Ethanol for a sustainable energy future

Renewable energy is one of the most efficient ways to achieve sustainable development. Increasing its share in the world matrix will help prolong the existence of fossil fuel reserves, address the threats posed by climate change, and enable better security of the energy supply on a global scale. Most of the "new renewable energy sources" are still undergoing large-scale commercial development, but some technologies are already well established. These include Brazilian sugarcane ethanol, which, after 30 years of production, is a global energy commodity that is fully competitive with motor gasoline and appropriate for replication in many countries.     

广州市花都区土地消费性功能供需差异研究

简述了生态足迹方法,对生物资源消费帐户和化石能源消费帐户的涵盖范围进行了界定。根据1990～2005年广东省广州市花都区土地利用及生态环境的相关数据,利用生态足迹分析方法研究了广州市花都区土地消费性功能的需求、供给及供需差异变化情况。结果表明,1990～2005年,人均生态足迹与生态足迹总量均呈迅速增长的趋势,生物资源消费所占比例较化石能源存在绝对优势,化石能源足迹增长速度快于生物资源足迹,但生态足迹总量的结构并未发生明显变化;花都区土地消费性功能的需求远远超出了该区的生态承载力,但其土地利用强度并未超出支撑土地利用系统消费性功能持续产出的生态环境阈值,从而说明花都区生态环境系统仍然是比较安全的。     

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.     

Global deforestation: contribution to atmospheric carbon dioxide

A study of effects of terrestrial biota on the amount of carbon dioxide in the atmosphere suggests that the global net release of carbon due to forest clearing between 1860 and 1980 was between 135 x 10(15) and 228 x 10(15) grams. Between 1.8 x 10(15) and 4.7 x 10(15) grams of carbon were released in 1980, of which nearly 80 percent was due to deforestation, principally in the tropics. The annual release of carbon from the biota and soils exceeded the release from fossil fuels until about 1960. Because the biotic release has been and remains much larger than is commonly assumed, the airborne fraction, usually considered to be about 50 percent of the release from fossil fuels, was probably between 22 and 43 percent of the total carbon released in 1980. The increase in carbon dioxide in the atmosphere is thought by some to be increasing the storage of carbon in the earth's remaining forests sufficiently to offset the release from deforestation. The interpretation of the evidence presented here suggests no such effect; deforestation appears to be the dominant biotic effect on atmospheric carbon dioxide. If deforestation increases in proportion to population, the biotic release of carbon will reach 9 x 10(15) grams per year before forests are exhausted early in the next century. The possibilities for limiting the accumulation of carbon dioxide in the atmosphere through reduction in use of fossil fuels and through management of forests may be greater than is commonly assumed.     

Industrial emissions of carbon dioxide in the United States: a projection

Carbon dioxide builds up in the eartht's atmosphere principally from increased use of fossil fuels. Estimates of the escalating uses of fossil fuels in the United States, especially for the generation of electric power and in the internal combustion engine, show that by the year 2000 emissions will have increased approximately eighteenfold from 1890. In the period 1965 to 1985 an emission-rate increase of around 4.0 percent per year compounded is expected. The expected intrusion and expansion of nuclear power will tend to lower the rates of increase of emission after 1985. Increases in emission rates in the rest of the world will probably equal or exceed the values projected for the United States.     

山西粮食安全面临的问题及对策

山西省受自身自然资源、耕地、水资源等多种因素的限制,粮食生产受到较大制约,历年粮食生产不能满足需求,产需缺口较大的矛盾将长期存在。应对山西省粮食短缺的方法有:稳定粮食播种面积,加强农田水利基本设施改造,发展现代特色农业,充分发挥科技创新的作用增产增收。     

