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Low-cost CO2 capture by chemical looping combustion
of waste-derived fuels

Project summary

The aim of this project is to prepare for a pre-commercial demonstration of Chemical Looping Combustion (CLC) of solid waste-derived fuels, an innovative process for generating power and heat from waste (waste-to-energy, WtE), providing a concentrated stream of CO2.

In CLC, an oxygen carrier transports oxygen from the air reactor to the fuel reactor, where combustion of the fuel with this oxygen produces a flue gas stream without N2, thereby enabling efficient CO2 separation. The CO2 leaving this CLC system is purified and can be directed in two different pathways:

  • One option is permanent storage, leading to a net sink of CO2 due to the biogenic carbon in waste.
  • Another option is the production of carbon-based energy vectors (e.g., methane or methanol) with hydrogen produced in an electrolyser during periods with a high availability of electricity from renewable sources (Power-to-X).

This project will demonstrate CLC of solid recovered fuel (SRF) through testing in a realistic environment, using pilot tests at a scale of up to 1 MWth (TRL 6). Concepts for utilizing spent oxygen carriers from CLC of solid waste in TiO2 processes will be developed, making the production processes more economic.

Experiments will be conducted to investigate the interaction of oxygen carrier materials with impurities in the solid waste-derived fuel.

1D and 3D simulation models of the CLC reactors using waste-derived fuels will be developed and validated by pilot data. A basic reactor design of a 10MWth CLC demonstration plant will be elaborated.

Business cases will be developed and evaluated for four cases in the different countries based on costs (CAPEX, OPEX) and revenues (power, heat, spent oxygen carrier, chemicals, incentives for negative CO2 emissions, etc.), and considering synergies with neighbouring industries. The impact of the full-scale WtE plants on the environment will be determined by life cycle analyses.

Objectives of the project

  • Demonstrate chemical looping combustion (CLC) of solid waste-derived fuels in a dual fluidized bed configuration, using ilmenite as the oxygen carrier, in a realistic environment (TRL 6), by pilot unit testing at scales of 150 kWth and 1 MWth, aiming for 90 % CO2 capture and 90 % CO2 purity.
  • Accelerate the deployment of CLC by providing the basic design for a 10 MWth CLC demonstration plant (TRL 7) for waste-derived fuels, and possibilities for retrofitting an existing fluidized bed boiler, including the required flue gas cleaning /CO2 processing steps for transport, storage, and utilization.
  • Increase commercial attractiveness by reducing CO2 avoidance costs by > 7 % through exploiting synergies with other industries – in particular, re-using > 90 % of spent oxygen carrier materials from CLC in the metal processing industry.
  • Provide business cases for waste-to-energy (WtE) plants that apply CLC technology, aiming at a net electrical efficiency > 35 %, CO2 avoidance costs < 25 €/t, and net negative CO2 emissions.

Outcomes and impacts

This project will investigate the feasibility of using solid recovered fuel (SRF) in CLC and demonstrate the technology in a real environment by pilot tests at a scale of up to 1 MWth (TRL 6). It will lay the foundation for a system prototype demonstration in an operational environment through the development of a basic design of a 10 MWth demonstration plant (TRL 7). The successful operation of this 10 MWth plant will encourage the realization of a commercial waste-to-energy plant based on CLC technology around the year 2030.

Assuming that half of the 50 Mt/year of SRF/RDF anticipated in 2050 is used for CLC with 90 % CO2 capture efficiency, the potential for avoidance of CO2 emissions in the EU is as high as 31 Mt/year. Further CO2 reductions are possible if CLC is also applied to other kinds of waste, such as biogenic residues or industrial wastes.

Project owner

TU Darmstadt, Energy Systems and Technology

Project period

01-10-2021 to 31-09-2024