Secure and sustainable energy supply is an urgent need worldwide. Renewable energy sources fit both goals. Among them, biodiesel is set to match several socio-economic goals for developing countries, and seems to be less impacting on food prices than bioethanol derived from cereals or other grain feedstocks. Recent studies on Life Cycle Assessment (LCA) of bioenergy chains based on dedicated crops showed that biodiesel scenarios are generally less impacting than other possible energy chains, but, on the other hand, the same studies pointed out that both in biodiesel and in BTL diesel, upstream processes and subsequent agricultural phases represent the largest sources of environmental pollution in the whole production chain. In order to reduce the uncertainty on such issues, six oil crops, suitable in tropical and sub-tropical areas, were compared on the base of different impact categories using a dedicated software (SimaPro7.0). The impact was calculated according to LCA methodology (ISO 14040-43), using two different functional units: hectare (ha) and energy (GJ). On hectare basis, the most impacting scenario was sunflower, in all considered categories, and in general both annual crops (sunflower and soybean) showed similar results. All perennials (castorbean, oil palm, coconut palm, Jatropha) showed significant environmental benefits with respect to annuals (Jatropha was clearly the lowest impacting crop). On energy basis, the most impacting scenario was again sunflower under all impact categories, whereas perennials still showed high benefits with respect to annuals (72 to 90% lower emissions). The energy ranking among perennials was quite different compared to the hectare based analysis, being oil palm the top yielding crop. Results in annual crops showed high levels of impact due to fertilization and tillage/sowing operations; the latter item is even more impacting than fertilization on human toxicity, because of the high direct (i.e. at farm) fuel consumption. In perennials, being establishment operations spread over plant lifespan, the most impacting step is clearly represented by fertilization above all categories. Family farming systems, reducing mechanical cropping operations and fertilization inputs (due to the lower expected yield), lead to lower environmental loads, thus the impact per ha is clearly lower if compared with large scale farming. Impact per energy unit in family farming is not so lower than in large-scale farming, as it is per land unit (hectare). Results showed that the greatest environmental benefit was obtained with organic fertilizer and reduced mechanization (50 to 90% less than reference scenario, according to impact categories).
Fazio S., Monti A., Barbanti L. (2011). Environmental assessment of tropical oil crops for biodiesel purposes. s.l : s.n.
Environmental assessment of tropical oil crops for biodiesel purposes
FAZIO, SIMONE;MONTI, ANDREA;BARBANTI, LORENZO
2011
Abstract
Secure and sustainable energy supply is an urgent need worldwide. Renewable energy sources fit both goals. Among them, biodiesel is set to match several socio-economic goals for developing countries, and seems to be less impacting on food prices than bioethanol derived from cereals or other grain feedstocks. Recent studies on Life Cycle Assessment (LCA) of bioenergy chains based on dedicated crops showed that biodiesel scenarios are generally less impacting than other possible energy chains, but, on the other hand, the same studies pointed out that both in biodiesel and in BTL diesel, upstream processes and subsequent agricultural phases represent the largest sources of environmental pollution in the whole production chain. In order to reduce the uncertainty on such issues, six oil crops, suitable in tropical and sub-tropical areas, were compared on the base of different impact categories using a dedicated software (SimaPro7.0). The impact was calculated according to LCA methodology (ISO 14040-43), using two different functional units: hectare (ha) and energy (GJ). On hectare basis, the most impacting scenario was sunflower, in all considered categories, and in general both annual crops (sunflower and soybean) showed similar results. All perennials (castorbean, oil palm, coconut palm, Jatropha) showed significant environmental benefits with respect to annuals (Jatropha was clearly the lowest impacting crop). On energy basis, the most impacting scenario was again sunflower under all impact categories, whereas perennials still showed high benefits with respect to annuals (72 to 90% lower emissions). The energy ranking among perennials was quite different compared to the hectare based analysis, being oil palm the top yielding crop. Results in annual crops showed high levels of impact due to fertilization and tillage/sowing operations; the latter item is even more impacting than fertilization on human toxicity, because of the high direct (i.e. at farm) fuel consumption. In perennials, being establishment operations spread over plant lifespan, the most impacting step is clearly represented by fertilization above all categories. Family farming systems, reducing mechanical cropping operations and fertilization inputs (due to the lower expected yield), lead to lower environmental loads, thus the impact per ha is clearly lower if compared with large scale farming. Impact per energy unit in family farming is not so lower than in large-scale farming, as it is per land unit (hectare). Results showed that the greatest environmental benefit was obtained with organic fertilizer and reduced mechanization (50 to 90% less than reference scenario, according to impact categories).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
