Environmental impacts of hybrid and electric vehicles—a review

Purpose

A literature review is undertaken to understand how well existing studies of the environmental impacts of hybrid and electric vehicles (EV) address the full life cycle of these technologies. Results of studies are synthesized to compare the global warming potential (GWP) of different EV and internal combustion engine vehicle (ICEV) options. Other impacts are compared; however, data availability limits the extent to which this could be accomplished.

Method

We define what should be included in a complete, state-of-the-art environmental assessment of hybrid and electric vehicles considering components and life cycle stages, emission categories, impact categories, and resource use and compare the content of 51 environmental assessments of hybrid and electric vehicles to our definition. Impact assessment results associated with full life cycle inventories (LCI) are compared for GWP as well as emissions of other pollutants. GWP results by life cycle stage and key parameters are extracted and used to perform a meta-analysis quantifying the impacts of vehicle options.

Results

Few studies provide a full LCI for EVs together with assessment of multiple impacts. Research has focused on well to wheel studies comparing fossil fuel and electricity use as the use phase has been seen to dominate the life cycle of vehicles. Only very recently have studies begun to better address production impacts. Apart from batteries, very few studies provide transparent LCIs of other key EV drivetrain components. Estimates of EV energy use in the literature span a wide range, 0.10?C0.24?kWh/km. Similarly, battery and vehicle lifetime plays an important role in results, yet lifetime assumptions range between 150,000?C300,000?km. CO₂ and GWP are the most frequently reported results. Compiled results suggest the GWP of EVs powered by coal electricity falls between small and large conventional vehicles while EVs powered by natural gas or low-carbon energy sources perform better than the most efficient ICEVs. EV results in regions dependant on coal electricity demonstrated a trend toward increased SO _x emissions compared to fuel use by ICEVs.

Conclusions

Moving forward research should focus on providing consensus around a transparent inventory for production of electric vehicles, appropriate electricity grid mix assumptions, the implications of EV adoption on the existing grid, and means of comparing vehicle on the basis of common driving and charging patterns. Although EVs appear to demonstrate decreases in GWP compared to conventional ICEVs, high efficiency ICEVs and grid-independent hybrid electric vehicles perform better than EVs using coal-fired electricity.     

Comparative life cycle assessment of conventional and Green Seal-compliant industrial and institutional cleaning products

Purpose  

The goal of this study was to use life cycle assessment (LCA) methodology to assess the environmental impacts of industrial and institutional cleaning products that are compliant with the Green Seal Standard for Cleaning Products for Industrial and Institutional Use, GS-37, and conventional products (non-GS-37-compliant) products.     

Coupling GIS and LCA for biodiversity assessments of land use

Purpose  

Geospatial details about land use are necessary to assess its potential impacts on biodiversity. Geographic information systems (GIS) are adept at modeling land use in a spatially explicit manner, while life cycle assessment (LCA) does not conventionally utilize geospatial information. This study presents a proof-of-concept approach for coupling GIS and LCA for biodiversity assessments of land use and applies it to a case study of ethanol production from agricultural crops in California.     

Assessing potential desertification environmental impact in life cycle assessment

Background, aim and scope  

Life cycle assessment (LCA) enables the objective assessment of global environmental burdens associated with the life cycle of a product or a production system. One of the main weaknesses of LCA is that, as yet, there is no scientific agreement on the assessment methods for land-use related impacts, which results in either the exclusion or the lack of assessment of local environmental impacts related to land use. The inclusion of the desertification impact in LCA studies of any human activity can be important in high-desertification risk regions.     

A life cycle comparison of disposal and beneficial use of coal combustion products in Florida

Background, Goal, and Scope

Currently, only 40%, or 44.5 million metric tons, of coal combustion products (CCPs) generated in the United States each year by electric utilities are diverted from disposal in landfills or surface impoundments and recycled. Despite promising economic and environmental savings, there has been scant attention devoted to assessing life cycle impacts of CCP disposal and beneficial use. The objective of this paper is to present a life cycle inventory considering two cases of CCP management, including the stages of coal mining and preparation, coal combustion, CCP disposal, and CCP beneficial use. Six beneficial uses were considered: concrete production, structural fills, soil amendments, road construction, blasting grit and roofing granules, and wallboard.