Food production and the energy crisis

The principal raw material of modern U.S. agriculture is fossil fuel, whereas the labor input is relatively small (about 9 hours per crop acre). As agriculture is dependent upon fossil energy, crop production costs will also soar when fuel costs increase two- to fivefold. A return of 2.8 kcal of corn per 1 kcal of fuel input may then be uneconomical. Green revolution agriculture also uses high energy crop production technology, especially with respect to fertilizers and pesticides. While one may not doubt the sincerity of the U.S. effort to share its agricultural technology so that the rest of the world can live and eat as it does, one must be realistic about the resources available to accomplish this mission. In the United States we are currently using an equivalent of 80 gallons of gasoline to produce an acre of corn. With fuel shortages and high prices to come, we wonder if many developing nations will be able to afford the technology of U.S. agriculture. Problems have already occurred with green revolution crops, particularly problems related to pests (57). More critical problems are expected when there is a world energy crisis. A careful assessment should be made of the benefits, costs, and risks of high energy-demand green revolution agriculture in order to be certain that this program will not aggravate the already serious world food situation (58). To reduce energy inputs, green revolution and U.S. agriculture might employ such alternatives as rotations and green manures to reduce the high energy demand of chemical fertilizers and pesticides. U.S. agriculture might also reduce energy expenditures by substituting some manpower currently displaced by mechanization. While no one knows for certain what changes will have to be made, we can be sure that when conventional energy resources become scarce and expensive, the impact on agriculture as an industry and a way of life will be significant. This analysis is but a preliminary investigation of a significant agricultural problem that deserves careful attention and greater study before the energy situation becomes more critical.     

近期水产品市场形势及未来5年走势研判

预计未来5年中国水产品供求关系比较稳定,总产量基本能够满足国内需求,但年增长率将有所下降。其中,捕捞产量增长基本停滞,养殖产量增长尚有较大潜力。水产品作为动物蛋白来源将变得日益昂贵,人均水产品消费量预计将扩大,但消费年均增长率将下降,水产品价格平稳上升。中国将保持世界水产品出口领导地位,进口增速预计超过出口。     

The prospects for China's food security and imports: Will China starve the world via imports?

China's food supply and demand have significant implications for both China's own national food security and that of the world. This study reviews China's food security prospects and their implications, focusing on international trade in the coming decade. The results show that China's policies for ensuring food security will be enhanced and China will move to sustainable agriculture. Most studies anticipate that China will increase its food and feed imports in the coming decade. China's overall food self-sufficiency is likely to fall from 94.5% in 2015 to around 91% by 2025. The greatest increases in imports are likely to be soybean, maize, sugar, and dairy products. However, within the production capacity of the major exporting countries and of many food-importing developing countries, China's additional imports of 3 to 5% of its total food consumption in the coming decade are unlikely to threaten global food security. Indeed, the projected imports of feed and several foods could provide opportunities for many exporting countries to expand their production and save global resources.     

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。     

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.     

Energy resources and global development

In order to address the economic and environmental consequences of our global energy system, we consider the availability and consumption of energy resources. Problems arise from our dependence on combustible fuels, the environmental risks associated with their extraction, and the environmental damage caused by their emissions. Yet no primary energy source, be it renewable or nonrenewable, is free of environmental or economic limitations. As developed and developing economies continue to grow, conversion to and adoption of environmentally benign energy technology will depend on political and economic realities.     

Brazil: energy options and current outlook

Brazil's energy options and current outlook are examined, and a summary of known reserves of fossil and renewable energy resources is given. Brazil has abundant renewable energy resources but very modest reserves of fossil fuels. Consequently, the emphasis in the future will have to be on the utilization of solar energy, hydroelectric power, and biomass in a program designed to preserve local traditions and culture.     

