Bioenergy potential from crop residues in China: Availability and distribution

The accurate estimate of the availability of crop residue resources is very important for the development of bioenergy in China, a large agricultural nation. Previous efforts to evaluate the bioenergy potential from converting straws to energy were mainly based on agricultural statistical data on the provincial/county level. Straw yield calculations generated by most of those works significantly overstate the amount of crop straws for ignoring environmental requirement and harvest constrain. The paper presents a GIS-based approach for the assessment of the availability and distribution of crop residues in China, taking into account a number of conservation issues: resources (total amount, spatial and temporal distribution), economy (transportation costs), environment, and technology. All data are converted into unified geographic unit (100 m × 100 m pixels), and integrated analysis is implemented with GIS software. The results indicate that considering conservation requirements, the production of net available crop residues is about 505.5 million tons per year. The bioenergy potential is about 253.7 million tons standard coal per year (7.4 EJ/year), which account for 8.27% of total energy consumption of the country in 2009. The results and dataset will present significant support for energy planning both at national and regional scale.     

Importance of biodiesel as transportation fuel

The scarcity of known petroleum reserves will make renewable energy resources more attractive. The most feasible way to meet this growing demand is by utilizing alternative fuels. Biodiesel is defined as the monoalkyl esters of vegetable oils or animal fats. Biodiesel is the best candidate for diesel fuels in diesel engines. The biggest advantage that biodiesel has over gasoline and petroleum diesel is its environmental friendliness. Biodiesel burns similar to petroleum diesel as it concerns regulated pollutants. On the other hand, biodiesel probably has better efficiency than gasoline. One such fuel for compression-ignition engines that exhibit great potential is biodiesel. Diesel fuel can also be replaced by biodiesel made from vegetable oils. Biodiesel is now mainly being produced from soybean, rapeseed and palm oils. The higher heating values (HHVs) of biodiesels are relatively high. The HHVs of biodiesels (39–41 MJ/kg) are slightly lower than that of gasoline (46 MJ/kg), petrodiesel (43 MJ/kg) or petroleum (42 MJ/kg), but higher than coal (32–37 MJ/kg). Biodiesel has over double the price of petrodiesel. The major economic factor to consider for input costs of biodiesel production is the feedstock, which is about 80% of the total operating cost. The high price of biodiesel is in large part due to the high price of the feedstock. Economic benefits of a biodiesel industry would include value added to the feedstock, an increased number of rural manufacturing jobs, an increased income taxes and investments in plant and equipment. The production and utilization of biodiesel is facilitated firstly through the agricultural policy of subsidizing the cultivation of non-food crops. Secondly, biodiesel is exempt from the oil tax. The European Union accounted for nearly 89% of all biodiesel production worldwide in 2005. By 2010, the United States is expected to become the world's largest single biodiesel market, accounting for roughly 18% of world biodiesel consumption, followed by Germany.     

微藻生物能源研究现状及展望

能源是现代社会发展的命脉,目前仍以化石燃料为主,而对化石燃料过度依赖导致的能源危机和环境问题日益突出,人类需要寻找可再生的清洁能源作为替代能源。微藻作为可持续的生物能源原料,具有巨大的发展潜力。本文综述了微藻原料获取各环节的研究现状,包括微藻育种、规模培养和采收,并重点论述了微藻生物质转化为生物能源产品的研究进展,包括生物柴油、生物乙醇、生物燃气、生物油,同时指出了微藻生物能源未来的研究方向。     

Technoeconomic analysis of an integrated microalgae photobioreactor, biodiesel and biogas production facility

As fossil fuel prices increase and environmental concerns gain prominence, the development of alternative fuels from biomass has become more important. Biodiesel produced from microalgae is becoming an attractive alternative to share the role of petroleum. Currently it appears that the production of microalgal biodiesel is not economically viable in current environment because it costs more than conventional fuels. Therefore, a new concept is introduced in this article as an option to reduce the total production cost of microalgal biodiesel. The integration of biodiesel production system with methane production via anaerobic digestion is proved in improving the economics and sustainability of overall biodiesel stages. Anaerobic digestion of microalgae produces methane and further be converted to generate electricity. The generated electricity can surrogate the consumption of energy that require in microalgal cultivation, dewatering, extraction and transesterification process. From theoretical calculations, the electricity generated from methane is able to power all of the biodiesel production stages and will substantially reduce the cost of biodiesel production (33% reduction). The carbon emissions of biodiesel production systems are also reduced by approximately 75% when utilizing biogas electricity compared to when the electricity is otherwise purchased from the Victorian grid. The overall findings from this study indicate that the approach of digesting microalgal waste to produce biogas will make the production of biodiesel from algae more viable by reducing the overall cost of production per unit of biodiesel and hence enable biodiesel to be more competitive with existing fuels.     

