• Energy Research

Due to the worrying observations about climate change and biodiversity reduction, attention is paid to assess the environmental impact of human activities, such like agricultural ones. Tools like "Life cycle assessment" have been developed to determine very precisely the environmental impact of agricultural products and activities. This paper presents a method to assess the energy performance of tractors used for spreading tasks. Long term monitoring equipments were installed on tractors in five agricultural equipment cooperatives in France. Each of them has to carry on spreading works that could differ in kind of sludge, but also in machine characteristics. Data were collected for more than a year representing 2000h of agricultural works and about 1000h of spreading works. The work is analysed through the comprehensive "tank unit", divided into four phases: filling up the tank of organic matter, transporting to field, spreading, and transport empty back. Then, average mission profiles are deduced from recorded data. It allows delivering a variety of indicators for spreading work. These indicators are then used in LCA to compare different spreading scenarios and study work organisation. The machine efficiency is also analysed. For sewage sludge, the significant impact of transport is shown on both duration and fuel consumption. Because the distance between the field and the storage area is longer, more than 75% of the total fuel used for a tank unit is dedicated to the transport phases. Finally, improved management scenarios for organic spreading are proposed. But the operator driving style clearly affects both work and fuel efficiency during spreading works.

A first general assessment of the biomass dust-fuelled engine concept by testing four biomass powders in a single-cylinder engine.

Second generational biofuels offer the possibility of using biomass residues such as agricultural or industrial wastes for use in internal combustion engines. However, biochemical and thermochemical conversions to liquid or gaseous fuels require elaborate and expensive pre-treatment facilities. Decreasing the complexity, size and cost of these facilities can alleviate sourcing constraints, increasing implementation in a wide range of applications. Remaining in its original solid form, biomass powder is a simplified biofuel requiring only drying and milling which is technically and economically feasible at a wide range of scale. By exploiting its explosive character, we can operate a standard diesel engine directly on powder for energy generation. The demand for a low-tech biofuel along with advances in milling techniques motivates the idea of using biomass powder in an engine. In this paper we provide experimental proof by operating a diesel engine on fumigated Wheat Straw and Pine Bark dust each for 35 minutes. Emissions, operational performance and combustion data show that biomass powders from agricultural residues should be considered for use as an adaptable technology for existing engine installations. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 618-621

Abstract The direct use of dry biomass dust as a fuel in reciprocating engines could be of great interest because of the large availability of plant matter and the versatility of Internal Combustion Engines (ICE). Coal dust was used in the past and mostly in slurries because of large production during industrial era in Europe but led to many problems caused by fuel handling and wear in ICE. In comparison, biomass has a CO2 neutral impact, and is almost ash and sulphur free. Biomass pulverization technologies are now mature and the raw material can be reduced to micronic size or even smaller. Among the various new and renewable fuels under research and development, solid raw biomass is certainly the most promising advanced biofuel. It requires no or little thermochemical or biological processing or upgrading and potentially does not generate waste, detrimental to the environment. After a general overview of the past attempts to run reciprocating engines with coal dust, this paper will assess the so far unconsidered use of dry biomass dust as a fuel in engines instead of abrasive, less volatile and more polluting coal dust.

