## 4 Discussion
However, as this operation will be carried out under limited periods of time, storing the material might be challenging as it again requires free area at the site. Somewhat large storage facilities would be required where the sieved bed material can be stored in dry conditions before it is used in the boiler. Dry bed material is needed as the internal boiler house bed material logistics in almost all cases includes some kind of pneumatic transport. The third option could potentially offer an attractive path for both the boiler owner and the material producer. This option has several similarities to the existing and well-established model used for silica sand handling. In this case, a third party working as a subcontractor handles the trading and logistics with the raw material producer, establishes the desired size fraction in accordance with the boiler owner's demands, stores the dry bed material, and handles the logistics to the boiler site. In this model, the boiler owner simply orders the amount that accommodates their bed material silo. In this way, both the boiler owner and material producer are offered a comfortable arrangement where the risks related to the material handling and potential investments are handled by the subcontractor. However, from a business perspective, one can argue that this option leads to the material producer losing the opportunity to refine their by-product and thus loses a possible market opportunity. Further, it is likely far from obvious that the boiler owner will adapt to a new bed material on the basis of that it can be provided in an attractive manner. The fourth option is a model that has many similarities to the ones used by e.g., Improved(tm) and Fescon and this is based on a combination of the options discussed. In this case, the material producer takes the first part of the value chain by handling the sieving to produce particles of the demanded size that will constitute the bed material. A subcontractor owns or procures a service for intermediate storage of the dry bed material and all the logistic from the material producer to the storage and from the storage to the boiler site. Additionally, the subcontractor provides a feasibility study for implementing the concept in the boiler. If there is a decision for implementation of the new bed material the subcontractor provides the technical competence needed for introducing the bed material in the boiler and educates the boiler staff. In this manner, the boiler owner can benefit from the accumulated experience in the field and secure that the needed competence is available. The discussion so far can be summarized to a few important reflections about the readiness of large-scale OCAC implementation. Not only is the technology proven with many hours of both dedicated experiments and commercial-scale operation, but practical solutions concerning aspects of bed material handling have also been developed and tested in some cases. The geographical proximity to large material sources in Sweden is furthermore positive from a transportation point of view, which can also be said of neighboring countries Finland and Norway, which have similar metallurgical industries. Thus, it seems likely that there are potentials for near-future implementation of OCAC with low-cost, available bed materials. This study is to some extent also relevant for future CLC implementation with biomass, since this technology can be assumed to have similar (high) regeneration of bed material. Low-cost oxygen carriers might be advantageous over synthetic ones when it comes to applications with high bed material regeneration.