A global renewable mix with proven technologies and common materials

ArticleinEnergy Policy 41 · December 2011with 189 Reads
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  • Article
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    We use the concept of Energy Return On energy Invested (EROI) to calculate the amount of the available net energy that can be reasonably expected from World oil liquids during the next decades (till 2040). Our results indicate a decline in the available oil liquids net energy from 2015 to 2040. Such net energy evaluation is used as a starting point to discuss the feasibility of a Renewable Transition (RT). To evaluate the maximum rate of Renewable Energy Sources (RES) development for the RT, we assume that, by 2040, the RES will achieve a power of 11 TW (10¹² Watt). In this case, by 2040, between 10 and 20% of net energy from liquid hydrocarbons will be required. Taking into account the oil liquids net energy decay, we calculate the minimum annual rate of RES deployment to compensate it in different scenarios. Our study shows that if we aim at keeping an increase of 3% of net energy per annum, an 8% annual rate of RES deployment is required. Such results point out the urgent necessity of a determined policy at different levels (regional, national and international) favoring the RT implementation in the next decades.
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  • Article
    Abstract Several recent studies have proposed fast transitions to energy systems based on renewable energy technology. Many of them dismiss potential physical constraints and issues with natural resource supply, and do not consider the growth rates of the individual technologies needed or how the energy systems are to be sustained over longer time frames. A case study is presented modelling potential growth rates of the wind energy required to reach installed capacities proposed in other studies, taking into account the expected service life of wind turbines. A sustained commissioning model is proposed as a theoretical foundation for analysing reasonable growth patterns for technologies that can be sustained in the future. The annual installation and related resource requirements to reach proposed wind capacity are quantified and it is concluded that these factors should be considered when assessing the feasibility, and even the sustainability, of fast energy transitions. Even a sustained commissioning scenario would require significant resource flows, for the transition as well as for sustaining the system, indefinitely. Recent studies that claim there are no potential natural resource barriers or other physical constraints to fast transitions to renewable energy appear inadequate in ruling out these concerns.
  • Article
    The coming fossil fuel peak may cause shortages in energy supplies and major disturbances in the global economy. The forecasts for the future of our way of life are very divergent depending on the prediction used for future human access to energy, and they range between collapse and indefinite growth. The LINEX production function, which depends on energy input, was modified, calibrated and used to model the gross domestic product (GDP) of the US economy under several different energy scenarios after the fossil fuel peak. The effects of information and communication technologies and technological innovation after energetic crises have been also modeled. A future renewable mix of global scale will require the use of a major fraction of the reserves of several important minerals. In this context, a future steady-state economy appears to be the best plausible scenario. Some of the implications and challenges derived from this steady-state economy are discussed.
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    A feasible way to avoid the risk of energy decline and to combat climate change is to build a worldwide, 100% renewable energy mix. Renewable energy can be scaled up to the range of 12 electric terawatts (TWe) if 10% of continental shelves are exploited with floating turbines to depths as low as 225 m, 5% of continents with ground turbines, and 5% of the main deserts with concentrating solar power (CSP) farms. However, a globally electrified economy cannot grow much above 12 TWe without approaching the limit of terrestrial copper reserves. New photovoltaic silicon panels do not use silver metallization pastes and could contribute up to 1 TW of decentralized residential power. Hydroelectricity has a potential of 1 TW but a fraction of this would have to be sacrificed for energy storage purposes. Hydro, CSP, wave energy and grid integration at continental scales may be sufficient to fit supply to demand, avoiding intermittency. The renewable energy mix would have an energy return on energy invested about 18, which is 25% lower than the estimated present one. That should be sufficient to sustain an industrialized economy provided that the substitution of electricity for fossil fuels is done intelligently.
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  • Preprint
    The Global Carbon Budget is the cumulative carbon emissions that human activities can generate while limiting the global temperature increase to less than 2°C. On this basis, most countries ratified the Paris Agreement 2015, pledging to reduce national emissions and the impacts of climate change. The European Union has planned to reduce emissions by 80% of their 1990 value by 2050 but such a target needs to be coupled with a further constraint on the cumulative greenhouse gases released along the path to 2050. The aim and the novelty of this study are to propose, for the first time, a carbon budget for the European Union, which represents the most significant physical characteristic to assess the feasibility of current EU-28 greenhouse gas reduction objectives under the goals of the 2015 Paris treaty
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    The Paris Agreement, ratified in 2015, pledged to reduce greenhouse gas emissions within a Global Carbon Budget that limits the global temperature increase to less than 2 °C. With the Roadmap 2050 mitigation measures, the European Union has a target to reduce emissions by 80% of their 1990 value by 2050 but without giving an estimation or a maximum ceiling for the total amount of cumulative greenhouse gases emissions over that period. Thus, the impact of the EU regulations on global warming remains unestimated. The aim and the novelty of this study are to develop a set of potential European emissions trajectories, within the Global Carbon Budget and at the same time satisfying the Roadmap 2050 goals. The result of the study highlights the urgency to reinforce mitigation measures for Europe as soon as possible because any delay in policy implementation risks the Roadmap 2050 mitigation package being insufficient to achieve the objectives of the Paris treaty.
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    Renewable energy technologies are of the highest priority in the plans to diminish carbon footprint of Germany. Although not emitting greenhouse gases while operation, renewables require substantial amount of natural resources on the manufacturing and construction phase. Many of the renewable energy technologies require scarce minerals which can only be imported to Germany from outside of European Union. Simultaneously, renewable energy projects have high embodied energy (energy investment to build). The aim of present thesis is to calculate the amount of mineral resources and energy needed in course of Energiewende in Germany for the period of 2015-2050. To address this issue, author has studied available literature and developed mathematical model of resources and energy consumption in German power generation sector. Model allows analysis of annual consumption of numerous materials for building of wind power, photovoltaics and power storage capacities after year 2014 in Germany. Resource demand in the model can be expressed as a function: D=ƒ(Ds; Cn; Cr; S; R; km), where D – material demand, Ds - specific material demand per Wp (Watt power) of capacity, Cn - new capacity, Cr - repowering capacity, S - share of technology (from 0 to 1), R – recycling coefficient (from 1 to 0), km – coefficient of specific material demand evolution (from 1 to 0). Energy demand in the model can be expressed as a function: E=ƒ(Es; Cn; Cr; ke), where E – energy demand, Es- specific energy demand per Wp capacity, ke – coefficient energy demand evolution (from 1 to 0). After accomplishing the model, author has introduced linear growth of capacities from 2015 values to the capacity targets taken from Fraunhofer ISE scenario of 2050 renewable mix. Where applicable, some intermediate capacities targets were used. Values of annual materials and consumption are obtained for the cases with dominating one type of technologies as well as some technologies mixes. Additionally, scenario with and without metals recycling were compared. Obtained results serve as a boundary values of future German resources consumption for the Energiewende. Some technologies options are found to be not sustainable in terms of scarce materials availability. Energy investment requirements are found to be quite substantial and in some years may constitute equivalent of 26% of gross domestic power generation. KEYWORDS: Energiewende, Germany, renewable energy, resources demand, energy demand, wind power, photovoltaics, power storage
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    This work quantifies how human interventions can modify the tidal energy potential in a mesotidal estuary and if these variations can be used to increase the production of renewable energy at a highly altered bay. The analysis is applied to Cádiz Bay (Southern Spain), where important human interventions are developing, specifically a new port terminal and a 5 km long bridge. Due to these interventions, significant impacts on the bay hydrodynamics are expected. To assess the variations on the tidal energy resource after interventions, a three dimensional numerical model is used to obtain the bay hydrodynamics (Delft3D model). It was calibrated and validated against water levels and currents at tidal and sub-tidal scales using the results of two extensive field surveys. Two scenarios are defined, corresponding to the pre and post interventions situations. Results show that before interventions, only one area has the potential to locate a Tidal Energy Converter (TEC) array. However, after interventions a new area arise due to the increase of flow velocities induced by human modifications of the bay geometry. The energy potential is assessed for these two locations, and their efficiencies (potential energy per device) are obtained, indicating that after interventions the new TEC array is even more efficient than that of the pre interventions scenario, and an increase of 20% in the energy that can be potentially produced is obtained.
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    Analyses proposing a high share of concentrated solar power (CSP) in future 100% renewable energy scenarios rely on the ability of this technology, through storage and/or hybridization, to partially avoid the problems associated with the hourly/daily (short-term) variability of other variable renewable sources such as wind or solar photovoltaic. However, data used in the scientific literature are mainly theoretical values. In this work, the actual performance of CSP plants in operation from publicly available data from four countries (Spain, the USA, India, and United Arab Emirates) has been estimated for three dimensions: capacity factor (CF), seasonal variability, and energy return on energy invested (EROI). In fact, the results obtained show that the actual performance of CSP plants is significantly worse than that projected by constructors and considered by the scientific literature in the theoretical studies: a CF in the range of 0.15–0.3, low standard EROI (1.3:1–2.4:1), intensive use of materials—some scarce, and significant seasonal intermittence. In the light of the obtained results, the potential contribution of current CSP technologies in a future 100% renewable energy system seems very limited.
