Climate change mitigation potential of kitchen waste utilization in China for combined heat and power production.

Given the concerns about climate change, energy sustainability, and public health, the reuse of kitchen wastes (KW) is attracting increasing interest. In China, the municipal solid waste sorting scheme has increased the available KW. To assess the available KW and the climate change mitigation potential of KW utilization for bioenergy in China, three scenarios (base, conservative, and ambitious) were defined. A new framework was implemented to assess the climate change impacts of bioenergy. The annual available KW ranged from 11.450 million dry tons (in metric) under the conservative scenario to 22.898 million dry tons in the ambitious scenario, and had the potential to produce 12.37 × 106-24.74 × 106 MWh heat and 9.62 × 106-19.24 × 106 MWh power. The total potential climate change impacts of KW for combined heat and power were 3.339-6.717 million tons CO2 eq in China. The highest eight provinces and municipalities contributed over half of the national total. Among the three components of the new framework, fossil fuel-derived greenhouse gas emissions and biogenic CO2 emissions were positive. The difference in carbon sequestration was negative and ensured a lower integrated life-cycle climate change impacts than that of natural gas-derived combined heat and power. The mitigation effects of using KW as a substitute for natural gas and synthetic fertilizers were 2.477-8.080 million tons CO2 eq. These outcomes can inform relevant policymaking and benchmark climate change mitigation in China. The conceptual framework of this study can also be adapted for applications in other countries or regions worldwide.

China's food loss and waste embodies increasing environmental impacts.

Food loss and waste (FLW) hampers global food security, human health and environmental sustainability. However, monitoring and benchmarking FLW reduction is often constrained by the lack of reliable and consistent data, especially for emerging economies. Here we use 6 yr large-scale field surveys and literature data to quantify the FLW of major agrifood products along the entire farm-to-fork chain in China. We show that 27% of food annually produced for human consumption in the country (349 ± 4 Mt) is lost or wasted; 45% of this is associated with postharvest handling and storage and 13% with out-of-home consumption activities. We also show that the land, water, carbon, nitrogen and phosphorus footprints associated with total FLW are similar to those of a medium-sized country (such as the United Kingdom's in the case of carbon footprint). These results highlight the importance of better primary data to inform FLW reduction actions and ensure food security and sustainability.

Spatiotemporal variability in urban HORECA food consumption and its ecological footprint in China.

Increasing hotel/restaurant/café (HORECA) food consumption (HFC) has become one of the most prominent features of food consumption transformation under the background of rapid urbanization in China. Combining direct-weighing data (using 11,883 dishes in 164 restaurants) and literature data, this study, for the first time, quantitatively calculated the amount of HFC and its ecological footprint (EF) in China in 2002 and 2015 to depict the environmental effects of this transformation. The results indicated that per capita HFC tripled from 320 g/cap/meal in 2002 to 852 g/cap/meal in 2015, representing an average annual growth rate of 13%. In addition, by scaling up the HFC in 31 provinces/municipalities/autonomous regions to the national scale, HFC in China increased by 12,612 tons from 2002 to 2015. Finally, the total EF in the HORECA sector increased nearly 33 times (or 44,440 global ha), from 1348 global ha in 2002 to 45,788 global ha in 2015. The EF of Guangdong increased the most, surpassing 4000 global ha in 2015. These findings provide a scientific basis to support improved food resource spatial allocation and mitigation of regional resource pressure to achieve sustainable consumption under the current background of rapid urbanization in China.

Efficiency and Carbon Footprint of the German Meat Supply Chain.

Meat production and consumption contribute significantly to environmental impacts such as greenhouse gas (GHG) emissions. These emissions can be reduced via various strategies ranging from production efficiency improvement to process optimization, food waste reduction, trade pattern change, and diet structure change. On the basis of a material flow analysis approach, we mapped the dry matter mass and energy balance of the meat (including beef, pork, and poultry) supply chain in Germany and discussed the emission reduction potential of different mitigation strategies in an integrated and mass-balance consistent framework. Our results reaffirmed the low energy conversion efficiency of the meat supply chain (among which beef was the least efficient) and the high GHG emissions at the meat production stage. While diet structure change (either reducing the meat consumption or substituting meat by edible offal) showed the highest emissions reduction potential, eliminating meat waste in retailing and consumption and byproducts generation in slaughtering and processing were found to have profound effect on emissions reduction as well. The rendering of meat byproducts and waste treatment were modeled in detail, adding up to a net environmental benefit of about 5% of the entire supply chain GHG emissions. The combined effects based on assumed high levels of changes of important mitigation strategies, in a rank order considering the level of difficulty of implementation, showed that the total emission could be reduced by 43% comparing to the current level, implying a tremendous opportunity for sustainably feeding the planet by 2050.

