The aim of this paper is to improve the basis for the comparison of energy products. The paper will discuss important methodological issues with regard to various energy indicators and it will, by means of a few selected energy indicators, show examples of results for hydropower, wind power and electricity from biomass, gas and coal. Lastly it will suggest methods to achieve results which are more consistent when comparing electricity production technologies. In general, methodological issues can affect the results of life cycle assessments. In this paper, the authors have focused on the effect of system boundaries for energy indicators and found that the internal ranking of cases within one electricity generation technology is dependent on the indicator used. These variations do not, however, alter the general ranking of the major technologies studied. The authors suggest that future assessments should focus on a smaller set of indicators: the Cumulative Energy Demand (CED), which is the most "universal" indicator, Energy Payback Ratio (EPR) for assessment of upstream activities, and a suggested "Cumulative Fossil Energy Demand" (CFED) for resource depletion assessments. There is also a need for stricter standardisation and increased transparency in the assessment of energy products. © 2013 Elsevier Ltd.