Energy and exergy analysis of solar hybrid adsorption refrigeration system

In this paper, performance of a solar hybrid adsorption refrigeration (AR) system is investigated experimentally. Such a system was built and tested under the conditions at National Institute of Technology Calicut, Kerala, India. The hybrid system has been designed for heating 50 l of water from 25 to 90°C as well as cooling 10 l of water from 25 to 10°C. The experimental results demonstrate that the refrigerator has a cooling capacity of 47–78 W with a cycle coefficient of performance (COP) of 0.19 and maximum possible COP of 0.45. In exergy analysis of the system, the irreversibility and exergetic efficiency of each component of the system have been calculated. The exergy analysis reveals that the main source of irreversibility is the adsorbent bed of the AR system, emphasising that the input heat energy is not utilised efficiently due to material constraints. The exergetic efficiencies of condenser, expansion device, evaporator and adsorbent bed are found as 42.3%, 79.8%, 54.7% and 11%, respectively.     

Viruses in wastewater sludges and in effluents used for irrigation

Disposal of sewage wastes is a problem of increasing magnitude in the United States. New control measures enacted by Congress require consideration of land disposal of sludges and effluents. The volume of wastes involved and the possibility of contaminating ground water supplies and vegetation has great public health significance. The effectiveness of the sewage treatment process to remove chemical and biological contaminants and the operational efficiency of many sewage treatment plants are factors that must be given careful consideration before final selection of disposal methodology. The quality of our future water and food supplies will be affected either beneficially or adversely by current management decisions.     

Energy efficiency and conservation for individual Americans

Americans make up only 4% of the world population, yet currently consume 25% of the world’s fossil fuels. The U.S. imports 63% of its oil and it is predicted that by 2020 the U.S. will be importing 95% of its oil resources. Over the past century, ample and affordable supplies of fossil fuels have powered the growth and prosperity of the economies of the US and other countries. Within this century, world oil supplies will decline while demand is projected to continue to increase, suggesting that we will have to transition to different fuels or become much more energy efficient or both. Looking ahead to the near decades, estimates are that consumers will have to reduce their energy use by at least 50%. This reduction will be necessary in large part due the decline in the availability of conventional oil and gas, but also because the U.S. population will continue to grow in number. Although government action is important, individuals too often discount their ability to make significant contributions to solving such major problems. This investigation identifies how informed and concerned individuals can collectively conserve fossil energy. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. An erratum to this article can be found at     

能源价格变动对中国节能降耗的影响效应

在分析我国能源比价扭曲对能耗强度影响效应的基础上,建立了Bayesian时变动态回归模型,测算了能源价格变动对能耗的影响效果及变动趋势。主要结论为:①能源比价关系的调整比单种能源价格的国际接轨更为重要。相比国际市场的能源比价结构,中国能源商品价格结构的扭曲度提高了中国的能耗强度,促进了第二产业的增长。②能源价格的变动对单位GDP能耗的影响效应具有显著的时变特征。在电力、煤炭、石油三种能源中,电力价格的变动对能耗强度的影响最大。电力价格变化对单位GDP能耗的影响边际效应在逐年下降,但节能的效果仍很显著。煤电价格联动制约及"从量计征"的资源税偏低使得煤炭价格的上涨反而加大了能耗强度,且1996年以来煤炭价格的提高对单位GDP能耗上升的影响效应还在不断加强,原油价格的提高对单位GDP能耗的影响在不同的时间段有不同的作用,但相对煤炭及电力价格来说,石油价格的影响效应最小。2002年以前石油价格的上升对能耗的上升起助推作用,2003年后石油价格的上升对能耗的上升起降低作用且强度逐年加大。     

能源消费与环境污染的边限协整分析

能源的使用是导致环境恶化的主要原因之一,所以研究能源消费与不同污染物之间的关系就很有必要。本文以1985-2007年的年度数据为样本,建立了自回归分布滞后—误差修正模型,并运用边限检验对我国的能源消费与环境污染之间的关系进行了实证研究。研究结果表明:长期来看能源消费总量、煤炭占能源消费总量的比重和水电、核电、风电占能源消费总量的比重对SO2的排放有重要影响,但是对工业烟尘排放量来说只有水电、核电、风电占能源消费总量的比重的影响是显著的;短期来看煤炭占能源消费总量的比重对SO2排放的影响是显著的,能源消费总量和水电、核电、风电占能源消费总量的比重对工业烟尘的排放有显著影响。由于能源消费总量和结构对不同污染物的长期和短期影响存在较大差异,所以在治理时应区别对待。     

