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a b s t r a c tIn this article different scenarios are analysed with the objective of increasing the penetration of renewable energies in the energy system of S. Vicente Island in Cape Verde. An integrated approach is used to analyse the electricity and water supply systems. The H 2 RES model, a tool designed to simulate the integration of renewable sources and hydrogen in the energy systems of islands or other isolated locations, is applied.There is no other source of fresh water available to supply the population of S. Vicente, apart from desalinated seawater. The electricity supply system of this Island is based on fossil fuel and wind. S. Vicente has important wind resources that are not fully used because of its intermittent nature. The topography of this Island is relatively uniform, with the exception of Mont Verde, a 774 m high mountain located in its centre, which could be suitable for pumped hydro storage.The present analysis incorporates the possibility of using pumped hydro as a storage technique to increase the penetration of renewable energy sources, using desalinated seawater.The results show that is possible to have more than 30% of yearly penetration of renewable energy sources in the electricity supply system, together with more than 50% of the water supplied to the population produced from wind electricity.

A novel bacterium, Gordonia alkanivorans strain 1B, was isolated from hydrocarbon-contaminated soil. Assessment of the biodegradation of distinct organic sulfur-compounds, such as dibenzothiophene (DBT), benzothiophene (BT), DBT sulfone, and alkylated tiophenic compounds, as the sole source of sulfur was investigated. G. alkanivorans strain 1B was able to remove selectively the sulfur from DBT while keeping intact the remaining carbon-carbon structure. Orthophenyl phenol (2-hydroxybiphenyl) was the only detected metabolic product. The bacterial desulfurization activity was repressed by sulfate. G. alkanivorans strain 1B consumed 310 microM DBT after 120 h of cultivation, corresponding to a specific desulfurization rate of 1.03 micromol/(g of dry cells x h). When an equimolar mixture of DBT/BT was used as a source of sulfur in the growth medium, G. alkanivorans strain 1B assimilated both compounds in a sequential manner, with BT as the preferred source of sulfur. Only when BT concentration was decreased to a very low level was DBT utilized as the source of sulfur for bacterial growth. The specific desulfurization overall rates of BT and DBT obtained were 0.954 and 0.813 micromol/(g of dry cells x h), respectively. The newly isolated G. alkanivorans strain 1B has good potential for application in the biodesulfurization of fossil fuels.

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An extracellular thermo-alkali-stable and cellulase-free xylanase from Geobacillus thermodenitrificans A333 was purified to homogeneity by ion exchange and size exclusion chromatography. Its molecular mass was 44 kDa as estimated in native and denaturing conditions by gel filtration and SDS-PAGE analysis, respectively. The xylanase (GtXyn) exhibited maximum activity at 70°C and pH 7.5. It was stable over broad ranges of temperature and pH retaining 88 % of activity at 60°C and up to 97 % in the pH range 7.5-10.0 after 24 h. Moreover, the enzyme was active up to 3.0 M sodium chloride concentration, exhibiting at that value 70 % residual activity after 1 h. The presence of other metal ions did not affect the activity with the sole exceptions of K

Biodesulfurization (BDS) aims at the removal of recalcitrant sulfur from fossil fuels at mild operating conditions with the aid of microorganisms. These microorganisms can remove sulfur from dibenzothiphene (DBT), a model compound, or other polycyclic aromatic used as sulfur source, making BDS an easy and environmental friendly process. Gordonia alkanivorans strain 1B has been described as a desulfurizing bacterium, able to desulfurize DBT to 2-hydroxybiphenyl (2-HBP), the final product of the 4S pathway, using d-glucose as carbon source. However, both cell growth and desulfurization can be largely affected by the nutrient composition of the growth medium, due to cofactor requirements of many enzymes involved in the BDS biochemical pathway. In this study, the main goal was to investigate the influence of several sugars, as carbon source, on the growth and DBT desulfurization ability of G. alkanivorans strain 1B. The results of desulfurization tests showed that the lowest values for the growth rate (0.025 hour(-1)) and for the overall 2-HBP production rate (1.80 μm/hour) by the strain 1B were obtained in glucose grown cultures. When using sucrose, the growth rate increase exhibited by strain 1B led to a higher biomass productivity, which induced a slightly increase in the 2-HBP production rate (1.91 μm/hour), conversely in terms of 2-HBP specific production rate (q2-HBP) the value obtained was markedly lower (0.718 μmol/g/hour in sucrose versus 1.22 μmol/g/hour in glucose). When a mixture of glucose and fructose was used as carbon source, strain 1B reached a value of q2-HBP=1.90 μmol/g/hour, close to that in fructose (q2-HBP=2.12 μmol/g/hour). The highest values for both cell growth (μ=0.091 hour(-1)) and 2-HPB production (9.29μm/hour) were obtained when strain 1B was desulfurizing DBT in the presence of fructose as the only carbon source, indicating a fructophilic behaviour by this bacterium. This fact is in agreement with the highest value of biomass productivity by strain 1B be in fructose, which resulted in a higher amount cells fulfilling the DBT-desulfurization. The greater number of functional cells conducted to a more effectiveness BDS process by strain 1B, as they attained a q2-HBP about 74% higher than in glucose grown cultures. Moreover, this significant BDS enhancement can better be observed in terms of the overall 2-HBP production rate, which increased over 5-fold, from 1.80 μm/hour (in glucose) to 9.29 μm/hour (in fructose).