Prospects of using microalgae for biofuels production: Results of a Delphi study

Advanced biofuels, such as those obtained from microalgae, are widely accepted as better choices for achieving goals of incorporating renewables and non-food fuel sources into the transportation sector, and for overcoming land use issues due to biofuel crops. Main challenges are currently the feasibility of large-scale commercialization of microalgae biofuels, since there are still some technical problems to overcome (e.g. the high energy consumption associated with biomass processing) and the majority of economic and financial analyses are based on pilot-scale projects. Therefore, this article presents the results of a Delphi study aiming to identify the main obstacles and most critical issues affecting the potential of large-scale commercialization of microalgae biodiesel and its incorporation into the fuel market. According to the authors' knowledge, this is the first Delphi study with this objective. The respondents are worldwide market specialists in the survey themes that ranged from biofuels economics to their environmental sustainability. One of the key findings is that most of the experts believe that production of microalgae biofuels will achieve its full commercial scale until 2020, and that from 2021 till 2030 it could represent from 1% to 5% of the worldwide fuel consumption. The study results also showed that environmental issues are where expert opinion differs more.     

中国农村生物质能消费的CO_2排放量估算

借助国际通用的CO2排放鼍计算方法,利用1996～2006年中国农村可再生能源统计资料,对中同农村生物质能消费的CO2排放情况及其空间分布进行分析探讨.结果表明,中国农村生物质能消费的CO2排放总量达到7.25×108t,约占农村生活能源消费CO22排放量的65%,占全国温窜气体总排放量的11.2%,其中秸秆、薪柴等传统生物质能利用方式贡献较大,可达98.64%～99.74%;中国农村生物质能消费CO2排放量的空间分布不均,四川、广西等省CO2排放量大,属超重排放区域,北京、天津、上海、西藏、青海等省(市、区)排放量小,属轻排放区域:区域生物质资源条件和经济社会水平是影响农村生物质能消费CO22排放的主要因素.     

Experimental investigation of the performance and emissions of a heavy-duty diesel engine fueled with waste cooking oil biodiesel/ultra-low sulfur diesel blends

The major obstacle to biodiesel commercialization is the high cost of raw materials. Biodiesel from waste cooking oil is an economical source and thus an effective strategy for reducing the raw material cost. Using waste cooking oil also solves the problem of waste oil disposal. This study investigated the emissions of polycyclic aromatic hydrocarbons (PAHs), carcinogenic potencies and regulated matters, and brake specific fuel consumption from a heavy-duty diesel engine under the US-HDD transient cycle for five test fuels: ultra-low sulfur diesel (ULSD), WCOB5 (5 vol% biodiesel made from waste cooking oil + 95 vol% ULSD), WCOB10, WCOB20, and WCOB30. Experimental results indicate using ULSD/WCOB blends decreased PAHs by 7.53%-37.5%, particulate matter by 5.29%-8.32%, total hydrocarbons by 10.5%-36.0%, and carbon monoxide by 3.33%-13.1% as compared to using ULSD. The wide usage of WCOB blends as alternative fuels could protect the environment.     

Biodiesel production from oleaginous microorganisms

High energy prices, energy and environment security, concerns about petroleum supplies are drawing considerable attention to find a renewable biofuels. Biodiesel, a mixture of fatty acid methyl esters (FAMEs) derived from animal fats or vegetable oils, is rapidly moving towards the mainstream as an alternative source of energy. However, biodiesel derived from conventional petrol or from oilseeds or animal fat cannot meet realistic need, and can only be used for a small fraction of existing demand for transport fuels. In addition, expensive large acreages for sufficient production of oilseed crops or cost to feed animals are needed for raw oil production. Therefore, oleaginous microorganisms are available for substituting conventional oil in biodiesel production. Most of the oleaginous microorganisms like microalgae, bacillus, fungi and yeast are all available for biodiesel production. Regulation mechanism of oil accumulation in microorganism and approach of making microbial diesel economically competitive with petrodiesel are discussed in this review.     

