Substituting fossil fuel with alternative fuel

Alternative fuels provide opportunities for reducing production costs. Further benefits are environment-related: reduction of emissions, utilization of energy from alternative fuels etc.

Fuels that are classified as alternative fuels are different kinds of plastics, paper, wood chips, organic solvents etc. Speaking about cement industry, even shredded car tires are used, as chips fed into the riser duct helping to keep the temperature high enough for pre-calcination. Over the past 30-40 years, cement companies have developed strong know-how on the use of alternative fuels. This know-how is recognized at national level in many countries.

Changes that appeared in the process

It is of great interest to be able to predict the changes that will occur in the burning process when alternative fuels are used (instead of coal for instance), the heat transmission in the kiln and chemical changes, such as the composition of raw meal and parameters controlling the clinker burning process. It is also important to find out how alternative fuel affects the product that leaves the clinker kiln.

The effective heating value (LHV) is an issue that, combined with the higher need for oxygen may have surprised the kiln operators the first time tires were used as fuel in the clinker manufacturing process. But effective use and great efforts within the research and testing programs made the world more familiar with the new fuel.

Fuelling the cement kiln

Cement production is a very energy intensive process. A typical medium sized cement line can consume over 600 tons of coal every day. The good news is that today it can be almost fully replaced by Solid Recovered Fuel (SRF) and what is even more important – clinker burning process complies with all requirements of the EU Directive 92/C130/01 concerning hazardous waste incineration.

Cement plants can indeed be huge off-takers for SRF, benefitting both the plant, the local community and the ecology.

SETCleanTech is fully aware that waste-derived fuels should be used in accordance with strictly defined rules so as to ensure that incineration products do not have an adverse impact on the process of clinker production, that is do not affect cement quality or cause pollution of gases discharged to the atmosphere.

With SETCleanTech’s approach, up to 100% Thermal Substitution Rates (TSR) are reachable, using SRF in both calciner and main burner. Simultaneously, the cement process safely binds the ash into cement, reducing the need for mined raw materials and eliminating the need for ash landfilling.

The cement subsector consumes approximately 12–15% of the total industrial energy use. Therefore, this subsector releases CO 2 emissions to the atmosphere as a result of burning fossil fuels to produce energy needed for the cement manufacturing process. The cement industry contributes about 7% of the total worldwide CO 2 emissions.

That’s why In addition to economic benefits, substituting fossil fuels by SRF will also lead to reduction in NO x as well as fossil CO 2 emissions.

Fossil fuel substitution in cement kilns by SETCleanTech


Many years of experience have shown that the use of wastes as alternative fuels by cement plants is both ecologically and economically justified. SETCleanTech solutions customize the SRF process and its implementation to individual cement plant processes.

The project begins with a thorough feasibility analysis:

  • Waste study
  • CFD (Computational Fluid Dynamics)
  • Plant engineering

The required quality of SRF can be evaluated only after the waste analysis.

Cement production requires extremely high temperatures and a stable flame. Reaching high temperatures sustainably demands high calorific value of SRF and most importantly consistent quality of the fuel.

  • Optimized mixing and combustion
  • Retention time (RT)
  • Higher incineration temperatures compared to other waste combustion technologies
  • The large area of the furnace
  • The significant length of the kiln
  • The alkaline environment inside the kiln
  • Oxidizing atmosphere
  • The lack of incineration wastes as all metallic and non-metallic incineration products undergo a complete absorption
  • Large heat-exchange surface
  • Good mixture of gases and products
  • Sufficient time (over 2 s) for the disposal of hazardous wastes

All of the above-mentioned makes co-processing a safer solution for the environment. Therefore, using SRF (fuel produced from MSW), as well as fuel produced by SETCleanTech from car tires can be used safely, economically and environmentally-friendly in industries, such as cement production.