Search

Abstract: Despite the fact that renewable energies offer a great theoretical potential of energy and that most of them have only a small share of global primary and final consumption (less than 2% of final World energy consumption was provided by wind, solar, geothermal, biomass and biofuels together) [1], their limits should be carefully analyzed. While other methodologies are based on theoretical efficiencies of renewable energies, generous estimations of effective global surface that could be occupied by the renewable infrastructure and/or ignore the mineral reserve limits, our assessment is based on a top-down methodology (de Castro et al. [2,3]) that takes into account real present and foreseeable future efficiencies and surface occupation of technologies, land competence and other limits such as mineral reserves. We have focused here on the net density power (electric averaged watts per square meter, We/m2) and compared our top-down assessment, based on real examples, with other theoretical based assessments; our results show that present and foreseeable future density power of solar infrastructures are much less (4–10 times) than most published studies. This relatively low density implies much bigger land necessities per watt delivered, putting more pressure on Earth than previously thought. On the other hand, mineral reserves of some scarce materials being used will also put pressure on this industry, because there is also a trade-off between solar park efficiencies and mineral limits. Although it is very difficult to give a global limit to the expansion of solar power, an overview of the land and materials needed for large scale implementation show that many of the estimations found in the literature are hardly compatible with the rest of human activities. Overall, solar could be more limited than supposed from a technological and sustainable point of view: around 60–120EJ/yr. [Copyright &y& Elsevier]

The aim of this paper is to develop a system dynamics model to assess the energy future up to 2050 for Ecuador considering its condition of oil producing country. Three scenarios have been developed with different assumptions regarding national and global oil availability under a Business-As-Usual narrative. Energy demand would have a 2.4-fold increase by 2050 with predominance of petroleum products in a BAU scenario with unlimited oil access. In constrained scenarios, restricted availability of oil might pressure final demand to be reduced in 31%–40% compared to BAU. Limited imports of oil and petroleum products might produce shortages in supply, causing a downfall in economic activity in sectors with high dependency on these fuels Electricity would partially substitute fossil fuels but is not enough to offset economy decay in constrained scenarios. Limiting oil exports would not have an important effect since the decline of Ecuador's oil wells is expected to be too fast. Oil exports would cease by 2030–2045. When BAU scenarios are evaluated considering limited fossil energy access in a decaying world oil production, arise the necessity to explore new strategies to deal with an energy/economic shock. • A system dynamics model assesses the energy future of a small oil producing country. • Under current trends energy demand might increase 2.4 times in the next 30 years. • Scarcity of oil would provoke energy demand reduction due to economic degrowth starting 2038. • Oil export policies might not avoid reserves depletion and extraction decline. • Strategies to avoid this collapse include energy efficiency and massive deployment of renewables. [ABSTRACT FROM AUTHOR]

The progressive reduction of high-quality-easy-to-extract energy is a widely recognized and already ongoing process. Although depletion studies for individual fuels are relatively abundant, few of them offer a global perspective of all energy sources and their potential future developments, and even fewer include the demand of the socio-economic system. This paper presents an Economy-Energy-Environment model based on System Dynamics which integrates all those aspects: the physical restrictions (with peak estimations for oil, gas, coal and uranium), the techno-sustainable potential of renewable energy estimated by a novel top-down methodology, the socio-economic energy demands, the development of alternative technologies and the net CO 2 emissions. We confront our model with the basic assumptions of previous Global Environmental Assessment (GEA) studies. The results show that demand-driven evolution, as performed in the past, might be unfeasible: strong energy-supply scarcity is found in the next two decades, especially in the transportation sector before 2020. Electricity generation is unable to fulfill its demand in 2025–2040, and a large expansion of electric renewable energies move us close to their limits. In order to find achievable scenarios, we are obliged to set hypotheses which are hardly used in GEA scenarios, such as zero or negative economic growth. [ABSTRACT FROM AUTHOR]