Biofuel availability and domestic use patterns in Kenya

The annual domestic consumption levels and patterns of various common biofuels in Kenya were surveyed. The main fuelwood sources were farmland trees, indigenous forests, woodlands and timber off-cuts from plantations. In 1997, about 15.4 million tonnes of firewood (air-dried) were consumed and an equivalent of 17.1 million tonnes round wood wet weight (w/w) was converted to charcoal. In the same year, 1.4 million tonnes of a variety of crop residues were also consumed as domestic fuel. Biofuel availability was the major factor influencing the reported annual spatial species use and consumption patterns. Competing demand for the commonly-used tree species (mainly eucalyptus trees) for commercial and other purposes accounts, to a large extent, for the reported dwindling amounts. Communities in various regions have responded by gradually shifting to other available types including those in gazetted forests. Such a response strategy has implications on the long-term spatial and temporal biofuel use patterns.     

Spatial and temporal variation in domestic biofuel consumption rates and patterns in Zimbabwe: implications for atmospheric trace gas emission

An ecologically nationwide and all-year-round domestic biofuel consumption study was conducted in Zimbabwe from January 1996 to March 1997. The study aimed at (a) establishing the determinants and magnitudes of spatial and temporal variations in biofuel consumption rates, (b) estimating the overall mean national rural and urban consumption rates, and (c) estimating the contribution of domestic biomass burning in Zimbabwe to the emission of atmospheric trace gases. The main source of spatial variation in biofuel consumption rates was found to be settlement type (rural or urban). Within a settlement type, per capita consumption rates varied in time and space with household size, ambient temperature, and physical availability. In rural areas wood and agricultural residues were consumed at national average rates of 1.3±0.2 and 0.07±0.01 tonnes capita⁻¹ year⁻¹, respectively. In urban centres wood was consumed at an average rate of 0.4±0.26 tonnes capita⁻¹ year⁻¹. These consumption rates translate into emission outputs from Zimbabwe of 4.6 Tg CO₂–C year⁻¹, 0.4 Tg CO–C year⁻¹, 5.3 Gg NO–N year⁻¹, 14.5 Gg CH₄–C year⁻¹, 24.2 Gg NMHC–C year⁻¹, 2.9 Gg organic acid–C year⁻¹ (formic and acetic acids) and 48.4 Gg aerosol–C year⁻¹. For CO₂, CO, and NO, these domestic biofuel emissions represent 41±6%, 67±6%, and 8±1%, respectively, of the total output of all sources evaluated and documented in Zimbabwe to date. This means that of the studied sources, domestic biomass burning is the major source of CO₂ and CO emission in Zimbabwe.     

Biomass availability, energy consumption and biochar production in rural households of Western Kenya

Pyrolytic cook stoves in smallholder farms may require different biomass supply than traditional bioenergy approaches. Therefore, we carried out an on-farm assessment of the energy consumption for food preparation, the biomass availability relevant to conventional and pyrolytic cook stoves, and the potential biochar generation in rural households of western Kenya. Biomass availability for pyrolysis varied widely from 0.7 to 12.4 Mg ha⁻¹ y⁻¹ with an average of 4.3 Mg ha⁻¹ y⁻¹, across all 50 studied farms. Farms with high soil fertility that were recently converted to agriculture from forest had the highest variability (CV = 83%), which was a result of the wide range of farm sizes and feedstock types in the farms. Biomass variability was two times lower for farms with low than high soil fertility (CV = 37%). The reduction in variability is a direct consequence of the soil quality, coupled with farm size and feedstock type. The total wood energy available in the farms (5.3 GJ capita⁻¹ y⁻¹) was not sufficient to meet the current cooking energy needs using conventional combustion stoves, but may be sufficient for improved combustion stoves depending on their energy efficiency. However, the biomass that is usable in pyrolytic cook stoves including crop residues, shrub and tree litter can provide 17.2 GJ capita⁻¹ y⁻¹ of energy for cooking, which is well above the current average cooking energy consumption of 10.5 GJ capita⁻¹ y⁻¹. The introduction of a first-generation pyrolytic cook stove reduced wood energy consumption by 27% while producing an average of 0.46 Mg ha⁻¹ y⁻¹ of biochar.     

