sustainability Review Future Perspectives of Biomass Torrefaction: Review of the Current State-Of-The-Art and Research Development Jorge Miguel Carneiro Ribeiro 1 ID , Radu Godina 2 ID , João Carlos de Oliveira Matias 1,3 ID and Leonel Jorge Ribeiro Nunes 1,3,* 1 DEGEIT—Department of Economics, Management, Industrial Engineering and Tourism, University of Aveiro, 3810-193 Aveiro, Portugal;
[email protected] (J.M.C.R.);
[email protected] (J.C.d.O.M.) 2 C-MAST—Centre for Aerospace Science and Technologies—Department of Electromechanical Engineering, University of Beira Interior, 6201-001 Covilhã, Portugal;
[email protected] 3 GOVCOPP—Research Unit on Governance, Competitiveness and Public Policies, University of Aveiro, 3810-193 Aveiro, Portugal * Correspondence:
[email protected] Received: 31 May 2018; Accepted: 4 July 2018; Published: 5 July 2018 Abstract: The growing search for alternative energy sources is not only due to the present shortage of non-renewable energy sources, but also due to their negative environmental impacts. Therefore, a lot of attention is drawn to the use of biomass as a renewable energy source. However, using biomass in its natural state has not proven to be an efficient technique, giving rise to a wide range of processing treatments that enhance the properties of biomass as an energy source. Torrefaction is a thermal process that enhances the properties of biomass through its thermal decomposition at temperatures between 200 and 300 ◦C. The torrefaction process is defined by several parameters, which also have impacts on the final quality of the torrefied biomass. The final quality is measured by considering parameters, such as humidity, heating value (HV), and grindability.