The hidden environmental footprint of fashion’s smallest parts

Aluminum production is a major energy consumer and important source of greenhouse gas (GHG) emissions globally. Estimation of the energy consumption and GHG emissions caused by aluminum production in China has attracted widespread attention because China produces more than half of the global aluminum. This paper conducted life cycle (LC) energy consumption and GHG emissions analysis of primary and recycled aluminum in China for the year 2020, considering the provincial differences on both the scale of self-generated electricity consumed in primary aluminum production and the generation source of grid electricity. Potentials for energy saving and GHG emissions reductions were also investigated. The results indicate that there are 157,207 MJ of primary fossil energy (PE) consumption and 15,947 kg CO2-eq of GHG emissions per ton of primary aluminum ingot production in China, with the LC GHG emissions as high as 1.5–3.5 times that of developed economies. The LC PE consumption and GHG emissions of recycled aluminum are very low, only 7.5% and 5.3% that of primary aluminum, respectively. Provincial-level results indicate that the LC PE and GHG emissions intensities of primary aluminum in the main production areas are generally higher while those of recycled aluminum are lower in the main production areas. LC PE consumption and GHG emissions can be significantly reduced by decreasing electricity consumption, self-generated electricity management, low-carbon grid electricity development, and industrial relocation. Based on this study, policy suggestions for China’s aluminum industry are proposed. Recycled aluminum industry development, restriction of self-generated electricity, low-carbon electricity utilization, and industrial relocation should be promoted as they are highly helpful for reducing the LC PE consumption and GHG emissions of the aluminum industry. In addition, it is recommended that the central government considers the differences among provinces when designing and implementing policies.

Introducing demand to supply ratio as a new metric for understanding life cycle greenhouse gas (GHG) emissions from rainwater harvesting systems

Life cycle assessment of primary energy demand and greenhouse gas (GHG) emissions of four propylene production pathways in China

Impacts of alternative fuel combustion in cement manufacturing: Life cycle greenhouse gas, biogenic carbon, and criteria air contaminant emissions

In the United States, concentrating solar power (CSP) is one of the most promising renewable energy (RE) technologies for reduction of electric sector greenhouse gas (GHG) emissions and for rapid capacity expansion. It is also one of the most price-competitive RE technologies, thanks in large measure to decades of field experience and consistent improvements in design. One of the key design features that makes CSP more attractive than many other RE technologies, like solar photovoltaics and wind, is the potential for including relatively low-cost and efficient thermal energy storage (TES), which can smooth the daily fluctuation of electricity production and extend its duration into the evening peak hours or longer. Because operational environmental burdens are typically small for RE technologies, life cycle assessment (LCA) is recognized as the most appropriate analytical approach for determining their environmental impacts of these technologies, including CSP. An LCA accounts for impacts from all stages in the development, operation, and decommissioning of a CSP plant, including such upstream stages as the extraction of raw materials used in system components, manufacturing of those components, and construction of the plant. The National Renewable Energy Laboratory (NREL) is undertaking an LCA of modern CSP plants, starting with those of parabolic trough design. Our LCA follows the guidelines described in the international standard series ISO 14040-44 [1]. To support this effort, we are comparing the life-cycle environmental impacts of two TES designs: two-tank, indirect molten salt and indirect thermocline. To put the environmental burden of the TES system in perspective, one recent LCA that considered a two-tank, indirect molten salt TES system on a parabolic trough CSP plant found that the TES component can account for approximately 40% of the plant’s non-operational GHG emissions [2]. As emissions associated with plant construction, operation and decommissioning are generally small for RE technologies, this analysis focuses on estimating the emissions embodied in the production of the materials used in the TES system. A CSP plant that utilizes an indirect, molten salt, TES system transfers heat from the solar field’s heat transfer fluid (HTF) to the binary molten salts of the TES system via several heat exchangers. The “cold tank” receives the heat from the solar field HTF and conveys it to the “hot tank” via another series of heat exchangers. The hot tank stores the thermal energy for power generation later in the day. A thermocline TES system is a potentially attractive alternative because it replaces the hot and cold tanks with a thermal gradient within a single tank that significantly reduces the quantity of materials required for the same amount of thermal storage. An additional advantage is that the thermocline design can replace much of the expensive molten salt with a low-cost quartzite rock or sand filler material. This LCA is based on a detailed cost specification for a 50 MWe CSP plant with six hours of molten salt thermal storage, which utilizes an indirect, two-tank configuration [3]. This cost specification, and subsequent conversations with the author, revealed enough information to estimate weights of materials (reinforcing steel, concrete, etc.) used in all components of the specified two-tank TES system. To estimate embodied GHG emissions per kilogram of each material, two life cycle inventory (LCI) databases were consulted: EcoInvent v2.0 [4], which requires materials mass data as input, and the US Economic Input-Output LCA database [5], which requires cost data as input. IPCC default global warming potentials (GWPs) give the greenhouse potential of each gas relative to that of carbon dioxide [6]. Where certain materials specified in Kelly [3] were not available in the LCI databases, the closest available proxy for those materials was selected based on such factors as peak process temperature, and similar input materials and process technology. The thermocline system was modeled using the two-tank system design as the foundation, from which materials were subtracted or substituted based on the differences and similarities of design [7]. Table 1 summarizes the results of our evaluation. Embodied emissions of GHGs from the materials used in the 6-hour, 50 MWe two-tank system are estimated to be 17,100 MTCO2e. Analogous emissions for the thermocline system are less than half of those for the two-tank: 7890 MTCO2e. The reduction of salt inventory associated with a thermocline design thus reduces both storage cost and life cycle greenhouse gas emissions. While construction-, operation- and decommissioning-related emissions are not included in this assessment, we do not expect any differences between the two system designs to significantly affect the relative results reported here. Sensitivity analysis on choices of proxy materials for the nitrate salts and calcium silicate insulation also do not significantly affect the relative results.

