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Amine scrubbing is widely used to remove acid gases, mainly CO2 and H2S, from various process gaseous streams, because of the enhancement due to chemical reactions occurring in the liquid phase. For designing the acid gas removal plant, information on the heats of absorption of carbon dioxide in amine aqueous solutions is of paramount importance. Due to the exothermicity of reactions, a temperature increase occurs in the absorber, affecting the equilibrium and the amount of absorbed acid gas, while in the regenerator the energy requirement at the reboiler strongly depends on the heat of desorption. This work is focused on the removal of CO2, a powerful greenhouse gas, from flue gases by means of aqueous solutions of monoethanolamine (MEA), an industrial technology which is part of carbon capture and sequestration, to limit global warming. The aim is the study of the CO2-MEA-water system, in particular as for thermodynamics. The Electrolyte- NRTL model is used for the description of Vapor-Liquid Equilibrium as well as for the computation of the heat of absorption, considering the influence exerted by thermodynamic parameters. The obtained parameters, checked against experimental data of VLE and of heat of absorption, can be implemented in the commercial software ASPEN Plus® and employed for simulations of the amine scrubbing scheme.

Often left in the background by media, biogas is a renewable energy source with a great potential for development. Its production is based on the anaerobic digestion of organic waste materials, which are usually livestock effluents, municipal and industrial sewage sludge, energy crops, agro-industrial wastes, MSW landfills, etc. To date, biogas is mainly used for the production of electrical energy, thanks to a more favorable regulatory and incentive framework. Installations may adopt a cogeneration arrangement, that allows to recover the heat produced by gas-fired engines for home or industrial reuse. In the near future, however, the biogas properly upgraded to biomethane will be used for transportation or fed into the natural gas grid directly reaching end consumers, both solutions adding value to biogas. The utilization of biogas is in line with the “20- 20-20” targets to be met by the Member States of the European Union by 2020, which provide that 20 % of EU energy consumption will have to come from renewable resources and that the share of energy from renewable sources in the transport sector in 2020 will be at least 10 %. Biomethane is obtained from properly treated biogas. Biogas is a mixture of mainly methane and CO2 with other contaminants (such as H2S, nitrogen and oxygen), whose type and amount depend upon the biogas source and determine which cleaning technique (and, to some extent, also upgrading technique) is the most suitable for gas purification. ”Cleaning” is referred to the pretreatment that allows the removal of all pollutants but carbon dioxide, while “upgrading” consists of CO2 removal. There are no clear guidelines for choosing among the different techniques, mainly in relation with the biomass source which affects the biogas composition. This work performs a techno-economic analysis of the biogas-to-biomethane process using three different biogases produced from sewage sludge, agro-industrial wastes and landfills, using water scrubbing and amine washing for the upgrading process. By means of process simulation with commercial software (such as Aspen Plus®), a comparison among performances, energy requirements and solvent type is carried out. In the end, an economic assessment of the two upgrading techniques for the three considered biogas sources is performed, taking into account the flow rate of the biogas to be treated.

Biomass-derived energy sources are rising their importance since both public opinion and legislation are currently calling for a sustainable development. Biogas is an energy source which can come from municipal sewage sludge digestion thus coupling the advantages of being a renewable energy source and of allowing a smart waste reutilization. In order to fully exploit the biogas potential as vehicle fuel or natural gas substitute, biogas itself must be treated in order to obtain biomethane. Biogas upgrading, i.e., the treatment for CO2 removal, can be performed by several techniques, each one characterised by a different energy demand. Since no clear guidelines are given in literature for choosing among different biogas upgrading processes, this work presents a quantitative analysis, from an energy view point, of water scrubbing, MEA (monoethanolamine) scrubbing, and MDEA (methyldiethanolamine) scrubbing when applied to obtain biomethane from municipal sewage sludge-derived biogas. Heat and electrical power consumptions of each of the above mentioned processes have been obtained by means of process simulation with commercial packages (such as Aspen Plus®). The aim of the work is theenergetic comparison among these different techniques. Such a comparison can help in assessing the impact of the biogas purification step on the energy balance of the whole biomethane production process.

This work relates to a comparison between process solutions for the production of H2 and the co-production of H2 and energy by means of a zero emission biomass integrated gasification and a combined cycle (BIGCC) power plant. The energy production is 10 MWe, in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia. H2 is obtained by supercritical water gasification (SCWG), a technology of interest for the processing of biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process solutions and to compare their convenience. The feedstock is 280,000 t/y of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in theState of Perak (Malaysia). The processes are designed with Aspen Plus® V7.2. The aim of this work is todevelop detailed process flow diagrams for the supercritical water gasification technology in order to study and compare the convenience and the sustainability of different scenarios that can be adopted in an industrial context. The processes have been developed to reach zero emissions and zero wastes. CO2 and solid residuals are recycled inside the palm oil lifecycle. A cost analysis has been performed to find out the convenience of the proposed solutions.