Methods

Primary data for raw material inputs and emissions of all stages considered were obtained from surveys and site visits of coal-burning utilities in Florida conducted in 2002, and secondary data were obtained from various published sources and from databases available in SimaPro 5.1 (PRé Consultants, Amersfoort, The Netherlands).

Results

Results revealed that 50 percent of all CCPs produced, or 108 kg per 1,000 kg of coal combusted, are diverted for application in a beneficial use; however, the relative amounts sold by each utility is dependent on the process operating parameters, air emission control devices, and resulting quality of CCP. Diversion of 50% of all CCPs to beneficial use applications yields a decrease in the total raw materials requirements (with the exception of gravel and iron) and most emissions to air, water, and land, as compared to 100% disposal.

Discussion

The greatest reduction of raw materials was attributed to replacing Portland cement with fly ash, using bottom ash as an aggregate in concrete production and road construction in place of natural materials, and substituting FGD gypsum for natural gypsum in wallboard. The use of fly ash as cementitious material in concrete also promised significant reductions in emissions, particularly the carbon dioxide that would be generated from Portland cement production. Beneficial uses of fly ash and gypsum showed reductions of emissions to water (particularly total dissolved solids) and emissions of metals to land, although these reductions were small compared to simply diverting 50% of all CCPs from landfills or surface impoundments.

Conclusions

This life cycle inventory (LCI) provides the foundation for assessing the impacts of CCP disposal and beneficial use. Beneficial use of CCPs is shown here to yield reductions in raw material requirements and various emissions to all environmental compartments, with potential tangible savings to human health and the environment.

Recommendations and Perspectives

Extension of this life cycle inventory to include impact assessment and sensitivity analysis will enable a determination of whether the savings in emissions reported here actually result in significant improvements in environmental and human health impacts.

     

Coupling GIS and LCA for biodiversity assessments of land use

Purpose  

Geospatial details about land use are necessary to assess its potential impacts on biodiversity. Geographic information systems (GIS) are adept at modeling land use in a spatially explicit manner, while life cycle assessment (LCA) does not conventionally utilize geospatial information. This study presents a proof-of-concept approach for coupling GIS and LCA for biodiversity assessments of land use and applies it to a case study of ethanol production from agricultural crops in California.     

Measuring ecological impact of water consumption by bioethanol using life cycle impact assessment

Purpose  

Though the development of biofuel has attracted numerous studies for quantifying potential water demand applying life cycle thinking, the impacts of biofuel water consumption still remain unknown. In this study, we aimed to quantify ecological impact associated with corn-based bioethanol water consumption in Minnesota in responding to different refinery expansion scenarios by applying a life cycle impact assessment method.     

Including CO<Subscript>2</Subscript>-emission equivalence of changes in land surface albedo in life cycle assessment. Methodology and case study on greenhouse agriculture

Purpose  

Climate change impacts in life cycle assessment (LCA) are usually assessed as the emissions of greenhouse gases expressed with the global warming potential (GWP). However, changes in surface albedo caused by land use change can also contribute to change the Earth’s energy budget. In this paper we present a methodology for including in LCA the climatic impacts of land surface albedo changes, measured as CO₂-eq. emissions or emission offsets.     

Life cycle assessment of desktop PCs in Macau

Purpose

With the tremendous growth in the worldwide electronic information and telecommunication industries, there continues to be an increasing awareness of the environmental impacts related to the accelerating mass production, electricity use, and waste management of electrical and electronic products (e-products). Although Macau is a small region with a total land area of about 29.5 km² and a population of 557,000 in 2011, there are two personal computers (PCs) for every household in Macau.

Methods

This paper aims to describe the application of life cycle assessment (LCA) to investigate the environmental performance of PCs in Macau. An assessment of the PC (focusing on the desktop PC) was carried out using a detailed modular LCA based on the international standards of the ISO 14040 series. The LCA was constructed using SimaPro software version 7.2 and expressed with both the Eco-indicator'99 method and the Centrum voor Milieuwetenschappen method. Life cycle inventory information was compiled by Ecoinvent 2.2 databases, combined with literature and field investigations of the actual situations.