We suggest a 2D-plot representation combined with life cycle greenhouse gas (GHG) emissions and life cycle cost for various energy conversion technologies. In general, life cycle assessment (LCA) not only analyzes at the use phase of a specific technology, but also covers widely related processes of before and after its use. We use life cycle GHG emissions and life cycle cost (LCC) to compare the energy conversion process for eight resources such as coal, natural gas, nuclear power, hydro power, geothermal power, wind power, solar thermal power, and solar photovoltaic (PV) power based on the reported LCA and LCC data. Among the eight sources, solar PV and nuclear power exhibit the highest and the lowest LCCs, respectively. On the other hand, coal and wind power locate the highest and the lowest life cycle GHG emissions. In addition, we used the 2D plot to show the life cycle performance of GHG emissions and LCCs simultaneously and realized a correlation that life cycle GHG emission is largely inversely proportional to the corresponding LCCs. It means that an expensive energy source with high LCC tends to have low life cycle GHG emissions, or is environmental friendly. For future study, we will measure the technological maturity of the energy sources to determine the direction of the specific technology development based on the 2D plot of LCCs versus life cycle GHG emissions.

LCA (Life Cycle Assessment) is a well known methodology to assess the impact on the environment over the life cycle of a product, process, or activity. This methodology is based on the LCI (Life Cycle Inventory) database, a data set of all resources (material and energy) that are consumed or emitted in order to produce 1 unit of the product. Because electricity is a basic infrastructure, a Thailand electricity grid LCI database is needed to assess the environmental impact not only for the product used in Thailand, but also for any product that is exported to other countries. A complete LCI database for the electricity grid in Thailand is not yet available, and the LCI database developed in this work applies from the fuel acquisition stage to the production stage. The analysis shows the unique characteristics of the Thailand electricity grid. An LCI database for each type of fuel and for each electricity generation system was developed. The characteristics of each type of fuel and electricity generation system are indicated in terms of Life Cycle GHG (Greenhouse Gas) emissions to reflect their global warming potential. Data on the Life Cycle GHG emission per kWh of electricity produced are also provided. The first Thailand LCI database for the fuels used in the electricity generation system was developed using data obtained from the EGAT (Electricity Generating Authority of Thailand), IPPs (Independent Power Producers), and PTT (Petroleum Authority of Thailand) during the Thai fiscal year 2005 (from October 2004 to September 2005). The database was used to analyze the current situation and the characteristics of the electricity generation system in Thailand and to compare it with the systems used in other developed countries.

