Abstract This paper addresses the impact of natural gas composition on both the operability and emissions of lean premixed gas turbine combustion system. This is an issue of growing interest due to the challenge for gas turbine manufacturers in developing fuel-flexible combustors capable of operating with variable fuel gases while producing very low emissions at the same time. Natural gas contains primarily methane (CH4) but also notable quantities of higher order hydrocarbons such as ethane (C2H6) can also be present. A deep understanding of natural gas combustion is important to obtain the highest combustion efficiency with minimal environmental impact. For this purpose, Large Eddy Simulations of an annular combustor sector equipped with a partially-premixed burner are carried out for two different natural gas compositions with and without including the effect of flame strain rate and heat loss resulting in a more adequate description of flame shape, thermal field and extinction phenomena. Promising results, in terms of NOx, compared against available experimental data, are obtained including these effects on the flame brush modelling, enhancing the fuel-dependency under non adiabatic condition.
The current geopolitical and energy market instability calls for speeding up the EU clean energy transition to increase energy security in all the European regions and make Europe the first climate-neutral continent by 2050. Among renewable energies, modern bioenergy is a promising near-zero-emission fuel for increasing energy security in the heating, electricity and transport sectors while promoting growth and job creation, especially in rural areas. In such a context, energy crops will continue to play a key role. Since agricultural planning is a complex issue, especially when energy crops could compete with food ones, we propose an agroecological–economic land use suitability model (AE-landUSE model) to promote the sustainable use of land resources. The AE-landUSE model was developed by integrating cost–benefit analysis (CBA) and land use suitability analysis (LSA) within geographic information systems (GISs). Tested in the Basilicata region (Southern Italy), comparing two different energy crops (rapeseed and cardoon), the results show the model’s utility in identifying suitable areas for energy crops where the investments will be cost-effective. The proposed model will help decision-makers in energy-agricultural planning to increase energy security sustainably.
Coppice management of forests in Tuscany, and particularly in the province of Florence, has had a chequered history, which has set the stage for the present problems of forestry policy. In Italy, the period between 1955 and 1975 saw a marked reduction in use of firewood in the home and its virtual elimination from the industrial context, leading to progressive abandonment of coppice management. Since 1975, wood-cutting has once again become an increasingly frequent practice, mainly in beech and deciduous oak forests, to the point that this phenomenon has been defined as a veritable revival of coppice management. This change is due partly to a rise in firewood prices but also to the greater yield obtainable from processing activities, although the observed increase is to be attributed not so much to technological progress (only a few enterprises have adequate equipment), as to the mass accumulated during the period of non-harvesting. Basing our opinion on these considerations we realized a project for assessing the actual economic, occupational and environmental potential of coppice management in the province of Florence for biomass production as an energy source. To this end, our work has tried to identify the new potential market area, the enterprises typology, and analyse the social and environmental impact. Moreover, we have evaluated economic efficiency and have taken into consideration the public intervention needed to develop new markets. We have seen that at the moment the possible market areas are tied not only to the traditional markets for house heating by traditional stove with low performance, but also to a new market tied to the most recent developments in heating technologies for dwelling places and small environments, that have allowed considerable technological improvement in heating systems using wood biomasses, which are now more economical and easier to use, have lower gas emission levels and offer greater safety. Another potential market is tied to the electric power production, through the transformation from energy produced by combustion of wood biomass into electric power energy, that we can use in times of peak power consumption in the area studied. The results of this study shows that use of wood biomasses in the energy sector is competitive with oil and gas fired systems, and that biomass production as an energy source is not only environmentally sustainable but also economically feasible and capable of creating job opportunities. Moreover, the possibility for development of two new market areas exists: the first is tied to production of heating energy with new technology plants that use a wood biomass, and result in a high performance; the second is the possibility to develop the electric energy market with the use of gasification or cogeneration plants. In both cases it is possible to create new activities for installation, maintenance and fueling of heating plants, for maintenance and fueling electric generator plants, which will be complementary to harvesting activity
