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Abstract With drastic fossil fuel depletion and environmental deterioration concerns, a move towards a more sustainable bioenergy-based economy is essential. Lately, the application of microwave (MW) irradiation for waste processing has been attracting interest globally. MW-assisted heating possesses several advantages such as the provision of high microwave energy into dielectric materials with deeper penetration for internal heat generation, showing beneficial features in improving the heating rate and reducing the reaction time. Consequently, the most recent literature regarding the applications of MW-assisted heating for biomass pretreatment as well as biofuel and bioenergy production was reviewed and consolidated in this study. An impressive increase in the product yield and improvement of the product properties are reported, with the use of MW-assisted heating in several conversion routes to produce biofuels. Despite being a promising technology for biofuel production, some major fundamental data of MW-assisted heating have not been comprehensively identified. Therefore, the feasibility of this technology for large-scale implementation is still subpar. Understanding the interaction between the feedstock and the microwave electromagnetic field, and the optimization of several operational and mechanical parameters are the two main keystones that would propel the industrialization of MW heating in the near future. This provides key insights leading to increased feasibility and more advanced application of MW heating.

Various theories and approaches have been introduced in the debate on how to address sustainable consumption. In this study, we first discuss different theoretical perspectives on sustainable consumption, particularly developed in the fields of economics, social psychology and environmental sociology. We argue that neither an ‘individualist’ nor a system- or structural perspective alone is sufficient for understanding and analysing the transition towards sustainable consumption. Therefore, we propose to apply the Social Practices Approach (SPA) that combines both human agency and social structures to understand sustainable consumption issues. Following the SPA framework, we review and summarize research on sustainable consumption in China in particular on three consumption fields: food, housing energy and mobility. It is found that introducing more efficient production technology is commonly taken as the focal point in these sectors when sustainable consumption was introduced to China. Despite a rising interest in consumers' perceptions of products' sustainability in recent years, research has rarely paid any attention to consumers' behavioural change or to the transition dynamics towards sustainable consumption. In general, ‘individualist’ perspectives have largely dominated Chinese sustainable consumption research. This paper proposes to move attention to a better understanding of Chinese consumption issues by emphasizing the link between the provision of sustainable products and the diverse sustainable consumption practices. Also, images of food, energy, mobility and other consumption products that are undergoing transitions need to be considered in future research as these have consequences for socio-technical changes, material infrastructures and for ‘lifestyle’ innovations.

Livestock production in peri-urban areas constitutes an important sub-sector of the agricultural production system in China, and contributes to environmental degradation and local air borne pollution contributing to smog. As a result, local policies are being implemented to safeguard the environment. However, there has been little attempt to quantify the impact of environmental policies on livestock production structure, spatial distribution and their related greenhouse gases (GHGs) and ammonia (NH3) emissions. Here, we calculated the inventories of GHGs and NH3 emissions for 2010 and 2014 for peri-urban livestock production in Beijing, using reliable spatially explicit data, which was collected from 1748 industrial farms in 2010 and 2351 industrial farms in 2014, including pig, dairy, beef cattle, poultry and sheep farms. Our estimates indicated that total industrial livestock production increased by 17% between 2010 and 2014, even under the more strict environmental protection polices, with farm size decreasing by between 7% and 47%. Up to 50% of the industrial livestock farms have remained in operation, with the rest closing down or being moved to other regions. Following this trend, total GHGs emission decreased from 5.0 to 4.5 Tg CO2-eq between 2010 and 2014. Most of the GHGs emission reduction was due to the lowering of energy related carbon dioxide (CO2) emission in 2014. Total NH3 emission decreased from 102 to 96 Gg between 2010 and 2014, mainly due to more stringent environmental regulations for new and extended farms (increased in farm size), e.g. Discharge standard for pollutants for livestock and poultry breeding. Our study identified that GHGs and NH3 emission hotspots were concentrated in suburban areas (around the city centre and with less agricultural resource and population density) in 2010. However, between 2010 and 2014 these hotspots moved to the exurban plain and mountain area following the closure or sub-division of intensive farms in suburban regions and construction of new and small farms in exurban areas (around the suburban and with more agricultural resource and lower population density). Scenario analysis suggests that total GHGs emission can be reduced by up to 1.0 Tg CO2-eq (23% of total livestock sector emissions) in Beijing, using a combination of modifications of farm type, livestock diet and manure management. The integrated scenario can reduce CH4, N2O and NH3 emissions by 27%, 9% and 35%, compared to the reference scenario. Within this short period of time (5 years), policies have had direct impacts on peri-urban livestock production in Beijing, resulting in marked changes in the structure of different livestock sectors, as well as the GHGs and NH3 emission inventories and their spatial distribution. Our analysis clearly shows that the success of these (and future) polices relies on optimizing spatial management of new livestock production systems. Policy and farmer guidance should focus on optimizing livestock diet and on-farm manure management, industrial production systems and the pig and poultry sectors in peri-urban regions.

AbstractThe selective and simultaneous production of hydrogen and chemicals from renewable alcohols, such as ethanol, glycerol, and ethylene glycol, can be accomplished by means of electrolyzers in which the anode electrocatalyst is appropriately designed to promote the partial and selective oxidation of the alcohol. In the electrolyzers described herein, the production of 1 kg of hydrogen from aqueous ethanol occurs with one‐third the amount of energy required by a traditional H2/O2 electrolyzer, by virtue of the much lower oxidation potential of ethanol to acetate vs. water to oxygen in alkaline media (E0=0.10 V vs. 1.23 V). The self‐sustainability of H2 production is ensured by the simultaneous production of 25 kg of potassium acetate for every kg of H2, if the promoting co‐electrolyte is KOH.

