Substitute fuels are produced from energy-rich waste that cannot be recycled. They are becoming increasingly important as an alternative energy source for Austria's industry.

24. May 2023

Substitute fuels: an alternative source of energy for industry in Austria

Substitute fuels are produced using energy-rich waste that cannot oth-erwise be recycled. The waste management industry in Austria is a world leader: since 2003, recycling professional Saubermacher and cement producer Holcim have produced around 1.5 million tonnes of high-grade substitute fuels at their joint plant in Retznei.

The use of these fuels in industry, and the cement industry in particular, has saved around 1.2 million tonnes of fossil CO₂[1] and has served as a substitute for 1.4 million tonnes of coal[2]. In addition, co-processing has also prevented mining of as many as 320,000 tonnes of mineral raw materials, including limestone[3]. Starting in 2024, Saubermacher will begin processing additional recycled materials at a new site in Graz and so doing, will be able to preserve additional primary resources in brick production. In addition to cement works, Saubermacher – as a leading producer of substitute fuels – supports other producers in the circular economy. All of this is helping to more Austrian industry towards a circular economy.

Cement production is an ecological challenge

Cement is an essential component in the construction and overhaul of buildings and infrastructure, including bridges and tunnels. Still, its production methods emit large quantities of greenhouse gases, consume ever scarcer raw materials and are extremely energy intensive. This makes ecological production methods increasingly important. A remedy is substitute fuels, which are produced using energy-rich waste in special production processes. Only waste that cannot be recycled, or for which no recycling process has yet been developed, is processed into substitute fuels. Saubermacher and Holcim are pioneers in this field through their ThermoTeam joint venture in Retznei.

‘With ThermoTeam, we have together set a new and global standard for the meaningful use of waste that cannot otherwise be recycled. The environmental benefits of substitute fuels are huge,’ explains Hans Roth, founder of Saubermacher, of the successful collaboration. Saubermacher is now the leading producer of substitute fuels in Austria and in Retznei alone produces some 100,000 tonnes annually. Highly advanced treatment processes, lots of analytics and many years of expertise help to ensure that customers’ high quality demands are met. In addition, the production of substitute fuels also has a positive impact on overall recycling rates – since 2003, ThermoTeam has sorted around 35,000 tonnes of scrap metal and PET and sent it for recycling.

Refuse-derived fuels are produced from energy-rich waste that cannot be recycled. They are becoming increasingly important as an alternative energy source for Austrian industry.

Cement production is an ecological challenge. So-called refuse-derived fuels (RDF), which are produced from energy-rich waste using special processes, provide a remedy.

Austrian cement industry a leader in the use of substitute fuels

Austrian cement works are global leaders in the use of substitute fuels, followed by Germany, Poland and the Czech Republic. Users of substitute fuels from ThermoTeam include the Holcim plant in Retznei. The two sites are connected by a conveyor system, so that transport by road is unnecessary. ‘The substitute fuel substitution rate in the plant is above 95 per cent, which is significantly higher than the Austrian average of more than 80 per cent, or the EU average of more than 40 per cent,’ explains Berthold Kren, CEO of Holcim Austria.

Co-processing reduces use of raw materials
Thanks to co-processing, substitute fuels are also recycled, thereby reducing the need for natural raw materials[4]. Studies by the University of Leoben indicate that up to 17 per cent of substitute fuels are currently recycled. In addition, there is no waste, which helps to reduce the amount sent to landfill. ‘This, combined with the 30 per cent increase in efficiency when compared to conventional waste incineration, clearly highlights the added value of industrial use,’ explains Ralf Mittermayr, CEO of Saubermacher AG. In addition to cement works, Saubermacher also supports the paper, fibre and chipboard industries in their pursuit of a circular economy by supplying them with dedicated substitute fuels. The EU still views the use of substitute fuels as purely thermal recycling. ‘The University of Leoben is currently working on an internationally valid ISO standard. We anticipate that the EU will then recognise the recycling portion and how the use of substitute fuels can contribute to recycling targets overall,’ explains Roland Pomberger, Professor in Waste Recycling Technology and Waste Management at the University of Leoben.

Construction and demolition waste is a valuable recycled raw material
The Austrian construction industry produces more than 11.4 million tonnes of mineral and construction waste and around 41 million tonnes of excavated material each year, making it the largest generator of waste in the country. When it comes to the circular economy, the (cement) industry is increasingly relying on waste-based raw materials, many of which are treated by Saubermacher. Holcim Austria is a market leader and recycles around 250,000 tonnes of construction waste each year. The global innovation leader is the newly developed ECOPlanet RC Zement, in which Holcim Austria has increased the overall input of recycled construction waste in cement to above 25 per cent and, additionally, is injecting CO₂ directly into the recycling material using an innovative ‘Rapid Carb’ process.

The circular economy meets the construction industry
Saubermacher has invested in a new site in Graz-Puntigam in order to supply the construction industry with ever increasing volumes of recycled materials. Since April 2023, the company has been treating a variety of different mineral wastes at the site before returning them to the construction industry as high-grade raw materials, e.g. quality-assured recycled construction materials. Starting in 2024, an additional 10,000 tonnes of recycled raw materials will replace mineral resources of the same order of magnitude at the cement works in Retznei. The central location of the site also halves waste transports in the wider Graz area.

‘Domestic industry is a pioneer in climate protection. This role is also highlighted by the results coming from this groundbreaking collaboration and underlines the leading international role being played by Austrian industry. Sufficient availability of high-grade secondary raw materials and alternative sources of energy at competitive prices is the key to the success of the circular economy and an essential component in the ongoing decarbonisation of industry,’ explains Peter Koren, Vice Secretary General of the Federation of Industries.

[1] Calculation as per CUTEC study 2016 or University of Leoben

[2] Calculation as per CUTEC Institute or University of Leoben

[3] Calculation as per University of Leoben based on the EBS recycling index

[4] The ash produced when substitute fuels are burned is used as a raw material in the production of cement bricks.