Net energy, that is, the energy remaining after accounting for the energy “cost” of extraction an... more Net energy, that is, the energy remaining after accounting for the energy “cost” of extraction and processing, is the “profit” energy used to support modern society. Energy Return on Investment (EROI) is a popular metric to assess the profitability of energy extraction processes, with EROI > 1 indicating that more energy is delivered to society than is used in the extraction process. Over the past decade, EROI analysis in particular has grown in popularity, resulting in an increase in publications in recent years. The lack of methodological consistency, however, among these papers has led to a situation where inappropriate comparisons are being made across technologies. In this paper we provide both a literature review and harmonization of EROI values to provide accurate comparisons of EROIs across both thermal fuels and electricity producing technologies. Most importantly, the authors advocate for the use of point-of-use EROIs rather than point-of-extraction EROIs as the energy ...
This paper exposes the many flaws in the article “Through the Eye of a Needle: An Eco-heterodox P... more This paper exposes the many flaws in the article “Through the Eye of a Needle: An Eco-heterodox Perspective on the Renewable Energy Transition, authored by Siebert and Rees and recently published in Energies as a Review. Our intention in submitting this critique is to expose and rectify the original article’s non-scientific approach to the review process that includes selective (and hence biased) screening of the literature focusing on the challenges related to renewable energies, without discussing any of the well-documented solutions. In so doing, we also provide a rigorous refutation of several statements made by a Seibert–Rees paper, which often appear to be unsubstantiated personal opinions and not based on a balanced review of the available literature.
California has set two ambitious targets aimed at achieving a high level of decarbonization in th... more California has set two ambitious targets aimed at achieving a high level of decarbonization in the coming decades, namely (i) to generate 60% and 100% of its electricity using renewable energy (RE) technologies, respectively, by 2030 and by 2045, and (ii) introducing at least 5 million zero emission vehicles (ZEVs) by 2030, as a first step towards all new vehicles being ZEVs by 2035. In addition, in California, photovoltaics (PVs) coupled with lithium-ion battery (LIB) storage and battery electric vehicles (BEVs) are, respectively, the most promising candidates for new RE installations and new ZEVs, respectively. However, concerns have been voiced about how meeting both targets at the same time could potentially negatively affect the electricity grid’s stability, and hence also its overall energy and carbon performance. This paper addresses those concerns by presenting a thorough life-cycle carbon emission and energy analysis based on an original grid balancing model that uses a com...
The rationale for integrating emergy and life cycle assessment (LCA) has been expounded in previo... more The rationale for integrating emergy and life cycle assessment (LCA) has been expounded in previous contributions to this same series of conferences over the last decade, as well as in a growing number of publications in scientific journals. Whereas we acknowledge that such integration may not always be required or even desirable, we maintain that, when dealing with industrial and agro-industrial systems, the applications in which the two approaches would benefit from it far outnumber those in which they would not. In recent years, many practical steps have been taken to identify and, insofar as possible, address the methodological issues ensuing from the different viewpoints offered by emergy and LCA. This paper summarizes the milestones along the path trodden so far, and briefly describes a newly-developed ‘emergy characterization factor’ library which may be put to practical use. It also aims to identify the lingering theoretical and practical obstacles that still need to be circ...
ABSTRACT The problem of evaluating the greenhouse gas emissions and energy return on energy inves... more ABSTRACT The problem of evaluating the greenhouse gas emissions and energy return on energy invested for an electricity system with a high level of installed PV is discussed and proposed solutions are put forward. A novel consequential lifecycle assessment (CLCA) approach is described that assess the impacts of PV at three distinct but inter-related levels. Firstly energy and material flows from raw materials through to end of life disposal or recycling PV products including panels, inverters and batteries. Secondly, changes to electricity distribution networks where the aggregate effects of PV require new infrastructure assets or new management and control approaches. Thirdly there are effects on the operation of the centralised electricity grid, both in terms of power flows into the grid and in terms of reducing from the grid at certain times through self consumption of PV output. The challenges of evaluating the impacts a distributed electricity generating technology in aggregate on a future electricity system require inter-disciplinary use of life cycle assessment, detailed scenario development and power system analysis.
Purpose This paper aims to provide an alternative method for calculating the environmental credit... more Purpose This paper aims to provide an alternative method for calculating the environmental credits associated with material recycling in life cycle assessment (LCA) of waste management systems. The method proposed here is more consistent with the general attributional approach in LCA than the hitherto common practice of simply assuming a 1:1 substitution of primary material production. Methods The formula proposed for estimating the environmental credit is applicable for the recovered materials that are reintroduced into the market (outputs of the recycling facilities), after all process losses in the various stages of the waste management system have been accounted for. It considers the displacement of materials by using the mix of virgin and recycled materials for each individual material that is used in the market for the production of goods. Moreover, it also considers the changes in the inherent properties of the materials undergoing a recycling process (‘down-cycling’), by int...
