Documents published in Scipedia

• Sources and uses of energy. Reverse the point of view

  G. Riba Sanmartí, C. Riba Romeva, J. Pujol-Soler

  Abstracts_4rceec (2024). 132

  
  

  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.

  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 [...]

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• Renewable energy capture and occupation of territory

  M. Estorach, E. Estany, J. Peiró Alemany, P. Centelles, C. Riba Romeva

  Abstracts_4rceec (2024). 129

  
  

  Abstract

  Today there is a broad consensus that mitigating the effects of the energy and climate crisis requires the substitution of fossil resources for renewable energies in the coming decades. The Paris Agreements of 2015 (COP 21) set a limit on the increase in the average temperature of the surface of the planet Earth of 1.5 ºC, which means leaving unburned about half of the reserves of fossil fuels. Since the nature of renewable energy sources is very different from that of fossil fuels, this transition will lead to changes in the way energy is used in the transition towards sustainable social development: we are facing a real change of civilization. One of the most significant effects is the need to recapture energy from solar radiation (photovoltaic and termosolar) and its derivatives (water flows, winds, biomass). Fossil fuels are the result of capture by photosynthesis and other chemical reactions that took place hundreds of millions of years ago for hundreds of millions of years. It is a finite resource that we are now burning at a rate of 1 million times faster than when they were formed. Estimates made by some authors allow us to affirm that the surface (and territory) requirements necessary to capture and manage renewable energies will be about 80 times those of the fossil and nuclear energy system. This aspect has not yet been internalized neither by the political representatives, nor by the economic managers, nor by the general population. This communication analyses the projection of these territorial requirements on a Catalan scale when, after reducing current energy expenditure by 21% with savings programs and good practices, it will be necessary to occupy an extension of around 124,000 hectares for photovoltaic and wind catchments of which 60,000 may be on anthropized soils and the remaining 64,000 on sensitive soils (agricultural, forests and woodlands). The lack of information and an executive plan together with the high dense and unbalanced population pose additional difficulties to Catalonia's energy transition. In order to provide criteria for catchment implementations and to establish bridges of dialogue, since 2021 the CMES association has promoted the Energy Transition and Territory project (Transició Energètica I Territori, TEiT project) in collaboration with entities and people from different counties of Catalonia. This communication shall put numbers to these realities and ends with the exposition of the most relevant aspects that have emerged from these meetings.

  Abstract
  Today there is a broad consensus that mitigating the effects of the energy and climate crisis requires the substitution of fossil resources for renewable energies in the coming [...]

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• Uses of materials and energy on a finite earth

  C. Riba Romeva, C. Lorés, L. Sanchís, J. Carreras, J. Fuertes

  Abstracts_4rceec (2024). 125

  
  

  Abstract

  In terms of energy, the Earth is an open system: it constantly receives energy from solar radiation and emits the same amount of energy in the form of more degraded radiation; the displacement of the equilibrium point between these two flows due to the growth of greenhouse gases, increases the average temperature of the Earth and causes climate change. On the other hand, in relation to matter, the Earth is a closed system, apart from the sporadic fall of some meteor. Nature has the ability to regenerate the organic materials of living beings but not with many other materials. Today, the volume of materials involved in human activities is 12.5 tons per person per year (1.5 to 4 times more in rich countries): 25% of the total comes from biomass (including food), 15% are fossil fuels, 10% are metal ores, 42% are other minerals (mainly for construction) and 8% are recycled. On the other hand, obtaining and transporting materials worldwide requires more than 40% of the energy of the human system, a value that is growing with the use of increasingly rare, scarce and dispersed materials. The overexploitation of resources coupled with the increasing use of non-renewable energy resources (fossil fuels and uranium), with the consequent energy and climate crisis and the deterioration of the environment, leads both to a change in the energy model and to rethinking the practices today dominant of continuous economic growth and the linear economy based on extract-use-throw. The purpose of this communication is, after presenting the figures on the global metabolism of materials, to reflect on some of the new attitudes and actions that will need to be adopted within the framework of sustainable development. By way of example, the following are cited: 1) Moderate, reduce, eliminate the use of materials where possible; 2) Extend the life of goods and material infrastructures; 3) Reuse, recover, recycle materials; 4) Return as much as possible biologically based materials, more recyclable; 5) Avoid, as far as possible, technologies based on rare or scarce materials; 6) Avoid the dispersion of materials in the environment (atmosphere, water, soil); 7) Encourage the use of local materials in order to minimize transport and its energy impact; 8) Take care of the quality and good health of basic resources: air, water and fertile soil.

  Abstract
  In terms of energy, the Earth is an open system: it constantly receives energy from solar radiation and emits the same amount of energy in the form of more degraded radiation; [...]

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