Rural energy consumption patterns with multiple objectives

The problem of designing a rural energy centre and thus obtain the emerging energy consumption patterns with multiple objectives, can be viewed as matching the various energy sources to cater fully to the energy needs of a wide variety of tasks such as cooking, lighting, ploughing, pumping water for irrigation, rural transport, etc. This, in fact, should satisfy several economic, technical as well as social objectives or goals. In order to arrive at a satisfactory solution, this has to be viewed as a multi-objective optimization problem. This communication develops a mathematical model for optimum energy planning in a rural environment. Goal programming approach is used in evolving a satisfactory solution to the above problem. The model developed is applied in the case of a typical South Indian village situated in a semi-arid region especially with respect to the major domestic energy needs of cooking and lighting. Results from the computer-simulated model are given.     

Inverted block or lifeline rates and micro-efficiency in the consumption of electricity

Recent evidence indicates that the marginal cost of electricity exceeds average electricity rates. A model is presented in this paper to investigate the conditions under which inverted block or ‘lifeline’ rates could contribute to minimizing the deadweight loss associated with electricity consumption. Although conditions exist where inverted block rates might aggravate deadweight loss, empirical evidence is presented suggesting that inverted block rates would, in fact, improve the efficiency of electricity consumption.     

海藻生物燃料产业化开发的进展

海藻种类多样、光合作用效率高、生长周期短、生物产量高、自身合成油脂能力强,同时还能大量吸收CO2,是制备生物柴油最佳的生物质原料之一。国内外对海藻生物燃料技术的研发均取得一定成果。海藻生物柴油的生产过程主要包括海藻大规模培养、海藻油萃取、酯交换反应、生物柴油后处理4个步骤,而最重要的是海藻的大规模培养。光生物反应器已成为高效、快速、大量培养藻类的关键没备,其一般分为开放式和封闭式两种。AlgaeLink NV公司的海藻光生物反应器是目前世界上唯一已商业化的小型装置。我国企业采用自主研发的反应器装置,通过对环境条件因素进行控制,在技术上已达到海藻含油率40％,日产量1～1．4kg／m^3。当海藻含油率达到60％,日产量平均达到3kg／m^3以上时,海藻生物柴油的生产成本将接近石油柴油的批发价,海藻生物柴油产业将成为一个新兴的替代能源产业。     

Biofuel production: Challenges and opportunities

It is increasing clear that biofuels can be a viable source of renewable energy in contrast to the finite nature, geopolitical instability, and deleterious global effects of fossil fuel energy. Collectively, biofuels include any energy-enriched chemicals generated directly through the biological processes or derived from the chemical conversion from biomass of prior living organisms. Predominantly, biofuels are produced from photosynthetic organisms such as photosynthetic bacteria, micro- and macro-algae and vascular land plants. The primary products of biofuel may be in a gas, liquid, or solid form. These products can be further converted by biochemical, physical, and thermochemical methods. Biofuels can be classified into two categories: primary and secondary biofuels. The primary biofuels are directly produced from burning woody or cellulosic plant material and dry animal waste. The secondary biofuels can be classified into three generations that are each indirectly generated from plant and animal material. The first generation of biofuels is ethanol derived from food crops rich in starch or biodiesel taken from waste animal fats such as cooking grease. The second generation is bioethanol derived from non-food cellulosic biomass and biodiesel taken from oil-rich plant seed such as soybean or jatropha. The third generation is the biofuels generated from cyanobacterial, microalgae and other microbes, which is the most promising approach to meet the global energy demands. In this review, we present the recent progresses including challenges and opportunities in microbial biofuels production as well as the potential applications of microalgae as a platform of biomass production. Future research endeavors in biofuel production should be placed on the search of novel biofuel production species, optimization and improvement of culture conditions, genetic engineering of biofuel-producing species, complete understanding of the biofuel production mechanisms, and effective techniques for mass cultivation of microorganisms.     

GHG reduction potential of changes in consumption patterns and higher quality levels: Evidence from Swiss household consumption survey

An effective consumer-oriented climate policy requires knowing the GHG reduction potential of sustainable consumption. The aim of this study is to draw lessons from differences in consumption between households with high and low GHG emissions. We evaluate a survey of 14,500 households and use a method that allows measuring changes in price level of consumption. Comparing the 10% of households with the highest GHG emissions per capita with the lowest 10% – controlling for differences in expenditure level and household structure – we find a range 5–17 tons of CO₂-equivalent per capita and year. The observed differences stem mainly from heating, electricity use, car use, and travel by aircraft. Consumption patterns with low GHG emissions are characterized by less spending on mobility, but more on leisure and quality oriented consumption (leading to higher prices per unit). Further characteristics are: a higher share of organic food, low meat consumption and fewer detached single family houses. Our findings imply that a significant reduction in GHG emissions would be possible by adopting real-world consumption patterns observable in society. The twin challenge is to shift consumption towards more climate friendly patterns, and to prevent any trend towards high emitting consumption patterns.     

