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With the wages for migrant workers increasing dramatically in China since 2003, the size of the agricultural labour forces has been shrinking rapidly. Intensively substituting agricultural machinery for the shrinking farm labour force is hardly possible for croplands in the mountainous regions of China where mechanization is difficult to achieve due to small field size and rough terrain. This has eventually led to cropland abandonment in these regions. Considering the high pressure for food security in China, cropland abandonment in the mountainous regions should not be ignored. By employing a novel method, this study estimates the extent of recently abandoned croplands (period 2000-2010) and the changes that can be expected in the future in China's mountainous areas. The results show that the total extent of abandoned croplands in Chinese mountainous counties during the period 2000 to 2010 is estimated at 147 million mu (1 mu=666.67m2); in total, about 28% of croplands in mountainous counties was abandoned, including croplands converted in the Grain for Green Programme (GGP). With three scenario assumptions, a sizeable extent, 114 to 203 million mu, of croplands may be abandoned from 2010 to 2030 with the rapid decrease and aging of projected farm labour forces. This could exacerbate the future challenges of maintaining China's food security. A substantial increase in agricultural project investments, including land consolidation and agricultural productive fixed assets, especially micro-tillage machines, could help mitigate the risk of cropland abandonment. Additionally, land-use and environmental policymaking should take into account the expanding cropland abandonment in mountainous regions.

Air pollution is one of the most harmful consequences of China's rapid economic development and urbanization. Particularly in the Beijing-Tianjin-Hebei (BTH) regions, particulate matter concentrations have consistently exceeded the national air quality standards. Over the last years, China implemented ambitious measures to reduce emissions from the power, industry and transportation sectors, with notable success during the 11th and 12th Five Year Plan (FYP) periods. However, such strategies appear to be insufficient to reduce the ambient PM2.5 concentration below the National Air Quality Standard of 35 μg m−3 across the BTH region within the next 15 years. We find that a comprehensive mitigation strategy for the residential sector in the BTH region would deliver substantial air quality benefits. Beyond the already planned expansion of district heating and natural gas distribution in urban centers and the foreseen curtailment of coal use for households, such a strategy would redirect some natural gas from power generation units towards the residential sector. Rural households would replace biomass for cooking by liquid petroleum gas (LPG) and electricity, and substitute coal for heating by briquettes. Jointly, these measures could reduce the primary PM2.5 and SO2 emissions by 28% and 11%, respectively, and the population-weighted PM2.5 concentrations by 13%, i.e., from 68 μg m−3 to 59 μg m−3. We estimate that such a strategy would reduce premature deaths attributable to ambient and indoor air pollution by almost one third. Keywords: Solid fuel substitution, PM2.5, Natural gas, Human exposure, Outdoor and indoor health benefits

Food, energy, and water (FEW) are interconnected pillars that underpin the security of people’s livelihoods. In this paper, we propose a decision-support model to better understand and aid management of regional FEW nexus systems under uncertainty. We apply the model to a case study focusing on fluctuations in water supply, which significantly affect production in the agriculture and energy sectors in Shanxi Province, China. We use a two-stage, stochastic, chance-constrained programming approach to the proposed spatially detailed cost-minimizing FEW nexus model under demand and natural resource (land and water) constraints. This approach translates the target reliability level (i.e., the probability that the devised solution can satisfy all constraints) into a penalty that has to be paid in the case of their non-fulfillment. On this basis, robust decisions (i.e., production options suitable for a broad variation in certainty of water supply) are derived. Using this approach, we estimate the penalties required to achieve given levels of reliability by incentivizing the deployment of water-saving technologies. For example, our model predicts that water storage would become cost-effective if the penalty for exceeding the available water supply were 2.5 times higher than the current price for industrial water; this would enable at least 40% reliability compared to 18% if the penalty were at the current water price level. Taking advantage of the differences in water intensity of crops in different sites, our model optimizes the reservoir location, which allows water withdrawal by agriculture to be reduced by 1.23%. We also evaluate the benefits of incorporating uncertainty and missed opportunity due to a lack of perfect information. In the case study, we show that the benefits of including uncertainty in the form of the two-stage stochastic programming approach appear to be quite significant, reaching 4% of the total solution costs. Water-importing costs, taxes, and subsidies are instruments that translate into the penalty in this model; the modeling approach presented here can thus be used to inform cost-effective and robust management of the FEW nexus in Shanxi Province, China, and other water-scarce regions around the world.

