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In this paper, the aerial biomass of citrus plantations in Spain was evaluated using destructive methods. Before cutting down the trees, their geometric variables were measured: trunk diameter at 10 cm from the ground (Dt), trunk perimeter at 10 cm from the ground (Pm), mean crown diameter (Dc), canopy height (Hc), and maximum crown height (Hmax). After geometric characterization of the tree, it was felled. This was performed with a chainsaw about 10 cm above the ground. After cutting down, trees with and without leaves were weighed, and biomass variables such as moisture, calorific value, elemental composition, and proximate analysis were measured. The predictive models obtained showed an r2 of 0.78. According to our analysis, in plantations in Spain, where the average plantation pattern is 4 × 4 m, the amount of carbon stored in a plot is 15 t of C per hectare. If leaves and wood are counted, the energy density in citrus plots can be estimated at 900 MJ/tree. However, if only wood is included in the calculation, the accumulated energy per tree is 750.3 MJ/tree, which represents 5.6 × 105 MJ/ha. [ABSTRACT FROM AUTHOR]

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Abstract: This paper reviews the production and consumption of traditional and renewable energy in Spain over the past two decades. It also presents an overview on the development of renewable energy, such as solar (photovoltaic and photothermal), wind, biomass, hydropower, marine and geothermal energies in Spain. A brief overview of the legislation regulating renewable energy in Spain is offered. It was shown that the installed renewable energy of 32,472MW represented 11.6% of the country׳s primary energy consumption. Furthermore, the installed renewable energy average of electric power in Spain was 0.7kW per capita and 59kW/km2. Wind energy continues to experience a good growth rate, and does not seem to be affected by regulations, which has made it the most sustainable renewable energy in Spain. Finally, an analysis of energy production and consumption, renewable and non-renewable energy by province is made. The data indicates that highly populated and industrialised provinces made more efficient use of their energy from an electrical consumption viewpoint. This uneven growth was not motivated solely by the existence or lack of renewable energy resources but by the autonomous community or province in their socio-economic context. [Copyright &y& Elsevier]

Abstract: As fossil fuels are not only a limited resource, but also contribute to global warming, a transition towards a more sustainable energy supply is urgently needed. Therefore, today''s environmental policies are largely devoted to fostering the development and implementation of renewable energy technologies. One important aspect of this transition is the increased use of biomass to generate renewable energy. Agricultural residues are produced in huge amounts worldwide, and most of this residue is composed of biomass that can be used for energy generation. Consequently, converting this residue into energy can increase the value of waste materials and reduce the environmental impact of waste disposal. This paper analyses the situation of biomass energy resources in Andalusia, an autonomous community in the south of Spain. More specifically, biomass is the renewable source which most contributes to Andalusian energy infrastructure. The residual biomass produced in the olive sector is the result of the large quantity of olive groves and olive oil manufacturers that generate byproducts with a potentially high energy content. The generation of agricultural and industrial residues from the olive sector produced in Andalusia is an important source of different types of residual biomass that are suitable for thermal and electric energy since they reduce the negative environmental effects of emissions from fossil fuels, such as the production of carbon dioxide. [Copyright &y& Elsevier]

Abstract: In this paper, we assess the potential for the generation of electricity in Spain from agro-industrial residues. The industries considered are olive-oil mills, rice mills, wineries, dairy plants, breweries and wood, meat and nut processing plants. The methodology used is based on statistical data, and is integrated into a Geographical Information System (GIS) from which geo-referenced results are obtained. The waste-to-electricity technologies analyzed are: grate firing followed by steam turbine, co-firing in coal power plants and anaerobic digestion plus internal combustion engine. The combined potential for the agro-industrial residues in Spain is estimated at 2625ktoe/year of primary energy (1.85% of the primary-energy consumption in Spain in 2008). Olive mill and wood processing residues have the largest energy potentials. Comparisons are presented with (partial) results from other studies. Considering only profitable plants, grate-firing followed by steam-turbine cycle is the conversion option with the largest potential, totaling 653MWe and an electrical generation of 4.57TWh (1.44% of the gross electrical generation in Spain in 2008). A complete sensitivity analysis is done to investigate the influence of the different economic parameters. A reduction by 50% of the investment costs of grate firing would increase profitable power to 1102MWe (and production to 7.70TWh). [Copyright &y& Elsevier]

Olive sector residues could contribute to increased use of renewable energies, especially in those areas where the olive crop is produced. This paper determines the maximum amount of electrical and thermal energy which could be obtained in Andalusia from olive sector residues, and the economic value that could be obtained from these energy uses. For this, the current data on installed power and electrical and thermal generation are compared with the calculated potential data which would be obtained at full capacity. The results show there is a 69.23% wastage of olive sector residues for energy purposes. Thus, using the resources at full capacity, 3.9 million tons of biomass per year could be obtained for energy purposes. Currently, only 2 million tons of biomass are used for energy purposes. This wastage translates into a below potential generation of electrical and thermal energy. The full use of these residues would allow 83.9% and 64.9% higher generation of electrical and thermal energy, respectively. The results obtained also show that the economic value of olive sector biomass is higher than the market price value, with the average values for each use being 248.20 €/t for domestic thermal use, 165.04 €/t for electrical use and 139.50 €/t for industrial thermal use. Thus, it is considered feasible that the olive sector biomass could be used to a greater degree than at present. In this sense, it is recommended that more electricity generation plants and thermal-generating systems be put into operation. • There is a 69.2% wastage of olive sector residues that could be used for energy purposes. • The full use of olive by-products would account for 6.2% of renewable electricity. • The full use of olive by-products would account for 26.7% of thermal generation. • Better use of residues would promote the start-up of 55 and 1762 electricity and thermal plants, respectively. • The economic value of olive sector biomass allows the value chain to be covered. [ABSTRACT FROM AUTHOR]