能量效率与可更新能源

一些可更新能源可减少甚至消除我们对化石能和核能的依赖,其中很多虽然已为人类使用数百年,但因为化石能的普遍使用,一直都为起人类的注意。人类已发明了新技术来利用这些可更新能源。其利用有赖于一定的技术是既定的事实,目前有成功建立这样的能源工业还是十分昂贵的。如果人类生产经济和市场允许的话,这些新技术经进一步改进和简化后,就可以降低成本,并且应用起来也很可靠。相对于开发应用核能,水能和化石能数以百万计的投资耗费来讲,用于可更新资源的资金可谓微乎其微。虽然传统能源和替代能源各具优点,但保护能源往往还是解决能源短缺最便宜,最容易的途径。     

能量效率与可更新能源

一可更新能源可减少甚至消除我们对化石能和核能的依赖,其中很多虽然已为人类使用数百年,但因为石能的普遍使用,一直都为起人类的注意。人类已发明了新技术利用这些可更新能源。其利用不赖于一定的技术是既定的事实,目前有成功建立这样的能源工业还是十分昂贵的。如果人类生产经济和市场允许的话,这些新的技术经进一步改进和简化后,就可以降低成本,并且应用起来也很可靠。相对于开发应用核能,水能和化石能数以百万计的投资耗费来讲,用于可更新资源的资金可谓微乎其微。虽然传统能源和替代能源各具优点,但保护能源往往还是解决能源短缺最便宜,最容易的途径。     

农村废弃生物质资源开发获重要突破

能源危机是当今世界面临的严峻挑战之一[1].化石能源是地球亿万年间积累起来的光合产物,是不可再生的资源.大量化石能源开挖后,沉睡了数亿年的"碳库"最终又要变成"碳源",这使人类本来任务艰巨的碳减排 "雪上加霜"[2,3].为逃脱化石能源怪圈,全球能源与环境科学家们,把精力转移到用太阳能、风能、生物质能等清洁能源代替化石能源上来,取得了重要进展.但新能源开发仍存在着成本高,经济效益差的不足[4～6].作为全球最大的发展中国家,中国科学家正努力寻找能高效利用农村生物质资源的新方法.研究成果一旦获得推广,可大大缓解能源紧缺状况,对全球碳减排意义重大 [7,8].     

干旱能源植物的发掘与应用策略

随着人类社会的快速发展和对化石能源的不合理开采,化石能源整体可开采量锐减;另一方面,化石能源的大量使用造成日益凸显的环境污染问题,发展生物质能源对解决能源危机、促进社会可持续发展具有重要意义。囿于人口持续增长和粮食需求不断增加,发展能源植物的重要突破口在于大力开发不与粮食作物争地争水的干旱能源植物。因此,从能源植物概念及其意义入手,论述国内外干旱能源植物应用现状和在实际种植生产过程中存在的问题,综合分析适合作为干旱能源植物的新类型,进而提出干旱能源植物的应用策略。     

能源植物新秀--芒草

化石能源日益紧缺,污染日趋严重,新能源的开发和利用成为时代的迫切要求。在寻找新能源的过程中,芒草逐渐进入人们的视线。随着研究的深入,“高个子”芒草已经成为能源植物中的佼佼者。     

基于CGE碳税政策对北京社会经济系统的影响分析

根据研究需要与北京市2010年投入产出表部门划分情况,尽可能地对能源部门进行细分,并编制社会核算矩阵。构建可计算一般均衡(CGE)模型模拟碳税政策对北京市社会经济的影响。实证结果显示:碳税政策具有显著的节能减排效果,对于化石能源密集型产业产出具有明显的抑制作用,但对于清洁能源、服务业等行业产出具有促进作用。因此严格限制煤炭、石油等高碳化石能源的使用、开发高碳能源低碳化利用技术是减排的重要措施。由于碳税会使产品价格上升,从而导致消费需求减少,碳税对国内生产总值和社会福利具有一定的负面影响,虽然影响程度的相对量有限,但影响的绝对效果较大,应该避免较高的碳税税率。     

生物炼制技术及其产业发展

由于过度消耗化石资源引发的石油紧缺和温室效应问题,巳逐步影响到人类社会可持续发展的宗旨,开发能替代化石能源需求的新能源日渐急迫.生物质能源是化石能源的替代能源之一,对生物质能源炼制的研究成为很多人的关注热点.生物炼制产品的工业化,是形成可持续性的生物炼制品产业经济的关键.我国政府已经把发展生物质能源作为国家发展战略的一部分,确定了具体的发展目标,制定了相应的研发计划,出台了一系列法规以促进生物质能产业的健康发展.我国生物炼制技术在生物燃料、生物柴油、生物基化学品等领域取得了明显进步.本文主要综述生物炼制技术的研究进展及其产业发展情况.     