Most existing life cycle assessment models of waste management have so far underplayed the import... more Most existing life cycle assessment models of waste management have so far underplayed the importance of the waste collection phase, addressing it only in a simplified fashion, either by requesting the total amount of fuel used as a direct user input or by calculating it based on a set of input parameters and fixed diesel consumption factors. However, if the main purpose of the study is to improve the efficiency of the collection system itself, a more detailed analysis of the collection phase is required, avoiding oversimplified and potentially misleading conclusions. The new LCA collection model presented here relies on a large number of parameters (number and type of containers, collection frequency, distances for the various legs of transport, etc.) and allows the detailed predictive analysis of alternative collection scenarios. The results of applying this newly developed model to a number of experimental case studies in Portugal are analyzed, discussed, and compared to those pr...
Abstract Modern intensive agriculture worldwide is generating increasing environmental pressure, ... more Abstract Modern intensive agriculture worldwide is generating increasing environmental pressure, which prevents its sustainable development. A number of agricultural sustainability assessment approaches and methodological frameworks have been developed by research worldwide to assess the environmental costs and impacts of resources used in agricultural production. A joint use of Life Cycle Assessment (LCA, to assess a process' performance and environmental impacts) and Emergy Accounting (EMA, to estimate environmental support to resource generation and provision) is proposed in this study. The goal is not only to ascertain the environmental ‘cost’ of production of selected chemical resources used in agricultural processes, but also to develop a reliable calculation procedure capable to integrate the two approaches (LCA and EMA), while considering their different allocation algebra and space-time scales of application. Specifically, the UEVs of glyphosate and urea, which are respectively the most used herbicide and nitrogen fertilizer used in worldwide agriculture, are calculated, yielding values of 2.47E+13 sej/kg and 7.07E+12 sej/kg, respectively. In order to do so, UEVs of intermediate process chemicals such as ammonia, acetic anhydride, chlorine gas, formaldehyde, phosphorous chloride, and sodium hydroxide have also been calculated or updated, thus providing at the same time a procedure and a set of values potentially useful for future studies. The LCA impacts of agro-chemicals in China are compared to worldwide averages from the Ecoinvent database, and the UEVs for several chemicals are also compared to previous estimates from published emergy literature.
2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018
This paper investigates the implications of transitioning to more renewable electricity generatio... more This paper investigates the implications of transitioning to more renewable electricity generation in Chile. The ongoing aggressive penetration of renewable energies in Chile reflects the large availability of solar, and to a lesser extent, wind-resources, and is a product of the ambitious national target to generate 60% of Chilean electricity from renewable sources by 2035. In addition, the electricity demand in Chile is expected to keep increasing over the next decades, and there are concerns about security of energy supply. We applied Net Energy Analysis (NEA) from a dynamic perspective, using a new metric, referred to as Power Return on Investment (PROI), which complements the information provided by the conventional Energy Return on Investment (EROI). We illustrated the methodological differences between these two indicators in terms of the direct electricity output, and equivalent primary energy. Results focus on photovoltaics (PV), and indicate significant opportunities for their large deployment, up to 40% of total electricity generation in the Chilean electric grids in 2035. Specifically, the PROIPE-eq trends of PVs, which quantify the year-by-year “energy cost” associated to the renewable energy transition, improve significantly over the course of less than two decades in both our future scenarios (respectively, 10-fold in the “best case”-and 6fold in the “worst case”).
This paper presents a detailed life-cycle assessment of the greenhouse gas emissions, cumulative ... more This paper presents a detailed life-cycle assessment of the greenhouse gas emissions, cumulative demand for total and non-renewable primary energy, and energy return on investment (EROI) for the domestic electricity grid mix in the U.S. state of California, using hourly historical data for 2018, and future projections of increased solar photovoltaic (PV) installed capacity with lithium-ion battery energy storage, so as to achieve 80% net renewable electricity generation in 2030, while ensuring the hourly matching of the supply and demand profiles at all times. Specifically—in line with California’s plans that aim to increase the renewable energy share into the electric grid—in this study, PV installed capacity is assumed to reach 43.7 GW in 2030, resulting of 52% of the 2030 domestic electricity generation. In the modelled 2030 scenario, single-cycle gas turbines and nuclear plants are completely phased out, while combined-cycle gas turbine output is reduced by 30% compared to 2018....
