Biofuels and food security

The major source of energy comes from fossil fuels.The current situation in the fi eld of fuel and energy is becoming more problematic as world population continues to grow because of the limitation of fossil fuels reserve and its pressure on environment.This review aims to fi nd economic,reliable,renewable and non-polluting energy sources to reduce high energy tariffs in Russian Federation.Biofuel is fuel derived directly from plants,or indirectly from agricultural,commercial,domestic,and/or industrial wastes.Other alternative energy sources including solar energy and electric power generation are also discussed.Over 100 Mt of biomass available for energy purposes is produced every year in Russian.One of the downsides of biomass energy is its potential threatens to food security and forage industries.An innovative approach proved that multicomponent fuel(80%diesel oil content for motor and 64%for in stove fuel)can remarkably reduce the costs.This paper proposed that the most promising energy model for future is based on direct solar energy conversion and transcontinental terawatt power transmission with the use of resonant wave-guide technology.     

Advanced technology paths to global climate stability: energy for a greenhouse planet

Stabilizing the carbon dioxide-induced component of climate change is an energy problem. Establishment of a course toward such stabilization will require the development within the coming decades of primary energy sources that do not emit carbon dioxide to the atmosphere, in addition to efforts to reduce end-use energy demand. Mid-century primary power requirements that are free of carbon dioxide emissions could be several times what we now derive from fossil fuels (approximately 10(13) watts), even with improvements in energy efficiency. Here we survey possible future energy sources, evaluated for their capability to supply massive amounts of carbon emission-free energy and for their potential for large-scale commercialization. Possible candidates for primary energy sources include terrestrial solar and wind energy, solar power satellites, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids, and fossil fuels from which carbon has been sequestered. Non-primary power technologies that could contribute to climate stabilization include efficiency improvements, hydrogen production, storage and transport, superconducting global electric grids, and geoengineering. All of these approaches currently have severe deficiencies that limit their ability to stabilize global climate. We conclude that a broad range of intensive research and development is urgently needed to produce technological options that can allow both climate stabilization and economic development.     

Hybrid cars now, fuel cell cars later

We compare the energy efficiency of hybrid and fuel cell vehicles as well as conventional internal combustion engines. Our analysis indicates that fuel cell vehicles using hydrogen from fossil fuels offer no significant energy efficiency advantage over hybrid vehicles operating in an urban drive cycle. We conclude that priority should be placed on hybrid vehicles by industry and government.     

木质纤维素类生物质转化生物乙醇预处理B2B工艺的发展研究

在能源问题日益紧张的时局下,寻求可再生的清洁能源成为目前亟待解决的关键问题,而乙醇燃料无疑是化石类能源的最佳替代能源。生物质转化为生物乙醇（简称B2B）工艺无论是从可行性、清洁性抑或是经济性来看都具有可大规模工业化应用的前景。基于木质纤维素物质来源广、成本低等特点,这类原料制备生物乙醇的研究取得了很大的进展。详细综述了木质纤维素类生物质转化生物乙醇中的预处理工艺进展和发展方向,并对各种预处理工艺的优缺点进行了论述,此外,对于双螺杆挤出爆破工艺也进行了详细阐释。     

中国生物质能源发展现状及问题探讨

当前世界正面临着严重的化石能源危机,生物质能源发展已受到越来越多国家的关注。文章综述了生物燃气、生物液体燃料、微藻能源、固体成型燃料等生物质能源技术的主要进展,分析了我国生物质能源产业发展中出现的一些问题,并基于此提出了完善和修改生物质能源产品价格补贴、强制性生物质液体燃料收购、鼓励生物质液体燃料消费等激励政策,设立专项加快开发和应用具有自主知识产权的国产化技术,以及大力度发展非粮生物质能源和利用边际土地建立生物质能源基地等政策建议。     

