Sustainability of biogas production with small-sized plant in South America

The environmental impacts of biogas systems are dependent on technical concepts and conditions of use. During a process chain, energy is consumed and greenhouse gases (GHGs) are emitted. Life Cycle Assessment (LCA) of biogas production is influenced by different factors, such as supplement of substrate, biogas production, and biogas and digestate utilization pathways. The goal of the study was to assess environmental impacts of biogas production in small scale in a South American country like Colombia. To calculate the specific GHG emissions of biogas production, the standardized methodology of LCA was followed, using the GaBi 6.0 tool (Thinkstep AG, Germany) with Ecoinvent database, while the ISO 14040 was used as standard for the LCA. The chosen substrates for the biogas production in small scale in Colombia represent common waste products of Latin American rural households. Most Colombian farmers own cows, therefore choosing cow manure as a basic substrate is a logic consequence. This substrate can either be directly taken out of the stable, if there is one, or must be collected from the pasture land and then be mixed with water to obtain a homogenous matter to feed the biogas digester. Where people cook, waste is produced, thus here we are taking a look at average medium-fat kitchen waste as an input option for the fermenter. A more specific waste product from daily cooking is potato peel because the potato counts as a staple food not only in Colombia but also in many South American countries. The co-substrate for the third scenario is the maize plant after the cob is harvested. The results show that the biogas scenarios are all a lot less climate-damaging than fossil reference systems which lead to clear recommendations to improve the management option by the biogas plant in Colombia.