Results and discussion

The established LCA study showed that the manufacturing and the use of such devices are of the highest environmental importance. In the manufacturing stage, the desktop contributes the most to the total environmental impacts (44.89 Pt), followed by the LCD screens (about 27.53 Pt), while the CRT screen, keyboard, and mouse are of minor importance. During the use phase, the environmental impact is due entirely to the consumption of electricity generated by coal, oil, natural gas, and hydropower. The electricity generated by coal is by far the most important, accounting for about 66 % of the total environmental impact, followed by oil and gas. Within the EoL treatment phase, using incineration, there will be little environmental impact. When adopting recycling technology in the EoL phase, apparent environmental benefits will be generated due mainly to avoiding emissions to water (arsenic ions and cadmium ions) and to air (SO₂) in the primary production phase. For the competing technologies of CRT and LCD screens, the environmental impacts are different in different phases, but the total impacts over their entire life cycle are similar.

Conclusions

Results from a life cycle assessment can be used to compare the relative environmental impacts of competing technologies; it can also help designers and managers to focus efforts toward making environmental improvements to a particular technology.     

Life cycle assessment of fine chemical production: a case study of pharmaceutical synthesis

Background, aim, and scope  

Pharmaceuticals have been recently discussed in the press and literature regarding their occurrence in rivers and lakes, mostly due to emissions after use. The production of active pharmaceutical ingredients (APIs) has been less analyzed for environmental impacts. In this work, a life cycle assessment (LCA) of the production of an API from cradle to factory gate was carried out. The main sources of environmental impacts were identified. The resulting environmental profile was compared to a second pharmaceutical production and to the production of basic chemicals.     

A system dynamics approach in LCA to account for temporal effects—a consequential energy LCI of car body-in-whites

Purpose  

The purpose of this paper is to take steps towards a life cycle assessment that is able to account for changes over time in resource flows and environmental impacts. The majority of life cycle inventory (LCI) studies assume that computation parameters are constants or fixed functions of time. This assumption limits the opportunities to account for temporal effects because it precludes consideration of the dynamics of the product system.     

Life cycle assessment of fuel ethanol from cane molasses in Thailand

Background, aim and scope

After China and India, Thailand is considered another emerging market for fuel ethanol in Asia. At present, ethanol in the country is mainly a fermentation/distillery product of cane molasses, although cassava and cane juice are considered other potential raw materials for the fuel. This study aims to evaluate the environmental impacts of substituting conventional gasoline (CG) with molasses-based gasohol in Thailand.

Materials and methods

The life cycle assessment (LCA) procedure carried out follows three interrelated phases: inventory analysis, characterization and interpretation. The functional unit for the comparison is 1 l gasoline equivalent consumed by a new passenger car to travel a specific distance.

Results

The results of the study show that molasses-based ethanol (MoE) in the form of 10% blend with gasoline (E10), along its whole life cycle, consumes less fossil energy (5.3%), less petroleum (8.1%) and provides a similar impact on acidification compared to CG. The fuel, however, has inferior performance in other categories (e.g. global warming potential, nutrient enrichment and photochemical ozone creation potential) indicated by increased impacts over CG.

Discussion

In most cases, higher impacts from the upstream of molasses-based ethanol tend to govern its net life cycle impacts relative to CG. This makes the fuel blend less environmentally friendly than CG for the specific conditions considered. However, as discussed later, this situation can be improved by appropriate changes in energy carriers.

Conclusions

The LCA procedure helps identify the key areas in the MoE production cycle where changes are required to improve environmental performance. Specifically, they are: (1) use of coal as energy source for ethanol conversion, (2) discharge of distillery spent wash into an anaerobic pond, and (3) open burning of cane trash in sugar cane production.