木质素与酶的作用机制及其在纤维素酶水解中的影响研究进展

化石燃料的持续开采与使用对环境产生了严重的负面影响，使得开发可再生清洁能源代替传统能源成为必然。木质纤维素是一种丰富的可再生资源，可转化为生物乙醇、氢气等生物质燃料，被认为是代替化石燃料的理想替代品。其中木质纤维原料转化为生物乙醇需经过预处理、酶水解以及微生物发酵这3个关键步骤，而纤维素酶水解通常会受到酶、水解条件、底物等诸多因素的影响。针对木质素对纤维素酶水解的影响研究进行综述，大量研究发现，木质素是纤维素酶水解过程中的主要抑制剂。木质素既可以吸附纤维素酶，与纤维素酶发生无效吸附；又可以作为物理屏障，阻碍酶对纤维素的生产性吸附。尽管通过预处理可以去除大部分的木质素，但依旧无法从根源上缓解木质素对纤维素酶水解的影响，研究木质素的结构单元对酶解效率的影响可能是当前生物乙醇转化中木质素在纤维素酶水解中的研究方向。     

A global and long-range picture of energy developments

Most studies of energy supply and demand ignore either global inter-dependence or the long time spans necessary to adjust to new energy sources. The International Institute for Applied Systems Analysis has therefore studied on a global scale, for seven major world regions, the balance between energy supply and demand for the next 50 years. Reported here are the results for two benchmark scenarios. In the "low" scenario world energy consumption increases from today's 8.2 terawatt-year per year to 22 terawatt-year per year in 2030; in the "high" scenario, consumption increases to 35 terawatt-year per year. The study showed that time will be the limiting constraint in adapting the energy supply infrastructure to changing resource availability; resources will be available until the second half of the next century, but a strong shift will be required to low-grade fossil fuels such as shale oil and tar sands. Each scenario studied indicated increased environmental problems associated with increased use of fossil fuels, and potential geopolitical problems associated with the world distribution of resources.     

Methanol: A Versatile Fuel for Immediate Use: Methanol can be made from gas, coal, or wood. It is stored and used in existing equipment

We believe that methanol is the most versatile synthetic fuel available and its use could stretch or eventually substitute for, the disappearing reserves of low-cost petroleum resources. Methanol could be used now as a means for marketing economically the natural gas that is otherwise going to waste in remote locations. If methanol were used as an additive to gasoline at a rate of 5 to 15 percent, for use in internal combustion engines, there would be an immediate reduction in atmospheric pollution, there would be less need for lead in fuel, and automobile performance would be improved. With increasing production of fuel-grade methanol from coal and other sources, we foresee the increasing use of methanol for electrical power plants, for heating, and for other fuel applications. We hope that a practical methanol fuel cell will be commercially available by the time that methanol becomes plentiful for fuel purposes. Methanol offers a particularly attractive form of solar-energy conservation, since agricultural and forest waste products can be used as the starting material. Indeed, at 1 percent conversion efficiency the forest lands could supply the entire present energy requirements of the United States.     

用排气管温度加热气化醇类燃料在柴油机上的试验研究

 针对高原地区空气含氧量低,发动机功率不足,以及有限的石油和空气污染严重等问题。结合柴油机的结构特点、醇类燃料的特性,在不改变原机结构的前提下,增设一套醇类燃料（甲醇或乙醇）供给装置,醇类燃料供给装置供给的醇类靠排气温度加热气化并同进气流一同流入气缸。醇类燃料供给装置与原供油装置相互配合,实现辅助燃料（轻柴油）引燃,主要燃料为甲醇或乙醇,从而在达到不降低发动机功率的状况下,醇类燃料替代柴油,并且有效降低排放的目的。试验表明：此方法简单可行,除在单缸柴油机上采用外,可向多缸机推广应用,这对解决能源紧缺,降低排放,实现可持续发展,有较强的现实意义。同时对改善高原地区发动机动力性,有着其特殊的作用。     

