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District heating is a network of pipes through which heat is delivered from a centralised source. It is expected to play an important role in the decarbonisation of the energy sector in the coming years. In district heating, heat is traditionally generated through fossil fuels, often with combined heat and power (CHP) units. However, increasingly, waste heat is being used as a low carbon alternative, either directly or, for low temperature sources, via a heat pump. The design of district heating often has competing objectives: the need for inexpensive energy and meeting low carbon targets. In addition, the planning of district heating schemes is subject to multiple sources of uncertainty such as variability in heat demand and energy prices. This paper proposes a decision support tool to analyse and compare system designs for district heating under uncertainty using stochastic ordering (dominance). Contrary to traditional uncertainty metrics that provide statistical summaries and impose total ordering, stochastic ordering is a partial ordering and operates with full probability distributions. In our analysis, we apply the orderings in the mean and dispersion to the waste heat recovery problem in Brunswick, Germany.

Abstract Lignin is considered as a renewable and sustainable resource for producing value-added aromatic chemicals and functional carbon materials. Herein, we develop a one-step catalyst-free depolymerization strategy to convert lignin into aryl monomers and carbon nanospheres simultaneously. Importantly, microwave-assisted depolymerization (MAD) in conjunction with dichloromethane (CH2Cl2) vapors is developed. The total mass yield of guaiacols reached the highest amount of 225.1 mg/g at 600 °C, and the highest yields of phenols (49.0 mg/g) and aromatic hydrocarbons (155.1 mg/g) were obtained at 700 °C. Hydrogen radicals and hydrogen chloride (HCl) are in-situ formed from CH2Cl2, significantly decreasing the activation barrier and reforming pyrolysis vapors to promote the formation of aryl monomers. Interestingly, uniform carbon nanospheres with an average size of 140 nm were produced as co-products at 700 °C. The microwave “hot-spots”, allied with the continuous surface erosion and the decrease in surface energy of lignin-derived carbon precursors by CH2Cl2 vapor, can be considered the driving force for the ultimate formation of carbon nanospheres. The CH2Cl2/MAD system produces aryl monomers (26.8 wt% yield) and carbon nanospheres (36.6 wt% yield) at 700 °C. We provide a facile, intriguing and scalable approach to convert lignin to valuable aryl monomers and sustainable carbon materials that can be applied in the chemistry, energy and environmental fields.

Access to reliable and affordable energy is vital for sustainable development. In the off-grid areas of developing countries, decentralized energy solutions have received increasing attention due to their contributions to reducing poverty. However, most of the rural population in many developing countries still has little or no access to modern energy technologies. This paper assesses the factors that determine the successes and failures of decentralized energy solutions based on local harmonized case studies from heterogeneous contexts from Asia, sub-Saharan Africa, and South America. The case studies were analyzed through the coupled lenses of energy transition and the Water–Energy–Food Security (WEF) Nexus. The findings indicate that access to modern decentralized energy solutions has not resulted in complete energy transitions due to various tradeoffs with the other domains of the WEF Nexus. On the other hand, the case studies point at the potential for improvements in food security, incomes, health, the empowerment of women, and resource conservation when synergies between decentralized energy solutions and other components of the WEF Nexus are present.

Currently, the world is facing two significant challenges: low-carbon development and overcapacity. Government departments must reexamine their development strategy of energy industry. Implementing environmental regulatory policies and technological innovation can help alleviate coal industry’s overcapacity, while sustainable development requires joint actions of governments, enterprises, and the market. Based on the evolutionary game theory, this study constructs a tripartite evolutionary game model of local government, power industry, and coal enterprise. Under the premise of bounded rationality, the evolution path of each player in the game under the market incentive environmental regulation is analyzed, and the influence of the change of parameters of each player on the result is numerically simulated. The study found that strengthening environmental regulation by local governments is an inevitable choice to promote the transformation and upgrading of coal industry and power industry. In addition, reducing law enforcement costs and technological innovation costs are the fundamental point of the coordinated development of the three parties. Technological innovation in the power industry will reduce the probability of coal companies’ choosing clean production strategies, while seeking low-cost clean production technology and financial support is the key to coal companies’ optimization of production capacity.

