Balance issues in input–output analysis: A comment on physical inhomogeneity, aggregation bias, and coproduction

Recently, Merciai and Heijungs (2014) demonstrated that monetary input–output (IO) analysis can lead to system descriptions that do not conserve mass when the assumption of homogeneous prices is violated. They warn that this violation of basic balance laws can lead to biased estimates of environmental impacts, and they therefore recommend performing IO analysis in a physically accounted framework. We take a broader scope on this issue and present price inhomogeneity as a special case of product mix inhomogeneity. We demonstrate that even a fully physically accounted IO analysis or lifecycle assessment will violate balance laws if it suffers from inhomogeneous aggregation. The core issue is not whether a system is described using monetary or physical units, but rather whether product groups are too aggregated to allow for the concurrent respect of energy, mass, financial and elemental balances. We further analyze the link between the violation of physical balances and the introduction of biases. We find that imbalances are neither a necessary nor a sufficient condition for the presence of systematic errors in environmental pressure estimates. We suggest two ways to leverage the additional explanatory power of multi-unit inventory tables to reduce instances of imbalances and aggregation biases

The effects of continuous venovenous hemofiltration on coagulation activation

INTRODUCTION: The mechanism of coagulation activation during continuous venovenous hemofiltration (CVVH) has not yet been elucidated. Insight into the mechanism(s) of hemostatic activation within the extracorporeal circuit could result in a more rational approach to anticoagulation. The aim of the present study was to investigate whether CVVH using cellulose triacetate filters causes activation of the contact factor pathway or of the tissue factor pathway of coagulation. In contrast to previous studies, CVVH was performed without anticoagulation. METHODS: Ten critically ill patients were studied prior to the start of CVVH and at 5, 15 and 30 minutes and 1, 2, 3 and 6 hours thereafter, for measurement of prothrombin fragment F1+2, soluble tissue factor, activated factor VII, tissue factor pathway inhibitor, kallikrein–C1-inhibitor and activated factor XII–C1-inhibitor complexes, tissue-type plasminogen activator, plasminogen activator inhibitor type I, plasmin–antiplasmin complexes, protein C and antithrombin. RESULTS: During the study period the prothrombin fragment F1+2 levels increased significantly in four patients (defined as group A) and did not change in six patients (defined as group B). Group A also showed a rapid increase in transmembrane pressure, indicating clotting within the filter. At baseline, the activated partial thromboplastin time, the prothrombin time and the kallikrein–C1-inhibitor complex and activated factor XII–C1-inhibitor complex levels were significantly higher in group B, whereas the platelet count was significantly lower in group B. For the other studied markers the differences between group A and group B at baseline were not statistically significant. During CVVH the difference in the time course between group A and group B was not statistically significant for the markers of the tissue factor system (soluble tissue factor, activated factor VII and tissue factor pathway inhibitor), for the markers of the contact system (kallikrein–C1-inhibitor and activated factor XII–C1-inhibitor complexes) and for the markers of the fibrinolytic system (plasmin–antiplasmin complexes, tissue-type plasminogen activator and plasminogen activator inhibitor type I). CONCLUSION: Early thrombin generation was detected in a minority of intensive care patients receiving CVVH without anticoagulation. Systemic concentrations of markers of the tissue factor system and of the contact system did not change during CVVH. To elucidate the mechanism of clot formation during CVVH we suggest that future studies are needed that investigate the activation of coagulation directly at the site of the filter. Early coagulation during CVVH may be related to lower baseline levels of markers of contact activation

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Prospective Environmental Impacts of Selected Low-Carbon Electricity Technologies

