We compiled 50 publications from the years 2005–2020 about life cycle assessment (LCA) of Li-ion batteries to assess the environmental effects of production, use, and end of life for application in ...electric vehicles. Investigated LCAs showed for the production of a battery pack per kWh battery capacity a median of 280 kWh/kWh_bc (25%-quantile–75%-quantile: 200–500 kWh/kWh_bc) for the primary energy consumption and a median of 120 kg CO2-eq/kWh_bc (25%-quantile–75%-quantile: 70–175 kg CO2-eq/kWh_bc) for greenhouse gas emissions. We expect results for current batteries to be in the lower range. Over the lifetime of an electric vehicle, these emissions relate to 20 g CO2-eq/km (25%-quantile–75%-quantile: 10–50 g CO2-eq/km). Considering recycling processes, greenhouse gas savings outweigh the negative environmental impacts of recycling and can reduce the life cycle greenhouse gas emissions by a median value of 20 kg CO2-eq/kWh_bc (25%-quantile–75%-quantile: 5–29 kg CO2-eq/kWh_bc). Overall, many LCA results overestimated the environmental impact of cell manufacturing, due to the assessments of relatively small or underutilized production facilities. Material emissions, like from mining and especially processing from metals and the cathode paste, could have been underestimated, due to process-based assumptions and non-regionalized primary data. Second-life applications were often not considered.
Background, aim, and scope
The availability of fossil resources is predicted to decrease in the near future: they are a non-renewable source, they cause environmental concerns, and they are subjected ...to price instability. Utilization of biomass as raw material in a biorefinery is a promising alternative to fossil resources for production of energy carriers and chemicals, as well as for mitigating climate change and enhancing energy security. This paper focuses on a biorefinery concept which produces bioethanol, bioenergy, and biochemicals from switchgrass, a lignocellulosic crop. Results are compared with a fossil reference system producing the same products/services from fossil sources.
Materials and methods
The biorefinery system is investigated using a Life Cycle Assessment approach, which takes into account all the input and output flows occurring along the production chain. This paper elaborates on methodological key issues like land use change effects and soil N
2
O emissions, whose influence on final outcomes is weighted in a sensitivity analysis. Since climate change mitigation and energy security are the two most important driving forces for biorefinery development, the assessment has a focus on greenhouse gas (GHG) emissions and cumulative primary energy demand (distinguished into fossil and renewable), but other environmental impact categories (e.g., abiotic depletion, eutrophication, etc.) are assessed as well.
Results
The use of switchgrass in a biorefinery offsets GHG emissions and reduces fossil energy demand: GHG emissions are decreased by 79% and about 80% of non-renewable energy is saved. Soil C sequestration is responsible for a large GHG benefit (65 kt CO
2
-eq/a, for the first 20 years), while switchgrass production is the most important contributor to total GHG emissions of the system. If compared with the fossil reference system, the biorefinery system releases more N
2
O emissions, while both CO
2
and CH
4
emissions are reduced. The investigation of the other impact categories revealed that the biorefinery has higher impacts in two categories: acidification and eutrophication.
Discussion
Results are mainly affected by raw material (i.e., switchgrass) production and land use change effects. Steps which mainly influence the production of switchgrass are soil N
2
O emissions, manufacture of fertilizers (especially those nitrogen-based), processing (i.e., pelletizing and drying), and transport. Even if the biorefinery chain has higher primary energy demand than the fossil reference system, it is mainly based on renewable energy (i.e., the energy content of the feedstock): the provision of biomass with sustainable practices is then a crucial point to ensure a renewable energy supply to biorefineries.
Conclusions
This biorefinery system is an effective option for mitigating climate change, reducing dependence on imported fossil fuels, and enhancing cleaner production chains based on local and renewable resources. However, this assessment evidences that determination of the real GHG and energy balance (and all other environmental impacts in general) is complex, and a certain degree of uncertainty is always present in final results. Ranges in final results can be even more widened by applying different combinations of biomass feedstocks, conversion routes, fuels, end-use applications, and methodological assumptions.
