Background: Both exergy and energy analysis methods are used for analysing energy efficiency in all kind of processes, and can be used also in agriculture. The study focuses on the connection of the three main process components (husbandry-crop-fishpond) in a typical farming household in an acid soil region in rural Vietnam. The concept of exergy analysis is used to underline the potential for energy efficiency in alternative processes in the agricultural system. To develop an integrated ecological system towards zero-emission, the analytical methods of material cycles and energy flows use a set of indicators of resource efficiency in a sustainable agriculture.
Results: The design of the ideal integrated farming system “Agro-Industrial Zero Emissions Systems” (AIZES) can increase the system efficiency by making use of indigenous natural materials and waste reuse, recycling. Recycling waste for energy, fish feed and fertilizing can result a decrease in half of environmental load. Using exergy analysis to calculate an indicator non-renewable yield ratio (NRYR), the systems imply sustainability of agriculture production.
Conclusions: The farming household will be able to replace fuel and electricity resulting in energy self-sufficiency to distribute surplus biogas to surrounding households. Biochar created by mixing the biomass residues with local plants can improve soil quality. Pig sludge can become nutritious fertilizer when mixed with biomass residues. Also, utilizing biogas can reduce purchased electricity.