Abstract The main purpose of the present research is to develop an environmentally more attractive process for the production of biodiesel by using a magnetic separable solid catalyst. To achieve this, hydroxyapatite-encapsulated γ-Fe 2 O 3 nanoparticles (HAp-γ-Fe 2 O 3 ) were prepared, and organic biguanide was then bound to the magnetic carrier via covalent attachments. The magnetic carrier and biguanide-functionalized HAp-γ-Fe 2 O 3 were fully characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectra, energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM) and nitrogen adsorption–desorption techniques. Results demonstrated that the biguanide was successfully immobilized on the HAp-γ-Fe 2 O 3 without damage to the morphology and structure of the HAp-γ-Fe 2 O 3 carrier. The so-prepared inorganic-organic hybrid nanocomposites exhibited a strong magnetic response and displayed better catalytic activities in the transesterification of soybean oil with methanol for the production of biodiesel. By using the methanol/oil molar ratio of 25:1 and catalyst loading of 3 wt%, the maximum oil conversion of 99.6% was achieved over the solid base catalyst at reflux of methanol after 3 h of reaction. Further, the solid catalyst could be recovered facilely by simple magnetic separation and maintains satisfactory catalytic activity after being recycled for five times.

Scientifically evaluating the level of low-carbon development in terms of theoretical and practical significance is extremely important to coal enterprise groups for implementing national energy-related systems. This assessment can assist in building institutional mechanisms that are conducive for the economic development of coal business cycle and energy conservation as well as promoting the healthy development of coal enterprises to realize coal scientific development and resource utilization. First, by adopting systematic analysis method, this study builds low-carbon development evaluation index system for coal enterprise groups. Second, to determine the weight serving as guideline and criteria of the index, analytic hierarchy process (AHP) is applied using integrated linear weighted sum method to evaluate the level of low-carbon development of coal enterprise groups. Evaluation is also performed by coal enterprise groups, and the process comprises field analysis and evaluation. Finally, industrial policies are proposed regarding the development of low-carbon coal conglomerate strategies and measures. This study aims mainly to guide the low-carbon development of coal enterprise groups, solve the problem of coal mining and the destruction of ecological environment, support the conservation of raw materials and various resources, and achieve the sustainable development of the coal industry.

As presented in the first companion paper, distributed mixed-integer fuzzy hierarchical programming (DMIFHP) was developed for municipal solid waste management (MSWM) under complexities of heterogeneities, hierarchy, discreteness, and interactions. Beijing was selected as a representative case. This paper focuses on presenting the obtained schemes and the revealed mechanisms of the Beijing MSWM system. The optimal MSWM schemes for Beijing under various solid waste treatment policies and their differences are deliberated. The impacts of facility expansion, hierarchy, and spatial heterogeneities and potential extensions of DMIFHP are also discussed. A few of findings are revealed from the results and a series of comparisons and analyses. For instance, DMIFHP is capable of robustly reflecting these complexities in MSWM systems, especially for Beijing. The optimal MSWM schemes are of fragmented patterns due to the dominant role of the proximity principle in allocating solid waste treatment resources, and they are closely related to regulated ratios of landfilling, incineration, and composting. Communities without significant differences among distances to different types of treatment facilities are more sensitive to these ratios than others. The complexities of hierarchy and heterogeneities pose significant impacts on MSWM practices. Spatial dislocation of MSW generation rates and facility capacities caused by unreasonable planning in the past may result in insufficient utilization of treatment capacities under substantial influences of transportation costs. The problems of unreasonable MSWM planning, e.g., severe imbalance among different technologies and complete vacancy of ten facilities, should be gained deliberation of the public and the municipal or local governments in Beijing. These findings are helpful for gaining insights into MSWM systems under these complexities, mitigating key challenges in the planning of these systems, improving the related management practices, and eliminating potential socio-economic and eco-environmental issues resulting from unreasonable management.

Alkali activation is a highly active and rapidly developing field of activity in the global research and development community. Commercial-scale deployment of alkali-activated cements and concretes is now proceeding rapidly in multiple nations. This paper reviews the key developments in alkali-activated materials since 2011, with a particular focus on advances in characterisation techniques and structural understanding, binder precursors and activation approaches, durability testing and design, processing, and sustainability. The scientific and engineering developments described in this paper have underpinned the on-going scale-up activities. We also identify important needs for future research and development to support the optimal and appropriate utilisation of alkali activated materials as a component of a sustainable future construction materials industry. The contributions of JLP were supported by the European Research Council 7th Framework Programme, through the Starting Grant “GeopolyConc” (StG-335928), those of C. Shi were supported by the National Natural Science Foundation of China under contract Nos. U1305243 and 51378196.