Recommendations and perspectives
This study demonstrated that the perennial grass switchgrass enhances carbon sequestration in soils if established on set-aside land, thus, considerably increasing the GHG savings of the system for the first 20 years after crop establishment. Given constraints in land resources and competition with food, feed, and fiber production, high biomass yields are extremely important in achieving high GHG emission savings, although use of chemical fertilizers to enhance plant growth can reduce the savings. Some strategies, aiming at simultaneously maintaining crop yield and reduce N fertilization application through alternative management, can be adopted. However, even if a reduction in GHG emissions is achieved, it should not be disregarded that additional environmental impacts (like acidification and eutrophication) may be caused. This aspect cannot be ignored by policy makers, even if they have climate change mitigation objectives as main goal.
The core objective of this paper is to analyze the energy and CO2 reduction potentials as well as the market prospects of biofuels in EU-15 in a dynamic framework till 2050. The most important result ...of this analysis is that 2nd generation biofuels might become economically competitive between 2020 and 2030, yet this can only be achieved if the following preconditions are fulfilled: (1) achievement of significant learning effects leading to considerably lower plant costs; (2) significant improvement of conversion efficiency from feedstock to fuel leading to lower feedstock costs and better ecological performance; (3) increases in conventional diesel and gasoline prices, e.g., due to CO2 based taxes.
With increasing use of biomass for energy, questions arise about the validity of bioenergy as a means to reduce greenhouse gas emissions and dependence on fossil fuels. Life Cycle Assessment (LCA) is ...a methodology able to reveal these environmental and energy performances, but results may differ even for apparently similar bioenergy systems. Differences are due to several reasons: type and management of raw materials, conversion technologies, end-use technologies, system boundaries and reference energy system with which the bioenergy chain is compared. Based on review of published papers and elaboration of software data concerning greenhouse gas and energy balances of bioenergy, other renewable and conventional fossil systems, this paper discusses key issues in bioenergy system LCA. These issues have a strong influence on the final results but are often overlooked or mishandled in most of the studies available in literature. The article addresses the following aspects: recognition of the biomass carbon cycle, including carbon stock changes in biomass and soil over time; inclusion of nitrous oxide and methane emissions from agricultural activities; selection of the appropriate fossil reference system; homogeneity of the input parameters in Life Cycle Inventories; influence of the allocation procedure when multiple products are involved; future trends in bioenergy (i.e. second-generation biofuels and biorefineries).
Because many key issues are site-specific, and many factors affect the outcome, it is not possible to give exact values for the amount of greenhouse gas emissions and fossil energy consumption saved by a certain bioenergy product, because too many uncertainties are involved. For these reasons, the results are here provided as a means of wide ranges. Despite this wide range of results, it has been possible to draw some important conclusions and devise recommendations concerning the existing bioenergy systems, and some emerging implications about the future deployment and trends of bioenergy products are pointed out.
In this paper, the greenhouse gas and energy balances of the production and use for space heating of substitute natural gas from biomass (bio-SNG) for space heat are analysed. These balances are ...compared to the use of natural gas and solid biomass as wood chips to provide the same service. The reduction of the greenhouse gas emissions (CO2-eq.) – carbon dioxide, methane and nitrous oxide – and of the fossil primary energy use is investigated in a life cycle assessment (LCA). This assessment was performed for nine systems for bio-SNG; three types of gasification technologies (O2-blown entrained flow, O2-blown circulating fluidised bed and air–steam indirect gasification) with three different types of feedstock (forest residues, miscanthus and short rotation forestry). The greenhouse gas analysis shows that forest residues using the air–steam indirect gasification technology result in the lowest greenhouse gas emissions (in CO2-eq. 32 kg MWh−1 of heat output). This combination results in 80% reduction of greenhouse gas emissions when compared to natural gas and a 29% reduction of greenhouse gases if the forest residues were converted to wood chips and combusted. The gasification technologies O2-blown entrained flow and O2-blown circulating fluidised bed gasification have higher greenhouse gas emissions that range between in CO2-eq. 41 to 75 kg MWh−1 of heat output depending on the feedstock. When comparing feedstocks in the bio-SNG systems, miscanthus had the highest greenhouse gas emissions bio-SNG systems producing in CO2-eq. 57–75 kg MWh−1 of heat output. Energy analysis shows that the total primary energy use is higher for bio-SNG systems (1.59–2.13 MWh MWh−1 of heat output) than for the reference systems (in 1.37–1.51 MWh MWh−1 of heat output). However, with bio-SNG the fossil primary energy consumption is reduced compared to natural gas. For example, fossil primary energy use is reduced by 92% when air–steam indirect gasification technology and forest residues is compared to natural gas. There is no significant difference of the fossil primary energy consumption between the use of solid biomass (0.13–0.15 MWh MWh−1 of heat output) and the bio-SNG systems (0.12–0.18 MWh MWh−1 of heat output).