The possibility of a spectrally tunable solar-like light source is drawing attention with the development of LEDs. We researched the market of high-power, monochromatic LEDs and established a database with 103 kinds of LED by a new model. We used the database to match the solar spectrum in the wavelength range 380–780 nm. The optimal combination maximising the fit to the solar spectral curve was obtained. The trade-off relationship between the selection of LEDs and the fit was investigated in detail. The results show that the optimal combination contains 34 types of LED with a maximum correlation index R2 of 88.67%. The value of R2 reduces to 85.06% when the number of LED types is reduced to 20, but the R2 value decreases sharply if the number of LED types is decreased to 16, with a R2 of 79.97%.

Across the world, human activity is approaching planetary boundaries. In northwest China, in particular, the coal industry and agriculture are competing for key limited inputs of land and water. In this situation, the traditional approach to planning the development of each sector independently fails to deliver sustainable solutions, as solutions made in sectorial ‘silos’ are often suboptimal for the entire economy. We propose a spatially detailed cost-minimizing model for coal and agricultural production in a region under constraints on land and water availability. We apply the model to the case study of Shanxi province, China. We show how such an integrated optimization, which takes maximum advantage of the spatial heterogeneity in resource abundance, could help resolve the conflicts around the water–food–energy (WFE) nexus and assist in its management. We quantify the production-possibility frontiers under different water-availability scenarios and demonstrate that in water-scarce regions, like Shanxi, the production capacity and corresponding production solutions are highly sensitive to water constraints. The shadow prices estimated in the model could be the basis for intelligent differentiated water pricing, not only to enable the water-resource transfer between agriculture and the coal industry, and across regions, but also to achieve cost-effective WFE management.

Labour migration across countries has been playing a key role in the process of economic integration in the countries of the Commonwealth of Independent States (CIS). The experience of labour migration in CIS appears to be characterized by growing complexity with an increasingly diverse array of countries of origin and destination. The main issues of this paper are: 1) to understand how wage dynamics defined by the labour demand/supply ratio feeds back to migration dynamics, which affects the migration flows between sending and receiving countries over time; 2) to explore how the age structure affects migration flow which in turn effects labour supply in the host country; and 3) to project the potential future migration flow and its impacts on surplus and deficit of labour resource, in order to provide the relevant for migration policies at the both national and regional levels. In this paper we analyse these issues within a dynamic framework; we consider migrant flow into a host region/country at certain moments of time depending on the relationship between expected earnings, costs, and age structure. In addition, we also consider how migration flows interact with natural population growth and age structure in sending and hosting countries.

Growing population, rapid urbanization, rising incomes, and changing consumption preferences stimulate intensification of livestock production and excessive fertilization of crops in China. We present an innovative approach that sheds light on options to prevent negative environmental consequences of food production. Trends indicate that agricultural production expansion will take place in “profitable” locations around densely populated areas, where there are generally insufficient natural resources to recycle production wastes. This will likely lead to increased environmental impacts and risks to human health, with the largest impacts in close proximity to population hotspots. We identify trends in Chinese agricultural production and devise and compare feasible mitigation scenarios. We present a spatial allocation procedure that facilitates management of agricultural production expansion, accounting for environmental and health constraints. This procedure, based on behavioral principles, uses a spatial risk preference structure induced by local conditions, including environment, production, and demand, with important research and policy implications.