Net energy, that is, the energy remaining after accounting for the energy “cost” of extraction an... more Net energy, that is, the energy remaining after accounting for the energy “cost” of extraction and processing, is the “profit” energy used to support modern society. Energy Return on Investment (EROI) is a popular metric to assess the profitability of energy extraction processes, with EROI > 1 indicating that more energy is delivered to society than is used in the extraction process. Over the past decade, EROI analysis in particular has grown in popularity, resulting in an increase in publications in recent years. The lack of methodological consistency, however, among these papers has led to a situation where inappropriate comparisons are being made across technologies. In this paper we provide both a literature review and harmonization of EROI values to provide accurate comparisons of EROIs across both thermal fuels and electricity producing technologies. Most importantly, the authors advocate for the use of point-of-use EROIs rather than point-of-extraction EROIs as the energy ...
This paper exposes the many flaws in the article “Through the Eye of a Needle: An Eco-heterodox P... more This paper exposes the many flaws in the article “Through the Eye of a Needle: An Eco-heterodox Perspective on the Renewable Energy Transition, authored by Siebert and Rees and recently published in Energies as a Review. Our intention in submitting this critique is to expose and rectify the original article’s non-scientific approach to the review process that includes selective (and hence biased) screening of the literature focusing on the challenges related to renewable energies, without discussing any of the well-documented solutions. In so doing, we also provide a rigorous refutation of several statements made by a Seibert–Rees paper, which often appear to be unsubstantiated personal opinions and not based on a balanced review of the available literature.
California has set two ambitious targets aimed at achieving a high level of decarbonization in th... more California has set two ambitious targets aimed at achieving a high level of decarbonization in the coming decades, namely (i) to generate 60% and 100% of its electricity using renewable energy (RE) technologies, respectively, by 2030 and by 2045, and (ii) introducing at least 5 million zero emission vehicles (ZEVs) by 2030, as a first step towards all new vehicles being ZEVs by 2035. In addition, in California, photovoltaics (PVs) coupled with lithium-ion battery (LIB) storage and battery electric vehicles (BEVs) are, respectively, the most promising candidates for new RE installations and new ZEVs, respectively. However, concerns have been voiced about how meeting both targets at the same time could potentially negatively affect the electricity grid’s stability, and hence also its overall energy and carbon performance. This paper addresses those concerns by presenting a thorough life-cycle carbon emission and energy analysis based on an original grid balancing model that uses a com...
The rationale for integrating emergy and life cycle assessment (LCA) has been expounded in previo... more The rationale for integrating emergy and life cycle assessment (LCA) has been expounded in previous contributions to this same series of conferences over the last decade, as well as in a growing number of publications in scientific journals. Whereas we acknowledge that such integration may not always be required or even desirable, we maintain that, when dealing with industrial and agro-industrial systems, the applications in which the two approaches would benefit from it far outnumber those in which they would not. In recent years, many practical steps have been taken to identify and, insofar as possible, address the methodological issues ensuing from the different viewpoints offered by emergy and LCA. This paper summarizes the milestones along the path trodden so far, and briefly describes a newly-developed ‘emergy characterization factor’ library which may be put to practical use. It also aims to identify the lingering theoretical and practical obstacles that still need to be circ...
ABSTRACT The problem of evaluating the greenhouse gas emissions and energy return on energy inves... more ABSTRACT The problem of evaluating the greenhouse gas emissions and energy return on energy invested for an electricity system with a high level of installed PV is discussed and proposed solutions are put forward. A novel consequential lifecycle assessment (CLCA) approach is described that assess the impacts of PV at three distinct but inter-related levels. Firstly energy and material flows from raw materials through to end of life disposal or recycling PV products including panels, inverters and batteries. Secondly, changes to electricity distribution networks where the aggregate effects of PV require new infrastructure assets or new management and control approaches. Thirdly there are effects on the operation of the centralised electricity grid, both in terms of power flows into the grid and in terms of reducing from the grid at certain times through self consumption of PV output. The challenges of evaluating the impacts a distributed electricity generating technology in aggregate on a future electricity system require inter-disciplinary use of life cycle assessment, detailed scenario development and power system analysis.
Purpose This paper aims to provide an alternative method for calculating the environmental credit... more Purpose This paper aims to provide an alternative method for calculating the environmental credits associated with material recycling in life cycle assessment (LCA) of waste management systems. The method proposed here is more consistent with the general attributional approach in LCA than the hitherto common practice of simply assuming a 1:1 substitution of primary material production. Methods The formula proposed for estimating the environmental credit is applicable for the recovered materials that are reintroduced into the market (outputs of the recycling facilities), after all process losses in the various stages of the waste management system have been accounted for. It considers the displacement of materials by using the mix of virgin and recycled materials for each individual material that is used in the market for the production of goods. Moreover, it also considers the changes in the inherent properties of the materials undergoing a recycling process (‘down-cycling’), by int...