  • Technical Report
    Full-text available
    This document documents the “World Limits Model” version 1.5 (WoLiM 1.5), reporting the methods, rationale and hypothesis applied. This model is an energy-economy-environment simulation system dynamics model that focus on future energy resource availability and its implications for human socioeconomic systems at world aggregated level. In this version, it aims to describe the relationship Economy-Energy-Environment focusing on biophysical limits and deployment potential of renewable and non-renewable energies, as well as on anthropogenic Climate Change. This report documents an updated version of the model applied in the published papers Capellán-Pérez et al (2014a) and Capellán-Pérez et al (2015), and documented in the previous Technical Report (Capellán-Pérez et al., 2014b). The main changes in this model version and documentation include: - Correction of minor errors, improvement of modelling structures and update of the model to more recent data - Improved and expanded documentation (within the model and in this Technical Report). - More depletion curves of non-renewable resources available for simulation. - Disaggregation between conventional and unconventional gas. - Inclusion of offshore wind resource. - Consideration of the potential of all renewable sources (bioenergy, geothermal and solar) for other uses than electricity which allows the confrontation of its supply and demand. - Rough estimation of the overcapacity required to integrate intermittent renewable energy sources in the electricity sector. - Consistent behavior under scenarios of GDP reduction. - Implementation in VENSIM and excel interface to run customized simulations (without requiring to install the VENSIM proprietary software). For illustrating the introduced changes and for the purpose of comparison, the 5 scenarios simulated in Capellán-Pérez et al (2014a) with WoLiM 1.0 are re-run. Finally, the main limitations and further developments of the model are reported.
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    There is increasing interest in mapping out how the world can move to a low-carbon energy system. We take the water, wind and solar (WWS) program of Jacobson and Delucchi as our starting point and examine in detail the technology and resource commitments needed to implement a WWS strategy. We recharacterize the approach as one that sees the world making a 10 TW ‘Big Push’ between 2010 and 2030, culminating in a global electric power system rated at 11.5 TW, where additions are 100% renewable. Our specific proposals are for a global power system to be constructed by 2030 consisting of 3 million wind turbines rated at an average of 6.5 MW each, 12,500 solar PV installations rated at 400 MW each. 14,000 CSP installations rated at 400 MW each and 1000 hydroelectric installations rated at 1.3 GW each. This gives a theoretical capacity of 10 TW of extra power needed (and an installed capacity of just over 30 TW), all achieved through manufacturing. We sketch the land and physical resources required to reach such a goal and a plausible pathway by which this could be achieved.
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    Among the existing methodologies to assess future availability of mineral resources, the Hubbert peak model is a direct approach that can provide useful information about non-fuel mineral depletion using BAU production trends. Using lithium as a case study, the influence on the fluctuations on extractable resources has been analyzed. Accounting only for conventional lithium resources, the peak is only delayed less than two decades even if the most optimistic resources values are doubled. Additionally, using resources information obtained mainly from USGS data, the maximum production peak of 47 mineral commodities has been estimated. For two of them, the maximum theoretical production peak has already been reached, 12 could have theirs in the next 50 years and a total of 30 commodities could reach their maximum production peak in the next century. Many factors can influence these values, changes in future extraction trends, ore grade, exploration and new discoveries and more accurate data on resources. With this information the most crucial elements (i.e. those peaking soon) can be identified and be used to put more emphasis on policies regarding sustainable use of non-renewable commodities.
  • Preprint
    Thermal Energy Storage (TES) systems are central elements of various types of power plants operated using renewable energy sources. Packed bed TES can be considered as a cost-effective solution in concentrated solar power plants (CSP). Such a device is made up of a tank filled with a granular bed through which a heat-transfer fluid circulates. However, in such devices, the tank might be subjected to an accumulation of thermal stresses during cycles of loading and unloading due to the differential dilatation between the filler and the tank walls. The evolution of tank wall stresses over thermal cycles, taking into account both thermal and mechanical loads, is studied here using a numerical model based on the discrete element method (DEM). Simulations were performed for two different thermal configurations: (i) the tank is heated homogeneously along its height or (ii) with a vertical gradient of temperature. Then, the stresses resulting from the two different loadings applied on the tank are compared as well the kinematic response of the internal granular material. The kinematics of the granular material are analyzed at the particles scale (i.e. discrete elements), with a focus on the effect of particle/particle and wall/particle friction. Results show that a faster rearrangement of the packing occur when a thermal gradient is moving along the tank, leading to higher values of stresses applied on the tank walls. In addition to this, the behavior of the packed bed is dependent on the friction levels in the tank, whether the friction between particles themselves or the friction at the contact of particles with the shell. The influence of the slenderness ratio of the tank is investigated as well. Moreover, a reduction of 20% of thermal applied stresses can be obtained when inclined wall boundaries are used. The combination of an homogeneous configuration with low levels of friction (using lubricants) in thermocline storage tanks with inclined fixed boundaries can decrease significantly the induced stresses applied on the wall.
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    a b s t r a c t The global financial system is a major component of our global society. The available analyses of sustainability, however, have poorly assessed the role of the financial system in scenarios of future global change. Here we contrast current global flows in the financial system with the future economic costs of a worldwide transition to renewable energies under the baseline and 450 ppm scenarios for emissions of greenhouse gases proposed by the IPCC. We show that annual global financial flows are three orders of magnitude greater than the annual economic costs of policies for global sustainability. A small global tax on financial transactions of 0.05% could thus provide the required funds for the deployment of renewable energies. To assess the roles of the financial sector in future policies for sustainability, we identified 14 key international actors and enumerated 16 key policies for sustain-ability that should be implemented to achieve effective global ecological and financial sustainability. We conclude that the proposed structural reforms to the financial system are essential steps urgently required for financing a global transition to a sustainable economy. Consequently, we suggest that the international scientific community should urgently pursue an academic consensus on policy recom-mendations for the financial sector.
  • Article
    Wind power technology is one of the cleanest electricity generation technologies that are expected to have a substantial share in the future electricity mix. Nonetheless, the expected increase in the market share of wind technology has led to an increasing concern of the availability, production capacity and geographical concentration of the metals required for the technology, especially the rear earth elements (REE) neodymium (Nd) and the far less abundant dysprosium (Dy), and the impacts associated with their production. Moreover, Nd and Dy are coproduced with other rare earth metals mainly from iron, titanium, zirconium, and thorium deposits. Consequently, an increase in the demand for Nd and Dy in wind power technology and in their traditional applications may lead to an increase in the production of the host metals and other companion REE, with possible implications on their supply and demand. In this regard, we have used a dynamic material flow and stock model to study the impacts of the increasing demand for Nd and Dy on the supply and demand of the host metals and other companion REE. In one scenario, when the supply of Dy is covered by all current and expected producing deposits, the increase in the demand for Dy leads to an oversupply of 255 Gg of total REE and an oversupply of the coproduced REE Nd, La, Ce and Y. In the second and third scenarios, however, when the supply of Dy is covered by critical REE rich deposits or Dy rich deposits, the increase in Dy demand results in an oversupply of Ce and Y only, while the demand for Nd and La exceeds their supply. In the case of an oversupply of REEs, the environmental impacts associated with the REEs production should be allocated to Dy and consequently to the technologies that utilize the metal. The results also show that very large quantities of thorium will be co-produced as a result of the demand for Dy. The thorium would need to be carefully disposed of, or significant thorium applications would need to be found.
  • Article
    a b s t r a c t Energy poverty and lack of electricity in the rural area exacerbate the poverty of the developing countries. The sustainable renewable technologies can be considered as efficient tools to reduce energy poverty whenever they are conducted based on an appropriate policy. Electricity can improve the human's lifestyle by increasing the level of health, education, welfare and technology. Currently, Sub-Sahara Africa with only 14.2% of rural electrification has the first rank in the world with lowest access to electricity, in that region around 585 million citizens has almost no access to electricity. The present study focuses on the general global policies to electrify the rural areas. In this regard, variety of plans and programs conducted by governmental and private institutes are investigated. In the year 2011, the International Energy Agency (IEA) has developed three global strategies based on the world energy market that defines the overall world energy approach. In the present work, different technologies for rural electrification are taken into account in two major categories of grid connected and off-grid systems. Furthermore, based on sustainable development with emphasis on environmental considera-tion, the feasibility of electrification by using different types of renewable energies such as solar, biomass, hydro, wind and wave have been studied. Despite reliability of grid connection, results indicate that renewable energy sources are the best choice especially in areas far from grid connections. Challenges between financial institutes and executive agencies result in resource management and technology development in order to overcome existing barriers and issues.
