Edgar G. Hertwich

Consumption and the Rebound Effect: An Industrial Ecology Perspective

Summary Measures taken to protect the environment often have other, unintended effects on society. One concern is that changed behavior may offset part of the environmental gain, something that has variously been labeled “take-back” or “rebound.” In energy economics, the rebound effect encompasses both the behavioral and systems responses to cost reductions of energy services as a result of energy efficiency measures. From an industrial ecology perspective, we are concerned about more than just energy use. Any given efficiency measure has several types of environmental impacts. Changes in the various impact indicators are not necessarily in the same direction. Both co-benefits and negative side effects of measures directed to solve one type of problem have been identified. Environment is often a free input, so that a price-based rebound effect is not expected, but other indirect effects not connected to the price, such as spillover of environmental behavior, also occur. If the costs and impact of products that are already environmentally friendly are reduced, the “rebound” can be in the opposite, desired direction. Furthermore, I identify technical spillover effects. Hence a number of related effects, often producing positive results, are not as well understood. Household environmental impact assessments and eco-efficiency assessments take into account the rebound effect, but they do not necessarily take into account these other effects. The analysis hence indicates that the current focus on the rebound effect is too narrow and needs to be extended to cover co-benefits, negative side effects, and spillover effects.

CO2 emissions from biomass combustion for bioenergy: atmospheric decay and contribution to global warming.

Carbon dioxide (CO2) emissions from biomass combustion are traditionally assumed climate neutral if the bioenergy system is carbon (C) flux neutral, i.e. the CO2 released from biofuel combustion approximately equals the amount of CO2 sequestered in biomass. This convention, widely adopted in life cycle assessment (LCA) studies of bioenergy systems, underestimates the climate impact of bioenergy. Besides CO2 emissions from permanent C losses, CO2 emissions from C flux neutral systems (that is from temporary C losses) also contribute to climate change: before being captured by biomass regrowth, CO2 molecules spend time in the atmosphere and contribute to global warming. In this paper, a method to estimate the climate impact of CO2 emissions from biomass combustion is proposed. Our method uses CO2 impulse response functions (IRF) from C cycle models in the elaboration of atmospheric decay functions for biomass‐derived CO2 emissions. Their contributions to global warming are then quantified with a unit‐based index, the GWPbio. Since this index is expressed as a function of the rotation period of the biomass, our results can be applied to CO2 emissions from combustion of all the different biomass species, from annual row crops to slower growing boreal forest.

Carbon, Land, and Water Footprint Accounts for the European Union: Consumption, Production, and Displacements through International Trade

A nations consumption of goods and services causes various environmental pressures all over the world due to international trade. We use a multiregional input-output model to assess three kinds of environmental footprints for the member states of the European Union. Footprints are indicators that take the consumer responsibility approach to account for the total direct and indirect effects of a product or consumption activity. We quantify the total environmental pressures (greenhouse gas emissions: carbon footprint; appropriation of biologically productive land and water area: land footprint; and freshwater consumption: water footprint) caused by consumption in the EU. We find that the consumption activities by an average EU citizen in 2004 led to 13.3 tCO(2)e of induced greenhouse gas emissions, appropriation of 2.53 gha (hectares of land with global-average biological productivity), and consumption of 179 m(3) of blue water (ground and surface water). By comparison, the global averages were 5.7 tCO(2)e, 1.23 gha, and 163 m(3) blue water, respectively. Overall, the EU displaced all three types of environmental pressures to the rest of the world, through imports of products with embodied pressures. Looking at intra-EU displacements only, the UK was the most important displacer overall, while the largest net exporters of embodied environmental pressures were Poland (greenhouse gases), France (land), and Spain (freshwater).

Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies

Significance Life-cycle assessments commonly used to analyze the environmental costs and benefits of climate-mitigation options are usually static in nature and address individual power plants. Our paper presents, to our knowledge, the first life-cycle assessment of the large-scale implementation of climate-mitigation technologies, addressing the feedback of the electricity system onto itself and using scenario-consistent assumptions of technical improvements in key energy and material production technologies. Decarbonization of electricity generation can support climate-change mitigation and presents an opportunity to address pollution resulting from fossil-fuel combustion. Generally, renewable technologies require higher initial investments in infrastructure than fossil-based power systems. To assess the tradeoffs of increased up-front emissions and reduced operational emissions, we present, to our knowledge, the first global, integrated life-cycle assessment (LCA) of long-term, wide-scale implementation of electricity generation from renewable sources (i.e., photovoltaic and solar thermal, wind, and hydropower) and of carbon dioxide capture and storage for fossil power generation. We compare emissions causing particulate matter exposure, freshwater ecotoxicity, freshwater eutrophication, and climate change for the climate-change-mitigation (BLUE Map) and business-as-usual (Baseline) scenarios of the International Energy Agency up to 2050. We use a vintage stock model to conduct an LCA of newly installed capacity year-by-year for each region, thus accounting for changes in the energy mix used to manufacture future power plants. Under the Baseline scenario, emissions of air and water pollutants more than double whereas the low-carbon technologies introduced in the BLUE Map scenario allow a doubling of electricity supply while stabilizing or even reducing pollution. Material requirements per unit generation for low-carbon technologies can be higher than for conventional fossil generation: 11–40 times more copper for photovoltaic systems and 6–14 times more iron for wind power plants. However, only two years of current global copper and one year of iron production will suffice to build a low-carbon energy system capable of supplying the worlds electricity needs in 2050.

Evaluating the environmental impact of products and production processes: a comparison of six methods

The desire of environmentally-conscious consumers and manufacturers to choose more environmentally benign products and processes has led to the development of life cycle assessment (LCA) and design for environment (DfE). In both of these areas, attention has focused initially on the development of inventories of emissions and raw materials consumption for particular products and processes. A number of methods for the comparison and evaluation of an inventorys dissimilar pollution loads and resource demands have been proposed, but no satisfactory solution has yet been identified. This paper compares the structure and properties of six different methods. The health hazard scoring (HHS) system uses the analytical hierarchy process (AHP) to weight workplace toxic effects and accident risks. The material input per service-unit (MIPS) aggregates the mass of all the material input required to produce a product or service. The Swiss eco-point (SEP) method scores pollutant loadings based on a sources contribution to an acceptable total pollution load and an environmental scarcity factor. The sustainable process index (SPI) determines the area that would be required to operate a process sustainably, based on renewable resource generation and toxic degradation; an extension of the dilution volume approach. The Society of Environmental Toxicology and Chemistrys life-cycle impact assessment (SETAC LCA) impact assessment method aggregates pollutants with similar impacts to equivalency potentials (measured in kg CO2 equivalent, kg benzene equivalent etc.) and uses decision analysis to assign weights to different adverse impacts. The environmental priority system (EPS) characterizes the environmental damage caused by equivalency potentials and expresses it in monetary terms, derived from environmental economics. Despite their use for the same purposes, the six methods differ in what they try to achieve, in the effects they consider, in the depth of analysis, in the way values influence the final score, and in use of ordinal or cardinal measures of impact. Two problem areas are identified: (1) to varying degrees, each of the methods has the potential to recommend an alternative that actually has a higher impact than other alternatives; (2) for some of the methods the data requirement is so extensive and the tolerance of imperfect data is so low that the application of the method for reasonably sophisticated products or processes would be too complicated.

Structural analysis of international trade: Environmental impacts of Norway

Abstract Final demand purchases initiate production processes that ultimately lead to environmental impacts. With the increase in international trade, many production processes occur outside of the country of final consumption. Whilst several studies have evaluated the pollution embodied in consumption and trade flows, few studies have investigated the structural linkages between domestic consumption and production in foreign regions. In this article we apply three complementary approaches to study the production network leading from the Norwegian economy to domestic and international environmental impacts: (1) the consumption perspective identifies final demand purchases that produce environmental impacts; (2) the production perspective identifies the production processes generating the pollution for a given demand; and (3) structural path analysis is used to provide the linkages between the global production networks linking consumption and production. We find that the three approaches provide different, but complementary information. For policy to focus on both sustainable consumption and production, all three approaches are required to fully identify environmentally important sectors in an economy.

Human and environmental impact assessment of postcombustion CO2 capture focusing on emissions from amine-based scrubbing solvents to air.

