Product Environmental Life-Cycle Assessment Using Input-Output Techniques

Life-cycle assessment (LCA) facilitates a systems view in environmental evaluation of products, materials, and processes. Life-cycle assessment attempts to quantify environmental burdens over the entire life-cycle of a product from raw material extraction, manufacturing, and use to ultimate disposal. However, current methods for LCA suffer from problems of subjective boundary definition, inflexibility, high cost, data confidentiality, and aggregation.
This paper proposes alternative models to conduct quick, cost effective, and yet comprehensive life-cycle assessments. The core of the analytical model consists of the 498 sector economic input-output tables for the U.S. economy augmented with various sector-level environmental impact vectors. The environmental impacts covered include global warming, acidification, energy use, non-renewable ores consumption, eutrophication, conventional pollutant emissions and toxic releases to the environment. Alternative models are proposed for environmental assessment of individual products, processes, and life-cycle stages by selective disaggregation of aggregate input-output data or by creation of hypothetical new commodity sectors. To demonstrate the method, a case study comparing the life-cycle environmental performance of steel and plastic automobile fuel tank systems is presented.     

The environmental impact of disposable versus re-chargeable batteries for consumer use

Goal, Scope and Background The most common system for powering small items of electronics by both consumers and industry in Australia is simply to repeatedly buy and use disposable alkaline batteries. A growing practice however is to invest in a small battery charger and buy more expensive rechargeables such as nickel metal hydride batteries. This latter course is promoted as being better for the environment. This study evaluates this assertion to guide future practice by both consumers and industry. The study compares re-chargeable AA batteries of both nickel cadmium (NiCd) and nickel metal hydride (NiMH) chemistry, each used either 400 times or 50 times with the number of AA alkaline batteries required to provide 1 kWh of energy to a device being powered. The scope of the analysis includes the materials and processes used in the production, distribution, use and disposal of the batteries and the battery charger and includes consideration of partial recycling and disposal to landfill. Methods The study is done by developing an inventory of the life cycle of each of the alternatives which in the case of re-chargeable batteries includes the charger and the discharge & re-charging process. Measurements were conducted of re-charging efficiencies of representative batteries and of battery charger energy efficiencies. Energy use in wholesale and retail parts of the distribution system are also accounted for. Sima Pro LCA software and associated Australian data bases are then used to analyse the data using the Eco Indicator 99 (E) model of environmental impact. Results The relative impacts of the three alternative systems on the categories human health, ecosystem quality and resource use showed little difference between the NiCd and NiMH batteries except for human health where the toxicity of cadmium gave a 20% advantage to NiMH batteries. When comparing rechargeable batteries with alkaline batteries, the former caused less damage by factors varying from 10 to 131 for an optimistic scenario of 400 cycles of discharge and charge. Significant factors in the impact of the re-chargeable batteries were the production of batteries themselves, the electricity used for whole saling and retailing, the transport to landfill and the copper and other components in the battery charger. For the disposable alkaline batteries the dominant impacts came from the electrical energy used for wholesaling and retailing the batteries, followed by the production of the batteries. Discussion Most of the results are in line with expectations but somewhat surprisingly, the impact in most categories is dominated by the energy used in wholesaling and retailing, particularly for the alkaline batteries where the number involved is large. Also surprising is the fact that the cadmium present in the NiCd batteries was less significant than many other factors. The results however agree broadly with those of Lankey and McMichael (2000). Conclusions Analysis results were overwhelmingly in favour of the re-chargeable battery option. This was true for every impact criteria studied and for less than optimistic scenarios of battery use such as significant shelf life or high discharge rates. Recommen dations and Perspectives Given the present very large market for disposable batteries in Australia, there is a need for education of the consumer population and, to a lesser extent, industry, of the environmental and economic advantages of moving to re-chargeable batteries. ESS-Submission Editor: Dr. Wulf-Peter Schmidt (wschmi18@ford.com)     

Comparative Energy, Environmental, and Economic Analysis of Traditional and E-commerce DVD Rental Networks