  • Article
    Present day electricity is a bargain. It frees mankind from a host of dirty, debilitating occupations—epitomized by the now endangered occupation of legger. Correctly applied, electricity would make a most excellent paramount energy carrier for a post-carbon world. It is, however, only an energy carrier and not a source of energy, the preeminent source for its generation being bargain-priced fossil carbon. But when, in less than a century, that is gone, electricity is a good bet to cost markedly more while being still a bargain. This paper once again shows that mankind's energy needs can be met by (i) renewable solar generation of electricity buffered by (ii) massive electricity storage and (iii) a robust distribution grid. The time available for making this switch from fossil carbon to solar is at best a century and possibly as little as fifty years.
  • Article
    The Anthropocene is a proposed time subdivision of the earth’s history correlated with the strong perturbation of the ecosystem created by human activity. Much debate is ongoing about what date should be considered as the start of the Anthropocene, but much less on how it will evolve in the future and what are its ultimate limits. It is argued here that the phenomena currently defining the Anthropocene will rapidly decline and disappear in times of the order of one century as a result of the irreversible dispersal of the thermodynamic potentials associated with fossil carbon. However, it is possible that, in the future, the human economic system may catalyze the dissipation of solar energy in forms other than photosynthesis, e.g., using solid-state photovoltaic devices. In this case, a strong human influence on the ecosystem may persist for much longer times, but in forms very different than the present ones.
  • Article
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    Growing scientific evidence shows that world energy resources are entering a period shaped by the depletion of high-quality fuels, whilst the decline of the easy-to-extract oil is a widely recognized ongoing phenomenon. The end of the era of cheap and abundant energy flows brings the issue of economic growth into question, stimulating research for alternatives as the de-growth proposal. The present paper applies the system dynamic global model WoLiM that allows economic, energy and climate dynamics to be analyzed in an integrated way. The results show that, if the growth paradigm is maintained, the decrease in fossil fuel extraction can only be partially compensated by renewable energies, alternative policies and efficiency improvements, very likely causing systemic energy shortage in the next decades. If a massive transition to coal would be promoted to try to compensate the decline of oil and gas and maintain economic growth, the climate would be then very deeply disturbed. The results suggest that growth and globalization scenarios are, not only undesirable from the environmental point of view, but also not feasible. Furthermore, regionalization scenarios without abandoning the current growth GDP focus would set the grounds for a pessimistic panorama from the point of view of peace, democracy and equity. In this sense, an organized material de-growth in the North followed by a steady state shows up as a valid framework to achieve global future human welfare and sustainability. The exercise qualitatively illustrates the magnitude of the challenge: the most industrialized countries should reduce, on average, their per capita primary energy use rate at least four times and decrease their per capita GDP to roughly present global average levels. Differently from the current dominant perceptions, these consumption reductions might actually be welfare enhancing. However, the attainment of these targets would require deep structural changes in the socioeconomic systems in combination with a radical shift in geopolitical relationships.
  • Article
    Full-text available
    The Anthropocene is a proposed time subdivision of the earth's history correlated to the strong human perturbation of the ecosystem. Much debate is ongoing about what date should be considered as the start of the Anthropocene, but much less on how it can evolve in the future and what are its ultimate limits. It is argued here that the phenomena currently defining the Anthropocene will rapidly decline and disappear in times of the order of one century as a result of the irreversible dispersal of the thermodynamic potentials associated to fossil carbon. However, it is possible that, in the future, the human economic system may catalyze the dissipation of solar energy in forms other than photosynthesis, e.g. using solid state photovoltaic devices. In this case, a strong human influence on the ecosystem may persists for much longer times, but in forms much different than the present ones.
  • Article
    In this article, we suggest a methodology that combines geographic information systems (GIS) and material flow analysis (MFA) into a secondary reserve-prospecting tool. The approach is two-phased and couples spatially informed size estimates of urban metal stocks (phase 1) to the equally spatially contingent efforts required to extract them (phase 2). Too often, even the most advanced MFA assessments stop at the first of these two phases, meaning that essential information needed to facilitate resource recovery, i.e., urban mining, is missing from their results. To take MFA one step further, our approach is characterized by a high resolution that connects the analysis of the stock to the social practices that arrange material flows in the city, thereby enabling an assessment of the economic conditions for secondary resource recovery. To exemplify, we provide a case study of the hibernation stock of copper found in disconnected power cables in Linköping, Sweden. Since 1970, 123 tonnes of copper or ≈1 kg per person have accumulated underneath the city, predominantly in old, central parts of the city and industrial areas. While shorter cables are more numerous than long ones, the longer ones contribute to a larger share of the stock weight. Resource recovery in specific projects reliant on digging comes at great costs, but integrating it as an added value to ordinary maintenance operations render eight locations and 2.2 tonnes of copper (2% of the stock) profitable to extract. Compared to the budget sizes of regular maintenance projects, the integrated recovery of a significant share of the stock comes with relatively small economic losses. Therefore, we suggest integrated resource recovery and regular maintenance as an interesting environmental measure for any infrastructure provider to engage with.
  • Article
    Full-text available
    A feasible way to avoid the risk of energy decline and combat climate change is to build a 100% renewable global energy mix. However, a globally electrified economy cannot grow much above 12 electric terawatts without putting pressure on the limits of finite mineral reserves. Here we analyze whether 12 TW of electricity and 1 TW of biomass (final) power will be able to fuel a future post-carbon economy that can provide similar services to those of a contemporary economy. Contrarily to some pessimistic expectations, this analysis shows that the principle economic processes can be replaced with sustainable alternatives based on electricity, charcoal, biogas and hydrogen. Furthermore, those services that cannot be replaced are not as crucial so as to cause a return to a pre-industrial society. Even so, land transport and aviation are at the limit of what is sustainable, outdoor work should be reorganized, metal primary production should be based on hydrogen reduction when possible, mineral production should be increasingly based on recycling, the petrochemical industry should shrink to a size of 40%-43% of the 2012 petrochemical sector, i.e., a size similar to that the sector had in 1985-1986, and agriculture may require organic farming methods to be sustainable.
  • Article
    Full-text available
    With the publication of the 2010 edition of its World Energy Outlook, the International Energy Agency recognized that crude oil plus condensates had reached a maximum extraction rate of 76 million barrels a day in 2006, a level that has maintained approximately constant since then. Detailed studies by Laherrere of the Ultimate Recoverable Resource (URR) of oil, coal and gas show that they must be about 400-420 Gtoe for oil (conventional and non-conventional), 300 Gtoe for gas, and 750 Gtoe for coal. With these parameters, historical data of production can be fitted to Hubbert models, and the predicted peaks take place at 2021 (oil), 2029 (gas) and 2060 (coal). The aggregated power produced by all the fossil fuels is expected to peak in 2025-2030. The period between 2006 and 2030 can hence be considered the start of a new era: the era of expensive fossil fuels, which is also the era of more pollutant and less net energy fuels. To compensate the stagnation (and foreseeable decline) in crude oil production, unconventional oil sources are gaining ground. Tar sands and extra-heavy oil were the first ones to be developed; biofuel production from conventional cultures ramped shortly after. During the last years new sources emerged: ultra deep-water marine wells, Arctic oil, tight oil, shale oil, and new biofuels. In parallel, a similar process of shifting to new, unconventional sources has taken place in gas production (shale gas, coal bed, tight gas, biodigestors, etc.). The situation for coal is different: no unconventional sources have been identified, but known reserves specially for lower quality coals are so vast that the focus has been put in new methods to exploit existing, lower grade ores (as, for instance, top mountain removal). Each one of these sources has associated greater economic costs than conventional ones, but less attention has been paid to externalities, which may imply a growing economic cost in the future and may also significantly dampen production prospects. Along with the high ecological costs that many of these sources have, we have paid special attention to two aspects that, to our understanding, will most severely limit future production: water use and net energy. Both peak of fossil fuels and ecological costs of unconventional fossil-fuels production may prevent the future growth of exergetic services. The importance of these services for economic output of developed countries has been emphasized by Ayres and illustrated also by other authors. Our conclusion is that economic decline may be avoided only by a major deployment of renewable sources, and by high improvement of energy saving and technological efficiency in energy conversion. In the longer term, we should prepare the transition to a new steady state economy which should be able to maintain the prosperity that western societies have reached, to balance the flagrant global inequality, and to make compatible these goals with a decreasing fossil energy supply and a steady economic output.