Cocaine and cannabinoids in the atmosphere of Northern Europe cities,comparison with Southern Europe and wastewater analysis

This study reports the first investigation of atmospheric illicit drug concentrations in Northern Europe using measurements of cocaine and cannabinoids in Amsterdam, London and Stockholm. Further, these measurements were compared to those made in Rome to explore the geographical and inter-city variability. Co-located measurements of atmospheric particulate mass and PAHs were used to help describe and interpret the illicit drug measurements with respect to atmospheric dispersion. Cocaine concentrations ranged from 0.03 to 0.14 ng/m³ in Amsterdam, from 0.02 to 0.33 ng/m³ in London and were below quantification limit (3 pg/m³) in Stockholm. Cannabinol was the only cannabinoid molecule detected in the three cities. During this campaign, London reported the highest concentrations of cocaine and meaningful differences were detected between the urban background and city centre London sites. Mean cocaine concentrations measured in Amsterdam during March 2011 were also compared with those measured simultaneously in eight Italian cities. The cocaine concentration in Amsterdam was comparable to that measured at an urban background in Milan and at a densely populated site in Florence. Although correlating atmospheric concentrations directly with drug prevalence is not possible using current data, links between concentrations of cocaine and estimates of abuse prevalence assessed by the more routinely used wastewater analysis were also examined. A statistically significant correlation was found between the two sets of data (R² = 0.66; p = 0.00131). Results confirmed that meteorology, population rate and habits of consumption influence the atmospheric concentrations of drugs. If these confounding factors were better controlled for, the techniques described here could became an easy and cost effective tool to index the impact of cocaine abuse in the area; especially where local hot spots need to be identified.     

Fuzzy synthetic evaluation of treated wastewater reuse for agriculture

Reuse of treated wastewater (TWW) for agriculture is in practice in many countries. TWW reuse requires wastewater collection, treatment and recycling, which is associated with cost as well as risk to human and ecological systems. In contrast, it can increase agricultural production and reduce environmental risks by reducing wastewater discharge into the natural environment. In Saudi Arabia, where available water resources are extremely limited, TWW reuse can save significant amount of non-renewable groundwater used in agricultural development, which is a strategic goal for the country. In this paper, a multicriteria decision-making approach was developed where cost, risk, benefits and social acceptance of TWW reuse were considered to be the main criteria. A multistage hierarchy risk management model was constructed for this evaluation. Fuzzy synthetic evaluation technique was incorporated where fuzzy triangular membership functions were developed to capture uncertainties of the basic criteria. The analytic hierarchy process was used to determine the relative importance of various criteria at different hierarchy levels. This study indicated that TWW reuse could have positive impact on agriculture, risk reduction and groundwater conservation.     

Energy analysis of algae-to-biofuel production chains integrated with a combined heat and power plant

ABSTRACT

This study examines the energy and mass balances of algae cultivation and different post-processing pathways. Flue gases and excess heat from a combined heat and power (CHP) plant are used in algae cultivation, with nutrients from municipal wastewater. In the studied pathways, algae are cultivated in open ponds and photobioreactors with or without artificial lighting. Algal mass is used for methane, biodiesel or ethanol production, or it is combusted in a boiler. Results show that in most process pathways energy output exceeds the energy consumption in processing, and the energy returns are approximately twice as large as the electricity input. A large fraction of input energy is low-temperature heat, while the products have a higher value. Energy outputs from different pathways are similar, but heat and electricity consumption in processing vary significantly. Supercritical water gasification pathway is identified as a possible future option, whereas lipid extraction pathways are suggested to be the most likely candidates for industrial scale operations.     