This study is a comparative life-cycle assessment (LCA) of two competing digital video disc (DVD) rental networks: the e-commerce option, where the customer orders the movies online, and the traditional business option, where the customer goes to the rental store to rent a movie. The analytical framework proposed is for a customer living in the city of Ann Arbor, Michigan in the United States. The primary energy and environmental performance for both networks are presented using a multicriterion LCA. The package selected by the traditional network is responsible for 67% of the difference in total energy consumption of the two alternatives. Results show that the e-commerce alternative consumed 33% less energy and emitted 40% less CO2 than the traditional option. A set of sensitivity analyses test the influence of distance traveled, transportation mode, and reuse of DVD and DVD packaging on the final results. The mode of transportation used by the customer in the traditional business model also affects global emissions and energy consumption. The customer walking to the store is by far the best option in the traditional network; however, the e-commerce option performed comparatively better despite all transportation modes tested. A novel economic indicator, ESAL, is used to compare different transportation modes based on the level of stress exerted on the pavement. The two networks are compared on the basis of cost accounting; consistent with its energy and environmental advantages, the e-commerce network also exerts lesser economic impact, by $1.17, for the functional unit tested.     

Service Sector Metabolism: Accounting for Energy Impacts of the Montjuic Urban Park in Barcelona

This article evaluates, from an industrial ecology (IE) perspective, the energy performance of the services inside an urban system and determines their global environmental impact. Additionally, this study determines which are the most energy demanding services and the efficiency of their energy use per visitor and per surface area unit.
The urban system under study is the Montjuïc urban park in Barcelona, Catalonia, Spain, which can be considered a services system. In this case study we distinguished the different patterns of consumption among the service fields and, by studying each field individually, found the most efficient facilities and identified the most critical services based on energy use per visitor or per square meter. These findings are based on the use of energy flow accounting (EFA), life-cycle assessment (LCA), and the energy footprint to analyze the Park's technical energy consumption.
Electricity consumption represents nearly 70% of the total energy consumed by the services at Montjuïc Park. The forest surface area required to absorb the CO2-equivalent emissions produced by the life cycle of the energy consumed at Montjuïc Park represents 12.2 times the Park's surface area. We conclude this article by proposing the incorporation of the methods of IE within the study of parks containing multiple services to improve energy management, and as a result, to raise the global environmental performance of the service sector.     

Key sectors in greenhouse gas emissions in Spain: An alternative input–output analysis

We develop an alternative input–output approach and apply it to the determination of key sectors in emissions. This methodology allows us to assess and classify the different productive sectors according to their greenhouse gas emissions and the role that they play in the productive structure, as well as the participation of their output in the total volume of production. In contrast with previous approaches, we do not focus on the responsibility of final demand, but on the responsibility of the total production of each sector. We apply our methodology to the 2014 input–output table for Spain provided by the World Input–Output Database (2016). The results show that the sectors that induce more emissions from other sectors are manufacture of food products, wholesale and retail trade, and construction. Those that are pulled to emit coincide with those that are relevant for their own final demand, being the most important electricity and gas provision, agriculture, and transportation. The classification obtained allows to orient the design of greenhouse gas emission mitigation policies for the different sectors.     

辽宁省能源消费与经济增长的灰色关联

我国能源消费与经济增长的矛盾日益突出.辽宁省是我国重工业基地和能源消耗大省,经济发展对能源依赖性强,能源供不应求的状态日益显著.为了深入了解辽宁省能源消费与经济增长的关系,提出科学的低碳发展建议,本文基于2000—2012年辽宁省能源消费与经济增长相关数据,应用灰色关联分析,分别对辽宁省能源消费产业和能源消费品种与经济增长的相关性进行实证分析.结果表明: 在各产业能源消费中,批发零售业和住宿餐饮业能源消费量很少,但与经济增长的关联程度最大,工业消费量最大,却与经济增长的关联度较弱;在能源消费品种中,石油和水电能源消费量与经济增长的灰色关联度显著,但煤炭能源消费量与经济增长的关联度不显著,表明煤炭的利用效率低.为实现低碳可持续发展,辽宁省应转变经济增长方式、调整产业结构、优化能源结构、提高能源利用效率,特别是应大力发展生产性服务业,推进清洁能源和可再生能源的开发.     