  • Article
    Full-text available
    El gobierno de las grandes corporaciones (gubernamentalidad corporativa), conformado históricamente, que fue transformando la sociedad en su conjunto, en un gobierno sobre todos los demás, induciendo el desarrollo de una serie de aparatos del gobierno y de saberes. Teniendo como eje central a la economía, que se materializa en el neoliberalismo, y es a partir de 1971 con el abandono del patrón-oro, cuando esta nueva gubernamentalidad comienza su periodo de consolidación. En estos casi cincuenta años, se desarrolla de la mano de la gubernamentalidad corporativa, la mayor desigualdad económica, una enorme precarización de la clase trabajadora y el fuerte incremento de los costes sociales del capitalismo. Este trabajo describe el proceso de concentración de la riqueza y sus efectos en la sociedad. También en este periodo, se produce el desplazamiento del eje central del capitalismo y de su sistema de apropiación, como lo fue el sistema de producción capitalista, por la apropiación mediante el sistema financiero-monetario (apropiación indirecta). Junto al traspaso de la planificación del Estado a manos de las empresas privadas. Finalmente este artículo, describe las debilidades del actual sistema de apropiación capitalista y el fin del imperio financiero angloamericano.
  • Chapter
    A vast majority of people cannot accept that living in affluence is coming to an end. They do not admit they will be obliged to implement some type of austerity. This chapter examines the psychosocial mechanisms and structural and mental inertias that prevent individuals from becoming aware of this problem. The cultural and behavioural legacy of the era of consumer abundance is linked to individualist views of the role of private and collective consumption that need to be overcome for everybody’s needs to be fulfilled on the basis of solidarity. The chapter puts forward a number of proposals for the construction of a cultural and moral project of alternative and supportive austerity.
  • Article
    The present article is a critical literature review about studies which are based on LCA (life cycle assessment) and about studies which include environmental issues about concentrating solar systems (concentrating photovoltaic (CPV), concentrating solar power (CSP), etc.). The results reveal that CPV environmental profile depends on several factors such as the materials of the concentrator and the direct solar radiation. On the other hand, there are different factors which influence CSP profile (from environmental point of view), including water use and materials e.g. for storage. By considering the literature review presented it can be noted that: 1) Regarding CPV, there is a need for more studies which investigate different concentration ratios, CPVT (concentrating photovoltaic/thermal) systems, low-concentration CPV, strategies to reduce the impact of certain components such as the tracking (especially for large-scale applications) and the concentrators, 2) Concerning CSP, there is a need for more investigations about dish-Stirling, storage materials, strategies for water savings, soiling effect, 3) In general, regarding concentrating solar systems, there is a need for more studies with Fresnel lenses and reflectors, for small-scale systems for buildings and for multiple final applications (desalination, drying, etc.), 4) With respect to the adopted methods/environmental indicators, certainly CO2.eq emissions, embodied energy and EPBT (energy payback time) can provide useful information for concentrating solar systems; nevertheless, there is a need for utilization of additional methods (e.g. based on midpoint, endpoint approaches) which can also offer useful information.
  • Article
    Solar thermal energy is a clean, climate-friendly and inexhaustible energy resource. It is therefore promising to cope with fossil fuel depletion and climate change. Thermal storage enables to make this intermittent energy resource dispatchable, reliable on demand and more competitive. Nowadays, most of the concentrated solar power plants equipped with integrated thermal storage systems use the two-tank molten salt technology. Despite its relative simplicity and efficiency, this technology is expensive and requires huge amounts of nitrate salts. In the short to medium term, packed-bed thermal energy storage with either liquid or gaseous heat transfer fluid is a promising alternative to reduce storage costs and hence improve the development of solar energy. To design reliable, efficient and cost-effective packed-bed storage systems, this technology, which involves many physical phenomena, has to be better understood. This paper aims to sum up some key aspects about design, operation, and performances of packed-bed storage systems. In the first part, most representative setups and their experience feedback are presented. The controllability of packed-bed storage systems and the special influence of thermal stratification are pointed out. In the second part, the various numerical models used to predict packed-bed storage performances are reviewed. In the last part, some useful correlations enabling to quantify the main physical phenomena involved in packed-bed operation and modeling are presented and compared. The correlations investigated enable to calculate fluid/solid and fluid/wall heat transfer coefficients, effective thermal conductivity and pressure drop in packed beds.
  • Article
    Full-text available
    Thermal energy storage (TES) systems are central elements of various types of power plants operated using renewable energy sources. Packed bed TES can be considered as a cost-effective solution in concentrated solar power plants. Such a device is made up of a tank filled with a granular bed through which a heat-transfer fluid circulates. However, in such devices, the tank might be subjected to an accumulation of thermal stresses during cycles of loading and unloading due to the differential dilatation between the filler and the tank walls. The evolution of tank wall stresses over thermal cycles, taking into account both thermal and mechanical loads, is studied here using a numerical model based on the discrete element method. Simulations were performed for two different thermal configurations: (i) the tank is heated homogeneously along its height or (ii) with a vertical gradient of temperature. Then, the stresses resulting from the two different loadings applied on the tank are compared as well the kinematic response of the internal granular material. The kinematics of the granular material are analyzed at the particles scale (i.e. discrete elements), with a focus on the effect of particle/particle and wall/particle friction. Results show that a faster rearrangement of the packing occur when a thermal gradient is moving along the tank, leading to higher values of stresses applied on the tank walls. In addition to this, the behavior of the packed bed is dependent on the friction levels in the tank, whether the friction between particles themselves or the friction at the contact of particles with the shell. The influence of the slenderness ratio of the tank is investigated as well. Moreover, a reduction of 20% of thermal applied stresses can be obtained when inclined wall boundaries are used. The combination of an homogeneous configuration with low levels of friction (using lubricants) in thermocline storage tanks with inclined fixed boundaries can decrease significantly the induced stresses applied on the wall.
  • Article
    Scaling up alternative energy systems to replace fossil fuels is a critical imperative. Concentrating Solar Power (CSP) is a promising solar energy technology that is growing steadily in a so far small, but commercial scale. Previous life cycle assessments (LCA) have resulted in confirmation of low environmental impact and high lifetime energy return. This work contributes an assessment of potential material restrictions for a large-scale application of CSP technology using data from an existing parabolic trough plant and one prospective state-of-the-art central tower plant. The material needs for these two CSP designs are calculated, along with the resulting demand for a high adoption (up to about 8000 TWh/yr by 2050) scenario. In general, most of the materials needed for CSP are commonplace. Some CSP material needs could however become significant compared to global production. The need for nitrate salts (NaNO3 and KNO3), silver and steel alloys (Nb, Ni and Mo) in particular would be significant if CSP grows to be a major global electricity supply. The possibilities for increased extraction of these materials or substituting them in CSP design, although at a marginal cost, mean that fears of material restriction are likely unfounded. Link: http://www.sciencedirect.com/science/article/pii/S036054421200374X
  • Article
    Full-text available
    This paper explores similarities and differences between the run-up of oil prices in 2007-08 and earlier oil price shocks, looking at what caused the price increase and what effects it had on the economy. Whereas historical oil price shocks were primarily caused by physical disruptions of supply, the price run-up of 2007-08 was caused by strong demand confronting stagnating world production. Although the causes were different, the consequences for the economy appear to have been very similar to those observed in earlier episodes, with significant effects on overall consumption spending and purchases of domestic automobiles in particular. In the absence of those declines, it is unlikely that we would have characterized the period 2007:Q4 to 2008:Q3 as one of economic recession for the U.S. The experience of 2007-08 should thus be added to the list of recessions to which oil prices appear to have made a material contribution.
  • Article
    Full-text available
    Motor manufacturers have long realized that because the electrical conductivity of copper is nearly 60% higher than that of aluminum, substituting copper for aluminum in the squirrel cage of the induction motor would markedly increase the electrical energy efficiency of the machine. Most motors larger than about 200 kW and a few special purpose smaller motors are built with copper squirrel cage structures manufactured by a time consuming and costly fabrication process. The intricate squirrel cage of smaller motors is produced by pressure die casting aluminum. Alternative cost-effective manufacturing methods have not been devised. A major barrier to adoption of copper for the rotor has been the high cost resulting from the short die life of the ordinary die steels experienced in die casting copper with its high melting temperature (1083°C compared to 660°C for aluminum).
  • Article
    Full-text available
    Ocean waves are a huge, largely untapped energy resource, and the potential for extracting energy from waves is considerable. Research in this area is driven by the need to meet renewable energy targets, but is relatively immature compared to other renewable energy technologies. This review introduces the general status of wave energy and evaluates the device types that represent current wave energy converter (WEC) technology, particularly focusing on work being undertaken within the United Kingdom. The possible power take-off systems are identified, followed by a consideration of some of the control strategies to enhance the efficiency of point absorber-type WECs. There is a lack of convergence on the best method of extracting energy from the waves and, although previous innovation has generally focused on the concept and design of the primary interface, questions arise concerning how best to optimize the powertrain. This article concludes with some suggestions of future developments.