找化石、寻铀矿,开发新能源

1942年费米等人在美国建造了第一座核反应堆,燃起了原子之“火”,引起世界各国物理学家对核能利用的极大关注和研究兴趣,在1954年终于建造了世界上第一座原子能发电站并投入运行。自此,核能的和平利用便跻身于世界能源利用的行列,和石油、煤炭、天然气、水力一起构成当今世界的五大能源。1973年波及全球的“石油危机”后而暴露出来的问题,提醒人们除开采煤炭、石油等传统能源以外,核能,也是当今颇有前途的能源。所谓核能,就是指那些具有放射性的元素,在一定的物理化学条件下,原子核发生裂变或聚变时释放出巨大的能量。虽然很多元素都有放射性,但目前常用     

微藻淀粉代谢研究进展

近200年来,化石燃料的大量燃烧导致过量的CO2被排放到空气中,造成全球气候变暖。这种环境问题引起了人类的关注深思,因此,开发一种新型的、可持续利用的能源已经迫在眉睫。相对于其它绿色能源,研究者认为微藻不仅能通过光合自养将CO2转变为有机质,而且还不占用农业土地,具有很好的发展前景。本综述介绍了微藻淀粉的国内外研究现状,淀粉的生物合成机制,提高淀粉积累的方法以及在分子层面上了解合成淀粉的代谢通路和调控基因,以便获得大量的淀粉来生产生物乙醇,给人类提供新能源。     

聚焦生物能源与生物基产品产业化发展

正无论从国家能源安全的需求还是从化工原料的多元化的角度来看,采用绿色生物工艺制造生物能源与生物基产品是我国产业结构转型升级的重要突破口。能源是科技进步与社会发展的基本驱动力,出于对常规化石能源储量与化石能源燃烧产生的环境污染的担忧,人类思考摆脱这一困境,开发并推广使用一种新的清洁、可再生能源势在必行。生物基化学品与生物基材料等的研发、工艺改良与规模化生产也是产业发展的重点方向。     

Energy production from biomass (Part 1): Overview of biomass

The use of renewable energy sources is becoming increasingly necessary, if we are to achieve the changes required to address the impacts of global warming. Biomass is the most common form of renewable energy, widely used in the third world but until recently, less so in the Western world. Latterly much attention has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuel energy sources. The type of biomass required is largely determined by the energy conversion process and the form in which the energy is required. In the first of three papers, the background to biomass production (in a European climate) and plant properties is examined. In the second paper, energy conversion technologies are reviewed, with emphasis on the production of a gaseous fuel to supplement the gas derived from the landfilling of organic wastes (landfill gas) and used in gas engines to generate electricity. The potential of a restored landfill site to act as a biomass source, providing fuel to supplement landfill gas-fuelled power stations, is examined, together with a comparison of the economics of power production from purpose-grown biomass versus waste-biomass. The third paper considers particular gasification technologies and their potential for biomass gasification.     

Energy use in the global food system

The global food system is a major energy user and a relevant contributor to climate change. To date, the literature on the energy profile of food systems addresses individual countries and/or food products, and therefore a comparable assessment across regions is still missing. This paper uses a global multi‐regional environmentally extended input–output database in combination with newly constructed net energy‐use accounts to provide a production and consumption‐based stock‐take of energy use in the food system across different world regions for the period 2000–2015. Overall, the ratio between energy use in the food system and the economy is slowly decreasing. Likewise, the absolute values point toward a relative decoupling between energy use and food production, as well as to relevant differences in energy types, users, and consumption patterns across world regions. The use of (inefficient) traditional biomass for cooking substantially reduces the expected gap between per capita figures in high‐ and low‐income countries. The variety of energy profiles and the higher exposure to energy security issues compared to the total economy in some regions suggests that interventions in the system should consider the geographical context. Reducing energy use and decarbonizing the supply chains of food products will require a combination of technological measures and behavioral changes in consumption patterns. Interventions should consider the effects beyond the direct effects on energy use, because changing production and consumption patterns in the food system can lead to positive spillovers in the social and environmental dimensions outlined in the Sustainable Development Goals.     

Renewable Energy from Willow Biomass Crops: Life Cycle Energy,Environmental and Economic Performance

Short-rotation woody crops (SRWC) along with other woody biomass feedstocks will play a significant role in a more secure and sustainable energy future for the United States and around the world. In temperate regions, shrub willows are being developed as a SRWC because of their potential for high biomass production in short time periods, ease of vegetative propagation, broad genetic base, and ability to resprout after multiple harvests. Understanding and working with willow's biology is important for the agricultural and economic success of the system.