Methanol as a gasoline extender: a critique

The tests conducted with the three vehicles at different emission control levels suggest that, in the area of fuel economy and emissions, potential benefits with methanol blends are related to carburetion and are only significant in the case of the rich-operating cars built before emission control standards were imposed. Theoretical considerations related to methanol's leaning effect on carburetion support this conclusion. Potential advantages for methanol in these areas are therefore continuously diminishing as the older cars leave the roads. At present, these older cars use only about one-fourth of the totalc motor gasoline consumed and, before methanol could be used on a large scale, this fraction would be much smaller. The use of methanol in gasoline would almost certainly create severe product quality problems. Water contamination could lead to phase separation in the distribution system and possibly in the car tank as well, and this would require additional investment in fuel handling and blending equipment. Excess fuel volatility in hot weather may also have adverse effects on car performance if the methanol blends include typical concentrations of butanes and pentanes. Removal of these light hydrocarbon components would detract from methanol's role as a gasoline extender and if current fuel volatility specifications were maintained, its use could lead to a net loss in the total available energy for use in motor fuels. Car performance problems associated with excessively lean operation would also be expected in the case of a significant proportion of late-model cars which are adjusted to operate on lean fuel-air mixtures. If methanol does become available in large quantities, these factors suggest that it would be more practical to use it for purposes other than those related to the extending of motor gasoline, such as for gas turbines used for electric power generation. In this case, the "pure" methanol would act as a cleanburning fuel, having none of the potentially severe product quality problems associated with its use in motor gasoline, while the fuel oil or natural gas cLirrently burned in these tuLrbines CotLild be diverted to other ulses.     

Energy and the u.s. Economy: a biophysical perspective

A series of hypotheses is presented about the relation of national energy use to national economic activity (both time series and cross-sectional) which offer a different perspective from standard economics for the assessment of historical and current economic events. The analysis incorporates nearly 100 years of time series data and 3 years of cross-sectional data on 87 sectors of the United States economy. Gross national product, labor productivity, and price levels are all correlated closely with various aspects of energy use, and these correlations are improved when corrections are made for energy quality. A large portion of the apparent increase in U.S. energy efficiency has been due to our ability to expand the relative use of high-quality fuels such as petroleum and electricity, and also to relative shifts in fuel use between sectors of the economy. The concept of energy return on investment is introduced as a major driving force in our economy, and data are provided which show a marked decline in energy return on investment for all our principal fuels in recent decades. Future economic growth will depend largely on the net energy yield of alternative fuel sources, and some standard economic models may need to be modified to account for the biophysical constraints on human economic activity.     

(Bio)fueling farm policy: the biofuels boom and the 2008 farm bill

In the mid-2000s, rising gas prices, political instability, pollution, and fossil fuel depletion brought renewable domestic energy production onto the policy agenda. Biofuels, or fuels made from plant materials, came to be seen as America’s hope for energy security, environmental conservation, and rural economic revitalization. Yet even as the actual environmental, economic, and energy contributions of a biofuels boom remained debatable, support for biofuels swelled and became a prominent driver of not only US energy policy but of US farm policy as well. This paper asks why biofuels became such a powerful force in farm policy debates, and draws on policy windows theory and discourse analysis to analyze biofuels’ contributions to the passage of the 2008 farm bill. It finds that budgetary and political factors combined with a particular set of patriotic biofuels-oriented discourses to carry energy policy debates into farm policy. It also comments on the implications of biofuels policies for conservation and sustainable land use in 2008 and beyond.     

Land clearing and the biofuel carbon debt

Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to low-carbon fuels a high priority. Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food crop-based biofuels in Brazil, Southeast Asia, and the United States creates a "biofuel carbon debt" by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions that these biofuels would provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials incur little or no carbon debt and can offer immediate and sustained GHG advantages.     

甘肃省能源消费的CO_2排放研究

根据联合国政府间气候变化专门委员会(IPCC)2006年提出的能源碳排放计算方法,计算了甘肃省1995～2009年化石燃料消费的CO2排放量。结果表明,1995年以来,甘肃省化石燃料消费的CO2排放量呈增加趋势,排放强度不断下降,由1995年的11.01 t/万元下降到2009年的3.42 t/万元。甘肃省化石燃料消费增长迅速,但化石燃料消费结构变化不大。未来甘肃省节能减排压力巨大,要提高化石燃料的利用效率,同时加大可再生能源在能源消费结构中的比重,尤其加大对太阳能和风能的利用。     

Lowering the temperature of solid oxide fuel cells

Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.     

Sustainable hydrogen production

Identifying and building a sustainable energy system are perhaps two of the most critical issues that today's society must address. Replacing our current energy carrier mix with a sustainable fuel is one of the key pieces in that system. Hydrogen as an energy carrier, primarily derived from water, can address issues of sustainability, environmental emissions, and energy security. Issues relating to hydrogen production pathways are addressed here. Future energy systems require money and energy to build. Given that the United States has a finite supply of both, hard decisions must be made about the path forward, and this path must be followed with a sustained and focused effort.     

