on the proposed extension of cable pooling compared to the existing Electricity Act. This enables us to combine solar and wind and storage, all in one connection. The Dutch Senate will vote on this on 13 February. Together with Netbeheer Nederland, we urged the House of Representatives to include a further extension of cable pooling in the new Energy Act to also enable combinations of feed-in and consumption.
Use of batteries
Batteries are an important element of the energy transition and make it possible to optimally utilise our grid. In 2023, we received around 65 requests for batteries with a total capacity of 1,300 MW, on top of the 50 requests for a total of 900 MW received in 2022. This challenge is huge, and Stedin is not able to provide this capacity. We will connect batteries only if there is capacity, and if battery operators are prepared to make arrangements on grid-neutral battery use. That is, only if they help us relieve overloaded grids.
