Sludge energy in southern Luxembourg

Projects such as this are helping the EU to become a smart, sustainable and inclusive economy by 2020, as set out in the EU 2020 growth strategy. The EU is facing some tough challenges, including an ageing population, an insufficiently qualified workforce, the need for greater innovation, striking a balance between economic growth and environmental degradation, and ensuring secure, clean energy supplies. Regional policy projects across the EU are playing an active role in dealing with these and many other challenges, by undertaking projects designed to generate employment, raise educational achievement, develop renewable energy sources, boost productivity and give all citizens access to opportunities. The projects and the regions play a pivotal role in this, as they generate real results that contribute to achieving the strategy’s key goals.

The process takes place in eight large glasshouse-type constructions in Bettembourg, where the dried sludge is compressed into bricks to produce heat. A massive 6 500 tonnes of sludge will be dried every year, resulting in about 2 500 heating bricks.

Economic and environmental gains

The organisations behind this project are the STEP Intercommunal Syndicat in Bettembourg and Luxembourg’s Ministry of the Economy. With rising disposal and transportation costs, it made sense from both an energy and economic point of view to minimise the sludge mass to be disposed of. This can now be achieved by extracting the water that makes up the majority of the sludge – in the case of liquid sludge, about 95%. The operating and investment costs compare favourably against conventional drying processes, with 100% of the thermal energy coming from the sun, any shortfalls being compensated for by waste heat. The project has also resulted in lower quantities of phosphates, nitrates and heavy metals on agricultural fields.

Simple ideas make a difference

The water is removed from the sludge using a simple method: environment-friendly solar energy. The benefits of the dried sludge include the fact that it has the calorific value of lignite, and can be burnt CO2-neutrally, and is neutral in odour, biologically stable and easy to store. For this reason, different storage, transport and disposal options are feasible, enhancing the added value of the process.

The plant itself is composed of a combination of fully transparent, enclosed shells, which can withstand hail, high winds and heavy snow. They have many automated features including air-circulation fans, ventilation flaps, speed-controlled fans, drainage floors, air-conditioning and intelligent, robust, maintenance-friendly turning machines in stainless steel to ensure process optimisation at all times.

Prize-winning project

The project has seen 16 businesses involved, each contributing their own expertise and helping bring benefits to local communities, notably in the form of the massive CO2 reductions (1 000 tonnes), five new jobs created and the facilities’ ability to support 95 000 population equivalents.  The success of this project has already been recognised, with the awarding of the 1st prize in the category ‘Communes et Villes 2010’ of the ‘Eurosolar 2010’ competition.