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A comparative experimental investigation was conducted to evaluate the performance and exhaust emissions of an agricultural tractor engine when fueled with sunflower oil, rapeseed oil, and cottonseed oil and their blends with diesel fuel (20/80, 40/60 and 70/30 volumetrically). Tests were also carried out with diesel fuel to be used as a reference point. Engine power, torque, BSFC, thermal efficiency, NO x and CO 2 were recorded for each tested fuel. All vegetable oils resulted in normal operation without problems during the short-term experiments. The 20/80 blends showed unstable results, in comparison to higher oil content fuels. Power, Torque and BSFC were higher as oil content was increased in the fuel. Rapeseed oil fuels showed increased power, torque and thermal efficiency with simultaneous lower BSFC in comparison to the other two vegetable oils. Cottonseed oil fuels gave better engine performance than sunflower oil fuels. In all oil types, NO x emissions were augmented when fuel oil percentage was increased. Cottonseed oil fuels led to higher NO x emission increase compared to rapeseed oil fuels. CO 2 emissions showed a tendency to be increased as the oil content was evolved. The highest CO 2 emissions were given by cottonseed oil fuels, followed by rapeseed and sunflower oil.

Purpose The aim of this study was to evaluate the costeffectiveness of bioethanol as regards to its carbon dioxide emissions. The production of the raw material accounts for more than 50 % of the total cost as well as having a significant part of greenhouse gases emitted during the entire process. For this reason, special emphasis is given to a change in agricultural land usage influenced by the demand of biofuel. Therefore, we have estimated the extent of policy influence according to its bioethanol cost-effectiveness. A case study on bioethanol production in an ex-sugar factory in the region of Thessaly, Greece, illustrates the above ideas. Methods A partial equilibrium micro-economic model of regional supply in the arable farming system of Thessaly was coupled to industrial processing sub-models of bioethanol production from beets and grains. The maximisation of total welfare determines the most suitable crop mix for farmers as well as the lowest cost configurations for industry and, eventually, the minimal level of support by the government for biofuel activity to take off. The environmental performance is assessed under the life cycle assessment (LCA) framework following three interrelated phases: data inventory, data analysis and interpretation. The economic burden to society to support the activity divided by avoided CO 2 eq. emissions indicates the bioethanol costeffectiveness, in other words, the cost of greenhouse gases emissions savings. Results The integrated agro-industry model has been parametrically run for a range of biofuel capacities. A change in direct land use results in lower emissions in the agricultural phase, since energy crops are a substitute for intensive cultivations, such as cotton and corn. A change in indirect land use moderates these estimations, as it takes in account imported food crops that are replaced by energy crops in the region. The savings in cost vary around 160 euros per ton of CO 2 eq. for the basic agricultural policy scenario. The current policy that supports cotton production by means of increased coupled area payment has increased up to 30 % the cost of greenhouse gas savings due to bioethanol production. Conclusions An integrated model, articulating the agricultural supply of biomass with ethanol processing, maximises the total surplus that is under constraints in order to determine the cost-effectiveness for different production levels. Results demonstrate that economic performances, as well as the environmental cost-effectiveness of bioethanol, are clearly affected by the parameters of agricultural policies. Therefore, bioenergy, environmental and economic performances, when based on LCA and the conceptual change in land usage, are context dependent. Agricultural policies for decoupling subsidies from production are in favour of cultivation in biomass for energy purposes.

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