liquid fuels (assuming the latters are not used in the processes of extraction and transformation). Additional EROI calculations There are three prominent expanded EROI calculations, they are point of use, extended and societal. Point of Use EROI expands the calculation to include the cost of refining and transporting the fuel during the refining process. Since this expands the bounds of the calculation to include more production process EROI will decrease. Extended EROI includes point of use expansions as well as including the cost of creating the infrastructure needed for transportation of the energy or fuel once refined. Societal EROI is a sum of all the EROIs of all the fuels used in a society or nation. A societal EROI has never been calculated and researchers believe it may currently be impossible to know all variables necessary to complete the calculation, but attempted estimates have been made for some nations. Calculations are done by summing all of the EROIs for domestically produced and imported fuels and comparing the result to the Human Development Index (HDI), a tool often used to understand well-being in a society. According to this calculation, the amount of energy a society has available to them increases the quality of life for the people living in that country, and countries with less energy available also have a harder time satisfying citizens' basic needs. This is to say that societal EROI and overall quality of life are very closely linked. EROI and payback periods of some types of power plants The following table is a compilation of sources of energy from German Wikipedia. The minimum requirement is a breakdown of the cumulative energy expenses according to material data. Frequently in literature harvest factors are reported, for which the origin of the values is not completely transparent. These are not included in this table. The bold numbers are those given in the respective literature source, the normal printed ones are derived (see Mathematical Description). (a) The cost of fuel transportation is taken into account (b) The values refer to the total energy output. The expense for storage power plants, seasonal reserves or conventional load balancing power plants is not taken into account. (c) The data for the E-82 come from the manufacturer, but are confirmed by TÜV Rheinland. ESOEI ESOEI (or ESOIe) is used when EROI is below 1. "ESOIe is the ratio of electrical energy stored over the lifetime