Carbon Capture and Storage (CCS) has become a key technology in climate change mitigation programs worldwide. CCS is well-studied in terms of greenhouse gas emission reduction potential and cost of implementation. Impacts on human health and the environment have, however, received considerably less attention. In this work, we present a first assessment of human health and environmental impacts of a postcombustion CO(2) capture facility, focusing on emissions from amine-based scrubbing solvents and their degradation products to air. We develop characterization factors for human toxicity for monoethanolamine (MEA) as these were not yet available. On the basis of the limited information available, our assessment indicates that amine-based scrubbing results in a 10-fold increase in toxic impact on freshwater ecosystems and a minor increase in toxic impacts on terrestrial ecosystems. These increases are attributed to emissions of monoethanolamine. For all other impact categories, i.e., human toxicity, marine ecotoxicity, particulate matter formation, photochemical oxidant formation, and terrestrial acidification, the CO(2) capture facility performs equally well to a conventional NGCC power plant, albeit substantial changes in flue gas composition. The oxidative degradation products of MEA, i.e., formaldehyde, acetaldehyde, and ammonia, do not contribute significantly to total environmental impacts.

Evaluation of process- and input-output-based life cycle inventory data with regard to truncation and aggregation issues.

Life cycle assessments (LCA) and environmentally extended input-output (EEIO) analyses both strive to account for direct and indirect environmental impacts of goods and services. Different methods have been developed to hybridize these two techniques and minimize the impact of their respective shortcomings on final assessments. These weaknesses, however, have not been extensively studied in a quantitative manner, especially not for complete LCA and EEIO databases. To this end, we jointly analyzed process-based and input-output-based data sets. We first evaluated their complementarity. Though the LCA data was more detailed overall, some sectors of the economy were more precisely represented in the EEIO database. We then contrasted the representation of the different economic sectors in the LCA database with the economic, environmental, and structural importance of these sectors. The weakness of the correlation results led us to conclude that process-inventory efforts have not been systematically directed at the most important sectors of the economy. The LCA data was also used to evaluate the sensitivity of EEIO data to aggregation uncertainty. This sensitivity proved highly inhomogeneous. We conclude the presence of important research inefficiencies stemming from the lack of hybrid perspective in the compilation of LCA and EEIO data.

Parameter Uncertainty and Variability In Evaluative Fate and Exposure Models

The human toxicity potential, a weighting scheme used to evaluate toxic emissions for life cycle assessment and toxics release inventories, is based on potential dose calculations and toxicity factors. This paper evaluates the variance in potential dose calculations that can be attributed to the uncertainty in chemical-specific input parameters as well as the variability in exposure factors and landscape parameters. A knowledge of the uncertainty allows us to assess the robustness of a decision based on the toxicity potential; a knowledge of the sources of uncertainty allows us to focus our resources if we want to reduce the uncertainty. The potential dose of 236 chemicals was assessed. The chemicals were grouped by dominant exposure route, and a Monte Carlo analysis was conducted for one representative chemical in each group. The variance is typically one to two orders of magnitude. For comparison, the point estimates in potential dose for 236 chemicals span ten orders of magnitude. Most of the variance in the potential dose is due to chemical-specific input parameters, especially half-lives, although exposure factors such as fish intake and the source of drinking water can be important for chemicals whose dominant exposure is through indirect routes. Landscape characteristics are generally of minor importance.

A Theoretical Foundation for Life‐Cycle Assessment

Summary The presence of value judgments in life-cycle impact assessment (LCIA) has been a constant source of controversy. According to a common interpretation, the international standard on LCIA requires that the assessment methods used in published comparisons be “value free.” Epistemologists argue that even natural science rests on “constitutive” and “contextual” value judgments. The example of the equivalency potential for climate change, the global warming potential (GWP), demonstrates that any impact assessment method inevitably contains not only constitutive and contextual values, but also preference values. Hence, neither life-cycle assessment (LCA) as a whole nor any of its steps can be “value free.” As a result, we suggest a more comprehensive definition of objectivity in LCA that allows arguments about values and their relationship to facts. We distinguish three types of truth claims: factual claims, which are based on natural science; normative claims, which refer to preference values; and relational claims, which address the proper relation between factual knowledge and values. Every assessment method, even the GWP, requires each type of claim. Rational arguments can be made about each type of claim. Factual truth claims can be assessed using the scientific method. Normative claims can be based on ethical arguments. The values of individuals or groups can be elicited using various social science methods. Relational claims must follow the rules of logic. Relational claims are most important for the development of impact assessment methods. Because LCAs are conducted to satisfy the need of decision makers to consider environmental impacts, relational claims about impact assessment methods should refer to this goal. This article introduces conditions that affect environmental decision making and discusses how LCA—values and all—can be defended as a rational response to the challenge of moving uncertain scientific information into the policy arena.