Phytoremediation of aquaculture wastewater for water recycling and production of fish feed

Five plants were examined for their ability to remove nutrients from aquaculture wastewater and suitability as fish feed: alfalfa, white clover, oat, fall rye, barley. The seeds were first germinated in water in a hydroponic system, and the plants were fed wastewater from Tilapia production facility. Clover and alfalfa seeds were infected with fungus shortly after germination, and their roots were completely destroyed by day 14. Oat, rye and barley had the fastest growth and showed greater tolerance to fungal disease compared with alfalfa and clover. Although substantial amounts of soluble and insoluble substances were released by the seeds during the germination period, the plants were able to remove all the pollutants in wastewater and significant portions of those released substances. The total reductions in total solids, COD, NO3-N, NO2-N, phosphate and potassium ranged from 54.7% to 91.0%, 56.0% to 91.5%, 82.9% to 98.1%, 95.9% to 99.5%, 54.5% to 93.6% and 99.6% to 99.8%, respectively. Oat, barley and rye grow well in this type of hydroponic system and can be used as a fish feed after being supplemented with fat, Ca, Na, Mn and Fe. Oil seeds and the chlorides of these elements could be added to these plants when formulating the fish feed. For a continuous operation, a two-unit system could be configured to allow for one week germination and one week cleaning and startup in one unit while the other unit is in operation.     

江苏省能耗结构优化及其节能与减排效应分析

综合考虑江苏省经济增长、能源节约与C02、SO2减排的目标,运用改善的GADS优化算法对江苏省能耗结构进行优化,并对比江苏省低碳发展的情景,测算了江苏省能源消费结构优化的节能减排效应.研究结果表明:①能耗结构优化主要表现为高碳能源低度化,低碳能源离度化的演变过程.煤炭仍占主导地位,且呈倒"U",型的发展趋势,2020峰值1.822×108 tce,而天然气与低碳能源在总量与结构上均呈上升趋势;②能源结构优化具有正负双向效应,一方面节能减排效应显著,2020年将节能2.244×108tce,CO2:减排1.275×108t,但难以实现2020年减排目标,还需其它方面的努力.另一方面由干能源成本等因素造成GDP较之于低碳情景将减少2.096×1012元;③以"低"代"商"的能源优化策略是转移环境压力的主要途径,但其先决条件是煤炭资源的清洁高效利用与新能源核心技术的突破.未来江苏省能源消费结构的优化应以煤炭资源的清洁、高效利用为主,同时加快风能、太阳能、生物质能等新能源资源的产业化、规模化发展.     

Energy futures and green chemistry: competing for carbon

Global energy demand is expected to increase from the current 400 ExaJ per year to as much as 700–1,000 ExaJ per year by the middle of this century. If fossil carbon resources continue to make up the bulk of the energy supply, not only will atmospheric carbon dioxide increase to levels not seen for the past 30–35 million years, but depleting fossil carbon resources will become increasingly less available for other purposes, particularly the production of chemicals on which society now depends. The chemical process industries are heavily dependent on the availability of low-price petroleum as a feedstock. Recent life-cycle analyses suggest that pursuing both strategies of renewable energy sources and renewable feedstocks (i.e. biomass) will be required to meet these competing demands. Reducing the global use of both energy and manufactured chemicals will be a challenge for sustainable development. Education of the next generation of chemists and chemical engineers will have to change significantly from its current emphasis on petrochemical-based manufacturing to include a much greater emphasis on renewable resources and bio-based processes.Brief accounts of this work were presented at the 7th International Symposium on Green Chemistry in China (Zhuhai, People’s Republic of China, May 2005) and at the Joint US–China Green Chemistry Workshop (Beijing, People’s Republic of China, May 2005; this workshop was supported by US National Science Foundation grant CHE-0522369).     