Most existing life cycle assessment models of waste management have so far underplayed the import... more Most existing life cycle assessment models of waste management have so far underplayed the importance of the waste collection phase, addressing it only in a simplified fashion, either by requesting the total amount of fuel used as a direct user input or by calculating it based on a set of input parameters and fixed diesel consumption factors. However, if the main purpose of the study is to improve the efficiency of the collection system itself, a more detailed analysis of the collection phase is required, avoiding oversimplified and potentially misleading conclusions. The new LCA collection model presented here relies on a large number of parameters (number and type of containers, collection frequency, distances for the various legs of transport, etc.) and allows the detailed predictive analysis of alternative collection scenarios. The results of applying this newly developed model to a number of experimental case studies in Portugal are analyzed, discussed, and compared to those pr...
Abstract Modern intensive agriculture worldwide is generating increasing environmental pressure, ... more Abstract Modern intensive agriculture worldwide is generating increasing environmental pressure, which prevents its sustainable development. A number of agricultural sustainability assessment approaches and methodological frameworks have been developed by research worldwide to assess the environmental costs and impacts of resources used in agricultural production. A joint use of Life Cycle Assessment (LCA, to assess a process' performance and environmental impacts) and Emergy Accounting (EMA, to estimate environmental support to resource generation and provision) is proposed in this study. The goal is not only to ascertain the environmental ‘cost’ of production of selected chemical resources used in agricultural processes, but also to develop a reliable calculation procedure capable to integrate the two approaches (LCA and EMA), while considering their different allocation algebra and space-time scales of application. Specifically, the UEVs of glyphosate and urea, which are respectively the most used herbicide and nitrogen fertilizer used in worldwide agriculture, are calculated, yielding values of 2.47E+13 sej/kg and 7.07E+12 sej/kg, respectively. In order to do so, UEVs of intermediate process chemicals such as ammonia, acetic anhydride, chlorine gas, formaldehyde, phosphorous chloride, and sodium hydroxide have also been calculated or updated, thus providing at the same time a procedure and a set of values potentially useful for future studies. The LCA impacts of agro-chemicals in China are compared to worldwide averages from the Ecoinvent database, and the UEVs for several chemicals are also compared to previous estimates from published emergy literature.
2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), 2018
This paper investigates the implications of transitioning to more renewable electricity generatio... more This paper investigates the implications of transitioning to more renewable electricity generation in Chile. The ongoing aggressive penetration of renewable energies in Chile reflects the large availability of solar, and to a lesser extent, wind-resources, and is a product of the ambitious national target to generate 60% of Chilean electricity from renewable sources by 2035. In addition, the electricity demand in Chile is expected to keep increasing over the next decades, and there are concerns about security of energy supply. We applied Net Energy Analysis (NEA) from a dynamic perspective, using a new metric, referred to as Power Return on Investment (PROI), which complements the information provided by the conventional Energy Return on Investment (EROI). We illustrated the methodological differences between these two indicators in terms of the direct electricity output, and equivalent primary energy. Results focus on photovoltaics (PV), and indicate significant opportunities for their large deployment, up to 40% of total electricity generation in the Chilean electric grids in 2035. Specifically, the PROIPE-eq trends of PVs, which quantify the year-by-year “energy cost” associated to the renewable energy transition, improve significantly over the course of less than two decades in both our future scenarios (respectively, 10-fold in the “best case”-and 6fold in the “worst case”).
This paper presents a detailed life-cycle assessment of the greenhouse gas emissions, cumulative ... more This paper presents a detailed life-cycle assessment of the greenhouse gas emissions, cumulative demand for total and non-renewable primary energy, and energy return on investment (EROI) for the domestic electricity grid mix in the U.S. state of California, using hourly historical data for 2018, and future projections of increased solar photovoltaic (PV) installed capacity with lithium-ion battery energy storage, so as to achieve 80% net renewable electricity generation in 2030, while ensuring the hourly matching of the supply and demand profiles at all times. Specifically—in line with California’s plans that aim to increase the renewable energy share into the electric grid—in this study, PV installed capacity is assumed to reach 43.7 GW in 2030, resulting of 52% of the 2030 domestic electricity generation. In the modelled 2030 scenario, single-cycle gas turbines and nuclear plants are completely phased out, while combined-cycle gas turbine output is reduced by 30% compared to 2018....
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Papers by Marco Raugei