This study assessed the techno-economic performance and life cycle greenhouse gas (GHG) emissions for various liquefied natural gas (LNG) supply chains in China in order to find the most efficient way to supply and use LNG. This study improves current literature by adding supply chain optimization options (cold energy recovery and hydrogen production) and by analyzing the entire supply chain of four different LNG end-users (power generation, industrial heating, residential heating, and truck usage). This resulted in 33 LNG pathways for which the energy efficiency, life cycle GHG emissions, and life cycle costs were determined by process-based material and energy flow analysis, life cycle assessment, and production cost calculation, respectively. The LNG and hydrogen supply chains were compared with a reference chain (coal or diesel) to determine avoided GHG emissions and GHG avoidance costs. Results show that NG with full cryogenic carbon dioxide capture (FCCC) is most beneficial pathway for both avoided GHG emissions and GHG avoidance costs (70.5–112.4 g CO2-e/MJLNG and 66.0–95.9 $/t CO2-e). The best case was obtained when NG with FCCC replaces coal-fired power plants. Results also indicate that hydrogen pathways requires maturation of new technology options and significant capital cost reductions to become attractive.

The Cross-Laminated Timber (CLT) has been receiving special attention in recent research as an alternative for climate change mitigation since it is a renewable source and can remove and stock high amounts of CO2 from the atmosphere. Some countries, such as Brazil, still do not have mature and large CLT industry. However, the development of this industry in other countries is expected since the CLT is considered the main wood material to be used in high-rise mass timber buildings. It is particularly important to have environmental information, especially concerning the climate change impacts, in terms of life cycle greenhouse gas (GHG) emissions, for this product to increase its competitiveness in a new market. In this context, this research aimed to evaluate three different Life cycle inventories (LCIs) for CLT production of studies from Japan and the United States. Based on the first findings, we summarized the critical items in the LCI of CLT production and listed some actions for the reduction of GHG emissions that occur in this process. The LCIs are adapted considering the context of Brazil (a country with a cleaner electricity matrix) and China (a country with the highest share of fossil fuels). The main inconsistencies present in the LCIs are presented and discussed. The GHG emissions are concentrated in the following hotspots: (1) Roundwood production; (2) electricity consumption; and (3) adhesives production for CLT production. Therefore, the reduction of the consumption of these materials and activities should be encouraged for the decrease of GHG emissions. The data of Roundwood used in the modelling severely affects the final results. Their GHG emissions are related to the consumption of diesel in forestry activities. This research brings insights into the evaluation of the life cycle GHG emissions from the production of CLT.

Life cycle greenhouse gas emissions and freshwater consumption of liquefied Marcellus shale gas used for international power generation

The primary goal of this work was to assess the magnitude and variability of published life cycle greenhouse gas (GHG) emission estimates for three types of geothermal electricity generation technologies: enhanced geothermal systems (EGS) binary, hydrothermal (HT) flash, and HT binary. These technologies were chosen to align the results of this report with technologies modeled in National Renewable Energy Laboratory's (NREL's) Regional Energy Deployment Systems (ReEDs) model. Although we did gather and screen life cycle assessment (LCA) literature on hybrid systems, dry steam, and two geothermal heating technologies, we did not analyze published GHG emission estimates for these technologies. In our systematic literature review of the LCA literature, we screened studies in two stages based on a variety of criteria adapted from NREL's Life Cycle Assessment (LCA) Harmonization study (Heath and Mann 2012). Of the more than 180 geothermal studies identified, only 29 successfully passed both screening stages and only 26 of these included estimates of life cycle GHG emissions. We found that the median estimate of life cycle GHG emissions (in grams of carbon dioxide equivalent per kilowatt-hour generated [g CO2eq/kWh]) reported by these studies are 32.0, 47.0, and 11.3 for EGS binary, HT flash, and HT binary, respectively (Figure ES-1). We also found that the total life cycle GHG emissions are dominated by different stages of the life cycle for different technologies. For example, the GHG emissions from HT flash plants are dominated by the operations phase owing to the flash cycle being open loop whereby carbon dioxide entrained in the geothermal fluids is released to the atmosphere. This is in contrast to binary plants (using either EGS or HT resources), whose GHG emissions predominantly originate in the construction phase, owing to its closed-loop process design. Finally, by comparing this review's literature-derived range of HT flash GHG emissions to data from currently operating geothermal plants, we found that emissions from operational plants exhibit more variability and the median of emissions from operational plants is twice the median of operational emissions reported by LCAs. Further investigation is warranted to better understand the cause of differences between published LCAs and estimates from operational plants and to develop LCA analytical approaches that can yield estimates closer to actual emissions.