海南省水资源开发利用特点及主要水资源问题

为正确认识海南省水资源开发利用特点及在开发利用过程中存在的主要问题,对海南省水资源开发利用(供水、用水、耗水、水资源利用、开发利用程度)进行了详细分析,指出海南省水资源特点:总量丰富,人均占有量多;时空分布不均,年际年内差异大;抗扰能力差,天然存蓄能力弱;供给需求不同步,对工程依赖程度高。水资源开发利用过程中存在的主要问题:用水效率较低,局部供需矛盾并存;水利基础设施不完善,抵御自然灾害防御能力有限;用水计量制度不健全,水费征收困难;地下水漏斗存在,污废水排放未得到有效遏制。文中还针对存在的问题给出了相关建议。     

Mortality and greenhouse gas impacts of biomass and petroleum energy futures in Africa

We analyzed the mortality impacts and greenhouse gas (GHG) emissions produced by household energy use in Africa. Under a business-as-usual (BAU) scenario, household indoor air pollution will cause an estimated 9.8 million premature deaths by the year 2030. Gradual and rapid transitions to charcoal would delay 1.0 million and 2.8 million deaths, respectively; similar transitions to petroleum fuels would delay 1.3 million and 3.7 million deaths. Cumulative BAU GHG emissions will be 6.7 billion tons of carbon by 2050, which is 5.6% of Africa's total emissions. Large shifts to the use of fossil fuels would reduce GHG emissions by 1 to 10%. Charcoal-intensive future scenarios using current practices increase emissions by 140 to 190%; the increase can be reduced to 5 to 36% using currently available technologies for sustainable production or potentially reduced even more with investment in technological innovation.     

中国玉米市场供需分析与展望

进入21世纪,中国玉米生产连年向好,除2003年和2009年因灾减产外,其他年份玉米生产总体均保持增长局面,国内供需关系基本实现了由长期短缺到总量大体平衡、丰年有余的历史性转变。玉米消费也由食用、饲用拓展到工业初、深加工领域。2012年中国玉米再创历史纪录,国内新增供给达到2．056亿t,加上急剧增加的进口玉米,国内玉米供求关系发生了较大变化,供给过剩压力初露端倪。2013年中国玉米丰收已成定局,国内供给将更加宽松,如果不考虑重大自然灾害,未来2～3年国内玉米供给将呈现宽松向平衡过渡态势。     

Alternative energy futures: the case for electricity

The energy trends of the past and their likely evolution in the next 50 years have been analyzed in the light of technological progress. It is concluded that society will tend to become less centralized than in the past and that it is possible to have future per capita values of energy consumption at the world level similar to those at present, with a substantial redistribution to allow for economic growth of the less developed countries. A condition for this is increasing penetration of electricity. The rationale for the suggested scenario is described, and prospects for electricity for both the industrialized and developing countries are discussed.     

Transformation of the nitrogen cycle: recent trends, questions, and potential solutions

Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-containing fertilizers. Optimizing the need for a key human resource while minimizing its negative consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-containing waste.     

甜菜制糖产业发展分析

本文阐述了中国食糖生产、消费、进口以及食糖价格形成机制,指出我国食糖价格受供求关系、能源及格以及政策等多方面因素的影响,呈周期性波动,未来十年中国食糖的生产和消费将呈缓慢增加总趋势,并且食糖消费增长会快于食糖生产的增长。通过分析甜菜主产区土地资源禀赋,甜菜生产具有的比较优势,以及甜菜制糖产业存在研究投入不足、研发能力不强、甜菜种植规模小、农业机械化技术水平低等问题,提出了国家应在政策上对甜菜制糖产业予以扶持、加大科技投入,提升甜菜研究水平和新产品开发力度,拓展产业链、提高企业竞争力等建议,挖掘甜菜制糖业产业发展潜力,促进甜菜制糖业产业稳定的可持续发展。     

中国生物能源开发利用发展策略

随着世界经济的发展,化石能源供应日趋紧张,供需差率越来越大,因此解决能源危机迫在眉睫,发展生物能源势在必得。就生物能源的基本概念、当前国内外对生物能源的开发和利用现状以及我国生物能源发展战略进行了综述,指出我国能源产业发展中所存在的一些问题,并对今后因地制宜、统筹安排地推动生物能源的发展提出了一些建议。