A comprehensive review on biodiesel as an alternative energy resource and its characteristics

As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum, and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production.It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.     

An overview of biomass energy utilization in Vojvodina

The Autonomous Province of Vojvodina is an autonomous province in Serbia. It is located in the northern part of the country, in the Pannonia plain. Vojvodina is an energy-deficient province. Energy plays a pivotal role in socio-economic development by raising the standard of living. Biomass has been used by mankind as an energy source for thousands of years. Traditional fuels like firewood, dung and crop residues currently contribute a major share in meeting the everyday energy requirements of rural and low-income urban households in Vojvodina. Contribution of the renewable energy sources in the total consumption of energy in Vojvidina is less than 1%, i.e. it amounts to 280 KWh/year. Production of biodiesel in the year 2008 was 0.07 million tons, what is for 133% higher with respect to the production in the year 2007 (0.03 million tons). In Vojvodina, as the raw materials for bioethanol production are seen primarily sugar beet, corn, wheat surpluses, potato surpluses and waste potato, as well as the raw materials intended for these purposes grown on the uncultivated soils, such as hybrid broomcorn, Jerusalem artichoke and triticale. With introduction of new technologies for cultivation and collecting of biomass production of the electrical energy could be raised to 6.4 GWh/m² year, what, with retention of the contemporary consumption, would represent the significant 9% of the total consumption in the province. According to programme of realisation of energy strategy of Vojvodina/Serbia in the field of the renewable energy sources for to period till the year 2010 and its completion, till the year 2015, in Vojvodina could be created conditions for the employment of about 24,000 workers, i.e. 4000 employed for maintenance of the newly constructed plants, 17,000 employed on designing and manufacturing of plants and 3000 employed in auxiliary activities.     

Biodiesel as an alternative motor fuel: Production and policies in the European Union

The purpose of this work is to investigate fuel characteristics of biodiesel and its production in European Union. Biodiesel fuel can be made from new or used vegetable oils and animal fats, which are non-toxic, biodegradable, renewable resources. The vegetable oil fuels were not acceptable because they were more expensive than petroleum fuels. Biodiesel has become more attractive recently because of its environmental benefits. With recent increases in petroleum prices and uncertainties concerning petroleum availability, there is renewed interest in vegetable oil fuels for diesel engines. In Europe the most important biofuel is biodiesel. In the European Union biodiesel is the by far biggest biofuel and represents 82% of the biofuel production. Biodiesel production for 2003 in EU-25 was 1,504,000 tons.     

Potentials of crop residues for commercial energy production in China: A geographic and economic analysis

China has become increasingly dependent on the international energy market owing to the rapid growth of demand for energy. To develop renewable energy and thus strengthen energy security for the future, it is important to consider the potential of crop residues. This paper contributes to this topic by mobilizing up-to-date statistical and remote-sensing data and by carrying out a geographic and economic analysis. Its assessment shows that China's total output of crop residues in 2010 amounted to 729 million tons, and the quantity could be used for commercial energy production is between 147 and 334 million tons, depending on the competition power of the commercial energy production relative to the traditional uses of crop residues. The analysis also shows that the distribution of crop residues in China is highly uneven. By taking into account the densities of crop residues available for energy production at the grid-cell level, the transportation cost constraints, and the economy-of-scale requirements of energy plants, this study further assesses the geographic distribution of the suitability for establishing crop residue based power plants and bioenergy plants in China.     

Competitiveness,role, and impact of microalgal biodiesel in the global energy future

This paper examines the competitiveness, role, and impact of microalgal biodiesel in the 21st century using a global energy system model with a detailed technological representation. The major conclusions are the following. First, the competitiveness of microalgal biodiesel decreases as CO₂ stabilization constraints become more stringent. The share of microalgal biodiesel and renewable jet fuel produced from it in total global final energy consumption over the time horizon 2010–2100 is 5.1% in the case without CO₂ constraints compared with 3.9% and 0.7% in the case of CO₂ stabilization at 550 ppmv and 400 ppmv, respectively. This is because production and combustion of microalgal biodiesel release as much CO₂ as is captured from anthropogenic sources and assimilated by microalgae and because CO₂ prices raised by stringent CO₂ stabilization constraints make the economics of microalgal biodiesel unattractive. Second, the competitiveness of microalgal biodiesel is also greatly affected by microalgal production cost and microalgal lipid yield. Under a 400 ppmv CO₂ stabilization constraint, a 50% microalgal production cost decrease leads to increase in total global microalgal biodiesel production over the time horizon by a factor of 6.5, while a 50% microalgal lipid yield increase leads to increase in it by a factor of 4.5. Third, microalgal biodiesel plays an important role in satisfying the energy demand in the transport sector, thereby replacing petroleum products and Fischer–Tropsch synfuels. An increasing proportion of microalgal biodiesel is converted into renewable jet fuel over time to be used as a fuel for aircraft. Fourth, either without CO₂ constraints or under the 550 ppmv CO₂ stabilization constraint, the participation of microalgal biodiesel in the global energy market would have a large impact on the global energy supply and consumption structure. This is not only because of its substitution for other forms of final energy, but also because of the need to satisfy the demand for CO₂ for microalgal production.     

