Purpose – The aim of the study is to identify main failure phenomena and to evaluate reparation costs, reparation time, loss of profit and their relationship with power plant and faulty components age. In this work, several machinery breakdowns occurred in thermal power plants fed by solid biomass, biodiesel, biogas and municipal solid waste, have been investigated. In the period between 2004 and 2012, 23 faults have been analyzed. Design/methodology/approach – Each fault has been classified considering: power plant technical specifications, type of damage, reparation cost, reparation time and loss of profit (when data are available). The whole data have been, therefore, compared to find out significant information. Findings – It has been pointed out that relevant property damages are mainly caused by old components failure. In addition, the loss of profit is generally much higher than the property damage (six times on average basis). Originality/value – The study provides useful information that can be of interest for personnel of energy utilities, banks and insurance companies in managing power plants risks and in planning the availability of energy services.