New Publication – Workshop report: Waste-to-Energy fly ash valorisation

Dec 2020

Report of a digital workshop held on October 7, 2020. The workshop was organized by representatives of SINTEF (Norway) and RISE (Sweden), within the framework of IEA Bioenergy Task 36 (Material and Energy Valorisation of Waste in a Circular Economy).

Fly ash from Waste-to-Energy (WtE) plants is usually considered as hazardous waste because of their chemical and physical properties (i.e. metals content, leaching), hence requiring specific handling, disposal and/or treatment. Most fly ashes are being landfilled, often after washing and/or stabilisation/solidification, in dedicated sites such as salt mines to prevent the leaching of hazardous substances to the environment. A significant portion of European fly ashes are being transported across borders (within the EU) for final disposal.

However, the push towards a more Circular Economy is calling for drastic changes in the situation, especially to recover valuable elements from fly ask as well as reduced landfilling. Fly ashes are promising candidates as they contain an array of metals, salts, and minerals, including strategically critical elements.

During this webinar, seven companies presented their fly ash treatment solutions, all offering (different degrees) of valorisation and/or re-use. Some of these technologies are commercially available, while others are under various stages of development. The webinar presentations clearly show that fly ash valorisation is a hot topic, especially as Circular Economy principles are slowly but surely unfolding into all aspects of society. Several technologies are (or will be) good candidates to contribute to more valorisation and/or re-use of WtE fly ash and possibly less hazardous waste landfilling. However, there is still a large acceptance in the public and the authorities for landfilling in many countries (which tends to be lowest cost in many regions), especially if (not in my backyard) NIMBY principles prevail for localising waste processing plants.