Fuzzy-modeling with Particle Swarm Optimization for enhancing the production of biodiesel from Microalga

Biodiesel is one of the promising energy sources that could replace petroleum oil in the near future. Microalgae is occupying a distinguished position among the promising sources for biodiesel production. Enhancement of the lipids production during the pretreatment is a key factor for the biodiesel production. High-pressure homogenizer is a better pretreatment procedure to enhance the lipid extraction from microalgae. In this research, a robust model of biodiesel system using fuzzy logic is built based on the experimental data for biodiesel system. Then, Particle Swarm Optimization (PSO) optimizer is applied for determining the best operating parameters of biodiesel system. The decision variables used in the optimization process are; pressure, number of passes, and reaction time that maximizes the percentage of recovery lipids of biodiesel. A comparison study was carried out between the optimized results thought PSO algorithm and those obtained by the experimental results and the optimized results through the Response Surface Methodology (RMS). Results demonstrated that using the proposed optimization methodology is significantly better than RSM, a nearly 78.7% increase in lipids extraction could be achieved according to the current model.     

Biodiesel production by microalgal biotechnology

Biodiesel has received much attention in recent years. Although numerous reports are available on the production of biodiesel from vegetable oils of terraneous oil-plants, such as soybean, sunflower and palm oils, the production of biodiesel from microalgae is a newly emerging field. Microalgal biotechnology appears to possess high potential for biodiesel production because a significant increase in lipid content of microalgae is now possible through heterotrophic cultivation and genetic engineering approaches. This paper provides an overview of the technologies in the production of biodiesel from microalgae, including the various modes of cultivation for the production of oil-rich microalgal biomass, as well as the subsequent downstream processing for biodiesel production. The advances and prospects of using microalgal biotechnology for biodiesel production are discussed.     

Renewable energy from agro-residues in China: Solid biofuels and biomass briquetting technology

China has the abundant agro-residue resources, producing more than 630 million tons of agro-residues in 2006, and amounting to about 20% of total energy consumption in rural areas. Efficient utilization of enormous agro-residues resource is crucial for providing bioenergy, releasing risk of environmental pollution, and increasing farmers’ income. The paper presented the feasibility of densified solid biofuels technology for utilizing agro-residues in China. The output and distribution of agro-residues in recent 10 years, the R&D of briquetting technology, and the market of densified solid biofuels from agro-residues in China have been analyzed. The result indicated that the abundant agro-residue resources can provide the economical and sustainable raw material for densified solid biofuels development in China. The R&D of briquetting technology at present can strongly support the large scale production of densified solid biofuels. With continued improvement and cost reduction of briquetting technology, along with the support of nation energy policy on biomass energy, the market of densified solid biofuels from agro-residues in China will be more fully deployed. Based on the above mentioned key factors, development of densified solid biofuels from agro-residues in China will be promising and feasible.     

Transesterification of marine macroalgae using microwave technology

Biodiesel is renewable and environmental friendly, with calori?c value equivalent to regular fossil fuel. This fuel can be produced from a variety of feedstocks, such as ?rst-generation biodiesel feedstock (corn, peanut, soybean), second generation (jatropha, animal fats, waste cooking oils, macroalgae), and third generation (microalgae). Among these feedstocks, biodiesel production from microalgae has drawn special attention for different reasons: they have high lipid content and high growth rates; they are tolerant to severe environmental conditions; they offer the possibility of sequester carbon dioxide from the ?ue gases; their harvesting and transportation are economical compared to other crops; and they have very high photosynthetic yields compared to other terrestrial plants. The advantage of using macroalgae recollected on the beaches as raw material is that allows to obtained energy from a residue.