Life cycle assessment of chemical agent resistant coatings

The Department of Defense (DoD) and the U.S. Environmental Protection Agency (EPA) have established a history of cooperation on a wide variety of pollution prevention research efforts, which apply the principles of Life-Cycle Engineering and Design (LCED) to DoD operations. DoD and EPA jointly sponsored this project, with funding from EPA and DoD’s Strategic Environmental Research and Development Program (SERDP), to focus on using Life Cycle Assessment (LCA) principles for optimizing the process of painting military vehicles with chemical agent resistant coatings (CARC). The objectives were to identify environmental and energy burdens of the CARC painting life cycle, and to identify and test potential improvements on a life cycle basis. This LCA of CARC includes difficulties and lessons learned while conducting all three LCA components. The streamlined life-cycle inventory (LCI) involved quantification of environmental and energy burdens associated with the CARC life cycle. Based on the results of the LCI, a preliminary scoping of potential impacts, and a knowledge of alternative CARC painting materials and equipment, five alternatives for the application of CARC were identified. The life-cycle impact assessment (LCIA) of these applications used the equivalency method for impact characterization. The life-cycle improvement assessment (LCImA) results suggested that one application, based on combining an alternative primer and the turbine high-velocity, low-pressure (HVLP) spray painting system, should be subjected to test and evaluation. The LCIA gave this alternative the lowest environmental impact potential scores for seven of nine impact categories compared to the five other alternative systems evaluated. The preferred alternative was technically evaluated in the laboratory against the baseline CARC system using test panels painted at two Army bases. Preliminary results indicate that the preferred alternative performs equal or better than the baseline system at lower cost and with reduced environmental impact potential.     

Effects of Using Heterogeneous Prices on the Allocation of Impacts from Electricity Use: A Mixed‐Unit Input‐Output Approach

Economic input‐output life cycle assessment (IO‐LCA) models allow for quick estimation of economy‐wide greenhouse gas (GHG) emissions associated with goods and services. IO‐LCA models are usually built using economic accounts and differ from most process‐based models in their use of economic transactions, rather than physical flows, as the drivers of supply‐chain GHG emissions. GHG emissions estimates associated with input supply chains are influenced by the price paid by consumers when the relative prices between individual consumers are different. We investigate the significance of the allocation of GHG emissions based on monetary versus physical units by carrying out a case study of the U.S. electricity sector. We create parallel monetary and mixed‐unit IO‐LCA models using the 2007 Benchmark Accounts of the U.S. economy and sector specific prices for different end users of electricity. This approach is well suited for electricity generation because electricity consumption contributes a significant share of emissions for most processes, and the range of prices paid by electricity consumers allows us to explore the effects of price on allocation of emissions. We find that, in general, monetary input‐output models assign fewer emissions per kilowatt to electricity used by industrial sectors than to electricity used by households and service sectors, attributable to the relatively higher prices paid by households and service sectors. This fact introduces a challenging question of what is the best basis for allocating the emissions from electricity generation given the different uses of electricity by consumers and the wide variability of electricity pricing.     

Life Cycle Perspectives to Achieve Business Benefits: From Concept to Technique

The purpose of this paper is to describe how one pollution prevention tool, life-cycle assessment, can be used to identify and manage environmental issues associated with product systems. Specifically, this paper will describe what life-cycle assessment is, determine the key players in its development and application, and present ideas on how life-cycle assessment can be used today. LCA provides a systematic means to broaden the perspective of a company's decisionmaking process to incorporate the consideration of energy and material use, transportation, post-customer use, and disposal, and the environmental releases associated with the product system. LCA provides a framework to achieve a better understanding of the trade-offs associated with specific change in a product, package, or process. This understanding lays the foundation for subsequent risk assessments and risk management efforts by decision-makers.     

