Supply security
We work continuously on the reliability of our grids. Supply security and preventing and reducing the number of failures and downtime are central to this.
On average, customers were not supplied with electricity for 22 minutes in 2022 (2021: 19 minutes). This was well above the target of not more than 17 minutes. Two large failures in Spijkenisse and Schiedam together accounted for almost 4 minutes. But even without these two failures, the electricity downtime would have been above the target at just over 20 minutes. Although we were able to deal with failures more quickly in 2022, the effect of this was offset by these two large failures. We also had to deal with a small number of complex failures in our electricity grid, meaning that resolving these failures actually took longer. For gas, the downtime in 2022 was 50 seconds (2021: 26 seconds).
The average downtime for electricity and gas in the Netherlands will be made known after the date of publication of this annual report.
Annual downtime for electricity (in minutes)
Annual downtime for gas (in seconds)
Supply reliability (in per cent)
Partly as a result of these two large failures, our supply reliability was slightly lower than in 2021.
Outage with significant impact: Spijkenisse
A fire in a distribution station in Spijkenisse in January 2022 affected 16,793 houses and businesses. The fire started under the switchgear, which is a rare occurrence. As there was no safety feature at this location to automatically switch off the electricity if something went wrong, the fire could have caused severe damage. We devoted all our efforts to remedying the situation with two emergency containers and eight emergency power generators. The investigation into this failure led to a tightening of the automatic safety systems at our 150 large distribution stations.
During the repair process, we were able to rely on the help and support of the security region, the municipality and the local residents. The security region coordinated the disaster response process and the municipality opened the town hall to shelter the residents and set up an emergency number. This was a unique disaster that rarely occurs on this scale. We will strive to prevent this happening again in future. We have separately informed the municipal council of Nissewaard regarding this matter.
Causes of downtime for electricity
Due to a different categorisation of the causes of failures, it may look as though there was an increase in the number of latent failures in 2022 (2021: 1.5%). This type of failure was previously included in the ‘Other’ category. There were only minor changes in the other categories.
Latent failure: smart circuit breaker
Much attention was devoted to reducing repeat failures in 2022. Repeat failures are failures that cause the same cable to be disabled every time, and the same customers are affected. It is sometimes difficult to identify the cause of these failures. One solution we are now applying is what is known as a smart circuit breaker. During a short circuit, this circuit breaker generates a fault location, showing the fitter the distance to the fault and where repairs are needed. A further advantage is that a smart circuit breaker can reactivate automatically after a short circuit without the intervention of a fitter. This means that the customer experiences hardly any disruption.
Causes of downtime for gas
For gas, there were only minor changes in the causes of downtime compared with 2021.
Ageing grids
The average age of the Stedin grid is increasing, and that is and remains a key point of attention. We seek to use the materials in our electricity and gas grids for as long as possible and only replace what is absolutely necessary, in order to keep the societal costs for the energy supply to a minimum. It goes without saying that we closely monitor safety and reliability at all times. Our use of data and predictions of failure curves enable us to make progressively better choices and take timely measures. Targeted interventions are needed to maintain the quality and safety of our grid in the long term. This means we must invest not only in the energy transition, but also in the quality of our existing grids with a view to the long term.
Accelerated replacement of brittle pipelines
We intend to replace all our brittle gas pipelines (grey cast iron and asbestos cement) to ensure the safety of our gas grid by 2028. We replaced 200 km of brittle pipelines in 2022 (2021: 193 km), whereas we had planned to replace 212 km. The planned numbers were not fully achieved because an increasing number of projects are located in complex areas, such as the inner city districts of The Hague and Rotterdam. For these areas, we believe it is important to agree our schedules with stakeholders such as the municipality, hospitality businesses and retailers. According to schedule, the 1,046 km of the remaining brittle pipelines will be replaced by 2028. Approximately 65% of brittle pipelines have already been replaced (2021: 60%). We check all our grey cast iron and asbestos cement gas pipelines for potential leaks every year.
Gas replacement at Zoutmanstraat, The Hague
A large gas project in the neighbourhood of de Zoutmanstraat in The Hague, in which Stedin worked closely with the water supply company Dunea, was carried out in 2022. This involved the replacement of nearly three kilometres of gas pipelines. The planning for this kind of project is complicated, due to the underground congestion in the centre of The Hague. The planning of the works by Stedin and Dunea was coordinated with the municipality of The Hague throughout the project, as there were also substantial civil works ongoing in the same area due to a diversion of tram line 16. Thanks to this coordination of planning and the joint resolution of issues, the streets did not have to be closed off for two separate periods.
Excavation activities
The number of activities below ground also increased again in 2022, by 10% compared with 2021. This increase in the number of excavation activities led to a 5% increase in excavation damage. The direct repair costs for this in our service area are around €4 to €5 million a year. These costs can largely be recovered from the party causing the excavation damage. The figures show that the measures we are taking to reduce the risk of excavation damage are having an effect. These measures include covenants with telecommunications companies and contractors for the safe construction of new networks, collaboration with municipalities and other grid managers, the application of robotics and monitoring damage performance by our contractors.
Smart, risk-based maintenance
Data-driven maintenance involves the use of data to pinpoint where maintenance is really needed and which elements need replacement. In addition to quality improvements, this yields annual savings. The following are a few examples of how we use data for maintenance:
In 2022 and 2023, we are installing 400 sensors at transformers. These sensors make it possible to continuously monitor the mechanical wear and tear of the control switch. This means that we can plan maintenance on the basis of the actual condition. We can also take action quickly if the switch is not functioning normally.
We are accelerating the roll-out of sensors for the protection of high-pressure gas pipelines. We use these sensors to measure the cathodic protection online. With continuous monitoring, we identify damage and therefore the risk of leakages at an early stage.
We also worked on underground self-contained fluid filled cables (SCFF) cables in 2022. Currently, we use analogue manometers to monitor oil leakages. This involves around 80 connections, of 800 km in total. These meters cannot detect latent leakages in time. With the advent of digital pressure sensors with wireless communication options, it has become possible to continually monitor oil pressure and detect these leakages in time. This prevents environmental pollution.
We are running a pilot project in the gas stations to collect the information from valve positions and inlet and outlet pressure. Besides the possibility of determining energy supply, this also indicates where the protective devices may be failing. This means we can undertake timely and more targeted maintenance before a failure occurs. We developed this further this year, in an Advanced Analytics model.
Substantial investment is also necessary to maintain our assets at the appropriate level. Further details on this are given in the ‘Financial and economic performance’ section.
