Issue 6

From 2009 to 2013 the survival percentages, apical growth, height and growth rate were studied for each species. Retama sphaerocarpa (91.7%), Pistacia lentiscus (83.3%) and Olea europaea var. sylvestris (70.8%) had the highest survival percentages at the end of the study period. In the same period, for those species that surpassed a survival percentage of 50%, the highest apical growths were shown by Retama Sphaerocarpa (37.04 cm), Pistacia lentiscus (26.4 cm) and Olea europaea var. sylvestris (25.8 cm), with average growth rate of 13.79 cm·year^-1, 7.60 cm·year^-1 and 7.14 cm· year^-1, respectively. These three species are the best adapted to the conditions in Mediterranean areas for use as hedges.

A set of experiments have been carried out in a heavy duty single cylinder engine using high EGR rates and different start of injection angles (SOI). Three different fuels (conventional diesel fuel, a diesel-ethanol mixture (e-diesel) and a Fischer-Tropsch fuel (GTL)) have been tested in order to evaluate their potential to achieve Low Temperature Combustion (LTC) conditions. Diesel and e-diesel have shown poor repeatability for the most delayed angle (4 deg aTDC) due to significant cycle-to-cycle variations. GTL has shown a heat release rate pattern typical of conventional diesel combustion for all the SOI values, while diesel and e-diesel show fully premixed combustion for delayed SOI (from 4 deg bTDC). A delay of SOI causes a decrease in the brake thermal efficiency and an increase in THC and CO emissions, the latter being more important when e-diesel is used. While late injection seems to considerably improve NOx emissions, no benefits have been obtained for diesel particles, maybe due to the low engine torque tested (which causes the soot production rate to be more significant than the oxidation rate). The low autoignition tendency together with the high volatility of ethanol makes e-diesel as a promising fuel to achieve LTC conditions while keeping acceptable fuel consumption and CO/THC emissions.

An unstandarised biodiesel made from Camelina sativa oil, having over a 90 percent by weight of unsaturated fatty acids, were transformed into an epoxidised biodiesel that satisfy the requirements for iodine value, linolenic acid methyl ester content, cetane number, polyunsaturated fatty acids content, and viscosity established by the EN 14214 and ASTM D 6751 standards. The epoxidation reaction was carried out at 60 °C using peroxyacetic acid generated in situ and sulphuric acid as catalyst. A conversion of 60 % of double bonds was reached after 3 hours of reaction. However, only one hour was needed to get standard requirements and to avoid the epoxide ring opening side reaction that leads to hydroxyl groups. Besides, it was also observed that the formation of hydroxyl groups increases the kinematic viscosity of the biodiesel, being deleterious for the biodiesel properties. 

This study investigates the effect of different pre-treatments on the bio-ethanol production from the soluble compounds of the organic fraction of the municipal solid wastes (OFMSW). The experimental evaluation was performed on leachate samples obtained after mixing OFMSW with water during 10 d. The most relevant result was that the acid and organosolv, using sulphuric acid as catalysts, pre-treatments yielded the best results. After the acid pre-treatment, the bio-ethanol production was 2.4 times higher than that obtained without pre-treatments. The main conclusion is that the pre-treatment significantly enhance the bio-ethanol production.