• Energy Research

Abstract Associated with the continuing increase of construction activities such as infrastructure projects, commercial buildings, and housing programs, China has been experiencing a rapid increase of construction and demolition (CD and the landfill space demands were estimated to range from 7504 million m3 (the worst scenario) to 706 million m3 (the most optimistic scenario) accordingly. Consequently, increasing the recycling rate and reducing landfill rate of C&D waste could not only improve the potential recycling economic values, but also dramatically reduce land use and potential environmental impacts.

Abstract The built environment stocks such as buildings and infrastructures are key to human development: they provide the fundamental physical settings that the provision of basic human needs such as food, shelter, and transport rely on, but also contribute to anthropogenic greenhouse gas (GHG) emissions throughout their construction, operation, and end-of-life management phases. These stocks usually exist in societies for relatively long time, from years to over a century, therefore their dynamics have long term impacts on human development and emission growth. Several recent studies, including the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), have discussed the lock-in effects of infrastructure stocks on emission pathways. However, there is still a lack of quantitative analysis and evidence to support this claim. Here, based on an empirical regression model and a new dataset that determines built environment stocks, we affirm the effect of built environment stock variable on CO 2 emission by proving that considering built environment stock variable can eliminate the asymmetric effect of GDP per capita growth and decline on CO 2 emission. These results quantitatively underline the role of built environment stocks in human development, future emission pathways, and relevant climate policy.

This article discusses the state of the practice, strength, and weakness of life cycle assessments (LCA) for achieving sustainability goals in the aluminum industry. Notable features of the reviewed LCAs include a limited geographical and life cycle scope and differentiated system boundaries, a common practice to use industry-wide inventory data, a polarized debate on allocation of aluminum recycling, and a predominant focus on energy and greenhouse gas emissions environmental metrics. Not surprisingly, the various studies have produced significantly different results, e.g., the greenhouse gas emissions per kilogram primary aluminum production range from 5.92 to 41.10 kg CO2-equivalent and the “break-even point” (the point when the fuel economy benefits of the lighter aluminum vehicle offset added emissions from the production stage) of vehicles lightweighting ranges from 50,000 to 250,000 km. These variations relate not only to real world differences (e.g., temporal and geographical characteristics), but also partly to data uncertainties and methodological choices. Particularly, the recyclability, long lifetime, and environmental benefits in the use phase of aluminum pose great challenges for LCA methodology, especially for the allocation of recycling. The identified uncertainties and deficiencies can serve as an important base for further improvement of subsequent LCA applications in the aluminum industry.

Abstract In the specific case of French onshore wind farms, waste management of these systems has become an important factor of the wind energy industry’s sustainability. The aim of this paper is to quantify wind turbine (WT) material wastes and flows across the Champagne-Ardenne (CA) region from 2002 to 2020. To do so, a material flow analysis (MFA) model was used. It included three maintenance strategies used for onshore wind turbines. Results show that more than 1 million tons of material will ultimately be generated at the EoL of CA wind farms. The main EoL materials are ferrous and non-ferrous metals, polymers, glass and concrete. The main EoL materials are ferrous and non-ferrous metals, polymers, glass and concrete. In this total, blades and composite EoL materials that need to be managed, account for more than 27,000 tons; there are 523,227 tons of steel and iron materials that need to be handled; 6617 tons of copper, and 28,179 tons of aluminum flows. Landfill concrete accounts for 734,230 tons. When the concrete in foundation is not considered, 73% of an average wind turbine can be recycled. With the first generation of WT reaching their EoL phase and taking into account that no dismantling or recycling facilities of WT components have emerged in the French territory, the potential of WT wastes available for treatment (recycle, incinerate, landfill etc.) is still increasing.

Abstract Waste generation and end-of-life (EoL) management of wind power systems (WPSs) have attracted increasing attention as the number of decommissioned wind turbines continues to increase. In this study, we have addressed this issue by applying a technology-specific, component-by-component, and stock-driven prospective dynamic material flow analysis model in the case of Guangdong, a province in South China with high wind power potential. A particular improvement in our model includes the consideration of the foundation type for offshore wind turbines and the impact of water depth. We set three scenario combinations, high, medium, and low, to reveal the scale of material stocks and flows of wind power development in Guangdong from 1989 to 2050. We found that, as the escalating development of wind power continues (particularly offshore), the total waste generation has increased from 0 tons in 1989 to 24 kilotons in 2018, and will further increase to 1,200, 740, and 490 kilotons in 2050 under the high, medium, and low, scenario combinations, respectively. This indicates a growing demand for waste disposal capacity (particularly for recycling) in the future and a necessity to consider such EoL management issue (particularly for EoL blades) and circular economy strategies (e.g., material efficiency) associated with a much-needed ambitious wind energy development plan. We also argue that relevant EoL policy for WPSs (including Extended Producer Responsibility) should be in place in advance and feasible business models should be explored with joint efforts of wind, waste, and utility industries.

