Emergy-based evaluation of resources input in Portugal

Abstract

This paper presents an emergy-based evaluation of the required Portugal resources inputs for the years 2000, 2005 and 2009. The main objective is to provide comprehensive emergy measures which seek to integrate the accountability values of all economic and environmental work contributions to annual national activities. Emergy (from embodied energy) was defined by Odum as being the available energy of one kind of previously used up directly or indirectly to make a service or product. The emergy methodology employed, based on existing statistical data, deals with energy systems and amplifies the perspective of analysis by extending it to the wider level of biosphere, by including all the processes that are involved in the formation of system inputs, either being devices of material, energy or money flows. Attention is given to emergy assigned to flow s of local renewable resources (R), local nonrenewable resources (N), imported resources (IMP) and exported resources (EXP). Results show a decline in the total amount of annual emergy required to support the country's activities (U) in 2009 relative to 2000 and as emergy per capita also decreased, it might indicates that the population wellbeing in 2009 might be inferior to the level attained in 2000, as less resources from the geobiosphere were invested in each person. Emergy from local nonrenewable flows was the major contribution to total emergy, and in period, more emergy was exported than imported. The contribution of the renewable emergy flow (R) is almost unchanged over time, contributing with approximately 4.5% of the total emergy, what questions the Portuguese government's efforts to reinforce the use of renewable energies.