Comparison of biogas options (on-farm and urban on-site generations) using lca

Abstract

Today more than half of the world population now lives in cities and they are responsible for a number of potential hazards due to their over consumption of natural resources. While natural gas, nowadays, is the cleanest burning of all fossil fuels, it is merely a limited resource. In rural area, most households in developing countries have to make choices of their lives to draw on traditional biomass materials such as wood, charcoal, and agricultural residue. Vietnam has been particularly concerned in such unsustainable situation and has worked to carry out domestic biogas practice to address this urgent energy need of rural households. However, excessive renewable energy from family-size biogas plants, which utilize animal manure, is a possible serious threat to the environment. In terms of sustainable development and protection of these small decentralized energy projects, it is utmost important to collect and connect the excessive biogas source to market demand. In order to reduce the distribution of excess biogas and extend capabilities of biogas obtained inside an urbanized area, a series of biogas supply systems were performed: total surplus biogas from 461 farms in a commune; surplus biogas and urban on-site biogas from food waste; surplus biogas and urban on-site biogas from food waste and human waste. This thesis mainly dealt with the environmental assessment of energy supply according to the principles of Life Cycle Assessment (LCA), from cradle-to-grave. Based on this comparative approach, the total normalized results showed that a system supplied by on-site biogas from food waste and human waste is the most environmentally favorable (-1.7E+4 point) compared to the later directions (total excessive biogas 1.25E+5 point and excess biogas and biogas from food waste 3.7E+4 point). All this proves conclusively that potential biogas from urban on-site food waste and food waste combined feces digestion plants contributed significantly to the suppl...