Input‐Output‐based Life Cycle Inventory

An input‐output‐based life cycle inventory (IO‐based LCI) is grounded on economic environmental input‐output analysis (IO analysis). It is a fast and low‐budget method for generating LCI data sets, and is used to close data gaps in life cycle assessment (LCA). Due to the fact that its methodological basis differs from that of process‐based inventory, its application in LCA is a matter of controversy. We developed a German IO‐based approach to derive IO‐based LCI data sets that is based on the German IO accounts and on the German environmental accounts, which provide data for the sector‐specific direct emissions of seven airborne compounds. The method to calculate German IO‐based LCI data sets for building products is explained in detail. The appropriateness of employing IO‐based LCI for German buildings is analyzed by using process‐based LCI data from the Swiss Ecoinvent database to validate the calculated IO‐based LCI data. The extent of the deviations between process‐based LCI and IO‐based LCI varies considerably for the airborne emissions we investigated. We carried out a systematic evaluation of the possible reasons for this deviation. This analysis shows that the sector‐specific effects (aggregation of sectors) and the quality of primary data for emissions from national inventory reporting (NIR) are the main reasons for the deviations. As a rule, IO‐based LCI data sets seem to underestimate specific emissions while overestimating sector‐specific aspects.     

Do foods imported into the UK have a greater environmental impact than the same foods produced within the UK?

Purpose

This study of seven foods assessed whether there are modes or locations of production that require significantly fewer inputs, and hence cause less pollution, than others. For example, would increasing imports of field-grown tomatoes from the Mediterranean reduce greenhouse gas (GHG) emissions by reducing the need for production in heated greenhouses in the UK, taking account of the additional transport emissions? Is meat production in the UK less polluting than the import of red meat from the southern hemisphere?

Methods

We carried out a life-cycle inventory for each commodity, which quantified flows relating to life-cycle assessment (LCA) impact categories: primary energy use, acidification, eutrophication, abiotic resource use, pesticide use, land occupation and ozone depletion. The system boundary included all production inputs up to arrival at the retail distribution centre (RDC). The allocation of production burdens for meat products was on the basis of economic value. We evaluated indicator foods from which it is possible to draw parallels for foods whose production follows a similar chain: tomatoes (greenhouse crops), strawberries (field-grown soft fruit), apples (stored for year-round supply or imported during spring and summer), potatoes (early season imports or long-stored UK produce), poultry and beef (imported from countries such as Brazil) and lamb (imported to balance domestic spring–autumn supply).

Results and discussion

Total pre-farm gate global warming potential (GWP) of potatoes and beef were less for UK production than for production in the alternative country. Up to delivery to the RDC, total GWP were less for UK potatoes, beef and apples than for production elsewhere. Production of tomatoes and strawberries in Spain, poultry in Brazil and lamb in New Zealand produced less GWP than in the UK despite emissions that took place during transport. For foods produced with only small burdens of GWP, such as apples and strawberries, the burden from transport may be a large proportion of the total. For foods with inherently large GWP per tonne, such as meat products, burdens arising from transport may only be a small proportion of the total.

Conclusions

When considering the GWP of food production, imports from countries where productivity is greater and/or where refrigerated storage requirement is less will lead to less total GWP than axiomatic preference for local produce. However, prioritising GWP may lead to increases in other environmental burdens, in particular leading to both greater demands on and decreasing quality of water resources.     

E‐Commerce Effects on Energy Consumption: A Multi‐Year Ecosystem‐Level Assessment

This research investigates the impact of e‐commerce on energy consumption in all four sectors of the U.S. economy (commercial, industrial, residential, and transportation), using macroeconomic data from 1992 to 2015. These data capture all the development phases of e‐commerce, as well as direct and rebound effects in and across sectors. Empirical dynamic models (EDMs), a novel methodology in industrial ecology, are applied to the e‐commerce/energy relationship to accommodate for complex system behavior and state‐dependent effects. The results of these data‐driven methods suggest that e‐commerce increases energy consumption mainly through increases in the residential and commercial sectors. These findings contrast with extant research that focuses on transportation effects, which appear less prominent in this investigation. E‐commerce effects also demonstrate state dependence, varying over the magnitude of e‐commerce as a percentage of the total retail sector, particularly in commercial and transportation realms. Assuming these effects will continue in the future, the findings imply that policy makers should focus on mitigating the environmentally deteriorating effects of e‐commerce in the residential sector. However, this investigation cannot provide root causes for the uncovered e‐commerce effects. Robustness of the empirical findings, limitations of the novel EDM methodology, and respective avenues for future methodological and substantial research are discussed.     

