• Energy Research

In some areas of Sub-Saharan Africa appropriate organic waste management technology could address development issues such as soil degradation, unemployment and energy scarcity, while at the same time reducing emissions of greenhouse gases. This paper investigates the role that carbon markets could have in facilitating the implementation of composting, anaerobic digestion and biochar production, in the city of Tamale, in the North of Ghana. Through a life cycle assessment of implementation scenarios for low-tech, small scale variants of the above mentioned three technologies, the potential contribution they could give to climate change mitigation was assessed. Furthermore an economic assessment was carried out to study their viability and the impact thereon of accessing carbon markets. It was found that substantial climate benefits can be achieved by avoiding landfilling of organic waste, producing electricity and substituting the use of chemical fertilizer. Biochar production could result in a net carbon sequestration. These technologies were however found not to be economically viable without external subsidies, and access to carbon markets at the considered carbon price of 7 EUR/ton of carbon would not change the situation significantly. Carbon markets could help the realization of the considered composting and anaerobic digestion systems only if the carbon price will rise above 75-84 EUR/t of carbon (respectively for anaerobic digestion and composting). Biochar production could achieve large climate benefits and, if approved as a land based climate mitigation mechanism in carbon markets, it would become economically viable at the lower carbon price of 30 EUR/t of carbon.

The study of the so-called rebound effect has traditionally pertained to the domain of neoclassical energy economics. In recent years, other disciplines have applied this concept in the context of the environmental assessment of products and policies, and multiple perspectives have unfolded more or less in parallel. Among these, the environmental rebound effect (ERE) perspective, focused on efficiency changes and indicators that go beyond energy to multiple environmental issues, has remained relatively unnoticed. This article thus asks the following questions: What are the foundational aspects of the ERE and how these relate to other perspectives? Are there irreconcilable differences between perspectives? And what is the value of the ERE towards a general framework? We map the fundamental ideas behind the ERE and find that the lack of articulation has resulted in inconsistent usage and lack of clarity. We also argue that the ERE offers many valuable insights for rebound assessment, such as the study of broader efficiency changes and of innovations aimed at tackling multiple environmental issues. Perhaps most importantly, the ERE helps bringing together the existing rebound perspectives, as its application shows that it is both possible and valuable to articulate broader definitions for the rebound effect. © 2016 Elsevier B.V.

Abstract Copper demand in China is expected to grow considerably over the coming decades, driving energy use and environmental impacts related to copper production. To explore the environmental impacts of copper production in China, we used a variant of Life Cycle Sustainability Analysis that combined the Life Cycle Assessment methodology with the Chinese copper demand projections from 2010 to 2050. The results indicate that the environmental impacts of pyrometallurgical copper production are expected to increase more than twofold during this period and remain the largest contributor to the environmental footprint. Secondary copper production emits the least pollutions. Increasing the share of secondary copper production is the most environmental friendly option for copper production. To this end, China may focus on improving the classification of waste copper products and recycling infrastructure for end-of-life management. Hard coal use and production are crucial contributors to climate change in the context of copper production. Cleaning up copper production processes and improving energy efficiency would also help reduce environmental impacts. Energy transition can significantly reduce the environmental impacts of copper production, but it also can increase copper requirement.It does not visibly contribute to reduce human toxicity as well.

We analyse how the global material stocks and flows related to the electricity sector may develop towards 2050. We focus on three electricity sub-systems, being generation, transmission and storage and present a model covering both bulk and critical materials such as steel, aluminium and neodymium. Results are based on the second Shared Socio-Economic Pathway scenario, with additional climate policy assumptions based on the IMAGE integrated assessment framework, in combination with dynamic stock modelling and an elaborate review of material intensities.Results show a rapid growth in the demand for most materials in the electricity sector, as a consequence of increased electricity demand and a shift towards renewable electricity technologies, which have higher material intensities and drive the expansion of transmission infrastructure and electricity storage capacity. Under climate policy assumptions, the annual demand for most materials is expected to grow further towards 2050. For neodymium, the annual demand grows by a factor 4.4. Global demand for steel and aluminium in the electricity sector grows by a factor 2 in the baseline or 2.6 in the 2-degree climate policy scenario.We show that the combination of rapid growth of capital stocks and long lifetimes of technologies leads to a mismatch between annual demand and the availability of secondary materials within the electricity sector. This may limit the sector to accomplish circular material flows, especially under climate policy assumptions. We also highlight the potential for electric vehicles to curb some of the material demand related to electricity storage through adoption of vehicle-to-grid services.

Biorefinery, an example of a multiple products system, integrates biomass conversion processes and equipment to produce fuels, power and chemicals from biomass. This study focuses on technical design, economic and environmental analysis of a lignocellulosic feedstock (LCF) biorefinery producing ethanol, succinic acid, acetic acid and electricity. As the potential worldwide demand of succinic acid and its derivatives can reach 30 million tons per year, succinic acid is a promising high-value product if production cost and market price are substantially lowered. The results of the economic analysis show that the designed refinery has great potentials compared to the single-output ethanol plant; even when the price of succinic acid is lowered or the capital investment doubled. In terms of eco-efficiency, the LCF biorefinery shows better environmental performances mainly in global warming potential due to CO(2) fixation during acid fermentation. The overall evaluation of the eco-efficiency depends on the importance attached to each impact category.

The issue of municipal solid waste (MSW) management has been highlighted in China due to the continually increasing MSW volumes being generated and the limited capacity of waste treatment facilities. This article presents a quantitative eco-efficiency (E/E) analysis on MSW management in terms of greenhouse gas (GHG) mitigation. A methodology for E/E analysis has been proposed, with an emphasis on the consistent integration of life cycle assessment (LCA) and life cycle costing (LCC). The environmental and economic impacts derived from LCA and LCC have been normalized and defined as a quantitative E/E indicator. The proposed method was applied in a case study of Tianjin, China. The study assessed the current MSW management system, as well as a set of alternative scenarios, to investigate trade-offs between economy and GHG emissions mitigation. Additionally, contribution analysis was conducted on both LCA and LCC to identify key issues driving environmental and economic impacts. The results show that the current Tianjin's MSW management system emits the highest GHG and costs the least, whereas the situation reverses in the integrated scenario. The key issues identified by the contribution analysis show no linear relationship between the global warming impact and the cost impact in MSW management system. The landfill gas utilization scenario is indicated as a potential optimum scenario by the proposed E/E analysis, given the characteristics of MSW, technology levels, and chosen methodologies. The E/E analysis provides an attractive direction towards sustainable waste management, though some questions with respect to uncertainty need to be discussed further.