中国现代城镇化发育的能源消费

城镇是现代社会财富积累的中心。矿物燃料为主的一次能源不仅是现代人类社会发展的基本动力来源,也是现代城镇化发育的基本动力来源。随着城镇化发育不断走向成熟,城镇的生存和发展对能源消费的依赖日趋强烈。这种消费需求不仅体现在总量增长方面,而且更体现在质量提高方面。世界和中国的实践均证明了这一点。所不同者,在产业发展政策和能源消费政策的作用下,中国现代城镇化发育的能源消费表现出明显的不尽人意:第一,能源消费总量增长迅速,甚至进入21世纪以来也是如此;第二,能源消费结构演进缓慢、特别是进入国家城镇化快速发育阶段后的表现更是如此;第三,能源产出效率提高有限,甚至出现一定程度的倒退。如此能源消费特征,对中国城镇化的持续发育构成了巨大挑战,因此,建议加快城镇产业结构调整、推进能源消费结构演进和提高城镇能源消费质量。     

Local policies for reducing the ecological impact of households: the case study of a suburban area in France

Since Rio, governments have increased measures to promote sustainable household consumption, but this has induced limited changes in consumers’ daily practices. This article argues that one of the reasons behind the poor efficiency of these policies is the low level of consideration granted to local decision-making. The article discusses the results of a study which aims at better ascertaining the practices and representations of local government leaders in promoting sustainable development in households. We shall analyse the motivations, obstacles, interaction of players, communication and action plans associated with promoting sustainable development, in which individual will and effort are the keywords. The results obtained show how important it is to introduce better management systems for information and resource exchange between the different institutions involved. The study was carried out in a suburban area of south-west France counting 71 small towns and villages, characteristic of the spatial dynamics triggered by the global phenomenon of urbanisation.     

Perception on untreated wastewater irrigation for vegetable production in Ghana

Using household-level survey data, this study investigates farmers’ perceptions on untreated wastewater use for irrigation of vegetable farms in urban and peri-urban Kumasi of Ghana. Empirical results from an ordered probit model show that there is some relationship between personal characteristics of farmers such as age, education and gender, and perceptions of farmers on health-related risks of untreated wastewater use for irrigation. Policy efforts should be geared toward updating the knowledge, skills and attitudes of producers through frequent training and workshops so that wastewater irrigation farmers in Ghana would better appreciate health-related risks of waster irrigation and how to adopt risk mitigating strategies. Further research for a more in-depth analysis on those relationships in the short-term with immediate emphasis on improving adoption of safer irrigation technologies among wastewater irrigation farmers is recommended.     

Energy and temperature performance analysis of geothermal (ground source) heat pumps integrated with permeable pavement systems for urban run-off reuse

Geothermal (ground source) heat pumps (GHP) and permeable pavement systems (PPS) have demonstrated their effectiveness in both industry and academic research during recent decades. To meet the rising demand for sustainable, recyclable and energy efficient techniques, research has focused on the combination of techniques to enhance existing or develop new applications.

This paper reports on an experimental programme that combined GHP with PPS for nutrient removal and system energy balancing. Experimental data collected over a 3-year period have provided evidence of highly efficient removal rates of up to 99% for ammonia–nitrate and biochemical oxygen demand; and 96% removal rates were obtained for orthophosphate–phosphorus. This paper also contains energy efficiency ratio (EER) and coefficient of performance (COP) calculations. Cyclic heat removal and heat rejection allowed for stable temperature and pump COP and EER sustainability. The results prove that PPS systems are appropriate for GHP installation, delivering high and stable pollutant removal with EER efficiencies between 1.5 and 5.5.

The combination of GHP with PPS has the potential to provide a new sustainable and eco-friendly practice.     

我国社会节能过程中的金融与政策支持

为了在能源问题日益突出的情况下探索我国社会节能的有效途径,本文采用实证和规范相结合的研究分析方法。研究发现,在我国社会节能过程中离不开金融与政策的支持,这不仅因为现行的财经制度和政策及其运行机制在很大程度上是传统经济的产物,对与现代经济社会发展相适应的社会节能过程的财经及其政策的研究还十分薄弱,还在于现行财经政策对推进我国社会节能的潜力还远没有释放。因此,一方面要运用金融政策工具,促进市场经济体制的建立和市场机制的形成,加强有利社会节能的信贷制度、金融法规的建设,促进其导向和规范功能;另一方面,要持续推进能源价格的市场化和政府调控价格的管理科学化,充分运用税收杠杆调控能源价格,逐步建立起适应中国国情的有效利用能源、保护环境的税收和收费政策体系。     

Energy and land use in worldwide agriculture: an application of life cycle energy and cluster analysis

