Energy and economic analysis of an ICE-based variable speed-operated micro-cogenerator

• Published in: Applied energy 2011-03, Vol.88 (3), p.659-671
• Main Authors: Caresana, Flavio, Brandoni, Caterina, Feliciotti, Petro, Bartolini, Carlo Maria
• Format: Article
• Language: English
• Subjects: Applied sciences; Automotive engineering; CHP; Cogeneration; Combined power plants; Distributed generation; Distributed generation Cogeneration Micro-CHP plant Internal Combustion Engine Variable speed Economic feasibility; Economic data; Economic feasibility; Economics; Electric energy; Electric power generation; Energy; Energy economics; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; General, economic and professional studies; Installations for energy generation and conversion: thermal and electrical energy; Internal Combustion Engine; Mathematical models; Micro-CHP plant; Natural gas; Residential; Spreads; Variable speed
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2010.08.016

Micro-combined heat and power (CHP) systems are a key resource to meet the EUCO 2 reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28 kW e natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant’s energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine’s rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit.