**Acknowledgements**

*Elements of Bioeconomy*

ing each technology [91].

**4. Conclusions**

**Figure 9.**

example, have higher capital costs due to technical hurdles and novelty status. As for integrated gasification combined cycle (IGCC), the costs vary widely as the process is still not established with significant cost reductions expected. The size of cost decline, however, is likely to be very dependent on geographical location and in line to the support given by global policy-makers and national frameworks regard-

*Capital cost (in \$/kW) for selected WtE power generation technologies [91–95].*

This chapter explored the possibility of using postprocess residues as abundant biorenewable and low-cost resources in future waste biorefineries. Available waste streams have a complex and varied composition according to its source, requiring new logistic platforms of assortment and valorization. With the exhaustion of the "collection and disposal" linear economy, new waste handling methods are unavoidable in the long term. As such, waste biorefineries that produce green energy and make virtually zero-waste high-value products in a "closed loop" and "up-cycling" approach are the "landfills" of the future. They are expected to be crucial in taking sustainable waste management into the real world allowing game-changing economic growth under the concept of circular economy. However, from the reviewed technologies, it can be concluded that single WtL and WtE processes are almost always limited in their scope, producing many times unwanted products. In this regard, the technology with more potential and scope in single applications is by far gasification; nonetheless, even this process has drawbacks such as reactor design, feeding system, and tar production that require costly posttreatment and/or further technological developments. Conversely, combining multiple WtE and WtL processes in an integrated waste biorefinery will allow the mitigation and elimination of each single process drawbacks. In gasification, for example, some of the unwanted substances generated may be utilized and valued by subsequent chemical processing, and even syngas can be upgraded. This novel waste valuation pyramid will create opportunities

**46**

Authors acknowledge the financial support received by the projects 0008\_ECO2CIR\_4\_E and 0049\_INNOACE\_4\_E co-funded by ERDF – European Regional Development Fund through INTERREG V-A Spain-Portugal Cooperation Programme (POCTEP). G. Lourinho also gratefully acknowledges FCT - Fundação para a Ciência e Tecnologia - for financial support within the scope of the grant SFRH/BDE/111878/2015.