Application of life cycle assessment to landfilling

A case study of a life-cycle assessment (LCA) is performed concerning the treatment of household solid wastes in a landfill. The stages considered in this LCA study are: goal and scope definition, inventory analysis and impact assessment. The data of the inventory include the consumption of raw materials and energy through the transport of wastes and the management of landfill, and the corresponding emissions to the environment. Abiotic resource depletion, global warming, acidification, eutrophication and human toxicological impacts have been considered as impact categories for the impact assessment phase of the LCA. A comparison of the environmental impact of the landfilling with and without energy recovery is carried out. Members of the Spanish Association for LCA Development (APRODACV)     

Comparative life-cycle assessments for biomass-to-ethanol production from different regional feedstocks

This study compares life-cycle (cradle-to-gate) energy consumption and environmental impacts for producing ethanol via fermentation-based processes starting with two lignocellulosic feedstocks: virgin timber resources or recycled newsprint from an urban area. The life-cycle assessment in this study employed a novel combination of computer-aided tools. These tools include fermentation process simulation coupled with an impact assessment software tool for the manufacturing process life-cycle stage impacts. The process simulation file was provided by the National Renewable Energy Laboratory (NREL) and was modified slightly to accommodate these different feedstocks. For the premanufacturing process life-cycle stage impacts, such as the fuels and process chemicals used, transportation, and some preparatory steps (wood chipping, etc.), a life-cycle inventory database (the Boustead Model) coupled with an impact assessment software tool were used (the Environmental Fate and Risk Assessment Tool). The Newsprint process has a slightly lower overall composite environmental index (created from eight impact categories) compared to the Timber process. However, the Timber process consumes less electricity, produces fewer emissions in total, and has less of a human health impact. The amount of life-cycle fossil energy required to produce ethanol is 14% of the energy content of the product, making the overall efficiency 86%. Process improvement strategies were evaluated for both feedstock processes, including recycle of reactor vent air and heat integration. Heat integration has the greatest potential to reduce fossil-derived energy consumption, to an extent that fossil-derived energy over the life cycle is actually saved per unit of ethanol produced. These energy efficiency values are superior to those observed in conventional fossil-based transportation fuels.     

A survey of life cycle approaches in waste management

Background, aim, and scope  

Life-cycle thinking and life-cycle approaches are concepts that are getting increased attention worldwide and in particular in EU Policies related to sustainability. The European Commission is launching a number of activities to strengthen life-cycle thinking in policy and business. EU policies aim to decrease waste generation through new waste prevention initiatives, better use of resources and shift to more sustainable consumption patterns. The approach to waste management is based on three principles: waste prevention, recycling and reuse and improving the final disposal and monitoring. In particular, concerning the prevention and recycling of waste, the definition of a waste hierarchy should be the basis for the prioritisation of waste management options. The benefit of using Life Cycle Assessment (LCA) in analysing waste management systems is the provision of a comprehensive view of the processes and impacts involved. However, it is also clear that the studies will always be open for criticism as they are simplifications of reality. Moreover, in order to become the LCA, a leading tool within businesses and government to understand and manage risks or opportunities related to waste management and treatment technologies, there are methodological choices required and a number of aspects that still need to be worked out. It is therefore important to review open and grey literatures, EU guidelines, relevant environmental indicators and databases for the waste sector and data easily usable in waste policy decision-making, with an agreed approach and methodology based on life-cycle thinking. The following survey gathers and describes the existing guidelines and methodologies based on life-cycle thinking and applicable in waste policy decision-making.     

Life Cycle Inventory Information of the United States Electricity System (11/17 pp)

