Although there is no global shortage of food or water, food security has not been achieved, as human activity has turned these vital resources into “waste”. Wasted food not only loses valuable water resources but em...Although there is no global shortage of food or water, food security has not been achieved, as human activity has turned these vital resources into “waste”. Wasted food not only loses valuable water resources but embedded calories of human energy and nutrients for healthy human populations. The Food and Agricultural Organization of the United Nations, in addressing these concerns, focuses on a global scale largely on an economic estimate of individual components of energy or water or nutrient loss. It is suggested that more information is required through local or regional assessments to provide better estimates, incorporating regional factors of the losses along the food supply chain. To address this suggestion, this study focused on an intensive agricultural and rapidly urbanizing region of Canada, the Lower Fraser Valley of British Columbia. Seven selected crops, including annual crops such as green peas, sweet corn and potato, and perennial crops that included three berry crops were assessed for their water, both constituent and virtual, as well as embedded energy, protein, and Vitamin C. Annual virtual water losses were higher for sprinkler than drip irrigation, ranging from 82 × 10<sup>6</sup> kg of water for strawberry to 7570 × 10<sup>6</sup> kg for blueberry. These high virtual water losses estimated along the food chain confirm the significance of food loss impacts on local water resources. Estimates of losses of food in kg were highest at the consumer level along the food chain and it was estimated that wasted food from the seven crops selected would have supplied the protein and caloric energy of over 33,000 men per year and Vitamin C of about 240,000 men per year. This assessment increases the awareness of food loss impacts from a regional perspective and provides a framework for future research on both environmental and nutritional implications of wasted food.展开更多
Food waste is a growing global concern. Data on the factors and magnitude are largely global estimates, thus local studies aid in providing information on the impacts of food waste. Three important agro-climatic zones...Food waste is a growing global concern. Data on the factors and magnitude are largely global estimates, thus local studies aid in providing information on the impacts of food waste. Three important agro-climatic zones in British Columbia and nine common crops, both annual and perennial, were selected to evaluate the environmental and nutritional implications of local food waste. Using Canadian estimates of total food waste, the constituent water, caloric content, protein, vitamin C, phosphorus and potassium wasted by each crop were estimated. Regionally, the total production and losses were the highest in the Lower Fraser Valley which had high production of potatoes and blueberries, followed by the Okanagan, with grapes and apples, and Vancouver Island, with potatoes. Virtual water was estimated by the BC Agriculture Water Calculator and used to assess the soil and climatic factors impacting the local water demand. Although soil texture seemed to influence water demand, the agro-climatic zone was the main factor controlling the water demand and the corresponding amount of water wasted. Dry agro-climatic zones had annual virtual water up to two times higher for the same crop and soil texture. Lower water demand crops, finer soils and more efficient irrigation systems were more congruent with water stress scenarios. Total losses for each region were based on conservative estimates and would have supplied the caloric energy and protein for over 40,000 adults, and vitamin C for over 300,000 adults for one year. Additionally, the total N, P and K wasted accounted for up to 32, 2 and 13 kg/ha respectively for common fertilizers used in British Columbia. This study confirmed the significance of food waste impacts on local water demand, human nutrition and soil management based on regional data for representative crops.展开更多
随着“双碳”战略的深入推进,虚拟电厂(virtual power plant,VPP)在整合和调度新能源方面展现出显著优势,深入挖掘新能源在无功支持领域的巨大潜力是提升VPP运行经济性的有效手段之一。首先,构建了一套计及有功出力和逆变器约束的新能...随着“双碳”战略的深入推进,虚拟电厂(virtual power plant,VPP)在整合和调度新能源方面展现出显著优势,深入挖掘新能源在无功支持领域的巨大潜力是提升VPP运行经济性的有效手段之一。首先,构建了一套计及有功出力和逆变器约束的新能源无功容量评估体系。其次,为提升无功优化模型的求解速度,针对有功网损和潮流约束的非线性特性,提出基于潮流迭代的有功网损估计方法和基于变量空间优化选择的潮流线性化方法;并构建了计及新能源无功潜力和基于变量空间优化选择的VPP线性潮流无功优化模型。最后,以改进IEEE 33节点主动配电系统为例,验证了所提模型的有效性。结果表明:VPP充分利用新能源无功支持能力时,系统电压偏差减少0.673 pu,运行成本减少1 254.9元。展开更多
文摘Although there is no global shortage of food or water, food security has not been achieved, as human activity has turned these vital resources into “waste”. Wasted food not only loses valuable water resources but embedded calories of human energy and nutrients for healthy human populations. The Food and Agricultural Organization of the United Nations, in addressing these concerns, focuses on a global scale largely on an economic estimate of individual components of energy or water or nutrient loss. It is suggested that more information is required through local or regional assessments to provide better estimates, incorporating regional factors of the losses along the food supply chain. To address this suggestion, this study focused on an intensive agricultural and rapidly urbanizing region of Canada, the Lower Fraser Valley of British Columbia. Seven selected crops, including annual crops such as green peas, sweet corn and potato, and perennial crops that included three berry crops were assessed for their water, both constituent and virtual, as well as embedded energy, protein, and Vitamin C. Annual virtual water losses were higher for sprinkler than drip irrigation, ranging from 82 × 10<sup>6</sup> kg of water for strawberry to 7570 × 10<sup>6</sup> kg for blueberry. These high virtual water losses estimated along the food chain confirm the significance of food loss impacts on local water resources. Estimates of losses of food in kg were highest at the consumer level along the food chain and it was estimated that wasted food from the seven crops selected would have supplied the protein and caloric energy of over 33,000 men per year and Vitamin C of about 240,000 men per year. This assessment increases the awareness of food loss impacts from a regional perspective and provides a framework for future research on both environmental and nutritional implications of wasted food.
文摘Food waste is a growing global concern. Data on the factors and magnitude are largely global estimates, thus local studies aid in providing information on the impacts of food waste. Three important agro-climatic zones in British Columbia and nine common crops, both annual and perennial, were selected to evaluate the environmental and nutritional implications of local food waste. Using Canadian estimates of total food waste, the constituent water, caloric content, protein, vitamin C, phosphorus and potassium wasted by each crop were estimated. Regionally, the total production and losses were the highest in the Lower Fraser Valley which had high production of potatoes and blueberries, followed by the Okanagan, with grapes and apples, and Vancouver Island, with potatoes. Virtual water was estimated by the BC Agriculture Water Calculator and used to assess the soil and climatic factors impacting the local water demand. Although soil texture seemed to influence water demand, the agro-climatic zone was the main factor controlling the water demand and the corresponding amount of water wasted. Dry agro-climatic zones had annual virtual water up to two times higher for the same crop and soil texture. Lower water demand crops, finer soils and more efficient irrigation systems were more congruent with water stress scenarios. Total losses for each region were based on conservative estimates and would have supplied the caloric energy and protein for over 40,000 adults, and vitamin C for over 300,000 adults for one year. Additionally, the total N, P and K wasted accounted for up to 32, 2 and 13 kg/ha respectively for common fertilizers used in British Columbia. This study confirmed the significance of food waste impacts on local water demand, human nutrition and soil management based on regional data for representative crops.
