From fossil fuels to renewable energies

This paper describes the model of an industrial society based on fossil fuels whose supply decreases and the society is forced to develop alternative energy sources. It is conceived as an abstract model that captures the basic aspect of such a change, but in a simple and schematic way. Despite this, most of the important dynamics of this problem are included in the model. The results show interesting trends: the transition is possible but not straightforward. The technological change requires time and investment, and the dynamics of such investments are of vital importance. The system can also fall into a stage where no technological change is possible and the industrial ability of the society is lost. 1. Introduccion Energy is becoming one of the most important problems at a global scale. The rising price of oil is threatening Worlds economies and, on the other hand, the pollution caused by fossil fuels, climate change, is becoming a major source of concern worldwide. The World Energy Outlook published in 2007 by the International Energy Agency (WEO2007), estimated a continuous growth in the demand of energy that would, by 2030, require 55% more energy that today. On the other hand, 86% of the actual energy demand is now meet with fossil fuels. Although the theories about peak oil have not received much attention from public institutions and governments, they are gaining some attachment and social concern as the data confirm their predictions (ASPO2008a, ASPO2007, Annett 2005, Hubbert 1956, Hubbert 1993, Campbell 2006). Those theories predict an early scarcity of fossil fuels (especially oil) as the oil camps reach the decline. When the stocks of oil in a field fall, its extraction becomes slower, therefore the extraction curve has a bell shape, and once the peak is reached, yearly production is less every year. The dependence of today’s world economy on fossils fuels is, thus, evident. It is also evident that, if there would be an important problem of access to these fuels as the peak oil theory predicts, the World would not be able to react in an immediate way. The substitution of 86% of the energy by another sources such as renewables (of atomic fusion) would not only need technological discoveries, but a long and costly adaptation process of technological development, adaptation of industrial processes, machines and housing. Most dynamic global models of energy-economy-and climate change (EECC) are oriented towards the political decision making (emissions market, energy/emission taxes, etc). The literature on this topic is very abundant (Tol 2006, Nordhaus 1989, Fiddaman 2002) and we could classify it into two groups: system dynamics models and integrated assessment models. Most models use with few feedback among these variables (energy, economy and climate change), even in the models of system dynamics (an exception could be the model of Meadows et al World 3). This way the models of energy/economy from a holistic point of view dynamic and with feedback are almost to be done. This paper focuses on the very general problem of the energy and the economy. It has a very global view and is only a first trial; therefore our point of view is also very general. Our aim is to study the effects of energy shortage in a society based on a non renewable energy source that wants to change to renewable energies. How is this society going to make this transition? On one hand a person with a simplistic view of technology would say that a revolutionary invention will occupy the place as soon as needed, with no delays in between. On the other hand, some claim that this substitution is not possible, since renewable energies are not independent of fossil fuels: they need a complex technological network in order to be set and this network does not work without fossil fuels. Tainter 1996 claims that human societies tend to become more complex, but in doing so, the societies find decreasing benefits from each level of complexity, until it comes to a point where the increases in complexity have negative returns and the society collapses. Tainter fears that the shortage of fossil energy will mean that the complexity of our technology cannot be sustained any more, and the renewable energies will requite more complex technology which will tend to increase complexity, and therefore, lead even more rapidly to collapse. The theory of Olduvai (Duncan 1996) is also another pessimistic view of society based on the correlation between historical data of population and energy consumption. It predicts that, when the fossil fuels are exhausted, the carrying capacity of the World would be that of a pre industrial society leading to a severe a decline in World population. What can system dynamics say about that? We know that the story of the system is important. Fossil fuels are an input external to human evolution, but the actual state of a system is not only the result of its inputs, but also the result of its past behaviour. Those who say that, once this input is removed, we would go back to the previous stage of development, might ignore the dynamics of the human system and its ability to keep memory. Can the accumulated stock of technological knowledge and material capital serve as a basis to lead the society to an equilibrium point of higher energy consumption and population than pre-fossil society? The model presented in this paper is an attempt to answer to these questions. It was only conceived as a sort of game, not a realistic model with estimated parameters. The idea is to capture the basic dynamics of this problem and gain insight into it, but never loosing the holistic view. Section 2 describes the main variables and feedback loops of the model, section 3 describes the parameters used in the model, while results of the simulations and conclusions are given in sections 4 and 5. 2. Model description The model has got three stock variables: material capital, non renewable resources and renewable energy infrastructure. Let us describe in detail the feedback loops associated with them. Material capital. We have considered the whole problem of a technological society that uses energy for all kinds of artefacts: industries, machines, housing, infrastructure.... All these artefacts are what we call material capital (see figure 1). Our material capital is not equivalent to the capital of economics, or GDP, it only covers the material aspects. If there is a shrink in the material capital it might mean, either that the society is becoming more austere while maintaining social stability, or that there is a complete social breakdown and industrial production is not possible. The social/economical or political aspects will not be considered so far, those aspects are too complex for this type of model. If there is enough energy, the material capital tends to growth exponentially at a rate greater than the depreciation of old material goods, this loop imitates the exponential growth of today’s economy, which is, to date, highly correlated to energy consumption (Hirsch 2008). Energy consumption use is proportional to material capital (consumE constant). This relationship has been made constant, since it is not very clear weather it tends to increase or decrease. On one hand technological improvements tend to make a society more efficient in the use of energy, but, on the other hand, when the energy available decreases it is more difficult to find good materials for sophisticated technologies and the efficiency of technology could decrease. depreciation_of_material_capital material_capital growth_of_material_capital growth_limtied energy_percent growth maximum_growth energy_useconsumE intensity