The energy, environmental, and economic performance of willow biomass production and conversion to electricity is evaluated using life cycle modeling methods. The net energy ratio (electricity generated/life cycle fossil fuel consumed) for willow ranges from 10 to 13 for direct firing and gasification processes. Reductions of 70 to 98 percent (compared to U.S. grid generated electricity) in greenhouse gas emissions as well as NO_x, SO₂, and particulate emissions are achieved.

Despite willow's multiple environmental and rural development benefits, its high cost of production has limited deployment. Costs will be lowered by significant improvements in yields and production efficiency and by valuing the system's environmental and rural development benefits. Policies like the Conservation Reserve Program (CRP), federal biomass tax credits and renewable portfolio standards will make willow cost competitive in the near term.

The avoided air pollution from the substitution of willow for conventional fossil fuel generated electricity has an estimated damage cost of $0.02 to $0.06 kWh^?1. The land intensity of about 4.9 × 10^?5 ha-yr/kWh is greater than other renewable energy sources. This may be considered the most significant limitation of willow, but unlike other biomass crops such as corn it can be cultivated on the millions of hectares of marginal agricultural lands, improving site conditions, soil quality and landscape diversity. A clear advantage of willow biomass compared to other renewables is that it is a stock resource whereas wind and PV are intermittent. With only 6 percent of the current U.S. energy consumption met by renewable sources the accelerated development of willow biomass and other renewable energy sources is critical to address concerns of energy security and environmental impacts associated with fossil fuels.     

Energy optimization schemes in cluster with virtual machines

Large scale clusters based on virtualization technologies have been widely used in many areas, including the data center and cloud computing environment. But how to save energy is a big challenge for building a “green cluster” recently. However, previous researches, including local approaches, which focus on saving the energy of the components in a single workstation without a global vision on the whole cluster, and cluster-wide energy saving techniques, which can only be applied to homogeneous workstations and specific applications, cannot solve the challenges. This paper describes the design and implementation of a novel scheme, called Magnet, that uses live migration of virtual machines to transfer load among the nodes on a multi-layer ring-based overlay. This scheme can reduce the power consumption greatly by regarding all the cluster nodes as a whole based on virtualization technologies. And, it can be applied to both the homogeneous and heterogeneous servers. Experimental measurements show that the new method can reduce the power consumption by 74.8% over base at most with certain adjustably acceptable overhead. The effectiveness and performance insights are also analytically verified.     

Energy budget of the biosphere and civilization: Rethinking environmental security of global renewable and non-renewable resources

How much and what kind of energy should the civilization consume, if one aims at preserving global stability of the environment and climate? Here we quantify and compare the major types of energy fluxes in the biosphere and civilization.It is shown that the environmental impact of the civilization consists, in terms of energy, of two major components: the power of direct energy consumption (around 15 × 10¹² W, mostly fossil fuel burning) and the primary productivity power of global ecosystems that are disturbed by anthropogenic activities. This second, conventionally unaccounted, power component exceeds the first one by at least several times.It is commonly assumed that the environmental stability can be preserved if one manages to switch to “clean”, pollution-free energy resources, with no change in, or even increasing, the total energy consumption rate of the civilization. Such an approach ignores the fact that the environmental stability is regionally and globally controlled by the functioning of natural ecosystems on land and in the ocean. This means that the climate and environment can only remain stable if the anthropogenic pressure on natural ecosystems is diminished, which is unachievable without reducing the global rate of energy consumption. If the modern rate of anthropogenic pressure on the ecosystems is sustained, it will be impossible to mitigate the degradation of climate and environment even after changing completely to “clean” technologies (e.g., to the “zero emissions” scenario).It is shown that under the limitation of preserving environmental stability, the available renewable energy resources (river hydropower, wind power, tidal power, solar power, power of the thermohaline circulation, etc.) can in total ensure no more than one tenth of the modern energy consumption rate of the civilization, not to compromise the delivery of life-important ecosystem services by the biosphere to the humanity.With understanding still lacking globally that the anthropogenic impact on the biosphere must be strictly limited, the potential availability of the practically infinite stores of nuclear fusion energy (or any other infinite energy sources) poses an unprecedented threat to the existence of civilization and life on the planet.     

