Advanced biofuel technologies : status and barriers

世界主要国家耕地动态变化及其影响因素

Status and barriers of advanced biofuel technologies: A review

Chapter Three - Biomass Conversion

Ruminant production systems in developing countries could be classified into three categories: the extensive systems, systems incorporating arable cropping and systems integrated with tree cropping. Systems have evolved in response to the agro-ecological environment, the availability and type of land, nature of cropping patterns, frequency and intensity of cropping, area of uncultivated land and animal species and animal numbers.Smallholder livestock farmers in most developing countries appear to have adopted a mixed system that incorporates the traditional extensive system and the system that combines arable cropping with livestock. Both in Africa and in Asia, livestock production is an important component of traditional agriculture, complementing arable cropping. Livestock utilize existing food resources such as communal grazing lands which are marginal for arable cropping, crop residues and agro-industrial by-products. Besides supplying meat and milk, organic manure and draft power, livestock are an investment and an insurance against crop failure.Crop residues and agro-industrial by-products are a major source of nutrients for ruminant livestock in developing countries, especially during periods of fodder shortage. Despite the large research effort on upgrading crop residues in recent years, there has been little improvement in the utilization of crop residues in developing countries. Reasons for this are many but include, the absence of detailed production patterns of crop residues within countries, including when and where they are produced, the difficulties of transporting and storing crop residues, inappropriate technology and the near absence of extension services.Both in the African and Asian continents, smallholder farmers who rear livestock for supplementary income are rather reluctant to change their traditional practices, when new technologies call for extra labour, time and capital, since the methods may be too demanding in relation to the benefit produced. The more likely application of any new technology will be with larger-scale operations where benefits are clearer and sufficiently large to warrant the extra efforts.

A range of energy crops can be grown on marginal land (i.e. land that is not suitable for food crop production or contaminated site) to provide feedstocks for bioenergy, non-food products and biofuels. The food versus fuel debate had a significant negative impact in Europe on first generation biofuels production from food crops (i.e. wheat, rapeseed, etc). A new approach involving the use of marginal land for the production of lignocellulosic species for the production of bioethanol is now pursued in Italy and in many other countries, where the demand for high quality water resources, arable land, food and fossil fuels is rapidly growing. With an emerging “feed versus fuel debate” there is a pressing need to find options for the use of marginal lands and wastewaters or saline ground waters to produce second generation biofuel or bio paper crops. Arundo donax was selected as a potential crop for use in these areas, since it produces more cellulosic biomass and sequesters more contaminants, using less land and pesticides than any other alternative crops reported in the literature. The objective of this paper is to evaluate economically a simplified process for the production of second generation bioethanol from A. donax. Process calculations and economic analyses are performed using the software SuperPro Designer®.

Recent socio-political and economic factors encourage development of bioenergy and biofuels. The aim of this paper is to provide an updated review of the most promising technologies for sustainable production of advanced liquid biofuels, specifically transportation fuels. The focus is on second generation biofuels since they do not compete with land required for arable and pastoral use; therefore, first generation biofuels are not included in this review. Upon evaluation the authors recognise the most promising liquid biofuels to include bioethanol, biobutanol, biodiesel, green diesel, biomethanol, dimethyl ether, bio-oil, and biojet fuel. The order of the paper follows a specific structure. Initially, a detailed description, including physical and chemical properties, is given for each liquid biofuel. Then a review of production pathways for each fuel is given, including details regarding the feasibility of integrating it into the current liquid fuel infrastructure. Furthermore, a discussion of the challenges associated with current production pathways is provided.

Recent trends in metabolic engineering of microorganisms for the production of advanced biofuels

Natural resources in the Middle East and North Africa (MENA) region base for agriculture are very fragile. Many countries in MENA region are suffering from a shortage of raw materials which are very necessary for agriculture activities, animal feed as well as industrial purposes. They are characterized by high population growth, erratic weather conditions, limited area of arable lands, with some of the biggest and harshest deserts and with acute water shortage at present. Water resources in many countries in the region are dwindling both in quantity and in quality as consequences of climate change. Exploitation of non-conventional resources such as agriculture wastes or residues for economic agricultural and industrial products is increasingly needed. Many countries in the region have realized, in the last decade, the advantages of agricultural residues (AGRs) on the economy, industry, and environment. Such renewable materials could be generated from the recycling of agriculture wastes or residues. Agricultural residues (AGRs) are the secondary product of agricultural activities such as vegetative parts left after harvesting vegetables, fruit tree pruning and wastes from food processing and agro-industries by-products. This chapter aims at casting lights on potential management and usages of common agriculture residues (wastes) in some countries in the MENA region. It focuses on identification of potential AGR and common utilization technologies. Constraints and strategies for management and utilization are also discussed. It is concluded that most of these residues are either burned in the field which has a negative impact on the environment or utilized in inefficient ways as a fuel, animal feeds, and composting. These agricultural residues when fully exploited would be expected to foster the development of small-scale agro-industries, create new job opportunities, and provide new arable lands. Most important is that the utilization of AGR to substitute forage crops for animal feed could save millions of hectares of lands that could be devoted for food production for human consumption, reduce the imports of wheat and other strategic crops. Thus reduce reliance on importation which improves food security, in addition to saving millions of dollars spent on importation of strategic materials. The AGRs are expected to play an important role in bridging the food gap in many countries in MENA region and improve the livelihood of the rural farmers. Some AGR technologies are developed and reached the implementation stage; others are at R&D and reached the pilot stage. Unfortunately, data are incomplete for some MENA region countries. There is a necessity to work out a strategy at both national and regional levels to foster the utilization of AGR and to encourage the collaboration of the leading countries for better utilization.

Development perspectives of promising lignocellulose feedstocks for production of advanced generation biofuels: A review

A methodology for estimating the ammonia emission from crop residues at a national scale

Optimizing biofuels production in an uncertain decision environment: Conventional vs. advanced technologies

9 - Advanced biofuels: Deoxygenation and hydrodeoxygenation catalytic reaction

Economic evaluation of technology for a new generation biofuel production using wastes

Supercritical reactors for the production of advanced bio-fuels: A review

The Energy Independence and Security Act of 2007 established the Renewable Fuels Standard which set forth goals for domestic renewable fuel production of cellulosic and advanced biofuels in the United States. A major issue confronting the achievement of these biofuel utilization goals is the probability that the eventual expansion of advanced cellulosic biofuel production would be sufficient to meet the stated goals. Current long range projections of cellulosic biofuel production are expected to remain significantly below statutory targets due to the limited supply and expected development of cellulosic biofuel production. The production capacity expansion of advanced cellulosic biofuel has been identified as a major challenge in meeting the Renewable Fuels Standard. Energy cane has been identified as a crop with having significant potential to be developed as a biofuel feedstock crop. The greatest challenge currently facing the production of energy cane is the ability to expand production of the crop outside temperate zones. Within the six-state study area, approximately 1.15 million hectares were identified as idle cropland having the greatest potential for energy cane production. With a low seed cane expansion planting ratio and harvest through a fourth stubble crop, total energy cane production costs were estimated to be $113 per dry metric ton of feedstock. At higher planting ratios, projected total energy cane production costs were below $70 per metric ton.