农村生活用能的区域分异——以关中临渭区为例

研究农村生活用能的区域分异,对于优化用能结构、制定合理的能源利用和生态环境保护政策具有重要意义。以关中临渭区为例,采用实地问卷调查、能源利用区位商、相关分析等方法,探究平原地区、黄土台塬与丘陵山区农村生活用能的分异特征及成因,得到以下结论:①平原地区具有区位优势的生活能源为煤炭、玉米棒芯、液化气、蜂窝煤、电能和太阳能,煤炭的区位商达2.671;黄土台塬为沼气、太阳能、作物秸秆、蜂窝煤、液化气和玉米棒芯,沼气的区位商达3.465;丘陵山区为薪柴,区位商为1.142。前两者用能多元化,商品能源较多;丘陵山区用能结构单一,木柴为主的非商品能源居多。②区域用能分异特征突出。平原地区市场化导向明显,多种能源互补利用;黄土台塬地区政策导向明显,沼气利用较多,用能组合多样;丘陵山区受自然条件影响,薪柴为主,其他燃料为辅。农村生活用能的区域分异取决于自然环境、生产结构、经济环境以及外界环境,是收入水平、温度、发展条件、政策影响等方面综合作用的结果。③平原地区人均收入高(7 056元),人均商品用能多(204.15 kgce);条件恶劣的丘陵山区人均收入低(5 750元),人均商品用能少(45.38 kgce)。人均非商品用能受人均收入影响小,相对稳定。人均有效耕地和人均耕地越多,人均商品用能越多,人均非商品用能越少,且人均有效耕地变化引起的用能类别的变化幅度较大。     

Flattening the carbon extraction path in unilateral cost-effective action

Internalizing the global negative externality of carbon emissions requires the flattening of the extraction path of world fossil energy resources (=world carbon emissions). We consider governments with sign-unconstrained emission taxes at their disposal and seeking to prevent world emissions from exceeding some binding aggregate emission ceiling in the medium term. Such a ceiling policy can be carried out either in full cooperation or by a sub-global climate coalition. Unilateral action has to cope with carbon leakage and high costs, which makes a strong case for choosing a policy that implements the ceiling in a cost-effective way. In a two-country, two-period general equilibrium model with a non-renewable fossil-energy resource, we characterize the unilateral cost-effective ceiling policy and compare it with its fully cooperative counterpart. We show that with full cooperation there exists a cost-effective ceiling policy in which only first-period emissions are taxed at a rate that is uniform across countries. In contrast, the cost-effective ceiling policy of a sub-global climate coalition is characterized by emission regulation in both periods. The share of the total stock of energy resources owned by the sub-global climate coalition turns out to be a decisive determinant of the sign and magnitude of unilateral cost-effective taxes.     

乙腈溶剂中单壁碳纳米管与常见有机化合物的相互作用

以单壁碳纳米管(SWCNTs)为固定相,采用高压匀浆法,制备HPLC色谱柱.测定乙腈相中18种有机化合物在SWCNTs色谱柱上的保留因子,研究SWCNTs与化合物的相互作用.结果表明,有机化合物取代基的种类和个数、杂原子的个数影响乙腈相中有机化合物与SWCNTs的相互作用.采用线性溶解能关系(LSER)定量表征SWCNTs与有机化合物的相互作用,所构建的LSER模型具有较强的拟合能力(R2=0.844)和稳健性(Q2LOO=0.768),发现π-/n-电子对作用和空穴/弥散作用是控制SWCNTs与有机化合物相互作用的主要因素.     

混凝土复合型裂缝的断裂能及其判据研究

首先通过理论分析得到断裂能与能量释放率的关系,继而根据试验研究测出的单一型裂缝的断裂能,进行单一型裂缝断裂能与断裂韧度的相关性分析,得到了单一型裂缝的断裂能与能量释放率之间的关系,再进行数值模拟,获得混凝土复合型裂缝的断裂能。基于Ⅰ型、Ⅱ型、Ⅲ型、二维复合型(Ⅰ-Ⅱ、Ⅰ-Ⅲ、Ⅱ-Ⅲ)和三维复合型(Ⅰ-Ⅱ-Ⅲ)的应力强度因子断裂临界曲线和临界曲面(即完整的系列K判据),通过各复合型裂缝的断裂韧度,得到相应的能量释放率,进而获得复合型裂缝的断裂能,绘出断裂能临界曲线和曲面,从而建立了完整的系列断裂能G判据。     

Changes in glucose uptake rate and in the energy status of PC-12 cells acutely exposed to hexavalent chromium,an established human carcinogen

In the 1920s, Otto Warburg reported a striking metabolic shift in solid tumors: contrary to their normal counter parts, which exhibited a nearly pure respiratory metabolism, where cancer cells relied strongly on lactic fermentation for energy production, even in the presence of ample oxygen. This metabolic shift, later named the Warburg effect, is now viewed as a nearly universal cancer phenotype. To investigate whether it is operating in hexavalent chromium (Cr(VI))-induced carcinogenesis, PC-12 cells were exposed to low Cr(VI) concentrations and effects determined on the rates of glucose uptake, lactate production and oxygen consumption, critical indicators of the type of energy metabolism adopted by the cells. Further, the influence on the cells’ energy charge, an important parameter in the evaluation of the cellular physiological state was assessed. In the presence of ample oxygen, concentration-dependent, statistically significant decreases in the energy charge were detected, which were accompanied by an increased glucose uptake rate. This enhanced uptake may constitute the first step in a compensatory mechanism aimed at counteracting the decrease in energy charge. Although these changes may be too small to exert an impact in the cellular functions, they may provide insight into the initial steps of Cr(VI)-induced carcinogenesis.     