Current development of biorefinery in China

To meet the demand of its fast growing economy, China has become already the second largest buyer of crude oil. China is facing critical problems of energy shortage and environment deterioration. Rational and efficient energy use and environment protection are both getting more attention in China. Biomass energy is renewable energy made from biological sources. China's biomass resources are abundant, which could provide energy for future social and economic development. However technologies for biomass resource conversion in China are still just beginning. In this paper, current biomass resource distribution and technologies of biomass energy, including power generation, biofuel production and biomass-based chemical production are reviewed.     

Energy and greenhouse gas balance of bioenergy production from poplar and willow: a review

Short‐rotation woody crops (SRWC) such as poplar and willow are an important source of renewable energy. They can be converted into electricity and/or heat using conventional or modern biomass technologies. In recent years many studies have examined the energy and greenhouse gas (GHG) balance of bioenergy production from poplar and willow using various approaches. The outcomes of these studies have, however, generated controversy among scientists, policy makers, and the society. This paper reviews 26 studies on energy and GHG balance of bioenergy production from poplar and willow published between 1990 and 2009. The data published in the reviewed literature gave energy ratios (ER) between 13 and 79 for the cradle‐to‐farm gate and between 3 and 16 for cradle‐to‐plant assessments, whereas the intensity of GHG emissions ranged from 0.6 to 10.6 g CO₂ Eq MJ_biomass^?1 and 39 to 132 g CO₂ Eq kWh^?1. These values vary substantially among the reviewed studies depending on the system boundaries and methodological assumptions. The lack of transparency hampers meaningful comparisons among studies. Although specific numerical results differ, our review revealed a general consensus on two points: SRWC yielded 14.1–85.9 times more energy than coal (ER_coal～0.9) per unit of fossil energy input, and GHG emissions were 9–161 times lower than those of coal (GHG_coal～96.8). To help to reduce the substantial variability in results, this review suggests a standardization of the assumptions about methodological issues. Likewise, the development of a widely accepted framework toward a reliable analysis of energy in bioenergy production systems is most needed.     

在矿山废弃地上发展可再生能源的潜力——以辽宁省为例

在国内外碳减排压力和我国能源结构调整需求下,我国可再生能源的开发压力较大.矿山具有丰富的废弃土地,发展可再生能源的潜力巨大,在矿山废弃地上开发可再生能源对我国的能源战略具有重要意义.本研究以辽宁省矿山废弃地为例,提出矿山废弃地的生物质能与太阳能发展预案,估算辽宁省矿山废弃地的可再生能源发展潜力.结果表明:辽宁省1227.6 km2的矿山废弃地面积发展可再生能源的潜力较大,不同预案的潜力差异显著.预案1以光伏发电最大化为目标模式,总计可发电量为79.4 TWh,折标煤量32.1 Mt,碳减排量为79.1Mt CO2.预案2以生物质能源利用最大化为目标模式,光伏与生物质能总的发电量可达到31.2~33.1 TWh,折标煤量12.7~13.4 Mt,碳减排量为31.1~33.0 Mt CO2.预案3以矿山能源综合利用最大化为目标并兼顾生态修复的发展模式,光伏与生物质能总的发电量可达到62.3~63.7 TWh,折标煤量25.1~25.7 Mt,碳减排量为62.1~63.5 Mt CO2.3种预案的发电量在31.2~79.4 TWh,占辽宁省2016年总电力消费量的15.3%~38.9%,折标煤量12.7~32.1 Mt,碳减排量为31.1~79.1 Mt CO2.本研究对在矿山废弃地上发展可再生能源潜力及其替代化石能源能力的评估,对于碳减排、能源结构的调整以及矿山废弃地的生态修复具有重要的研究意义.     

Energy and the food system

Modern agriculture is heavily dependent on fossil resources. Both direct energy use for crop management and indirect energy use for fertilizers, pesticides and machinery production have contributed to the major increases in food production seen since the 1960s. However, the relationship between energy inputs and yields is not linear. Low-energy inputs can lead to lower yields and perversely to higher energy demands per tonne of harvested product. At the other extreme, increasing energy inputs can lead to ever-smaller yield gains. Although fossil fuels remain the dominant source of energy for agriculture, the mix of fuels used differs owing to the different fertilization and cultivation requirements of individual crops. Nitrogen fertilizer production uses large amounts of natural gas and some coal, and can account for more than 50 per cent of total energy use in commercial agriculture. Oil accounts for between 30 and 75 per cent of energy inputs of UK agriculture, depending on the cropping system. While agriculture remains dependent on fossil sources of energy, food prices will couple to fossil energy prices and food production will remain a significant contributor to anthropogenic greenhouse gas emissions. Technological developments, changes in crop management, and renewable energy will all play important roles in increasing the energy efficiency of agriculture and reducing its reliance of fossil resources.