  • Article
    Full-text available
    Worldwide power resources that could be extracted from Ocean Thermal Energy Conversion (OTEC) plants are estimated with a simple one-dimensional time-domain model of the thermal structure of the ocean. Recently published steady-state results are extended by partitioning the potential OTEC production region in one-degree-by-one-degree "squares" and by allowing the operational adjustment of OTEC operations. This raises the estimated maximum steady-state OTEC electrical power from about 3 TW (10(9) kW) to 5 TW. The time-domain code allows a more realistic assessment of scenarios that could reflect the gradual implementation of large-scale OTEC operations. Results confirm that OTEC could supply power of the order of a few terawatts. They also reveal the scale of the perturbation that could be caused by massive OTEC seawater flow rates: a small transient cooling of the tropical mixed layer would temporarily allow heat flow into the oceanic water column. This would generate a long-term steady-state warming of deep tropical waters, and the corresponding degradation of OTEC resources at deep cold seawater flow rates per unit area of the order of the average abyssal upwelling. More importantly, such profound effects point to the need for a fully three-dimensional modeling evaluation to better understand potential modifications of the oceanic thermohaline circulation.
  • Article
    As the extent of the shortage becomes clear, an interagency task force is giving scientific users priority, but some say the material is not available at any price.
  • Article
    Demand for the elements is expected to surge in tandem with hybrid-electric vehicles, wind turbines, and other green technologies.
  • Article
    Full-text available
    About 2.1 billion gallons of fuel ethanol was used in the United States in 2002, mainly in the form of gasoline blends containing up to 10% ethanol (E10). Ethanol use has the potential to increase in the U.S. blended gasoline market because methyl tertiary butyl ether (MTBE), formerly the most popular oxygenate blendstock, may be phased out owing to concerns about MTBE contamination of the water supply. Ethanol would remain the only viable near-term option as an oxygenate in reformulated gasoline production and to meet a potential federal renewable fuels standard (RFS) for transportation fuels. Ethanol may also be blended with additives (co-solvents) into diesel fuels for applications in which oxygenation may improve diesel engine emission performance. Numerous studies have been conducted to evaluate the fuel-cycle energy and greenhouse gas (GHG) emission effects of ethanol-gasoline blends relative to those of gasoline for applications in spark-ignition engine vehicles (see Wang et al. 1997; Wang et al. 1999; Levelton Engineering et al. 1999; Shapouri et al. 2002; Graboski 2002). Those studies did not address the energy and emission effects of ethanol-diesel (E-diesel or ED) blends relative to those of petroleum diesel fuel in diesel engine vehicles. The energy and emission effects of E-diesel could be very different from those of ethanol-gasoline blends because (1) the energy use and emissions generated during diesel production (so-called ''upstream'' effects) are different from those generated during gasoline production; and (2) the energy and emission performance of E-diesel and petroleum diesel fuel in diesel compression-ignition engines differs from that of ethanol-gasoline blends in spark-ignition (Otto-cycle-type) engine vehicles. The Illinois Department of Commerce and Community Affairs (DCCA) commissioned Argonne National Laboratory to conduct a full fuel-cycle analysis of the energy and emission effects of E-diesel blends relative to those of petroleum diesel when used in the types of diesel engines that will likely be targeted first in the marketplace. This report documents the results of our study. The draft report was delivered to DCCA in January 2003. This final report incorporates revisions by the sponsor and by Argonne.
  • Article
    This report summarizes the current status of the CPV industry and is updated from previous versions to include information from the last year. New information presented at the CPV-8 conference is included along with the addition of new companies that have announced their interest in CPV, and estimates of production volumes for 2011 and 2012.
  • Article
    This report provides data and analysis of the land use associated with modern, large wind power plants (defined as greater than 20 megawatts (MW) and constructed after 2000). The analysis discusses standard land-use metrics as established in the life-cycle assessment literature, and then discusses their applicability to wind power plants. The report identifies two major 'classes' of wind plant land use: 1) direct impact (i.e., disturbed land due to physical infrastructure development), and 2) total area (i.e., land associated with the complete wind plant project). The analysis also provides data for each of these classes, derived from project applications, environmental impact statements, and other sources. It attempts to identify relationships among land use, wind plant configuration, and geography. The analysts evaluated 172 existing or proposed projects, which represents more than 26 GW of capacity. In addition to providing land-use data and summary statistics, they identify several limitations to the existing wind project area data sets, and suggest additional analysis that could aid in evaluating actual land use and impacts associated with deployment of wind energy.
  • Article
    In August of 1984 a utility assumed independent operation of Solar One. This ten Megawatt electric (MW/sub e/) solar powered thermal generating plant is now operated by Southern California Edison as an integrated part of its plant mix. During a three-year period, detailed records will be kept to determine operating cost, availability, capacity factor, reliability, performance, failure modes, degradation rates, and other needed data. It is expected that this information will convince a majority of those in the utilities, regulatory agencies, and investment community who are yet uncertain about this promising alternative energy source that its commercial application is feasible and worthwhile. With sufficient confidence in the technology and with a growing economy expanding energy requirements, there is every reason to expect that several new solar power tower plants in the 30-100 MW/sub e/ commercial scale will be ordered to meet increased intermediate load requirements in the rapidly growing sunbelt. Modest federal support to lower the investment cost of the first few demonstration facilities can lead directly to significant cost reductions in future plants, making them competitive immediately with gas or oil-fired units and eventually with coal-fired plants designed to meet environmental constraints. The cost economies will follow from the reduction of engineering and development costs for the majority of the plant, and from cost reductions associated with mass production and learning or experience curves for the heliostats and receiver panels, the solar collecting component of the facility. 3 tables.
  • Article
    Report of levelized cost in 2005 U.S. dollars, energy use, and GHG emission benefits of seven hydrogen production, delivery, and distribution pathways.
  • Article
    The vertical temperature distribution in the open ocean can be simplistically described as consisting of two layers separated by an interface. The upper layer is warmed by the sun and mixed to depths of about 100 m by wave motion. The bottom layer consists of colder water formed at high latitudes. The interface or thermocline is sometimes marked by an abrupt change in temperature but more often the change is gradual. The temperature difference between the upper (warm) and bottom (cold) layers ranges from 10°C to 25°C, with the higher values found in equatorial waters. This implies that there are two enormous reservoirs providing the heat source and the heat sink required for a heat engine. A practical application is found in a system (heat engine) designed to transform the thermal energy into electricity. This is referred to as OTEC for Ocean Thermal Energy Conversion. Several techniques have been proposed to use this ocean thermal resource; however, at present it appears that only the closed cycle (CC-OTEC) and the open cycle (OC-OTEC) schemes have a solid foundation of theoretical as well as experimental work. In the CC-OTEC system, warm surface seawater and cold seawater are used to vaporize and condense a working fluid, such as anhydrous ammonia, which drives a turbine-generator in a closed loop producing electricity. In the OC-OTEC system, seawater is flash-evaporated in a vacuum chamber. The resulting low-pressure steam is used to drive a turbine-generator. Gold seawater is used to condense the steam after it has passed through the turbine. The open-cycle can, therefore, be configured to produce desalinated water as well as electricity.
  • Article
    a b s t r a c t Based on economic and policy considerations that appear to be unconstrained by geophysics, the Intergovernmental Panel on Climate Change (IPCC) generated forty carbon production and emissions scenarios. In this paper, we develop a base-case scenario for global coal production based on the physical multi-cycle Hubbert analysis of historical production data. Areas with large resources but little production history, such as Alaska and the Russian Far East, are treated as sensitivities on top of this base-case, producing an additional 125 Gt of coal. The value of this approach is that it provides a reality check on the magnitude of carbon emissions in a business-as-usual (BAU) scenario. The resulting base-case is significantly below 36 of the 40 carbon emission scenarios from the IPCC. The global peak of coal production from existing coalfields is predicted to occur close to the year 2011. The peak coal production rate is 160 EJ/y, and the peak carbon emissions from coal burning are 4.0 Gt C (15 Gt CO 2) per year. After 2011, the production rates of coal and CO 2 decline, reaching 1990 levels by the year 2037, and reaching 50% of the peak value in the year 2047. It is unlikely that future mines will reverse the trend predicted in this BAU scenario.
