• Energy Research

Abstract In this paper we study how international trade allows the geographical separation between the place where carbon emissions occur and the place where income from those emissions is derived. We do so by studying the carbon emissions enabled by the primary inputs of products downstream along the production chain. We find that 18% of global carbon emissions are enabled abroad and that Developed Economies, Fossil Fuel Exporters and Asia account for 80% of the downstream emissions enabled by international trade. Both Developed Economies and Fossil Fuel Exporters exhibit a positive trade balance of enabled emissions while for Asia the opposite is true. Developed Economies and Fossil Fuel Exporters enable emissions mainly through the export of manufactured products (690 Mt) and fossil fuels (684 Mt), respectively, while Asia exhibits an outflow of enabled emissions through the import of fossil fuels (209 Mt). The measurement of enabled emissions allows the understanding of how a region's income is derived from carbon emissions occurring abroad.

Animal production systems are increasingly required to co-produce meat products and other ecosystem services. Sown biodiverse pastures (SBP) were developed in Portugal as an improvement over semi-natural pastures (SNP). SBP increase yields and animal intake during grazing, are substantial carbon sinks, and the abundance of legumes in the mixtures provides plants with a biological source of nitrogen. However, the data available and the data demands of most models make integrated modelling of these effects difficult. Here, we developed “BalSim”, a mass balance approach for the estimation of carbon and nitrogen flows and the direct greenhouse gas (GHG) balance of the two production systems. Results show that, on average, the on-farm GHG balance is −2.6 and 0.8 t CO2e/ha.yr for SBP and SNP, respectively. Ignoring the effects of carbon sequestration, and taking into account only non-CO2 emissions, the systems are responsible for 17.0 and 16.3 kg CO2e/kg live weight.yr. The annual analysis showed that non-CO2 emissions were highest in a drought year due to decreased yield and stocking rate. We also showed through scenario analysis that matching the grazing level to the yield is crucial to minimize emissions and ensure reduced feed supplementation while maintaining high soil carbon stocks.

Feed production is an important contributor to the environmental impacts caused by livestock production. In Portugal, non-dairy cattle are commonly fed with a mixture of grazing and forages/concentrate feed. Sown biodiverse permanent pastures rich in legumes (SBP) were introduced to provide quality animal feed and offset concentrate consumption. SBP also sequester large amounts of carbon in soils. Here, we used a comparative life cycle assessment approach to test the substitution of concentrate through installation of high-yield SBP. Using field data for the Alentejo region in Portugal, we compare the global warming potential of a baseline scenario where cattle is fed in low-yield, semi-natural pastures supplemented with feeds that vary in the ratio of silage to concentrate, and a second scenario where the feed is substituted with high-yield SBP. Although SBP use more fertilizers and machinery, this replacement avoids the emission of about 3 t CO2eq/ha even after SBP stop sequestering carbon. Using crude fiber to establish the equivalence between scenarios leads to higher avoided impact, owing to the fact that the fiber content of SBP is also higher. SBP can avoid 25% emissions from beef production per kg of live animal weight.

Energy return on investment (EROI) is a ratio of the energy obtained in relation to the energy used to extract/produce it. The EROI of fossil fuels is globally decreasing. What do the declining EROIs of energy sources imply for society as a whole? We answer this question by proposing a novel EROI measure that describes, through one parameter, the efficiency of a society in managing energy resources over time. Our comprehensive societal EROI measure was developed by (1) expanding the boundaries of the analysis up to the useful stage; (2) estimating the amount of energy embodied in the energy-converting capital; (3) considering non-conventional sources such as the muscle work of humans and draught animals; and (4) considering the influence of imported and exported energy. We computed the new EROI for Portugal as a case study. We find a considerably lower EROI value, at around 3, compared to those currently available, which is stable over a long-time range (1960–2014). This suggests an independence of EROI from economic growth. When estimated at the final stage, using conventional methods (i.e., without applying the four novelties here introduced), we find a declining societal EROI. Therefore, our results imply that the production of new and more efficient final-to-useful energy converting capital has historically kept societal EROI around a stable value by offsetting the effects of the changing returns of energy sources at the primary and final stages. This will be crucial in the successful transition to renewables.

Land use is increasingly important for impact assessment in life cycle assessment (LCA). Its impacts on biodiversity and provision of ecosystem services are crucial to depict the environmental performance of products. Life cycle impact assessment (LCIA) models are commonly selected by consensus through processes frequently misinformed by the absence of practical application studies. Here, we performed an assessment of all free and peer-reviewed LCIA models for land use. We started with spatial correlation analysis at the country scale. Models that use the same indicators are strongly correlated, suggesting that regionalization is no longer a decisive issue in model selection. We applied these models in a case study for cattle production where feeds are replaced by sown biodiverse pastures (SBP). We tested (1) a non-regionalized inventory from an LCA database and, (2) a regionalized inventory that explicit considered the locations of land occupation and transformation. We found the same qualitative result: the installation of SBP avoids impacts due to feed substitution. Each hectare of SBP installed avoids the occupation of 0.5 hectares per year for feed ingredient production. Adding inventory regionalization for 70% of land use flows leads to a change of 15% in results, suggesting limited spatial differentiation between country-level characterization factors.

Abstract Energy intensity measures, defined as the ratio of energy use to gross domestic product of a country, are widely used to study the productivity of energy use in an economy. Unlike conventional primary and/or final energy intensities, useful work intensity (useful work/gross domestic product) addresses the problem of aggregating in a single measure the different energy forms used, and allows for a clear distinction between thermodynamic efficiencies and structural changes in the demand for energy end-uses. Here, our aim is twofold: (1) Disclose the factors that control the useful work intensities across the EU-15 countries over the deindustrialization process, performing a decomposition of the useful work intensities from 1960 to 2009. (2) Describe a methodology for the automatization of useful work accounting, based on a general mapping of energy end-uses from IEA (International Energy Agency) energy balances. We show that, in contrast to the other conventional energy intensity measures, useful work intensity depends only on the intensity of high temperature heat uses and the relative size of residential energy needs. Aggregate thermodynamic efficiencies slightly increased as a consequence of technological improvements, but were negatively affected by deindustrialization, as a consequence of a transition to less efficient and productive energy uses.

Abstract The relation between Thermodynamics and Economics is a paramount issue in Ecological Economics. Two different levels can be distinguished when discussing it: formal and substantive. At the formal level, a mathematical framework is used to describe both thermodynamic and economic systems. At the substantive level, thermodynamic laws are applied to economic processes. In Ecological Economics, there is a widespread claim that neoclassical economics has the same mathematical formulation as classical mechanics and is therefore fundamentally flawed because: 1) utility does not obey a conservation law as energy does; 2) an equilibrium theory cannot be used to study irreversible processes. Here, we show that neoclassical economics is based on a wrong formulation of classical mechanics, being in fact formally analogous to equilibrium thermodynamics. The similarity between both formalisms, namely that they are both cases of constrained optimisation, is easily perceived when thermodynamics is looked upon using the Tisza–Callen axiomatisation. In this paper, we take the formal analogy between equilibrium thermodynamics and economic systems far enough to answer the formal criticisms, proving that the formalism of neoclassical economics has irreversibility embedded in it. However, the formal similarity between equilibrium thermodynamics and neoclassical microeconomics does not mean that economic models are in accordance with mass, energy and entropy balance equations. In fact, neoclassical theory suffers from flaws in the substantive integration with thermodynamic laws as has already been fully demonstrated by valuable work done by ecological economists in this field.