正丁醇作为生物燃料在生产和应用方面的进展

作为车用替代燃料,丁醇的热值比乙醇高30%左右,挥发性只有乙醇的1/6左右,吸湿性远小于甲醇、乙醇和丙醇,具有适度的水溶性,腐蚀性低,安全性更高。但丁醇直接应用到发动机上也存在一些问题,如其热值比传统汽油或柴油低,使得燃料消耗量增加;燃烧效率低于甲醇、乙醇;当应用于点燃式发动机时,丁醇较高的黏度将产生潜在的沉积或腐蚀等问题。目前许多研究者将正丁醇作为替代生物燃料进行研究,现有的研究主要是将丁醇与汽油或柴油混合应用在发动机上,或是应用在一些基本的燃烧反应器中。综合各方面的研究成果,正丁醇在混合燃料中体积分数小于20%时,无需调整发动机就可获得与汽油燃料相同的发动机功率;当达到30%时,发动机最大功率开始下降;随着正丁醇体积的增加,燃料消耗量增加。CO、THC、NOx排放的减少或增加取决于具体的发动机、操作条件、丁醇-汽油的混合比等。混合燃料与纯汽油相比,未燃烧醇的排放增加,而且丁醇的比例越高,未燃烧醇的排放越高。     

Fuel consumption rates of passenger cars in China: Labels versus real-world

Recently, China has implemented many policy measures to control the oil demand of on-road vehicles. In 2010, China started to report the fuel consumption rates of light-duty vehicles tested in laboratory and to require new vehicles to show the rates on window labels. In this study, we examined the differences between the test and real-world fuel consumption of Chinese passenger cars by using the data reported by real-world drivers on the internet voluntarily. The sales-weighted average fuel consumption of new cars in China in 2009 was 7.80 L/100 km in laboratory and 9.02 L/100 km in real-world, representing a difference of 15.5%. For the 153 individual car models examined, the real-world fuel consumption rates were −8 to 60% different from the test values. The simulation results of the International Vehicle Emission model show that the real-world driving cycles in 22 selected Chinese cities could result in −8 to 34% of changes in fuel consumption compared to the laboratory driving cycle. Further government effort on fuel consumption estimates adjustment, local driving cycle development, and real-world data accumulation through communication with the public is needed to improve the accuracy of the labeling policy.     

Time-of use rates and peak period electricity consumption : An empirical note

Data on seven Californian hydraulic cement plants are used to estimate the effect of time-of-use electricity rates on peak period electricity usage. The results indicate a small dampening of on-peak demand which is more pronounced in the winter. There is also weak support for a reduction in peak demand variance, but this is more evident in the summer.     

Analysis on exergy consumption patterns for space heating in Slovenian buildings

Problem of high energy use for heating in Slovenian buildings is analyzed with exergy and energy analysis. Results of both are compared and discussed. Three cases of exterior building walls are located in three climatic zones in winter conditions. Results of energy analyses show that the highest heating energy demand appears in the case with less thermal insulation, especially in colder climate. If the comparison is made only on the energy supply and exergy supply, the results of exergy analysis are the same as those of energy analysis. The main difference appears, if the whole chain of supply and demand is taken into consideration. Exergy calculations enable us to analyze how much exergy is consumed in which part, from boiler to building envelope. They also reveal how much energy is supplied for the purpose of heating. Results show that insulation has much bigger effect than effect of boiler efficiency. However, the most effective solution is to improve building envelope together with boiler efficiency. Better thermal insulation also makes an important contribution to the improvement of thermal comfort conditions. It causes higher surface temperatures resulting in a larger warm radiant exergy emission rate and consequently better thermal comfort.     

Fuelwood consumption patterns in Fakot watershed, Garhwal Himalaya, Uttarakhand

Biomass is one of the key energy sources in rural India and constitutes 75% of the total energy consumption. In the tough mountain terrain, the consumption pattern depends on the availability of the resources as well as socio-economic conditions of the people. The present study is conducted at Fakot micro-watershed in Garhwal district of Uttarakhand, India. The present paper explores the variations in fuelwood consumption pattern in the watershed level at different altitudes with respect to family size. In the present study, the fuelwood consumption in the watershed is in the range of 455-2388 gm/person/day. Absence of serial autocorrelation in the seasonal fuel consumption data is observed. Season specific models for fuel consumption are proposed.     