Dans le monde, le pétrole assure 96% des besoins des transports, lesquels mobilisent 65% dupétrole consommé et participent à hauteur de 20% aux émissions de CO2. Afin de réduire la consommationde ressources fossiles, une des alternatives est notamment l’utilisation de « biocarburants ». Cesbiocarburants sont classés en trois générations successives. Les biocarburants de première génération sontissus des parties alimentaires de plantes de grande culture : le bioéthanol et le biodiesel. Les biocarburantsdits « avancés » de seconde génération sont issus de ressources lignocellulosiques (bois, résidus agricoles...)valorisées soit en bioéthanol soit en hydrocarbures de synthèse. Une troisième génération repose sur la culture de micro-algues productrices d’acides gras transformés en biodiesel. Les biodiesels de première génération, tout comme ceux de deuxième et troisième générations, sont sujets à certaines critiques notamment le CAS (changement d’affectation des sols) et la compétition alimentaire/énergétique. L’objectif de ce travail est d’examiner l’intérêt de deux filières prometteuses. Les biodiesels basés sur des cultures dédiées conduisent à des impacts environnementaux plus réduits mais jouent un rôle dans la problématique des CAS. Alors que celles basées sur les résidus n’y entrent pas et montrent des niveaux de réduction des émissions de gaz à effet de serre entre 83 et 90% contre 60 à 80% pour un biodiesel classique par rapport à un carburant diesel fossile. Les esters butyliques d’huiles alimentaires usagées et de graisses animales s’affichent comme des biodiesels « plus verts » et représentent une opportunité pour les biocarburants de deuxième génération et pour une oléochimie « plus verte ». In the world, oil provides 96% of transport needs, which mobilize 65% of the oil consumed and contribute 20% to CO2 emissions. One of the alternatives to reduce the consumption of fossil resources is the use of "biofuels". These biofuels are classified into three successive generations. The first generation biofuels come from the food parts of field crops: bioethanol and biodiesel. Second generation "advanced" biofuels come from lignocellulosic resources (wood, agricultural residues, etc.) valued either as bioethanol or synthetic hydrocarbons. A third generation is based on the culture of micro-algae producing fatty acids transformed into biodiesel. The first generation biodiesels, like those of the second and third generations, are subject to certain criticisms in particular the LUC (Land-Use Change) and the food versus energy competition. The objective of this work is to examine the interest of two promising ways. Biodiesel based on dedicated crops lead to reduced environmental impacts but play a role in the problem of LUC. While those based on residues are not part of the problem and show levels of reduction of greenhouse gas emissions between 83 and 90% against 60 to 80% for a conventional biodiesel compared to a fossil diesel fuel. Butyl esters of used edible oils and animal fats are displayed as "greener" biodiesels and represent an opportunity for second generation biofuels and for a greener oleochemistry.

Dans le monde, le pétrole assure 96 % des besoins des transports, lesquels mobilisent 65 % du pétrole consommé et participent à hauteur de 20 % aux émissions de CO2. Afin de réduire la consommation de ressources fossiles, une des alternatives est notamment l’utilisation de « biocarburants ». Ces biocarburants sont classés en trois générations successives. Les biocarburants de première génération sont issus des parties alimentaires de plantes de grande culture : le bioéthanol et le biodiesel. Les biocarburants dits « avancés » de seconde génération sont issus de ressources lignocellulosiques (bois, résidus agricoles...) valorisées soit en bioéthanol soit en hydrocarbures de synthèse. Une troisième génération repose sur la culture de micro-algues productrices d’acides gras transformés en biodiesel. Les biodiesels de première génération, tout comme ceux de deuxième et troisième générations, sont sujets à certaines critiques notamment le CAS (changement d’affectation des sols) et la compétition alimentaire/énergétique. L’objectif de ce travail est d’examiner l’intérêt de deux filières prometteuses. Les biodiesels basés sur des cultures dédiées conduisent à des impacts environnementaux plus réduits mais jouent un rôle dans la problématique des CAS. Alors que celles basées sur les résidus n’y entrent pas et montrent des niveaux de réduction des émissions de gaz à effet de serre entre 83 et 90 % contre 60 à 80 % pour un biodiesel classique par rapport à un carburant diesel fossile. Les esters butyliques d’huiles alimentaires usagées et de graisses animales s’affichent comme des biodiesels « plus verts » et représentent une opportunité pour les biocarburants de deuxième génération et pour une oléochimie « plus verte ».

Although vegetable oils are apparently an advantageous alternative fuel for direct use in traditional diesel engines with no modification necessary, in practice many problems are regularly discussed in the literature including filter clogging, breakage of certain types of injection pumps, and deposits of carbon on the cold parts of engines.Several technological solutions have been proposed to overcome these problems but the majority of papers discuss them individually and have not actually compared them in similar conditions. The purpose of the present study was to use the same experimental device to compare the three most widely recognised technological options for the use of Jatropha curcas vegetable oil as a fuel in a direct injection diesel engine: preheating, blending with diesel, and recirculating exhaust gases. Power output, specific consumption, thermal efficiency and exhaust gas emissions were compared to those of diesel used as the reference. The results obtained were similar for preheated and non-preheated Jatropha oil, but differed from the results obtained with diesel. Similar combustion performance and similar emissions were obtained with a blend of 20% Jatropha oil and diesel to those obtained with diesel alone. Exhaust gas recirculation (EGR) with Jatropha oil could lead to fouling in the combustion chamber. In contrast to widely accepted theory, this study also clearly demonstrates that the viscosity of vegetable oil is not the main cause of poorer combustion quality and, consequently, of deposits in the combustion chamber. Keywords: Jatropha curcas, Vegetable oil, Biofuel, Direct injection diesel engine