Agriculture is a major source of water, air and soil pollution. Pollution rates are often linked to intensification of agricultural activities, i.e., large-scale livestock production and excessive fertilization of crops. In this paper, we develop a concept of a spatially and temporally explicit model for sustainable agriculture production planning, which operates at a detailed spatial scale and integrates demand and agricultural production activities at national and sub-national levels. It distinguishes environmental loads and sources of agricultural pollution originating from two main agricultural activities: livestock raising and crop production. The indicators used to reflect the impacts of agricultural production comprise of fluxes to air (emissions of ammonia and nitrous oxide) and water (nitrate leaching). Possible domains of the indicator variables are subdivided into sub-domains of different impact severity classes. Risk functions indicate the degree of risk associated with agricultural production, similar to fuzzy logic approaches. Alternative production scenarios are compared in terms of human exposure to risk, i.e., the number of people in different risk classes. In this way the model allows for assessment and testing of strategies for mitigating agricultural pollution. Application of the integrated model is illustrated by a case study of agricultural production development in China. China is of global importance due to its huge size and is of scientific interest due to its heterogeneity. Experience gained from the case study can be used for similar research in other regions.

The goal of improving the performance of proton exchange membrane fuel cell (PEMFC) has attracted a great deal of attention. Many performance models of PEMFC have been developed. The aim of this paper is to introduce a novel modelling method for the performance of PEMFC based on fuzzy model identification and to present a simple and accurate T-S model of the performance of PEMFC. In this modelling method, only the experimental data of operating parameters, such as cell/stack temperature, pressure and humidity of reactant gas, and external load, are required; other property parameters that are difficult to obtain are not needed. Thus the modelling process is simplified. By contrast with the models proposed in the literature, the T-S model of the performance of PEMFC is simple and accurate. In addition, this model can be conveniently applied to control of PEMFC system.

In this chapter we present an integrated model for long term and geographically explicit planning of agricultural activities to meet demands under resource constraints and ambient targets. Environmental, resource and production feasibility indicators permit estimating impacts of agricultural practices on environment to guide agricultural policies regarding production allocation, intensification, and fertilizer application while accounting for local constraints. Physical production potentials of land are incorporated in the model, together with demographic and socio-economic variables and behavioral drivers to reflect spatial distribution of demands and production intensification levels. The application of the model is demonstrated with a case study of nitrogen accounting at the level of China counties. We discuss current intensification trends and estimate the ranges of agricultural impacts on China’s environment under plausible pollution mitigation scenarios with a particular focus on nitrogen sources and losses.

The aim of this paper is to understand the sustainability of urban spatial transformation in the process of rapid urbanization, and calls for future research on the demographic and economic dimensions of climate change. Shanghai towards its transformation to a metropolis has experienced vast socioeconomic and ecological change and calls for future research on the impacts of demographic and economic dimensions on climate change. We look at the major questions (1) to explore economic and demographic growth, land use and land-cover changes in the context of rapid economic and city growth, and (2) to analyze how the demography and economic growth have been associated with the local air temperature and vegetation. We examine urban growth, land use and land-cover changes in the context of rapid economic development and urbanization. We assess the impact of urban expansion on local air temperature and vegetation. The analysis is based on time series data of land use, normalized difference vegetation index (NDVI), and meteorological, demographic and economic data. The results indicate that urban growth has been driven by mass immigration; as a consequence of economic growth and urban expansion, a large amount of farmland has been converted to paved road and residential buildings. Furthermore, the difference between air temperature in urban and exurban areas has increased rapidly. The decrease of high mean annual NDVI has mainly occurred around the dense urban areas.

A high-temperature molten carbonate fuel cell stack was studied experimentally and computationally. Experimental data for fuel cell temperature was obtained when the stack was running under given operational conditions. A 3-D CFD numerical model was set up and used to simulate the central fuel cell in the stack. It includes the mass, momentum and energy conservation equations, the ideal gas law and an empirical equation for cell voltage. The model was used to simulate the transient behavior of the fuel cell under the same operational conditions as those of the experiment. Simulation results show that the transient temperature and current and power densities reach their maximal values at the channel outlet. A comparison of the modeling results and the experimental data shows the good agreement.