Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente, Perfil de Gestão e Sistemas AmbientaisGreenhouse gas abatement policies (as a measure of preventing further contribution to global warming) are expected to increase the demand for renewable sources of energy driving a growing attention on Biomass as a valuable option as a renewable source of energy able to reduce CO2 emissions, by displacing fossil fuel use. The vulnerability of the Iberian Peninsula (IP) to climate changes, along with the fact that it is a water-limited region, drive a great concern and interest in understand the potentials of biomass for energy production under projected climate changes, since water shortage is a projected consequence of it.
Henceforth the goals stated for this work include the understanding of the impact magnitude that climate changes and the solely effect of rising CO2 (in accordance to the prescribed in A1B scenario from IPPC) have on biomass and productivity over the IP; the modeling of the interannual variability in terrestrial productivity and biomass across de region (having the period 1960-1990 as reference) and the energy potentials derived by biomass in future scenarios (2060-2090 and 2070-2100 periods). The carbon fluxes were modeled by JSBACH model and its results were handled using GIS and statistical analysis. A better understanding of the applicability (and reliability) of this model on achieving the latter stated goals was another goal purposed in this work.
IP has shown a broadly positive response to climate change, i.e. increased productivity under scenarios admitting elevation of atmospheric CO2 concentration (increases in GPP by ~41%; in forest NPP by ~54% and herbaceous NPP by ~36%, for 2060-2090 period), and smaller and negative response under scenarios disregarding rising CO2 levels (i.e. CO2 constant at 296ppm). The productivity and biomass correlation with changing climate variables also differed between different CO2 scenarios. The increase of water-use efficiency by 58% was as a result of CO2 fertilization effect, could explain the increase of productivity, although many limitations of the model (such as disregard of nitrogen cycle and land-use dynamics) poses many considerations to the acceptability of results and the overestimating productivity comparatively to many projections for the IP. Notwithstanding the comparison of changes in climate variables, showed a great correlation of results with other authors.
A comprehensive analysis of biomass supply and its availability during scenarios with elevated CO2, shown that by 2060-2090, residues from thinning and logging activities over forest biomass have a potential of 0,165 and 0,495 EJ, and residues from agricultural activities (herbaceous biomass) have a potential of 0,346 EJ under a HIGH-YIELD scenario (assuming 40% of residues removal rate), corresponding to a share of current energy consumption of 13, 42 and 30%, respectively. The reasonability of these results was assessed by comparing with similar studies during the reference period
