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Transporting electricity is our core business. To do our job, we need to construct and maintain a physical network of transmission lines and cables, substations and other infrastructure on land and sea. This work has an unavoidably impact on nature. We are fully aware that we have a responsibility to care for the well-being of the natural environment and to protect green spaces and wildlife for future generations. Open and transparent communication with society is crucial to finding solutions to minimise our impact and address any environmental concerns.

InputStrategic prioritiesChallengesOutput
Natural resourcesAnticipate and address what society wants and needs through dialogue and innovationWeighing up environmental aspects in business decisions58 environmental incidents
There is no effective and cost-efficient insulator alternative for SF6 yetCarbon footprint of 2,278,396 (tonnes CO2 e)


Commitment to nature

Our assets are located throughout the Netherlands and Germany, in national and international waters and often in areas of natural beauty. This can impact biodiversity, ecosystems and the landscape. Where possible, we use the natural environment to minimise our impact by making use of natural screening and noise reduction and by creating secure areas around our substations, lines and cables. Our Commitment to Nature vision underlines our approach and illustrates the responsibility we feel we have to avoid and minimise our environmental impact and protect and improve local nature. We always strive to balance our business activities with the impact they have on nature. Since stakeholder cooperation is crucial in making sure we come up with the best solution for nature, we signed the Green Deal Infranatuur in April 2016. This public-private initiative aims to reduce the impact of Dutch infrastructure on biodiversity and underlines our commitment to biodiversity in the Netherlands. We undertook several activities in 2016 that had a clear positive contribution to local nature.

"Together with TenneT, we share the ambition to realise more offshore wind energy in the Dutch North Sea. TenneT sets an example on how to include stakeholders, such as us NGOs, in their projects. We work together on creating societal awareness for offshore wind, including other environmental NGOs in the process. TenneT always listens very carefully and takes our ecological advice for the offshore grid very seriously. TenneT’s position is crucial for the current offshore wind plans but also for future plans.”
Tjerk Wagenaar, CEO of Natuur & Milieu

Our operational activities can have a negative impact on nature, because leakages and spills can never be entirely prevented. Most of our environmental incidents are due to oil leakage from our transformers and cables. For new projects however, we use polyethylene cables, which do not contain any oil. Oil leakage in 2016 was significantly lower than in 2015, when we had a major spill. In total, there were 58 environmental incidents in 2016.

Commitment to nature201620152014
Oil leaked (litres)2,08714,0918,283
Environmental incidents588449

Carbon footprint

The nature of our business results in some unavoidable losses of energy as it is transported through our grid. Compensating for these grid losses increases demand for energy, and we are reporting the corresponding CO2 emissions. Over 95% of our carbon footprint is caused by our grid losses. Sulphur hexafluoride (SF6) leakage and the electricity we use in our own operations account for the rest. Since we 'green' our electricity use to the maximum extent permissible by law, we report a gross carbon footprint (without greening) and a net carbon footprint (with greening).

For more detailed information about our carbon footprint calculation, conversion factors and impact per year and country, click here.

Grid losses are the difference between the amount of produced electricity that enters our transmission system and the amount that is available for consumption. The distance the electricity must travel, the amount of electricity transported and grid utilisation (including redispatch measures) determine the grid losses. All are strongly influenced by the geographical spread of renewable energy sources, such as offshore wind, and the integration of the European electricity market. Since grid losses account for most of our carbon footprint, an increase in grid losses increases our carbon footprint. Divided by the electricity that we transport, the relative carbon footprint is increasing due to the large transport distances, but the increase of this ratio is less compared to 2015, because we see a small positive effect of the increase of renewables in the energy mix. To raise awareness of how our investment decisions impact our grid losses, we now use an internal carbon price. We applied this to one investment decision in 2016 and will continue to use this methodology in the coming year.

Carbon footprint201620152014
Grid losses (GWh)4,2123,8792,824
Carbon footprint/transported electricity (ton CO2 /GWh)
SF6 leaked (%)0.38%0.35%0.56%
SF6 leaked (kg)1,2481,1061,410

SF6 is used in high-voltage equipment on substations because it is an excellent electrical insulator and is necessary for interrupting currents in circuit breakers. However, SF6 is a strong contributor to greenhouse gas emissions. We aim to reduce our relative SF6 emissions by 20% in 2020 compared to 2015. On top of this, we have set an absolute target to keep SF6 leakage until 2020 below the 2015 level. Knowing that our asset base will increase substantially, this target is ambitious. Our 2016 results show that both our relative and absolute emissions increased. In the coming years SF6 reduction will be more prominently considered in our replacement and maintenance program, notably in the Dutch 110/150 kV substations where highest leakage levels are observed. This will create a modern and standardised landscape where it is easier to keep SF6 leakage to a minimum.

"Besides reducing leakage rate, replacing SF6 gas with an alternative gas or the use of alternative dry-type insulation where available is a logical and important next step to realise our ambitious SF6 targets."
Wilfried Breuer, Director Offshore TenneT

The energy use of our power stations is another main contributor to our energy footprint. To reduce this, we launched a pilot at one of our substations in the Netherlands, using solar panels to generate electricity for our own use. The findings from this pilot will be used to decide whether we should apply this in new-built stations.

Carbon emissions are not only a result of TenneT's own activities. As such, we are challenging our contractors to minimise their carbon emissions during construction work. For one Dutch project in Bergen op Zoom, this resulted in significant energy savings with respect to drilling. Another example of a positive contribution is the PowerToGas plant in the northern part of our German grid, operated by Audi. This is a balancing power plant that provides negative balancing power to the TenneT grid. This is often required to stabilise the grid in situations where there is a high amount of offshore wind power being fed into the grid while demand is low. During these periods of power surplus, the PowerToGas plant converts water into oxygen and hydrogen. Hydrogen and carbon dioxide are used to produce methane gas, which is almost identical to fossil natural gas and is distributed to service stations. Driving with this gas releases only as much CO2 as was previously consumed by production in the plant.

Cooling for free

At our stations we use lots of small air-cooling units containing cooling fluids to keep our automated systems at the right temperature. Although these small units do not consume enormous amounts of energy individually, we could potentially save as much energy as xx households consume per year if this cooling was ‘for free’ using outside air instead of air-conditioned air. On top of that it would mean moving away from the use of cooling fluids. We are investigating this alternative way of cooling at one substation. If the pilot is successful, we will certainly use it this more widely. This is a great example where a positive impact on the environment leads to cost savings as well.

Our challenges in environment

1 SF6 leakage is an important issue within our overall environmental management. Despite its harmful properties, there is no effective alternative to SF6 . It is a highly effective insulator and the only technical solution to interrupt currents at the highest voltage levels in our grid.We are working closely with suppliers to look for an alternative gas with the same isolation properties but a lower environmental impact. We also challenge the industry to develop a SF6 free switchgear, probably based on vacuum, to be used in a pilot in the lowest voltage level of 110 kV.
2Weighing up environmental aspects in business decisions is a challenge since monetary impact is difficult to measure.We have started to use a carbon price in our investment decisions, as an initial step towards more weighted decisions.

Looking ahead

On the one hand we see society putting more and more pressure on the energy industry to move towards a sustainable future. On the other hand, there is less acceptance of the impact of new infrastructure on the environment. The energy transition requires TenneT to expand the landscape. Given our commitment to our environmental and social responsibilities, we will continue to go the extra mile to address environmental concerns.