Abstract: As one of the main contributors to greenhouse gas (GHG) emissions, the global electricity production sector faces the challenge of mitigating its emissions by transitioning towards cleaner production technologies. In light of this transition, it has been shown that even though renewable energy technologies have clear benefits over fossil generation technologies, there are trade-offs from an environmental and material perspective (Hertwich et al. 2015; Singh et al. 2015). Within the broader scope of sustainable development, care must be taken in climate change mitigation to avoid problem-shifting between environmental impacts. The aim of this thesis is to shed light on the prospective environmental impacts of low-carbon electricity production technologies. Life Cycle Assessment (LCA) was chosen as assessment method for its comprehensive scope. It is detailed enough to estimate prospective impacts with a level of detail that is typically not available for other types of environmental assessment methods. Two key challenges associated with the LCA of electricity technologies were identified: input data variability and uncertainty, and the challenge of matching electricity supply and demand due to intermittent solar and wind resources. It is of importance to take these challenges into account in the environmental assessment of electricity technologies. Against this background, four papers are presented in this thesis. The first paper discusses the influence of fugitive methane emissions on the life cycle GHG emissions of fossil fuel based electricity generation. The other three papers investigate more closely the environmental impacts of electricity technologies, while taking into account the variability and market dispatch of supply from renewable resources. Paper II aims to quantify the additional environmental impacts of extending an offshore wind farm with compressed air energy storage (CAES) for balancing purposes. The influence of economic electricity dispatch on capacity factor assumptions and environmental impacts is studied in Paper III. The prospective environmental impacts of high-renewable electricity production regimes, including intermittency and economic dispatch, are discussed in the final paper. It is shown in Paper I that GHG emissions from fossil fuel power generation vary more widely than commonly acknowledged as a result of large variability in fugitive methane emissions. Where CO2 capture and storage (CCS) reduces the GHG emissions at power plants, it increases the upstream fugitive emissions per unit generation. The high variability in results points to a need for more measured data to reduce the uncertainty in the dataset, as well as a potential mitigation opportunity by capturing methane during fossil fuel extraction. It is shown in Paper II that the additional environmental impacts related to balancing offshore wind power with CAES are limited and combined impacts are well below average grid impacts. Both conventional and adiabatic CAES are investigated. The majority of environmental impacts can be attributed to either the combustion of natural gas in conventional compressed air systems, or the thermal energy storage in adiabatic systems. It is shown in Paper III that the utilization of electricity technologies is determined by the economic dispatch, and is of influence on the capacity factor estimation of individual technologies. The sensitivity of impact assessment for the capacity factor estimation is large for infrastructure intensive technologies and can vary across different impact categories. It is shown in Paper IV that increasing the share of renewable electricity in the mix, decreases impacts significantly. Impact indicators are aggregated into a single impact according to four distinct weighting methods. Large variation in impact is observed for scenarios with comparable levels of renewable electricity production, but different shares of individual technologies. Specific renewable technology targets could inform the setting of renewable energy targets motivated by impact reduction. The thesis as a whole shows that, while the impacts of low-carbon electricity cannot be underestimated, there is significant environmental improvement potential related to the transition to a low-carbon electricity system. The additional environmental pressures associated with balancing electricity supply and demand appear to be relatively limited. The impact reductions achieved by additional low-carbon capacity more than outweigh the potential adverse effects related to its construction

State-of-the-art technologies, measures, and potential for reducing GHG emissions from shipping – A review

CO2 emissions from maritime transport represent around 3% of total annual anthropogenic greenhouse gas (GHG) emissions. These emissions are assumed to increase by 150–250% in 2050 in business-as-usual scenarios with a tripling of world trade, while achieving a 1.5– 2 C climate target requires net zero GHG emissions across all economic sectors. Consequentially, the maritime sector is facing the challenge to significantly reduce its GHG emissions as contribution to the international ambition to limit the effects of climate change. This article presents the results of a review of around 150 studies, to provide a comprehensive overview of the CO2 emissions reduction potentials and measures published in literature. It aims to identify the most promising areas, i.e. technologies and operational practices, and quantify the combined mitigation potential. Results show a significant variation in reported CO2 reduction potentials across reviewed studies. In addition, no single measure is sufficient to achieve meaningful GHG reductions. Emissions can be reduced by more than 75%, based on current technologies and by 2050, through a combination of measures if policies and regulations are focused on achieving these reductions. In terms of emissions per freight unit transported, it is possible to reduce emissions by a factor of 4–6

Multiregional environmental comparison of fossil fuel power generation - Assessment of the contribution of fugitive emissions from conventional and unconventional fossil resources

In this paper we investigate the influence of fugitive methane emissions from coal, natural gas, and shale gas extraction on the greenhouse gas (GHG) impacts of fossil fuel power generation through its life cycle. A multiregional hybridized life cycle assessment (LCA) model is used to evaluate several electricity generation technologies with and without carbon dioxide capture and storage. Based on data from the UNFCCC and other literature sources, it is shown that methane emissions from fossil fuel production vary more widely than commonly acknowledged in the LCA literature. This high variability, together with regional disparity in methane emissions, points to the existence of both significant uncertainty and natural variability. The results indicate that the impact of fugitive methane emissions can be significant, ranging from 3% to 56% of total impacts depending on type of technology and region. Total GHG emissions, in CO2-eq./kWh, vary considerably according to the region of the power plant, plant type, and the choice of associated fugitive methane emissions, with values as low as 0.08 kg CO2-eq./kWh and as high as 1.52 kg CO2-eq./kWh. The variability indicates significant opportunities for controlling methane emissions from fuel chains

