*Article* **Simulating the E**ff**ect of Torrefaction on the Heating Value of Barley Straw**

### **Dimitrios K. Sidiras \*, Antonios G. Nazos, Georgios E. Giakoumakis and Dorothea V. Politi**

Laboratory of Simulation of Industrial Processes, Department of Industrial Management and Technology, School of Maritime and Industrial Studies, University of Piraeus, 80 Karaoli & Dimitriou, GR 18534 Piraeus, Greece; anazos@yahoo.gr (A.G.N.); ggiakoum@unipi.gr (G.E.G.); doritapoliti@yahoo.gr (D.V.P.) **\*** Correspondence: sidiras@unipi.gr; Tel.: +30-210-4142360

Received: 29 December 2019; Accepted: 5 February 2020; Published: 7 February 2020

**Abstract:** Many recent studies focused on the research of thermal treated biomass in order to replace fossil fuels. These studies improved the knowledge about pretreated lignocellulosics contribution to achieve the goal of renewable energy sources, reducing CO2 emissions and limiting climate change. They participate in renewable energy production so that sustainable consumption and production patterns can by ensured by meeting Goals 7 and 12 of the 2030 Agenda for Sustainable Development. To this end, the subject of the present study relates to the enhancement of the thermal energy content of barley straw through torrefaction. At the same time, the impact of the torrefaction process parameters, i.e., time and temperature, was investigated and kinetic models were applied in order to fit the experimental data using the severity factor, *R*0, which combines the effect of the temperature and the time of the torrefaction process into a single reaction ordinate. According to the results presented herein, the maximum heating value was achieved at the most severe torrefaction conditions. Consequently, torrefied barley straw could be an alternative renewable energy source as a coal substitute or an activated carbon low cost substitute (with/without activation treatment) within the biorefinery and the circular economy concept.

**Keywords:** barley straw; torrefaction; higher heating value; severity factor; sustainable development; enhancement factor; energy yield