Residential energy consumption patterns: the case of Lebanon

In an attempt to fill a significant gap in baseline information, 509 households have been studied to analyse the residential consumption patterns in the urban environment in Lebanon. The average annual household energy consumption has been found to be 6907 kWh, whereas per capita consumption is 1727 kWh. Seasonal and monthly variations are analysed indicating increased energy consumption in the summer months accounting for 28% of total annual consumption. Correlations are indicated for energy consumption with apartment price, area, income and number of residents. Multiple regression analysis indicated statistical significance of income, area and number of residents to the energy consumption. Based on current consumption and electricity generating technologies, 1.6 tons of CO₂, 7.3 kg of SO₂ in addition to other pollutants are generated per resident. Comparative analysis indicates that Lebanon has electricity consumption similar to that of Western Europe, paving the way for significant energy saving potential. Copyright © 2005 John Wiley & Sons, Ltd.     

Biofuel investment in Tanzania: Omissions in implementation

Increasing demand for biofuels as a component of climate change mitigation, energy security, and a fossil fuel alternative attracts investors to developing countries like Tanzania. Ample unused land is critical for first generation biofuels production and an important feature to attract foreign direct investments that can contribute towards agricultural modernization and poverty reduction initiatives. Despite the economic justifications, the existing institutional and infrastructural capacities dictate the impacts of biofuels market penetrations. Furthermore, exogenous factors like global recessionary pressure depressed oil prices below the level at which biofuel production were profitable in 2007, making Tanzania’s competitiveness and potential benefits questionable.     

藻类生物燃料研究开发进展

藻类生物燃料作为一种非粮生物质燃料已成为当今的研究热点,具有广阔的发展前景,有可能成为未来最重要的可再生能源之一。介绍了藻类制备生物燃料的研发概况,综述了国内外研究开发历程与最新进展,分析了目前藻类生物燃料研究开发中存在的困难和问题,指出了当前和今后的研发方向。     

Biofuel and biomass from marine macroalgae waste

Nowadays, biofuel production of new raw materials has gained renewed interest. For that reason, the objective of this work is to use marine macroalgae for biodiesel and biomass production. The obtained results show that macroalgae are a suitable energy source for biodiesel production by direct transesterification, avoiding the previous step of oil extraction. It is an effective process because 95% of the oil is extracted. To analyze the optimum reaction conditions, the reaction was carried out at different amounts of methanol, catalyst concentrations, reaction temperatures, and reaction times. In addition, the macroalgae residue after transesterification was analyzed and it is suitable as fuel in biomass boilers.     

我国发展生物液体燃料的资源与技术潜力分析

发展生物质液体燃料有利于满足高品质能源的需求,改善生态环境,提高生物质能源综合利用水平和增加农民收入。清楚地认识和界定我国生物质的资源潜力和技术潜力,是科学、有序和有效地的发展生物液体燃料的关键问题。本文对我国生物质液体燃料资源潜力的分析结果表明,我国生物资源潜力大,但在现有技术和条件下,实际可利用潜力相对较小,缺乏技术经济优势。所以,应根据资源和技术条件,选择适当的技术路径,加强技术研发,并逐步完善产业管理。     

Biofuel production: Prospects,challenges and feedstock in Australia

The growing demands for energy coupled with ever increasing environmental concerns have allowed the global production of biofuels to rise significantly in recent years. Many countries across the world have begun utilising biofuels on a national scale, while many more are in the process of planning and implementing similar steps. While Australia has an abundance of fossil fuels in the form of coal, natural gas, and oil, and currently employs a variety of alternative energy sources, the technology to produce and implement biofuels in Australia is in its embryonic stage. Today, Australia is using first generation feedstock as the main source for the production of biofuel, but is progressively broadening into second-generation biofuel production technology. Australia has an enormous amount of biomass available in the form of agricultural and forestry residues, bagasse and feedstock currently unused for the production of biofuels. The technology for the conversion of lignocellulosic biomass into biofuels warrants further research to maximise yield to the point of industrial feasibility. This review discusses the current state of ethanol production in Australia, the key technological challenges involved in the production of second-generation biofuel and the availability of various kinds of lignocellulosic biomass for biofuel production.