马铃薯生产燃料乙醇的性能分析

我国能源安全正面临严峻挑战,洁净的可再生能源燃料乙醇被认为是化石能源的理想替代物。首先介绍了马铃薯的基本属性和以其为原料生产燃料乙醇的必要性;其次在同其它几种原料比较了生产性能的基础上,认为发展马铃薯燃料乙醇具有一定的优势;最后指出以马铃薯为原料生产燃料乙醇在我国有较好的产业化前景。     

Net energy analysis of alcohol production from sugarcane

Energy requirements were calculated for the agricultural and the industrial phase of ethyl alcohol production from sugarcane grown in Louisiana. Agricultural energy requirements comprised 54 percent of all energy inputs, with machinery, fuel, and nitrogen fertilizer representing most of the energy subsidies. Overall net energy benefits (output:input) for alcohol production ranged from 1.8:1 to 0.9:1 depending on whether crop residues or fossil fuels were used for industrial processes.     

Nuclear eclectic power

The uranium and thorium resources, the technology, and the social impacts all seem to presage an even sharper increase in nuclear power for electric generation than had hitherto been predicted. There are more future consequences. The "hydrogen economy." Nuclear power plants operate best at constant power and full load. Thus, a largely nuclear electric economy has the problem of utilizing substantial off-peak capacity; the additional energy generation can typically be half the normal daily demand. Thus, the option of generating hydrogen as a nonpolluting fuel receives two boosts: excess nuclear capacity to produce it, plus much higher future costs for oil and natural gas. However, the so-called "hydrogen economy" must await the excess capacity, which will not occur until the end of the century. Nonelectric uses. By analyses similar to those performed here, raw nuclear heat can be shown to be cheaper than heat from many other fuel sources, especially nonpolluting ones. This will be particularly true as domestic natural gas supplies become more scarce. Nuclear heat becomes attractive for industrial purposes, and even for urban district heating, provided (i) the temperature is high enough (this is no problem for district heating, but could be for industry; the HTGR's and breeders, with 600 degrees C or more available, have the advantage); (ii) there is a market for large quantities (a heat rate of 3800 Mw thermal, the reactor size permitted today, will heat Boston, with some to spare); and (iii) the social costs become more definitely resolved in favor of nuclear power. Capital requirements. Nuclear-electric installations are very capital-intensive. One trillion dollars for the plants, backup industry, and so forth is only 2 percent of the total gross national product (GNP) between 1974 and 2000, at a growth rate of 4 percent per year. But capital accumulation tends to run at about 10 percent of the GNP, so the nuclear requirements make a sizable perturbation. Also increasing the electric share of energy provision means increasing electric power utilization, which has a high technological content and demands yet more capital. Thus, provision of capital is a major problem ahead, especially for electric utilities. The need for people. The supply of available trained technologists, environmental engineers, and so on, especially in the architect-engineer profession, is insufficient for the task ahead, especially since the same categories of people will be in demand to build up a synthetic fuels industry and do other new things. Beyond these specific items and beyond the technological discussion, one can feel deeper currents running in this debate. Issues that started out seeming technological ended up being mainly societal: prevention of clandestine use, either by vigilance or by public spirit; a determination to maintain quality and to safeguard wastes that transcends narrow interests; a perception of social benefits and damage much more holistic than before; the need to manage programs more openly and better than before. Questions and doubts become more acute, answers and methods less sure. Here is a final question. We have never before been given a virtually infinite resource of something we craved. So far, increasingly large amounts of energy have been used to turn resources into junk, from which activity we derive ephemeral benefit and pleasure; the track record is not too good. What will we do now?     

Energy sources: a realistic outlook

Projections to the middle of the next century indicate that unabated historical global energy trends would lead to an annual global energy demand about four times present levels, primarily due to population and economic growth. But extensive global conservation and energy-efficient systems might reduce this value by half. The cumulative effect of the coming half century's use may strain the world's low-cost resources, particularly oil. The future fuel mix is further complicated by the environmental thrust to reduce the global use of carbon-based fuels. The interaction of the principal factors influencing future energy resource and technology options are projected.