Missing Food, Missing Data? A Critical Review of Global Food Losses and Food Waste Data.

Food losses and food waste (FLW) have become a global concern in recent years and emerge as a priority in the global and national political agenda (e.g., with Target 12.3 in the new United Nations Sustainable Development Goals). A good understanding of the availability and quality of global FLW data is a prerequisite for tracking progress on reduction targets, analyzing environmental impacts, and exploring mitigation strategies for FLW. There has been a growing body of literature on FLW quantification in the past years; however, significant challenges remain, such as data inconsistency and a narrow temporal, geographical, and food supply chain coverage. In this paper, we examined 202 publications which reported FLW data for 84 countries and 52 individual years from 1933 to 2014. We found that most existing publications are conducted for a few industrialized countries (e.g., the United Kingdom and the United States), and over half of them are based only on secondary data, which signals high uncertainties in the existing global FLW database. Despite these uncertainties, existing data indicate that per-capita food waste in the household increases with an increase of per-capita GDP. We believe that more consistent, in-depth, and primary-data-based studies, especially for emerging economies, are badly needed to better inform relevant policy on FLW reduction and environmental impacts mitigation.

The weight of unfinished plate: A survey based characterization of restaurant food waste in Chinese cities.

Consumer food waste has attracted increasing public, academic, and political attention in recent years, due to its adverse resource, environmental, and socioeconomic impacts. The scales and patterns of consumer food waste, especially in developing countries, however, remain poorly understood, which may hinder the global effort of reducing food waste. In this study, based on a direct weighing method and a survey of 3557 tables in 195 restaurants in four case cities, we investigated the amount and patterns of restaurant food waste in China in 2015. Food waste per capita per meal in the four cities was 93g, consisting mainly of vegetables (29%), rice (14%), aquatic products (11%), wheat (10%), and pork (8%). This equals to approximately 11kg/cap/year and is not far from that of western countries, although per capita GDP of China is still much lower. We found also that food waste per capita per meal varies considerably by cities (Chengdu and Lhasa higher than Shanghai and Beijing), consumer groups (tourists higher than local residents), restaurant categories (more waste in larger restaurants), and purposes of meals (friends gathering and business banquet higher than working meal and private dining). Our pilot study provides a first, to our best knowledge, empirically determined scales and patterns of restaurant food waste in Chinese cities, and could help set targeted interventions and benchmark national food waste reduction targets.

Impacts of dung combustion on the carbon cycle of alpine grassland of the north Tibetan plateau.

Alpine grassland of Tibet is a frangible ecosystem in terms of carbon (C) emission. Yak dung is an important resident energy with about 80 % of yak dung combusted for energy in the north Tibetan plateau. This paper investigated the impact of dung combustion on the C cycle of the alpine grassland ecosystem in north Tibet, China. During the growing season of 2011, from a field survey and household questionnaires, the main impacts of dung collection for fuel on the C cycle of the ecosystem were identified. (1) The C sequestration and storage capacity, including the dung-derived C stored in soil and C captured by vegetation, decreased. The net primary production decreased remarkably because of the reduction of dung returned to soil. (2) In a given period, more C was emitted to the atmosphere in the dung combustion situation than that in the dung returned to soil situation. (3) The energy grazing alpine meadow ecosystem changed into a net C source, and the net biome production of the ecosystem dropped to -15.18 g C/m2 year in the dung combustion situation, 42.95 g C/m2 year less than that in the dung returned situation. To reduce the CO2 emission derived from dung use, the proportion of dung combustion should be reduced and alternative renewable energy such as solar, wind, or hydro energy should be advocated, which is suitable for, and accessible to, the north Tibetan plateau.

[Effects of different rice farming systems on paddy field weed community].

Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on Monochoia vaginalis and Rotala indica being 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community.

[Approaches to evaluate the effects of hydraulic engineering on river ecosystem services].

To evaluate the effects of hydraulic engineering on river ecosystem services, a set of indicator system and quantitative methods, which included the appraisal principles, classification of river services and indicator selection were established. The river ecosystem services could be classified into four types: water supply and related services (e.g., transportation and hydroelectric generation), ecological supporting functions, regulation and control, and aesthetic and cultural services. Based on relative studies, the quantitative approaches were established to measure the indices reflecting the ecological effects of hydraulic engineering involving the change of biodiversity and purification services. The methods mainly contained exponent methods and BOD-DO model. These approaches will be helpful for further analysis and assessment on the effects of hydraulic engineering impact on river ecosystem services.