Goal and Scope This study estimates the life cycle inventory (LCI) of the electricity system in the United States, including the 10 NERC (North American Electric Reliability Council) regions, Alaska, Hawaii, off-grid non-utility plants and the US average figures. The greenhouse gas emissions associated with the United States electricity system are also estimated. Methods The fuel mix of the electricity system based on year 2000 data is used. The environmental burdens associated with raw material extraction, petroleum oil production and transportation for petroleum oil and natural gas to power plants are adopted from the DEAMTM LCA database. Coal transportation from a mining site to a power plant is specified with the data from the Energy Information Administration (EIA), which includes the mode of transportation as well as the distance traveled. The gate-to-gate environmental burdens associated with generating electricity from a fossil-fired power plant are obtained from the DEAMTM LCA database and the eGRID model developed by the United States Environmental Protection Agency. For nuclear power plants and hydroelectric power plants, the data from the DEAMTM LCA database are used.Results and Discussion Selected environmental profiles of the US electricity system are presented in the paper version, while the on-line version presents the whole LCI data. The overall US electricity system in the year 2000 released about 2,654 Tg CO2 eq. of greenhouse gas emissions based on 100-year global warming potentials with 193 g CO2 eq. MJe–1 as an weighted average emission rate per one MJ electricity generated. Most greenhouse gases are released during combusting fossil fuels, accounting for 78–95% of the total. The greenhouse gas emissions released from coal-fired power plants account for 81% of the total greenhouse gas emissions associated with electricity generation, and natural gas-fired power plants contribute about 16% of the total. The most significant regions for the total greenhouse gas emissions are the SERC (Southeastern Electric Reliability Council) and ECAR (East Central Area Reliability Coordination Agreement) regions, which account for 22% and 21% of the total, respectively. A sensitivity analysis on the generation and consumption based calculations indicates that the environmental profiles of electricity based on consumption are more uncertain than those based on generation unless exchange data from the same year are available because the exchange rates (region to region import and export of electricity) vary significantly from year to year.Conclusions and Outlook Those who are interested in the LCI data of the US electricity system can refer to the on-line version. When the inventory data presented in the on-line version are used in a life cycle assessment study, the distribution and transmission losses should be taken into account, which is about 9.5% of the net generation [1]. The comprehensive technical information presented in this study can be used in estimating the environmental burdens when new information on the regional fuel mix or the upstream processes is available. The exchange rates presented in this study also offer useful information in consequential LCI studies.     

Institutionalization of Life-Cycle Thinking in the Everyday Discourse of Market Actors

The widespread popularity of life-cycle assessment (LCA) is difficult to understand from the point of view of instrumental decision making by economic agents. Ehrenfeld has argued, in a 1997 issue of this journal, that it is the world-shaping potential of LCA that is more important than its use as a decision-making tool. The present study attempts to explore the institutionalization of this "LCA world view" among ordinary market actors. This is important because environmental policy relies increasingly on market-based initiatives. Cognitive and normative assumptions in authoritative LCA documents are examined as empirical data and compared with data from focus group interviews concerning products and the environment with "ordinary" manufacturers, retailers, and consumers in Finland. These assumptions are (1) the "cradle-to-grave" approach, (2) the view that all products have an environmental impact and can be improved, (3) the relativity of environmental merit, and (4) the way responsibility for environmental burdens is attributed. Relevant affinities, but also differences, are identified. It is argued that life-cycle thinking is not primarily instrumental, but rather is gaining a degree of intrinsic value. The study attempts to establish a broader institutional context in which the popularity of LCA can be understood. From the point of view of this broader context, some future challenges for the development of LCA and life-cycle thinking are suggested.     

The Value of Remanufactured Engines: Life-Cycle Environmental and Economic Perspectives

Remanufacturing restores used automotive engines to like-new condition, providing engines that are functionally equivalent to a new engine at much lower environmental and economic costs than the manufacture of a new engine. A life-cycle assessment (LCA) model was developed to investigate the energy savings and pollution prevention that are achieved in the United States through remanufacturing a midsized automotive gasoline engine compared to an original equipment manufacturer manufacturing a new one. A typical full-service machine shop, which is representative of 55% of the engine remanufacturers in the United States, was inventoried, and three scenarios for part replacement were analyzed. The life-cycle model showed that the remanufactured engine could be produced with 68% to 83% less energy and 73% to 87% fewer carbon dioxide emissions. The life-cycle model showed significant savings for other air emissions as well, with 48% to 88% carbon monoxide (CO) reductions, 72% to 85% nitrogen oxide (NOx) reductions, 71% to 84% sulfur oxide (SOx) reductions, and 50% to 61% nonmethane hydrocarbon reductions. Raw material consumption was reduced by 26% to 90%, and solid waste generation was reduced by 65% to 88%. The comparison of environmental burdens is accompanied by an economic survey of suppliers of new and remanufactured automotive engines showing a price difference for the consumer of between 30% and 53% for the remanufactured engine, with the greatest savings realized when the remanufactured engine is purchased directly from the remanufacturer.     