► Greenhouse gas and energy balances of bio-SNG for space heating. ► Comparison to natural gas and solid biomass. ► Results depend on feedstock and gasification technology used. ► Bio-SNG can be beneficial alternative to natural gas.
•Increased adoption of EVs is assessed on a well-to-wheel basis for five countries.•EVs emit less greenhouse gases than gasoline-fueled vehicles in all countries.•Complexity of EV analysis across ...boundaries complicates communication of benefits.
In this paper, we aim to assess the potential influence of increased adoption of electric vehicles (EVs) on a well-to-wheel (WTW) basis in the four countries with highest passenger car sales (Germany, the United States, China, and Japan), and Norway which represents a highly renewable energy market on greenhouse gas emissions. To characterize these emissions, we define critical parameters regarding fleet composition, activity, efficiency and fuel production in each country. Overall, with today’s technology at a national average level, on a per km driven basis, battery electric vehicles emit fewer greenhouse gases than conventional vehicles in all countries. Though vehicle energy consumption is similar in all countries, electricity production energy efficiency and greenhouse gas emissions per kWh electricity vary considerably, with Norway and China representing the low and high emitting endpoints, respectively. As electricity generation decarbonizes, EVs have the potential to be lower greenhouse-gas emitting than gasoline vehicles in all countries considered. The complexity of EV analysis across international boundaries, time periods, and environmental media complicates communication of EV benefits to stakeholders. Analysts must continue to address and clearly communicate the influence of EV and electricity production technology advancement into the future on EV impacts on all environmental media (air, water, land).
Globalization has been one main driver affecting our whole economy. Thus, greenhouse gas emissions (GHGs) associated with imports and exports should get addressed in addition to the national emission ...inventory according to the United Nations Framework Convention on Climate Change (UNFCCC), which is focused on territorial emissions only. To enable a correct calculation for imports and exports and to find the most emission‐intensive products and their origin, a product‐ and technology‐specific approach would be favorable which has not been applied up to now. This article addresses this research gap in developing and applying such an approach to calculate the GHGs behind consumption of products in Austria. It is based on physical flows combined with life‐cycle‐based emission factors and emission intensities derived from sector‐ and country‐specific energy mix, for calculating all emissions behind the production chain (resources to final products) of products consumed in Austria. The results have shown that consumption of products in Austria leads to about 60% more emissions than those of the national inventory and that the main part of these emissions comes from the provision of products. The most emission‐intensive products are coming from the chemical and the metal industry. In particular, imports are the main driver of these emissions and are more emission intensive than those produced in Austria. As a result, it is necessary to look at practical measures to reduce emissions along the production chain not only in Austria, but especially abroad as well.
The goal to decrease greenhouse gas (GHG) emissions is spurring interest in renewable energy systems from time-varying sources (e.g., photovoltaics, wind) and these can require batteries to help load ...balancing. However, the batteries themselves add additional GHG emissions to the electricity system in all its life cycle phases. This article begins by investigating the GHG emissions for the manufacturing of two stationary lithium-ion batteries, comparing production in Europe, US and China. Next, we analyze how the installation and operation of these batteries change the GHG emissions of the electricity supply in two pilot sites. Life cycle assessment is used for GHG emissions calculation. The regional comparison on GHG emissions of battery manufacturing shows that primary aluminum, cathode paste and battery cell production are the principal components of the GHG emissions of battery manufacturing. Regional variations are linked mainly to high grid electricity demand and regional changes in the electricity mixes, resulting in base values of 77 kg CO2-eq/kWh to 153 kg CO2-eq/kWh battery capacity. The assessment of two pilot sites shows that the implementation of batteries can lead to GHG emission savings of up to 77%, if their operation enables an increase in renewable energy sources in the electricity system.
PDF