Energy transformations in two tropical Oxbow lakes

The flow and pattern of energy utilization in two tropical ecosystems where polyculture of fishes was practiced were studied. The rates of organic production made by the two tropical natural aquatic systems (oxbow lakes) were studied for two annual cycles. The study of utilization of energy in two tropical lakes revealed that herbivores were more efficient in energy utilization than autotrophs. The energy available in these systems was supplied by allochthonous source. Silver carp and grass carp were found to be most efficient in conversion of energy in the grazing food chain of the lake. The efficiency of the system to fish production was found to be 0.06 (OL-I) ?0.05% (OL-II) of the total available solar radiation. Various forms of life are all accompanied by energy changes, in the studied lakes were found to form a food web.     

Market interactions,farmers' choices,and the sustainability of growing advanced biofuels: a missing perspective?

Advanced biofuels such as cellulosic ethanol are of great interest in the USA. With agriculture being the major source of feedstock for advanced biofuels, how farmers would respond to markets and policy incentives in providing such feedstock can directly affect sufficient and sustainable supply of advanced biofuels and their environmental sustainability. In this study, we developed an economic model to examine farmers' production choices in a context where agricultural markets are linked to energy markets. We identified the economic conditions under which farmers could maximize their profits by converting current grain cropland to grow cellulosic biomass crops. An empirical illustration showed that with current technology, farmers are unlikely to grow switchgrass as a dedicated energy crop instead of corn on cropland. The biofuel incentives in the 2008 Farm Bill can improve the competitiveness of switchgrass, but may stimulate corn production as well, with corn residues as an alternative feedstock for advanced biofuels. The continuous, possibly expanding, corn production in future raises the same issues for advanced biofuels as for corn grain-based ethanol. To assure the environmental sustainability of advanced biofuel production, further research is needed to help design environmental policies alongside existing biofuel initiatives.     

Biofuels and agriculture: a past perspective and uncertain future

The US corn ethanol industry has grown from virtually nothing in the early 1980s to over 14 billion gallons in 2011. Subsidies have been an important impetus for the industry, and they have existed in one form or another throughout the life of the industry. This paper provides (1) a brief look at the history of the linkages between energy and agriculture and how they have changed with biofuels; (2) a review of some of the major impacts of the US corn ethanol program; and (3) analysis of prospective impacts of cellulosic biofuels. There is no doubt that biofuels have brought about a new era for global agriculture. Historically, the prices of agricultural and energy products moved in response to supply and demand factors relevant to each market, but moved largely independent of one another. Corn ethanol has changed that, and today there is a link between crude oil and corn that is driven by the demand side. Since agricultural commodity prices are linked both on the demand and supply sides, the corn–crude oil link spills over to other agricultural commodities as well. Development of cellulosic biofuels has been much slower than hoped. The feedstocks are more expensive than initially believed. Conversion technologies remain uncertain and expensive. There are many uncertainties through the cellulosic supply chain, and government policy remains uncertain as well. Thus, the future of the cellulosic biofuels industry is, at this point, an open question.     

Incorporating greenhouse gas effects to evaluate energy efficiency in China

Reducing greenhouse gas emissions without hampering economic growth is a significant issue for China. Taking into account environmental sustainability principles, this study analysed the energy efficiency of 30 regions of China for the period 2002–2007. By employing a data envelopment analysis (DEA) approach, this study included undesirable CO₂ and SO₂ outputs and the desirable GDP output in the model. Empirical outcomes demonstrated that the overall average technical efficiency (TE) of China is 0.843, indicating a 15.70% input inefficiency. Among three geographic areas, the east has the highest technical efficiency, with the highest ability to set up clean-burning power plants based on best technology available. Performance in the west is less good because of much inefficient technology. Finally, the study demonstrates detailed management implications of the BCG matrix. The most important contribution of this paper is a detailed demonstration of an energy performance evaluation mechanism for China. The valuable results and insights gained can be equally effectively applied to studies in other developing countries facing the same gaseous emissions.     

Fostering food and energy security through by-product valorization within agricultural and agro-industrial networks: study of the province of Santiago de Cuba

ABSTRACT

The aim of this study is to investigate of how the concept of ‘integrated food and energy systems’ or IFES production networks could be applied – within the specific context of Eastern Cuba’s agricultural and agro-industrial sectors – as an innovative approach to improve food and energy security. The Province of Santiago de Cuba in southeast Cuba was the focus of this study; its existing operations, infrastructure, resource flows and scarcities, and actor relationships provide the basis of the data used for the evaluation.

The authors investigated the regional context, identify potential members of an agricultural and agro-industrial network in three municipalities of the province, and identify the main residuals and by-products of key facilities. Potential avenues for by-product valorization are investigated along with the possible influence/impacts on the sustainability of the surrounding systems and actors. A conceptual model for a regional network for integrated food and energy production is then provided based upon the development of three agricultural/agro-industrial scenarios: influence at the farm level, regional agro-industrial networks, and ‘anchor tenant’ eco-industrial systems. The main challenges and opportunities for the development of the networks are described with recommendations for addressing such where possible.