Fuel cells are one of the technologies available for CHCP, combined heat, cooling and power production, systems. They offer several advantages over more conventional systems, but they still need to overcome a number of barriers until they are readily available for commercialization. At this stage, it is important to fund demonstration projects that experiment with fuel cell technology in pre-commercial situations. In this context, a CHCP system, using a high temperature fuel cell (SOFC) and an absorption chiller, was designed in order to meet the energetic demands of a hospital for electricity, cooling, heating and hot water. The hospital load profile was determined taking into consideration the hourly energy consumption for four different typical days in the year. The CHCP system was designed so that the fuel cell meets the electrical demand of the hospital and, since the SOFC did not produce enough thermal energy, a boiler was considered. The artificial thermal efficiency of the CHCP system is 68%. The investment analysis is presented and it is concluded that, at the present and at three other scenarios, the system is not financially feasible. Despite this conclusion, it is important to invest on demonstration projects to help fuel cells reaching commercialization.
The current status and legal framework of biogas production in Portugal are analyzed and compared to that of five other European countries, characterized by wideranging diversity of substrates and biogas applications. With this comparison, and with the calculation of the biogas energy potential in Portugal, the authors want to assess the significance of developing the Portuguese biogas sector. This study illustrates that the highest biogas feed-in tariffs are applied in the countries with a more developed sector. In Portugal, despite the fact that the organic effluents are a relevant energy source (873 Mm 3 biogas year -1 ; 4889 GWh year -1 ) and that new feed-in tariffs were established, biogas valorisation is still at an early stage. The importance of anaerobic digestion was only recognized in 2007 and the present installed power is about 10% of the potential electrical power (229 MW). Therefore, it is desirable to strengthen the national and regional biogas market.
a b s t r a c tThe use of forest and agricultural residues for energy production presents multiple benefits, but the link between bioenergy and the environment is complex and not all of the energetic options have the same impacts. This work evaluates the net positive effect of valorizing residual biomass in the context of a rural area of Portugal, Estremoz. It focuses on the combined assessment of biomass availability, technoeconomic feasibility and environmental aspects of utilizing forest and agricultural residues to produce bioheat. At first, the energy potential of the residual biomass available in the municipality is evaluated using a geographical information system database. The assessment with RETScreen of the technoeconomic feasibility of replacing electricity by biomass for heating local public schools follows. The results show that around 27 314 t of residues, corresponding to about 267 680 GJ, are produced each year in Estremoz, more than half in montado areas. The use of this biomass for the replacement of the existing electric heating systems of nine local schools by biomass-based ones offers good project profitability. As far as the environment is concerned, the energetic valorization of the residual biomass in Estremoz has multiple benefits. It contributes to climate change mitigation by saving greenhouse gas emissions and promoting the preservation of the traditional extensive uses of the ecosystems. Moreover, a correct vegetation management decreases the fire risk, potentiates the increase in biodiversity, offers better conditions for native species and allows to maintain the ecosystems.
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