  • Article
    Full-text available
    This is a review of the literature available on data for the EROI (prior to this special issue) of the following 12 sources of fuel/energy: oil and natural gas, coal, tar sands, shale oil, nuclear, wind, solar, hydropower, geothermal, wave/tidal and corn ethanol. Unfortunately, we found that few studies have been undertaken since the 1980s, and such as have been done are often marked more by advocacy than objectivity. The most recent summary of work and data on the EROI of fuels was conducted in the summer of 2007 at SUNY ESF and appeared on The Oil Drum website and in a readable summary by Richard Heinberg. This paper summarizes the findings of that study, and also those preceding and subsequent to it where available. It also summarizes issues raised by some concerning the findings of these studies and with the calculations within. While there are many who believe that such EROI studies are critical to understanding our financial and social future there seems to be very little interest by governments and industries in supporting this research or in using or promulgating such research as has been done. We view this as critical as our main fuels are progressively depleted and as we are faced with making extremely important decisions on a very meager analytical and data base, and with few scientists trained to cut through the reams of insufficiently analyzed energy advocacy saturating our media and the blogosphere.
  • Article
    Climate change, pollution, and energy insecurity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and policy of WWS energy. We estimate that ~3,800,000 5Â MW wind turbines, ~49,000 300Â MW concentrated solar plants, ~40,000 300Â MW solar PV power plants, ~1.7 billion 3Â kW rooftop PV systems, ~5350 100Â MW geothermal power plants, ~270 new 1300Â MW hydroelectric power plants, ~720,000 0.75Â MW wave devices, and ~490,000 1Â MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only ~0.41% and ~0.59% more of the world's land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today.
  • Article
    Full-text available
    This paper presents a societal level exergy analysis approach developed to analyse transitions in the way that energy is supplied and contributes to economic growth in the UK, the US, Austria and Japan, throughout the last century. We assess changes in exergy and useful work consumption, energy efficiency and related GDP intensity measures of each economy. The novel data provided elucidate certain characteristics of divergence and commonality in the energy transitions studied. The results indicate that in each country the processes of industrialization, urbanisation and electrification are characterised by a marked increase in exergy and useful work supplies and per capita intensities. There is a common and continuous decrease in the exergy intensity of GDP. Moreover for each country studied the trend of increasing useful work intensity of GDP reversed in the early 1970s coincident with the first oil crisis.
  • Book
    Full-text available
    This is the second report issued by ITPOES (the UK Industry Taskforce on Peak Oil and Energy Security). The interpretation of the current position, and the viewpoints expressed in the final recommendations, are those of the ITPOES membership - a group of private British companies whose interests span a wide range of business sectors. The work therefore represents an independent, businessminded, view of the national position. Like its predecessor, published in the autumn of 2008, this report addresses the question of future oil supply and its potential consequences for the UK. It does not address the questions of climate change and carbon reduction directly - there are many other texts which do that - but there are massive areas of overlap between the distinct issues of resource depletion and atmospheric pollution. In some parts of our report that overlap is recognised but the main thrust of the report focuses on the questions of oil price and availability over the coming decade. In particular, it seeks to highlight issues which are likely to confront the new government following the General Election in 2010. It follows the style of the first ITPOES report, titled “The Oil Crunch, Securing the UK’s energy future” in that two expert opinions have been commissioned and used as the basis for an analysis by the ITPOES membership.
  • Article
    Full-text available
    This paper explores similarities and differences between the run-up of oil prices in 2007-08 and earlier oil price shocks, looking at what caused the price increase and what effects it had on the economy. Whereas historical oil price shocks were primarily caused by physical disruptions of supply, the price run-up of 2007-08 was caused by strong demand confronting stagnating world production. Although the causes were different, the consequences for the economy appear to have been very similar to those observed in earlier episodes, with significant effects on overall consumption spending and purchases of domestic automobiles in particular. In the absence of those declines, it is unlikely that we would have characterized the period 2007:Q4 to 2008:Q3 as one of economic recession for the U.S. The experience of 2007-08 should thus be added to the list of recessions to which oil prices appear to have made a material contribution.
  • Chapter
    Full-text available
    The issues surrounding energy are far more important, complex and pervasive than normally considered from the perspective of conventional economics, and they will be extremely resistant to market-based, or possibly any other, resolution. We live in an era completely dominated by readily available and cheap petroleum. This cheap petroleum is finite and currently there are no substitutes with the quality and quantity required. Of particular importance to society’s past and future is that depletion is overtaking technology in many ways, so that the enormous wealth made possible by cheap petroleum is very unlikely to continue very far into the future. What this means principally is that investments will increasingly have to be made into simply getting the energy that today we take for granted, the net economic effect being the gradual squeezing out of discretionary investments and consumption. While there are certainly partial “supply-side” solutions to these issues, principally through a focus on certain types of solar power, the magnitude of the problem will be enormous because of the scale required, the declining net energy supplies available for investment and the relatively low net energy yields of the alternatives. Given that this issue is likely to be far more immediate, and perhaps more important, than even the serious issue of global warming it is remarkable how little attention we have paid to understanding it or its consequences.
  • Article
    Full-text available
    Research on corn ethanol is overly focused on whether corn ethanol is a net energy yielder and, consequently, has missed some other fundamental issues, including (1) whether there is significant error associated with current estimates of the EROI of corn ethanol, (2) whether there is significant spatial variability in the EROI of corn ethanol production, (3) whether yield increases will translate linearly to increases in EROI, (4) the extent to which assumptions about co-product credits impact the EROI of corn ethanol, and (5) how much of the ethanol production from biorefineries is net energy. We address all of these concerns in this research by: (1) performing a meta-error analysis of the calculation of EROI, (2) calculating the EROI for 1,287 counties across the United States, and (3) performing a sensitivity analysis for the values of both yield and co-products within the calculation of EROI. Our results show that the average EROI calculated from the meta-error analysis was 1.07±0.2, meaning that we are unable to assert whether the EROI of corn ethanol is greater than one. The average EROI calculated across 1,287 counties in our spatial analysis was 1.01, indicating that the literature tended to use optimal values for energy inputs and outputs compared to the average conditions across the Unites States. Increases in yield had a trivial impact on EROI, while co-product credits had a large impact on EROI. Based on our results from the spatial analysis and the location of biorefineries across the United States, we conclude that the net energy supplied to society by ethanol is only 0.8% of that supplied from gasoline. Recent work indicates that only energy sources extracted at EROIs of 3:1 or greater have the requisite net energy to sustain the infrastructure of the transportation system of the United States. In light of this work, we conclude that production of corn ethanol within the United States is unsustainable and requires energy subsidies from the larger oil economy. KeywordsCorn–Ethanol–EROI–Net energy–Gradients–Spatial analysis
  • Conference Paper
    Processes with a two-phase heat transfer fluid (e.g. water/steam) require isothermal energy storage. Latent heat storage systems are an option to fulfil this demand. For high temperature applications nitrate salts are suitable materials for phase change storage. The main drawback of these materials is the low thermal conductivity, limiting the power density during the charging/discharging process. At DLR the so called sandwich-concept has been developed to realize latent heat storage with high power densities for applications in solar thermal power plants and process industry. This concept has already been demonstrated successfully for three different storage units ranging from 2-100 kW at melting temperatures of 142 °C and 222 °C. In 2008, a test storage using sodium nitrate as phase change material (PCM) with a melting temperature of 306 °C was operated in a 5 kW laboratory loop. The designed heat transfer rate was achieved and after 172 cycles no degradation was observed.
  • Article
    Of the three generations of biodiesel feedstocks described in this paper, food crops, non-food crops and microalgae-derived biodiesel, it was found that the third generation, microalgae, is the only source that can be sustainably developed in the future. Microalgae can be converted directly into energy, such as biodiesel, and therefore appear to be a promising source of renewable energy. This paper presents a comparison between the use of microalgae and palm oil as biodiesel feedstocks. It was found that microalgae are the more sustainable source of biodiesel in terms of food security and environmental impact compared to palm oil. The inefficiency and unsustainability of the use of food crops as a biodiesel source have increased interest in the development of microalgae species to be used as a renewable energy source. In this paper, the main advantages of using microalgae for biodiesel production are described in comparison with other available feedstocks, primarily palm oil.