Recommendations and perspectives

Measures to improve the overall life cycle energy and environmental impacts of MoE are: (1) substituting biomass for fossil fuels in ethanol conversion, (2) capturing CH₄ from distillery spent wash and using it as an energy supply, and (3) utilizing cane trash for energy instead of open burning in fields.     

Climatic impact of land use in LCA—carbon transfers between vegetation/soil and air

Background, aim, and scope  

Human use of land areas leads to impacts on nature in several ways. Within the framework of the UNEP/SETAC Life Cycle Initiative, it was stated that life cycle assessment (LCA) of land use should assess at least the impact on biodiversity, the impact on biotic production, and the impact on the regulating functions of the natural environment. This study focuses on the climatic impact of land use as determined by the CO₂ transfers between vegetation/soil and the atmosphere in the course of terrestrial release and re-storage of carbon.     

Life cycle assessment of Australian sugarcane production with a focus on sugarcane growing

Purpose  

Past life cycle assessments (LCA) of sugarcane (Saccharum officinarum) production have commonly been based on limited datasets, and variability has not been well described. In this work, Australian sugarcane production was assessed more comprehensively in order to generate a robust set of LCA results for use in subsequent assessments of sugarcane products and also to investigate: (1) variability due to regional differences, (2) factors influencing variability, and (3) significance of the impacts.     

Ecotoxicity impact assessment of laundry products: a comparison of USEtox and critical dilution volume approaches

Purpose  

There is an increasing interest in the assessment and comparison of the environmental impacts of consumer products. Schemes such as Grenelle de l’Environnement, currently under development in France, aim to assess and communicate the life cycle impacts of consumer products. Freshwater ecotoxicity is one of the impact categories under consideration. This paper presents the results of a comparison of USEtox and critical dilution volume (CDV) approaches for assessing laundry products.     

Environmental product development: replacement of an epoxy-based coating by a polyester-based coating

Purpose  

The purpose of this study is to document and assess the environmental impacts associated with two competing powder coating solutions using current life cycle assessment (LCA) methods and available data and to check whether there is a conflict between environmental performance and occupational health issues.     

Preliminary assessment for global warming potential of leading contributory gases from a 40-in. LCD flat-screen television

Purpose  

As liquid crystal display (LCD) flat-screen televisions increase in popularity, their potential contribution to global warming has received wide attention. This study presents global warming impacts resulting from the life cycle assessment (LCA) of LCD flat-screen televisions for key global warming contributors from the “cradle-to-gate” and use stages of the product’s life cycle. The emissions from nitrogen trifluoride (NF₃), a greenhouse gas with a global warming potential (GWP) 17,000 times more potent than carbon dioxide (CO₂), are not monitored in the Kyoto Protocol. Emissions in the cradle-to-gate and use stages were modeled in this study according to their GWP (kg CO₂ equivalent), focusing and analyzing the most significant source of NF₃ emissions.     

Defining the baseline in social life cycle assessment

Background, aim and scope  

A relatively broad consensus has formed that the purpose of developing and using the social life cycle assessment (SLCA) is to improve the social conditions for the stakeholders affected by the assessed product’s life cycle. To create this effect, the SLCA, among other things, needs to provide valid assessments of the consequence of the decision that it is to support. The consequence of a decision to implement a life cycle of a product can be seen as the difference between the decision being implemented and ‘non-implemented’ product life cycle. This difference can to some extent be found using the consequential environmental life cycle assessment (ELCA) methodology to identify the processes that change as a consequence of the decision. However, if social impacts are understood as certain changes in the lives of the stakeholders, then social impacts are not only related to product life cycles, meaning that by only assessing impacts related to the processes that change as a consequence of a decision, not all changes in the life situations of the stakeholders will be captured by an assessment following the consequential ELCA methodology. This article seeks to identify these impacts relating to the non-implemented product life cycle and establish indicators for their assessment.     

Consequential life cycle assessment: a review

Purpose  

Over the past two decades, consequential life cycle assessment (CLCA) has emerged as a modeling approach for capturing environmental impacts of product systems beyond physical relationships accounted for in attributional LCA (ALCA). Put simply, CLCA represents the convergence of LCA and economic modeling approaches.