Rapid remediation with minimal ecological footprint to ensure uninterrupted energy supply

Due to years of industrial activity, glass processing until 1949 and then coal storage for the old power plant, the site's soil was heavily contaminated. So before the construction of the new power plant could start, thorough remediation work is needed. Now, let that just be one of the specialisms of Jan De Nul and its environment division Envisan.

Race against the clock

We started the remediation works in January 2022 and completed them barely three months later. A record time, in which we removed a total of 220,000 tonnes of soil. That short deadline has been set for a reason, explains Benoit Liégeois, Project Manager at ENGIE: "Belgium is currently facing huge energy challenges. Some nuclear reactors, which in the past provided about half of our electricity, will have to close by 2025.  We must be able to compensate for that loss in a very short time. And gas power plants will play an important role in this."

As Belgium's historical power producer, ENGIE is co-investing in that substitute production capacity. One such example is the construction of the high-tech CCGT power plant in Flémalle. Benoit: "The plant must be fully operational by 1 November 2025 to ensure our country's energy supply. This short deadline obviously has an impact on all construction phases. Therefore, a tight timing of only three months was set for the remediation works. And Jan De Nul and Envisan meticulously respected that."

Responsiveness and transparency

The short deadline was not the only challenge, by the way. When starting the works, the amount of contaminated soil turned out to be much higher than anticipated. "Not only did we have to remediate much more soil than we thought, we also encountered large stones and a lot of glass during the works”, explains Benoit. "Fortunately, this did not affect the deadline. In fact, Jan De Nul responded quickly and always involved us in full transparency in every decision. Thanks to that swift response, we were able to process a larger amount of soil within the pre-imposed time frame."

Water transport and circularity

Throughout the operation, attention to the environment was central. We avoided truck transports and let four of our vessels carry out synchronised transports over inland waterways.

"Sustainability was a very important criterion in our search for a partner for the remediation works”, says Benoit. "ENGIE always pushes hard to keep its impact on the environment as low as possible. Also for this project. The fact that Jan De Nul could transport such huge quantities of soil by water was a decisive factor for us."

The transport by water allowed us to convey up to 7,000 tonnes of soil per day, without creating mobility problems in Liege. We saved our roads almost 8,500 truck trips with trailers and emitted 3.5 times less CO2. We also included circularity in our approach. Using the first physicochemical washing plant within the Walloon Region, Envisan converted a significant amount of the contaminated soil into washed sand and granulates, which in turn were sold on the local construction market.

Supplementing irregular renewable energy

For ENGIE, the remediation works were just the beginning. The combined-cycle gas turbine in Flémalle is a crucial project for both the energy company and the Belgian state. "It may come a bit as a surprise that we are banking on gas today. Yet, it is a step we cannot avoid, as long as we cannot yet rely 100% on renewable energy”, Benoit explains. "On the one hand, we still don’t have sufficient solar and wind energy capacity to ensure powering the whole country. On the other hand, the sun does not shine, nor does the wind blow every day. In this sense, renewable energy has not stolen its name: it is not constant. As long as these renewable energy sources cannot fully meet our energy needs, we must try to adapt to their rhythm as much as possible."

That is exactly what ENGIE aims to do with its new CCGT power plant: creating a flexible energy source that complements its – for the time being – irregular renewable counterparts. 'For the time being' is the operative word here, because we will do everything, we can to maximise the share of renewable energy in the future. As the production of renewable energy sources increases, that of the power plant can decrease.

"The Flémalle plant will have an impressive capacity of 875 MW, almost as much as a nuclear power plant. Moreover, it has a very high efficiency of 63% that used flexibly compensates for any lack of renewable energy on those days without much sun or wind. In the long run, the plant could even run on hydrogen, biogas or synthetic methane instead of fossil gas and thus become carbon-neutral”, Benoit concludes. Bottom line? There are many ways to a sustainable future. Jan De Nul and ENGIE are very happy to unlock them.

This interview is an extract from our Annual Report 2022. Read the full report via the button below.