  • This paper describes the development of a forecasting model in the tradition of system dynamics. It is called Resource EXergy Services (REXS). The model simulates economic growth of the US through the 20th century and extrapolates the simulation for several decades into the next century. The REXS model differs from previous energy–economy models such as DICE and NICE [Nordhaus, W.D., 1991. The cost of slowing climate change: a survey. The Energy Journal 12 (1), 37–66] by eliminating the assumption of exogenously driven exponential growth along a so-called ‘optimal trajectory’. Instead, we suggest a simple model representing the dynamics of technological change in terms of decreasing energy (exergy) intensity and endogenously increasing efficiency of conversion of raw material and fuel inputs (exergy) to primary exergy services (‘useful work’).In our model, the traditional assumption of exogenous technological progress (total factor productivity) increasing at a constant rate is replaced by two learning processes based, respectively, on (i) cumulative economic output and (ii) cumulative energy (exergy) service (useful work) production experience. The initial results of simulation for the period 2000–2050 have significant implications for future trends in economic output. These implications are important for purposes of scenario analysis. The REXS modules are the focus of ongoing research. We discuss briefly the many possibilities for elaboration of each module to enrich the feedback dynamics, policy levers and post-scenario analyses.
  • Article
    The present paper reviews the reactions and the path of acceptance of the theory known as “peak oil”. The theory was proposed for the first time by M.K. Hubbert in the 1950s as a way to describe the production pattern of crude oil. According to Hubbert, the production curve is “bell shaped” and approximately symmetric. Hubbert's theory was verified with good approximation for the case of oil production in the United States that peaked in 1971, and is now being applied to the worldwide oil production. It is generally believed that the global peak of oil production (“peak oil”) will take place during the first decade of the 21st century, and some analysts believe that it has already occurred in 2005 or 2006. The theory and its consequences have unpleasant social and economical implications. The present paper is not aimed at assessing the peak date but offers a discussion on the factors that affect the acceptance and the diffusion of the concept of “peak oil” with experts and with the general public. The discussion is based on a subdivision of “four stages of acceptance”, loosely patterned after a sentence by Thomas Huxley.
  • Article
    Debates about whether or not to invest heavily in nuclear fusion as a future innovative energy option have been made within the context of energy technology development strategies. This is because the prospects for nuclear fusion are quite uncertain and the investments therefore carry the risk of quite large regrets, even though investment is needed in order to develop the technology. The timeframe by which nuclear fusion could become competitive in the energy market has not been adequately studied, nor has roles of the nuclear fusion in energy systems and the environment. The present study has two objectives. One is to reveal the conditions under which nuclear fusion could be introduced economically (hereafter, we refer to such introductory conditions as breakeven prices) in future energy systems. The other objective is to evaluate the future roles of nuclear fusion in energy systems and in the environment. Here we identify three roles that nuclear fusion will take on when breakeven prices are achieved: (i) a portion of the electricity market in 2100, (ii) reduction of annual global total energy systems cost, and (iii) mitigation of carbon tax (shadow price of carbon) under CO2 constraints. Future uncertainties are key issues in evaluating nuclear fusion. Here we treated the following uncertainties: energy demand scenarios, introduction timeframe for nuclear fusion, capacity projections of nuclear fusion, CO2 target in 2100, capacity utilization ratio of options in energy/environment technologies, and utility discount rates. From our investigations, we conclude that the presently designed nuclear fusion reactors may be ready for economical introduction into energy systems beginning around 2050–2060, and we can confirm that the favorable introduction of the reactors would reduce both the annual energy systems cost and the carbon tax (the shadow price of carbon) under a CO2 concentration constraint.
  • Article
    The stabilization of future CO2 atmospheric concentrations to levels that might prevent anthropogenic alterations of the world climate calls for tens of terawatts of carbon free renewable energy resources. The combined energy production potential of all known non-solar carbon-free renewable resources seems insufficient to meet these targets. Consequently, over the next decades solar energy, and in particular photovoltaics, is expected to fill the gap.In this work several mature photovoltaic technologies, ranging from silicon to thin films, and solar concentrator systems are analyzed. The estimates of the energy production limits are established for each technology, based on available global material reserves. It is shown that many existing technologies, albeit playing an important in the present sub-gigawatt energy production levels, are affected by severe material shortages, that would prevent their scale-up to the terawatt range. This is the case for thin film solar cells technologies based on CdTe and CIGS where the showstopper is the scarcity of tellurium and indium respectively. Despite the abundance of silicon, crystalline Si-based solar cells will hardly reach the terawatt range as additional scale-up of the technology will be impeded by the global reserves of silver, commonly used as electrode material. As for amorphous silicon and dye sensitized thin film technologies, avoiding the use of indium tin oxide transparent conductor films appears as a must for exceeding the few tenth of terawatt barrier. For existing III–V concentrator cells, operating under moderate concentration (<200X), terawatt year level may be afforded by circumventing the use of Ge substrates and by minimizing the use of In and Au in the cell fabrication process.In conclusion the study summarizes current material challenges for terawatt level deployment of the existing solar cells, and for each technology, identifies improvements and innovations needed for further scale-up.
  • Article
    Measurements from the GEOSAT, ERS-1 and 2 and Topex/Poseidon satellites have now accumulated to over 15 years of global ocean wave and wind data. Extraction of wave height, wind speed and wave period from the satellite altimeters and directional wave spectra from the synthetic aperture radars are reviewed along with recent validation and calibration efforts. Applications of the data to a variety of problems illustrate the potential of satellite wave measurements.
  • Article
    The tides represent a large and benign source of renewable energy which can be converted to electricity using well-proven technology. The origin and nature of tidal power is summarized first. The main components of a tidal barrage, and the method of operation are described. The parts of the world where the tidal range and coastline are suitable for tidal barrages of substantial size and capable of generating electricity at an acceptable cost are relatively small in number but the UK has a substantial share.
  • Article
    The paper reviews the performance characteristics of various passive solar heating systems for buildings, the main design factors affecting their performance, the relative advantages and main problems associated with them, and their applicability to different building types and climatic regions. Emphasis is placed on the architectural design issues associated with the different passive solar heating systems and to the problems that may be encountered when passive solar heating is applied in regions with hot summers.
  • Article
    So far, solar energy has been viewed as only a minor contributor in the energy mixture of the US due to cost and intermittency constraints. However, recent drastic cost reductions in the production of photovoltaics (PV) pave the way for enabling this technology to become cost competitive with fossil fuel energy generation. We show that with the right incentives, cost competitiveness with grid prices in the US (e.g., 6–10 US¢/kWh) can be attained by 2020. The intermittency problem is solved by integrating PV with compressed air energy storage (CAES) and by extending the thermal storage capability in concentrated solar power (CSP). We used hourly load data for the entire US and 45-year solar irradiation data from the southwest region of the US, to simulate the CAES storage requirements, under worst weather conditions. Based on expected improvements of established, commercially available PV, CSP, and CAES technologies, we show that solar energy has the technical, geographical, and economic potential to supply 69% of the total electricity needs and 35% of the total (electricity and fuel) energy needs of the US by 2050. When we extend our scenario to 2100, solar energy supplies over 90%, and together with other renewables, 100% of the total US energy demand with a corresponding 92% reduction in energy-related carbon dioxide emissions compared to the 2005 levels.
  • Article
    The global demand for platinum has consistently outgrown supply in the past decade. This trend likely will continue and the imbalance may possibly escalate into a crisis. Platinum plays pivotal roles in both conventional automobile emissions control and the envisioned hydrogen economy. A platinum crisis would have profound implications on energy and environment. On the one hand, inadequate platinum supply will prevent widespread commercialization of hydrogen fuel-cell vehicles. On the other hand, expensive platinum may enhance the competitiveness of hybrid, plug-in hybrid, and battery-powered electric cars. Policymakers should weigh the potential impacts of a platinum crisis in energy policy.
  • Article
    Vehicle-to-grid power (V2G) uses electric-drive vehicles (battery, fuel cell, or hybrid) to provide power for specific electric markets. This article examines the systems and processes needed to tap energy in vehicles and implement V2G. It quantitatively compares today's light vehicle fleet with the electric power system. The vehicle fleet has 20 times the power capacity, less than one-tenth the utilization, and one-tenth the capital cost per prime mover kW. Conversely, utility generators have 10–50 times longer operating life and lower operating costs per kWh. To tap V2G is to synergistically use these complementary strengths and to reconcile the complementary needs of the driver and grid manager. This article suggests strategies and business models for doing so, and the steps necessary for the implementation of V2G. After the initial high-value, V2G markets saturate and production costs drop, V2G can provide storage for renewable energy generation. Our calculations suggest that V2G could stabilize large-scale (one-half of US electricity) wind power with 3% of the fleet dedicated to regulation for wind, plus 8–38% of the fleet providing operating reserves or storage for wind. Jurisdictions more likely to take the lead in adopting V2G are identified.