Despite the ever-growing body of life cycle assessment (LCA) literature on electricity generation technologies, inconsistent methods and assumptions hamper comparison across studies and pooling of published results. Synthesis of the body of previous research is necessary to generate robust results to assess and compare environmental performance of different energy technologies for the benefit of policy makers, managers, investors, and citizens. With funding from the U.S. Department of Energy, the National Renewable Energy Laboratory initiated the LCA Harmonization Project in an effort to rigorously leverage the numerous individual studies to develop collective insights. The goals of this project were to: (1) understand the range of published results of LCAs of electricity generation technologies, (2) reduce the variability in published results that stem from inconsistent methods and assumptions, and (3) clarify the central tendency of published estimates to make the collective results of LCAs available to decision makers in the near term. The LCA Harmonization Project's initial focus was evaluating life cycle greenhouse gas (GHG) emissions from electricity generation technologies. Six articles from this first phase of the project are presented in a special supplemental issue of the Journal of Industrial Ecology on Meta-Analysis of LCA: coal (Whitaker et al. 2012), concentratingmore » solar power (Burkhardt et al. 2012), crystalline silicon photovoltaics (PVs) (Hsu et al. 2012), thin-film PVs (Kim et al. 2012), nuclear (Warner and Heath 2012), and wind (Dolan and Heath 2012). Harmonization is a meta-analytical approach that addresses inconsistency in methods and assumptions of previously published life cycle impact estimates. It has been applied in a rigorous manner to estimates of life cycle GHG emissions from many categories of electricity generation technologies in articles that appear in this special supplemental supplemental issue, reducing the variability and clarifying the central tendency of those estimates in ways useful for decision makers and analysts. Each article took a slightly different approach, demonstrating the flexibility of the harmonization approach. Each article also discusses limitations of the current research, and the state of knowledge and of harmonization, pointing toward a path of extending and improving the meta-analysis of LCAs.« less

A probabilistic fleet analysis for energy consumption, life cycle cost and greenhouse gas emissions modelling of bus technologies

Impacts of pre-treatment technologies and co-products on greenhouse gas emissions and energy use of lignocellulosic ethanol production

We integrate life cycle indicators for various technologies of an energy system model with high spatiotemporal detail and a focus on Europe and North Africa. Using multi-objective optimization, we calculate a pareto front that allows us to assess the trade-offs between system costs and life cycle greenhouse gas (GHG) emissions of future power systems. Furthermore, we perform environmental ex-post assessments of selected solutions using a broad set of life cycle impact categories. In a system with the least life cycle GHG emissions, the costs would increase by ~63%, thereby reducing life cycle GHG emissions by ~82% compared to the cost-optimal solution. Power systems mitigating a substantial part of life cycle GHG emissions with small increases in system costs show a trend towards a deployment of wind onshore, electricity grid and a decline in photovoltaic plants and Li-ion storage. Further reductions are achieved by the deployment of concentrated solar power, wind offshore and nuclear power but lead to considerably higher costs compared to the cost-optimal solution. Power systems that mitigate life cycle GHG emissions also perform better for most impact categories but have higher ionizing radiation, water use and increased fossil fuel demand driven by nuclear power. This study shows that it is crucial to consider upstream GHG emissions in future assessments, as they represent an inheritable part of total emissions in ambitious energy scenarios that, so far, mainly aim to reduce direct CO2 emissions.