In algal pond used for treating wastewater, a part of the solar radiation (PAR) is used by algae for photosynthesis, and rest of the solar energy is wasted. To date, no studies have been conducted that optimize these aspects (wasted solar radiation for heat production) from an operational cost perspective. Therefore, a model is developed for the estimation of photosynthetically active radiation (PAR) from solar radiation. Subsequently, derived PAR was utilized in the optimization algorithm. Experimental data on PAR and solar radiation were used to obtain empirical parameters of the developed model. Using empirical parameters, diurnal PAR was estimated for other locations for which the diurnal variation of solar radiation was not available. Afterwards, the estimated solar radiation was used to obtain the cost of algal biomass production using wastewater. For this purpose, a cost function was minimized. The cost function contains various cost components of algae-based wastewater treatment. The major costs of the treatment were incurred by the sunlight harvesting, and distribution equipment, whereas the major income was registered through the conversion of sunlight to heat and biomass production. The yearly cost of treating 1m3 wastewater in the proposed wastewater treatment plant could be varied from 186 to −44 (Rs, INR). The capital cost of constructing a proposed treatment plant having a capacity of 1000 m3/day varied from 11–45 crores INR.

Global aluminum demand is anticipated to triple by 2050, by which time global greenhouse gas (GHG) emissions are advised to be cut 50-85% to avoid catastrophic climate impacts. To explore mitigation strategies systematically, a dynamic material flow model was developed to simulate the stocks and flows of the U.S. aluminum cycle and analyze the corresponding GHG emissions. Theoretical and realistic reduction potentials were identified and quantified. The total GHG emissions for the U.S. aluminum cycle in 2006 amount to 38 Mt CO(2)-equivalence. However, the U.S. has increasingly relied on imports of aluminum embodied in various products. The in-use stock is still growing fast in most product categories, which limits current scrap availability for recycling and emissions saving. Nevertheless, there is still large emission mitigation potential through recycling. The potentials from "100% old scrap collection" and "low emission energy" were each calculated to be higher than all process technology potential. Total emissions will decrease dramatically and mitigation priorities will change significantly under a stock saturation situation as much more old scrap becomes available for recycling. The nature of in-use stock development over the coming decades will be decisive for the aluminum industry to reach deeper emission cuts.

Abstract Private passenger vehicles, with its high emissions of CO2 and air pollutants, poses a severe threat to global climate and human health, particularly for a large developing country like China. Although both energy efficiency improvement of internal combustion engine vehicles (ICEVs) and the wide adoption of electric vehicles (EVs) could contribute to reducing emissions, how they should be jointly implemented in provinces with a heterogeneous context to maximize their net benefits remains insufficiently explored. Here, based on an integrated modeling framework associated with one factual (REF) and four counterfactual scenarios to explore the priority and best-ranked ordering of both EVs’ penetration and high energy-efficient ICEVs in 31 Chinese provinces to achieve the most environmental and human health benefits from 2011 to 2018. The results demonstrate that electrification of the passenger fleet, which is charged by a slightly cleaner power source relative to 2011, yields significant co-benefits of CO2 reduction and air quality improvement. Compared with REF, the fleet electrification scenario would lead to 3167 cases of avoided mortality and attain US$4.269 billion of health benefits in 2018, accounting for 0.03% of China’s gross domestic product. Nonetheless, highly efficient ICEVs are found to harbor decarbonization potential and health benefits in northern China. Based on these results, Sichuan, Hebei and seven other provinces in east China should promote EVs imminently; conversely, eight provinces with a high share of thermal power must continually advance their implementation of ICEVs in the near future. Such prioritization of EVs and ICEV development at the provincial level provides timely insights for devising tailored policies regarding passenger car transition and for maximizing climate and health benefits based on regional heterogeneity.