With concerns of energy shortages, China, like the United States, European Union, and other countries, is promoting the development of biofuels. However, China also faces high future demand for food and feed, and so its bioenergy program must try to strike a balance between food and fuel. The goals of this paper are to provide an overview of China's current bioethanol program, identify the potential for using marginal lands for feedstock production, and measure the likely impacts of China's bioethanol development on the nation's future food self-sufficiency. Our results indicate that the potential to use marginal land for bioethanol feedstock production is limited. Applying a modeling approach based on highly disaggregated data by region, our analysis shows that the target of 10 million t of bioethanol by 2020 seems to be a prudent target, causing no major disturbances in China's food security. But the expansion of bioethanol may increase environmental pressures due to the higher levels of fertilizer use. This study shows also that if China were able to cultivate 45% of its required bioethanol feedstock on new marginal land, it would further limit negative effects of the bioethanol program on the domestic and international economy, but at the expense of having to apply another 750 thousand t of fertilizer.

Abstract Grate-firing technology is one of the commonly used technologies for municipal solid waste incineration, which recovers energy and largely reduces the volume of the solid wastes for landfilling. In grate-fired incinerators, the solid wastes are packed in the fuel bed on the grate, where the major heterogeneous conversion takes place. A proper modeling of the fuel conversion process in the bed not only benefits an in-depth understanding of the in-bed incineration but also facilitates the freeboard simulation. In this paper, a comprehensive model is developed to simulate solid wastes incineration in a packed bed, which advances the state-of-the-art with corrected boundary conditions, homogeneous reactions, and calculation method for pyrolysis products. The model is first validated by a simplified analytical problem. Then, the model is validated in detail by a dedicated experimental study in literature, in which the pyrolysis and gas combustion front and the subsequent char oxidation front both propagate from the bed surface to the grate due to the abundant oxygen availability in the fuel bed. The model also outperforms a latest modeling study in literature for reproducing the same experimental study. Finally, a model-based parametric study is conducted to investigate the effects of solid waste particle sizes and solid waste incineration in high-altitude areas. This paper also clearly explains the methods to transfer the packed-bed model to travelling grates and to accommodate the different waste fractions in real municipal solid waste, in order to make the model applicable to travelling grate-firing of real municipal solid wastes.

The environmental profile of two municipal solid waste incineration (MSWI) technologies with semi-dry flue gas cleaning, namely grated firing incinerators (GFI) and fluidised bed incinerators (FBI) that are commonly used in China were evaluated and compared by life-cycle assessment (LCA) using the EASEWASTE model. All emissions of key pollutants as well as energy, resource and material inputs and outputs associated with the two MSWI technologies were determined and the corresponding environmental impact potentials were modelled. Incineration of MSW with a lower heating value (LHV) around 4.5 MJ kg—1 demands that auxiliary fuel is used, and both GFI and FBI caused environmental loads by contributing with environmental impact potentials in most categories except for some saving in global warming (GW100) and hazardous waste (HW). Coal combustion in FBI is a main contributor to the environmental impact potentials and thus should always be limited to a minimum. Auxiliary fuels can be avoided when the LHV of MSW is higher than 5—6 MJ kg— 1. For all scenarios, GFI saves more global warming potentials than FBI due to its higher net power generation from combustion of MSW itself. Leachate from the bunker could be sprayed into the furnace for evaporation under high temperature, as an alternative to waste-water treatment, without major changes in the environmental profile of the incinerator. The presented evaluations may contribute to a more balanced environmental assessment of the two incineration technologies with respect to incineration of MSW with low heating values as often found in Asia and China.

After more than a decade of successful collaboration in participatory plant breeding (PPB) between farmers and maize breeders in southwest China, and release of new improved varieties and hybrids, it was realised that their conservation objectives could not also be secured unless farmers had incentives to maintain their traditional cultivars in production. This article explores their experience of expressing the public value of farmers' cultivars through organizing novel relationships among public and private actors, by means of PPB programmes and market-based arrangements. The researchers reached beyond common agri-food development practices and theories, to apply concepts used in public administrations studies, in order to consider public and private interest and value in relation to the direct, indirect and option value of the plant genetic resources (PGRs) represented by farmers' cultivars. In this paper, seven organizational options from selected countries are examined in relation to their roles in (i) creating indirect and options values; (ii) sustaining the legitimacy of and support for related practices; and (iii) developing operational capacity of the associated organizations and actors. The three main findings are (a) innovations in breeding and conservation developed through PPB are key factors in the management by smallholders of the indirect and option value of agro-biodiversity; (b) market-based arrangements and the creation of new sets of property rights in the products developed from farmer-bred cultivars legitimize and support PPB and PGRs conservation; and (c), the organization of the indirect and option value of farmer-bred cultivars calls for the integration of the joint efforts of producers, consumers, market actors and public sector agencies in networked governance, that can take a variety of forms. Lessons are drawn from and for China, where legal and regulatory practices in the seed sector are still under development and smallholders still maintain crop and varietal diversity by their agricultural practices.