Abstract
For any proposal on energy transition, it is necessary to know the energy reality (sources, transformations, uses, impacts), so it is necessary to have suitable tools for its measurement and accounting.
The method of energy measurement and accounting most used today to assess energy needs on a large scale (regional, national and global) is a top-down approach based on the use of aggregate values of primary energies (coal, oil and derivatives, natural gas, nuclear, hydroelectric, biomass/waste, other renewable sources) with their energy value normalized to that of oil. These, once transformed, give rise to the final energy (or energy vectors: electricity, heat and commercial fuels). The balance sheets are usually completed with a breakdown of the economic sectors to which the energy flows are addressed (agriculture/forestry, fishing, industry, commercial and public services, transport, residential, non-specified and non-energy uses). Absent is the analysis of the transformations of energy in user processes to useful energy, which actually provides the effects and activates the processes (heat, light, movement, conformation of matter, information, communication, etc.).
This methodology was developed during the second half of the XX century, and especially from the creation of the main Western energy agencies, such as the Energy Information Administration (EIA) of the United States, or the International Agency for Energy (IEA) of the OECD during the 70s, and agrees with the reality of the time, based on the extraction, trade and use of fossil fuels. Its use is universal among energy agencies, think tanks, and governments around the world and is one of the main tools for determining energy policies.
This approach to energy accounting has been useful while the energy reality was fundamentally based on fossil stocks of high energy density, but it has been unable to incorporate renewable energies satisfactorily due to their dispersed and distributed nature of flows, temporarily variable, but permanent and inexhaustible.
The purpose of this communication is to highlight the shortcomings of the current model and to propose a new energy accounting that reverses the path to be taken: starting from the needs of useful energy (at user level) and taking the reverse path upstream in the search for the most efficient energy sources and itineraries. By focusing attention on the uses of useful energy, this accounting recovers some of the lost complexity and has the virtue of generating very important pedagogical effects on users, planners and society as a whole in terms of needs and the uses of energy.
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Sources and uses of energy. Reverse the point of view 