Microwave-assisted extraction and transesteri?cation of microalgae is being researched as a solution for biodiesel production by its benefits, such as shorter reaction times and less amount of heat energy to obtain biodiesel. It is due to the fact that microwaves can easily penetrate through the cell wall structure to extract and transesterify the oils into biodiesel.

The aim of this research was to explore the possibility of carrying out the microwave-assisted transesterification of three marine macroalgae (brown and green). Different experimental runs were carried out with different process parameters such as macroalgae-to-methanol ratio, reaction time and catalyst concentrations. Based on the obtained results, the best conditions for microwave-assisted transesteri?cation reaction were macroalgae-to-methanol ratio of 1:15 (wt/vol), sodium hydroxide concentration of 2 wt% and reaction time of 3 min.     

A review on microwave-assisted production of biodiesel

Energy is the most important necessity for human existence on the earth. Limited crude petroleum resources and increasing awareness regarding the environmental impacts of fossil fuels are driving the search for new energy sources and alternative fuels. Biodiesel is a fuel which is renewable, biodegradable, environmentally friendly, and non-toxic in nature and has attracted considerable attention during the past decades. The costs of feedstock and the production process are two major hurdles to large-scale biodiesel production in particular. Various technologies have been developed to reduce the production cost. This paper attempts to extensively review microwave-assisted technology for biodiesel production. Additionally, different types of feedstocks for biodiesel production have been summarized in this paper. It is concluded that the microwave-assisted technique reduces the reaction time significantly in comparison with conventional methods. In addition, a high quality biodiesel can be obtained from microwave-assisted transesterification of different kinds of oils. Finally, the energy payback for 1kg biodiesel produced by microwave-assisted technology is calculated in this paper and it indicated that the system is sustainable. Therefore it can be a suitable method of decreasing the cost of biodiesel and can also help the commercialization of this fuel.     

我国生物质能源现代化应用前景展望(二)——生物质制备液体燃料的转化途径

利用可再生生物质资源转化制备液体燃料已成为全球关注的热点。常见的生物质能源原料主要有草本植物、木本植物、微藻和脂肪类生物质资源,丰富的生物质资源为生物质液体燃料的生产提供了广泛的原料来源,也为生物质能源的多样性发展提供了坚实的物质基础。不同的生物质原料种类和转化方式可生产出性能各异的多种液体燃料,主要包括醇类燃料(乙醇、丁醇等)、烃类燃料和生物柴油等,由此构建出生物质转化制备液体燃料的转化途径网络。醇类燃料的生物质转化途径主要包括生物质直接发酵、生物质合成气发酵、生物质合成气化学合成等;烃类燃料的生物质转化途径主要有生物质液化加氢、微藻热化学途径、生物质合成气费托合成、生物质发酵脂肪酸加氢及油脂类加氢途径等;生物柴油的转化途径主要有油脂酯交换和微藻萃取酯交换。在这些液体燃料的转化途径中,只有生物质发酵制乙醇途径和油脂酯交换途径基本实现了商业化应用,其他大部分转化途径仍处于开发阶段。     

Screening of marine microalgae for biodiesel feedstock

Biodiesel production from microalgae lipids is increasingly regarded as a more sustainable and feasible alternative to conventional biodiesel feedstocks derived from terrestrial bioenergy crops. A total of ninety-six strains of marine microalgae, with an elevated biomass productivity and intracellular lipid content, were isolated from the coastal waters of Singapore using an automated flow cytometric cell-sorting technique. Cell sorting was based on the two-dimensional distribution of algal cells for red fluorescence (representing chlorophyll auto-fluorescence) against forward-light scatter (representing cell size) and red vs. green fluorescence. Twenty-one of the strains were further characterized with respect to cell growth rate, biomass concentration, lipid content (total and neutral lipid) and fatty acid profile. The growth rates of Skeletonema costatum, Chaetoceros and Thalassiosira species were greatest among the entire strains, but in terms of absolute lipid yield Nannochloropsis strains predominated. Nannochloropsis strains had a lipid content ranging from 39.4% to 44.9% of dry weight biomass. Transesterification of the lipids yielded 25-51% of fatty acid methyl ester (FAME) i.e. biodiesel, where total FAME content ranged between 11 and 21% of dry weight biomass. This study describes the microalgae screening process and demonstrates that Nannochloropsis is a promising species for biodiesel feedstock.