Multiregional environmental comparison of fossil fuel power generation-Assessment of the contribution of fugitive emissions from conventional and unconventional fossil resources

In this paper we investigate the influence of fugitive methane emissions from coal, natural gas, and shale gas extraction on the greenhouse gas (GHG) impacts of fossil fuel power generation through its life cycle. A multiregional hybridized life cycle assessment (LCA) model is used to evaluate several electricity generation technologies with and without carbon dioxide capture and storage. Based on data from the UNFCCC and other literature sources, it is shown that methane emissions from fossil fuel production vary more widely than commonly acknowledged in the LCA literature. This high variability, together with regional disparity in methane emissions, points to the existence of both significant uncertainty and natural variability. The results indicate that the impact of fugitive methane emissions can be significant, ranging from 3% to 56% of total impacts depending on type of technology and region. Total GHG emissions, in CO2-eq./kWh, vary considerably according to the region of the power plant, plant type, and the choice of associated fugitive methane emissions, with values as low as 0.08kg CO2-eq./kWh and as high as 1.52kg CO2-eq./kWh. The variability indicates significant opportunities for controlling methane emissions from fuel chains

Multiregional environmental comparison of fossil fuel power generation-Assessment of the contribution of fugitive emissions from conventional and unconventional fossil resources

In this paper we investigate the influence of fugitive methane emissions from coal, natural gas, and shale gas extraction on the greenhouse gas (GHG) impacts of fossil fuel power generation through its life cycle. A multiregional hybridized life cycle assessment (LCA) model is used to evaluate several electricity generation technologies with and without carbon dioxide capture and storage. Based on data from the UNFCCC and other literature sources, it is shown that methane emissions from fossil fuel production vary more widely than commonly acknowledged in the LCA literature. This high variability, together with regional disparity in methane emissions, points to the existence of both significant uncertainty and natural variability. The results indicate that the impact of fugitive methane emissions can be significant, ranging from 3% to 56% of total impacts depending on type of technology and region. Total GHG emissions, in CO2-eq./kWh, vary considerably according to the region of the power plant, plant type, and the choice of associated fugitive methane emissions, with values as low as 0.08kg CO2-eq./kWh and as high as 1.52kg CO2-eq./kWh. The variability indicates significant opportunities for controlling methane emissions from fuel chains

Feasibility study for asphalt rubber pavements in Norway. ‘Rubber Road’ feasibility study.

RubberRoad proposes to use rubber from used tires in the production of asphalt for road and bicycle ways. This recycling approach has not gained much attention in Norway despite its apparent advantages, such as noise reduction, increased durability, safer shock impact, and reduced climate and environmental impacts. The Life Cycle Analysis carried out during this project feasibility study has demonstrated a series of environmental benefits in the use of rubber in asphalt production. It has also helped identify relevant knowledge gaps related to the use phase of the rubberized asphalt and its impact to noise, air and micro-plastic pollution. Better understanding of these effects would probably result in even larger environmental benefits of rubberized asphalt with respect to standard asphalt production. However, while the tire recycling industry is generally positive to the disposal of used tires in asphalt production, additional incentives need to be put in place for the Norwegian asphalt producers to consider actively contributing to this development

Using elemental analyses and multivariate statistics to identify the off-site dispersion from informal e-waste processing

Electronic waste (e-waste) is informally processed and recycled in Agbogbloshie in Accra (Ghana), which may be the largest such site in West Africa. This industry can lead to significant environmental contamination. In this study, surface dust samples were collected at a range of sites within Accra to establish the offsite consequences of such activities. Fifty-one samples were collected and analysed for 69 elements by ICP-mass spectrometry after nitric acid digestion. The data indicated a significant enrichment in metals associated with solder and copper wire at the site itself and a downwind dispersion of this source material to a distance of approximately 2.0 km. Chlorine and bromine were also elevated at this site as residues from polyvinyl chloride combustion and flame retardants respectively. The elemental composition indicated that only low technology electrical equipment was being treated this way. Multivariate statistical analyses by principal components analysis and polytopic vector analysis identified three sources contributing to the system; (i) burn site residue dispersing within 2 km from the source site, (ii) marine matter on the beaches alone and (iii) the baseline soil conditions of the city of Accra. Risk ratios and hazard quotients developed from the measured concentrations indicated that copper was providing the greatest risk to inhabitants in most cases although nickel, vanadium, chromium and zinc also contributed.acceptedVersio