<p>Biomass and wastes upgrading are environmentally friendly alternatives to replace fossil fuels and to reduce the environmental impact of energy conversion processes. As these energy resources have to be converted in an efficient and sustainable way into a diversity of forms of useful energy (electricity, fuels and chemicals), the exergy analysis proved to be a powerful tool to evaluate the quality of those energy conversion processes. This comprehensive approach can deal not only with the thermodynamics analysis, but also includes economic and environmental aspects and impacts of energy conversion processes, allowing to identify sustainable ways of energy resources utilization.</p> <p>This lecture will describe and discuss six applications regarding the exergy and environmental assessment of energy conversion processes in the production of fuels, chemicals and electricity generation. These studies aim to highlight the contributions that the exergy method offers to reduce wastes and environmental impact on the production routes that employ biomass and wastes as energy resources. Performance parameters will be presented and applied to these processes in order to quantify and compare the efficiency, renewability, renewable and non-renewable unit exergy cost and the cumulative CO₂ emissions of the value added products of these processes.</p> <p>The six studies and applications are the following:</p> <ul> <li>Renewable and non-renewable exergy costs and CO₂ emissions in the production of fuels for Brazilian transportation sector.</li> <li>Bioethanol production routes (conventional, biochemical and thermochemical).</li> <li>Biomass based ammonia production routes.</li> <li>Black liquor upgraded gasification in an integrated Kraft pulp and ammonia production plant.</li> <li>Biogas fuelled solid oxide fuel cell with internal reforming and hydrogen co-production.</li> <li>Renewable and non-renewable exergy cost and specific CO₂ emission of electricity generation: Comparison of the Brazilian and the Netherlands cases.</li> </ul>