  • Article
    This paper presents a summary of the thermal performance of five different passive solar test-cells (Direct Gain, Trombe-wall, Water-wall, Sunspace, and Roofpond) and a control test-cell during the 2002-2003 heating season in Muncie, Indiana. The results discussed in this article correspond to the initial phase of a longer study (data were collected from December of 2002 until August of 2004). The project’s original intent was to identify any barriers to achieving thermal comfort within a space when passive solar heating systems are employed in severe winter climates with predominant overcast sky conditions. Because of the original intent of this project, the test-cells were arranged with their smaller facades oriented to the north and south and the longer facades facing east and west. This arrangement permitted to study temperature differences throughout the day (diurnal operative temperature swings) and also simultaneous temperature differences throughout the space (a simultaneous comparison of four points instrumented within each cell to detect variations between the south side and the north side of the test-cells).
  • Article
    Energy is a fundamental factor of industrial production. The industrial process consists of work performance and information processing, in terms of which the production factors and the output can be defined and aggregated. The equation of growth relates the growth of output Q to the growth of the production factors capital K, labor L, and energy flow E. It can be solved in zero order approximation with respect to time, if one assumes that the characteristic properties of the industrial system are not changed by human creativity and that the economy is far from its thermodynamic limits to growth. Then Q must be a unique function of K, L and E. The integrability conditions result in three differential equations for the elasticities of production. They are solved subject to asymptotic boundary conditions. The integral of the equation of growth with the calculated, factor-dependent elasticities of production yields the production function q = e × exp }}a0[2 − (l + e)/k] + a0ct(l/e − 1){{, with q, k, l and e being the relative values of Q, K, L, and E; a0 and ct, are the two free parameters of the theory. For given factor inputs, the GNP and the output of the industrial sector of West Germany and the output of the sector “Industries” of the United States are calculated for the years 1960–78. Deviations of theory from reality are generally less than 5%. The slump during the energy crisis (1973–75) and the subsequent recovery are well reproduced. The influence of energy prices on factor inputs and growth is discussed. An assessment of future economic developments is given, including a calculation of the impact on U.S. industrial growth of solar power satellites from space manufacturing facilities.
  • Article
    Sustainability of biomass based fuel use requires that in biomass production erosion and water usage do not exceed addition to stocks of soil and water and that levels of nutrients and organic matter in soils do not decrease. Levels of volatile carbon compounds and N2O in the atmosphere should remain unaffected. To maintain ecosystems services of nature useful to mankind, restriction of biomass production to degraded and currently fallow land is to be preferred. Also sustainability of biomass-for-energy use requires a high efficiency recycling of nutrients present in ashes and low emissions of persistent organics, acidifying compounds and heavy metals due to biomass combustion. Meeting such conditions requires major efforts.
  • Article
    Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO2, wastewater treatment, in human health, as food additive, and for aquaculture.
  • Article
    Full-text available
    Thispaperreviewsandranksmajorproposedenergy-relatedsolutionstoglobalwarming,airpollutionmortality,andenergysecuritywhileconsideringotherimpactsoftheproposedsolutions,suchasonwatersupply,landuse,wildlife,resourceavailability,thermalpollution,waterchemicalpollution,nuclearproliferation,andundernutrition.Nineelectricpowersourcesandtwoliquidfueloptionsareconsidered.Theelectricitysourcesincludesolar-photovoltaics(PV),concentratedsolarpower(CSP),wind,geothermal,hydroelectric,wave,tidal,nuclear,andcoalwithcarboncaptureandstorage(CCS)technology.Theliquidfueloptionsincludecorn-ethanol(E85)andcellulosic-E85.Toplacetheelectricandliquidfuelsourcesonanequalfooting,weexaminetheircomparativeabilitiestoaddresstheproblemsmentionedbypoweringnew-technologyvehicles,includingbattery-electricvehicles(BEVs),hydrogenfuelcellvehicles(HFCVs),andflex-fuelvehiclesrunonE85.Twelvecombinationsofenergysource-vehicletypeareconsidered.Uponrankingandweightingeachcombinationwithrespecttoeachof11impactcategories,fourcleardivisionsofranking,ortiers,emerge.Tier1(highest-ranked)includeswind-BEVsandwind-HFCVs.Tier2includesCSP-BEVs,geothermal-BEVs,PV-BEVs,tidal-BEVs,andwave-BEVs.Tier3includeshydro-BEVs,nuclear-BEVs,andCCS-BEVs.Tier4includescorn-andcellulosic-E85.Wind-BEVsrankedfirstinsevenoutof11categories,includingthetwomostimportant,mortalityandclimatedamagereduction.AlthoughHFCVsaremuchlessefficientthanBEVs,wind-HFCVsarestillverycleanandwererankedsecondamongallcombinations.Tier2optionsprovidesignificantbenefitsandarerecommended.Tier3optionsarelessdesirable.However,hydroelectricity,whichwasrankedaheadofcoal-CCSandnuclearwithrespecttoclimateandhealth,isanexcellentloadbalancer,thusrecommended.TheTier4combinations(cellulosic-andcorn-E85)wererankedlowestoverallandwithrespecttoclimate,airpollution,landuse,wildlifedamage,andchemicalwaste.Cellulosic-E85rankedlowerthancorn-E85overall,primarilyduetoitspotentiallylargerlandfootprintbasedonnewdataanditshigherupstreamairpollutionemissionsthancorn-E85.Whereascellulosic-E85maycausethegreatestaveragehumanmortality,nuclear-BEVscausethegreatestupper-limitmortalityriskduetotheexpansionofplutoniumseparationanduraniumenrichmentinnuclearenergyfacilitiesworldwide.Wind-BEVsandCSP-BEVscausetheleastmortality.Thefootprintareaofwind-BEVsis2-6ordersofmagnitudelessthanthatofanyotheroption.Becauseoftheirlowfootprintandpollution,wind-BEVscausetheleastwildlifeloss.Thelargestconsumerofwateriscorn-E85.Thesmallestarewind-,tidal-,andwave-BEVs.TheUScouldtheoreticallyreplaceall2007onroadvehicleswithBEVspoweredby73000-1440005MWwindturbines,lessthanthe300000airplanestheUSproducedduringWorldWarII,reducingUSCO2by32.5-32.7%andnearlyeliminating15000/yrvehicle-relatedairpollutiondeathsin2020.Insum,useofwind,CSP,geothermal,tidal,PV,wave,andhydrotoprovideelectricityforBEVsandHFCVsand,byextension,electricityfortheresidential,industrial,andcommercialsectors,willresultinthemostbenefitamongtheoptionsconsidered.Thecombinationofthesetechnologiesshouldbeadvancedasasolutiontoglobalwarming,airpollution,andenergysecurity.Coal-CCSandnuclearofferlessbenefitthusrepresentanopportunitycostloss,andthebiofueloptionsprovidenocertainbenefitandthegreatestnegativeimpacts.
  • Article
    With the right mix of leadership and policy, a completely renewable electricity sector for New Zealand and the United States is feasible, achievable, and desirable.
  • Article
    The assessment of future global oil production presented in the IEA's World Energy Outlook 2008 (WEO 2008) is divided into 6 fractions; four relate to crude oil, one to non-conventional oil, and the final fraction is natural-gas-liquids (NGL). Using the production parameter, depletion-rate-of-recoverable-resources, we have analyzed the four crude oil fractions and found that the 75Â Mb/d of crude oil production forecast for year 2030 appears significantly overstated, and is more likely to be in the region of 55Â Mb/d. Moreover, analysis of the other fractions strongly suggests lower than expected production levels. In total, our analysis points to a world oil supply in 2030 of 75Â Mb/d, some 26Â Mb/d lower than the IEA predicts. The connection between economic growth and energy use is fundamental in the IEA's present modelling approach. Since our forecast sees little chance of a significant increase in global oil production, our findings suggest that the "policy makers, investors and end users" to whom WEO 2008 is addressed should rethink their future plans for economic growth. The fact that global oil production has very probably passed its maximum implies that we have reached the Peak of the Oil Age.
  • Article
    Algae are an attractive source of biomass energy since they do not compete with food crops and have higher energy yields per area than terrestrial crops. In spite of these advantages, algae cultivation has not yet been compared with conventional crops from a life cycle perspective. In this work, the impacts associated with algae production were determined using a stochastic life cycle model and compared with switchgrass, canola, and corn farming. The results indicate that these conventional crops have lower environmental impacts than algae in energy use, greenhouse gas emissions, and water regardless of cultivation location. Only in total land use and eutrophication potential do algae perform favorably. The large environmental footprint of algae cultivation is driven predominantly by upstream impacts, such as the demand for CO(2) and fertilizer. To reduce these impacts, flue gas and, to a greater extent, wastewater could be used to offset most of the environmental burdens associated with algae. To demonstrate the benefits of algae production coupled with wastewater treatment, the model was expanded to include three different municipal wastewater effluents as sources of nitrogen and phosphorus. Each provided a significant reduction in the burdens of algae cultivation, and the use of source-separated urine was found to make algae more environmentally beneficial than the terrestrial crops.