| Abstract [eng] |
The urge to use renewable fuels has become fundamental across the globe to diminish the utilization of fossil fuels in today's generation. One of the emerging resources such as renewable methane which is also called biomethane capable to be utilized in automobiles, injecting in natural gas grid heating and cooking purposes. It is a profitable asset as it conserves resources, provides utmost flexibility in usage and production, reduces carbon dioxide by creating a smaller carbon footprint, can be generated locally which makes it value-added biofuel and also competitive along with meeting the legal requirements of the EU. Three technological routes were analyzed to produce 1kWhthermal biomethane. A reference scenario such as anaerobic digestion and membrane separation, 1st integrated process, such as gasification and methanation combined to the reference process, 2nd integrated process as the incorporation of the air plasma aided gasifier and methanation to the reference process. Therefore, mass and energy flows were analyzed to make the inventory data and to interpret the behaviour of the producing 1kWhthermal biomethane. Thus, the goal of this thesis is propose sustainable methods to produce renewable methane via thermal technologies and methanation processes. The outcome revealed that 2nd integrated scenario leads to the higher efficiency of methane production, although there is an additional energy consumption during this process. A life cycle assessment was evaluated to determine the environmental impact of the reference scenario, 1st scenario and 2nd integrated scenario, where four main categories were analyzed specifically human health, climate change, resources as well as ecosystems based on IMPACT 2002+ for environmental impact evaluation. It was concluded that the 2nd integrated process requires 1.34 times a lesser number of resources and emits lesser pollutants by 1.25 times than the 1 st integrated process. Another way to produce renewable methane along with eliminating carbon dioxide can be via carbon dioxide methanation. A lab-scale experimental process was set up introducing gases such as hydrogen and carbon dioxide to produce methane and water. Temperature and gas composition was analyzed based on the molar ratio of CO2 and H2. The desired temperature for achieving the highest CO2 conversion was ranging between 200-500°C. The gas compositions achieved for CH4, CO, CO2, H2 was 50% - 70%, 0%, 0% - 2%, 20% to 65% respectively. The CO2 conversion rate was also determined which ranged around 85% to 100%. |