Variable impact transportation (VIT) model for energy and environmental impact of hauling truck operation

Purpose

Fuel economy and emissions of heavy-duty trucks greatly vary based on vehicular/environmental conditions. Large-scale infrastructure construction projects require a large amount of material/equipment transportation. Single-parameter generic hauling models may not be the best option for an accurate estimation of hauling contribution in life cycle assessment (LCA) involving construction projects; therefore, more precise data and parameterized models are required to represent this contribution. This paper discusses key environmental/operational variables and their impact on transportation of materials and equipment; a variable-impact transportation (VIT) model accounting for these variables was developed to predict environmental impacts of hauling.

Methods

The VIT model in the form of multi-nonlinear regression equations was developed based on simulations using the U.S. Environmental Protection Agency (EPA)’s Motor Vehicle Emission Simulator (MOVES) to compute all the impact categories in EPA’s TRACI 2.1 and energy consumption of transportation. Considering actual driving cycles of hauling trucks recorded during a pavement rehabilitation project, the corresponding environmental impacts were calculated, and sensitivity analyses were performed. In addition, an LCA case study based on historical pavement reconstruction projects in Illinois was conducted to analyze the contribution of transportation and variability of its impacts during the pavements’ life cycle.

Results and discussion

The importance of vehicle driving cycles was realized from simulation results. The case study results showed that considering driving cycles using the VIT model could increase the contribution of hauling in total life cycle Global Warming Potential (GWP) and total life cycle GWP itself by 2–4 and 3–5%, respectively. In addition to GWP, ranges of other hauling-related impact categories including Smog, Ozone Depletion, Acidification, and Primary Energy Demand from fuel were presented based on the case study. Ozone Depletion ranged from 9 to 45%, and Smog ranged from 11 to 48% of the total relevant life cycle impacts. The GWP contribution of hauling in pavement LCA ranged between 5 and 32%. The results indicate that the contribution of hauling transportation can be significant in pavement LCA.

Conclusions

For large-scale roadway infrastructure construction projects that need a massive amount of material transportation, high fidelity models and data should be used especially for comparative LCAs that can be used as part of decision making between alternatives. The VIT model provides a simple analytical platform to include the critical vehicular/operational variables without any dependence on an external software; the model can also be incorporated in those studies where some of the transportation activity data are available.

     

Digital versus Print: Energy Performance in the Selection and Use of Scholarly Journals

Advances in digital technology and the growth of information networks are revolutionizing human activity. The Internet has been championed as a new tool for environmental improvement. A life-cycle energy analysis of digital libraries, a growing application of information technology, was conducted to test this premise.
Life-cycle models were compared for journal collections in digital and traditional formats. The basis for analysis was the amount of information in a typical scientific journal article (∼12 pages), which is equivalent to 0.97 hr of on-screen reading time. Digital system elements such as servers, routers, laser printers, and computer workstations were modeled. Journal production, delivery, storage, binding, interlibrary loan, and photocopying were examined for the traditional system. Building-related infrastructure, office paper, and personal transportation of the library patron were analyzed for both cases. In all, the study incorporated nearly 30 model elements, 90 input variables, and numerous fixed parameters.
Five primary scenarios were constructed to consider increasing levels of complexity. Scenario 1 assumes only one reading per article (unit of analysis). Additional scenarios assume 1,000 readings and vary the following: laser printing, photocopying, and personal transportation. Energy consumed by the digital collection ranged between 4.10 and 216 MJ. The traditional system realized burdens from 0.55 to 525 MJ. Four significant effects were uncovered: (1) Energy consumption per unit was highly influenced by the number of readings per article. (2) Networking infrastructure by itself had a relatively small effect on total energy consumed by the digital system. (3) When personal transportation was considered, its effects tended to dominate. (4) The impact of making personal copies varied. Photocopying always increased energy consumption, whereas laser printing actually saved energy when it substituted for on-screen reading.