Agriculture is expected to provide food in a sustainable manner while also partially contributing to the energy problem as well as to bio-material supply. Moreover, fossil fuels scarcity calls for an increase of energy efficiency in agricultural processes. This study evaluates patterns, trends, driving factors and trade-offs of energy use in selected agricultural systems and aims at grouping them into clusters with similar energy and social performances. Results show that in 2010 the highest power densities and energy intensities of production are found by crop sector of cluster 5 (China: 59.19 GJ/ha, 15.29 MJ/kg dm) and cluster 3 (Japan: 50.11 GJ/ha, 12.32 MJ/kg dm) as well as by livestock sector of cluster 3 (Japan: 328.47 GJ/ha, 103.08 MJ/kg dm), while the lowest values in clusters 2 and 4, including selected developing countries and USA. Cluster 3 (Japan) also shows the lowest energy intensity of economic value of crops (2.75 MJ/$), while cluster 5 (China) the highest one (23.96 MJ/$). Cluster analysis also sheds light on trends, identifying two groups: cluster 1*, gathering most European countries, USA and Japan, characterized by a decreasing trend of all energy indicators; and cluster 2*, including developing countries, the Netherlands and Spain, characterized by an increasing trend of indicators. Results highlight the importance of an integrated framework for evaluating energy use as well as of a multi-criteria approach to understand the trade-offs and interplay of performance indicators.     

Energy revolution:for a sustainable future

The discovery and use of fossil fuels have not only helped the evolution of human society from agricultural civilization to industrial civilization,but also caused serious environmental and climate problems.The earth is calling for a sustainable future,and a change from industrial civilization to ecological civilization based on the new"energy revolution".A macroscopic quantitative analysis of China’s environmental capacity and climate capacity shows that China is in urgent need of changing the extensive developing mode and having an energy revolution.It is foreseeable that fossil fuels will remain the most consumed source of energies in China now and in the next few decades.Although the efficient and clean use of fossil fuels are very important,this is not an energy revolution or the fundamental solution to environmental and climate problems.Unconventional gases including shale gas play an important role in the mitigation of environmental problems and climate change,but"shale gas revolution"or"shale gas era"is not suitable to China since the proportion of natural gas in primary energy structure in China can only be increased by a maximum of 20%.The transition of Chinese energy structure from fossil-fuels-dominating stage to multiple-energy-sources stage and then to a nonfossil-fuels-dominating stage is the inevitable future,with the help of great contribution from renewable energy and nuclear energy.Among renewable energies,the proportion of non-hydro renewable energies will gradually increase.Improvement of their market competitiveness(economic efficiency)relies on technological innovation.Renewable energies will be the main energy source for the earth in future.Despite the impact of the Fukushima nuclear disaster,the whole world,including China,will not give up nuclear energy development.Safe,steady,and large-scale development of nuclear power is a rational choice of China.Transition from nuclear fission power plant to nuclear fusion power plant is the inevitable future.Nuclear energy will be a sustainable energy source and another main energy source of the earth in future.China needs to enhance energy security consciousness,promote energy saving,and change the energy supply-demand patterns,that is the transition from"meet a too-fast-growing demand with an extensive supply"to"meet a reasonable demand with a rational supply".All countries need to work together to address global environmental problems and climate change.Energy revolution is the foundation for a sustainable future.With a wide range of international cooperation,the win-win cooperation is the only way of overcoming these challenges.     

The closed-loop cycle for industrial wastewater: The future pollution solution

The paper discusses the trend in all the U.S. industries toward increased water recycling and reuse. Also presented are the water use demands by various industries, and the water use by functions. Data are given on industrial water quality in use for various functions among selected high water using industries. Presented is an over-all system designed for a closed-loop cycle for industrial wastewater. This will be practical for industry to implement by 1985 or soon thereafter if the required technology is properly developed. Research and development needs to achieve this closed-loop system are identified. Rather than a discussion of economics with typical costs based on amount of water treated or on the specific processes employed, the paper presents data on the total cost of removal of controlling factors from a hypothetical wastewater.Future demands and restrictions on industrial wastewater are stated and ten references are cited.