Carbon footprint comparison between traditional diesel and synthetic diesel production pathways
Shrestha, Pallav (2020)
Diplomityö
Shrestha, Pallav
2020
School of Energy Systems, Ympäristötekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20201210100237
https://urn.fi/URN:NBN:fi-fe20201210100237
Tiivistelmä
The objective of this Master’s thesis is to compare the carbon footprints of traditional fossil diesel to synthetic diesel produced from Fischer-Tropsch synthesis (FTS) using electricity. Carbon footprint analysis was conducted in accordance to ISO 14067:2018 and ISO 14040:2006 standards using life cycle assessment (LCA) approach. GaBi (Education version 9.2.1) was used to model and calculate the carbon footprints. The carbon footprint comparisons were conducted with a modelled euro-6 diesel vehicle for a journey of 1000km distance with each fuel. Solid oxide electrolysis cell (SOEC) and alkaline electrolysis cell (AEC) were modelled for hydrogen synthesis. Flue gas capture (FGC) and direct air capture (DAC) were modelled for carbon source. Finnish grid (2015) was used as the electricity source. Comparison with German grid (2015), wind based grid (Finland) and solar photo voltaics (PV) based grid (Finland) were also conducted.
It was found that synthetic diesel had 85% less carbon footprint from vehicle emissions than traditional diesel but had 2% to 40% more carbon footprint than traditional diesel when the whole process was considered. SOEC had the highest carbon footprint followed by AEC. Both carbon capture methods had negative footprint while DAC had higher energy consumption than FGC. Synthetic diesel had 75% higher carbon footprint when German grid (2015) electricity was used instead of Finnish grid (2015). When renewable energy sources were used, synthetic diesel had a negative carbon footprint. Usage of wind based grid had a lower footprint than solar PV based grid.
With modifications to SOEC to use waste heat from FTS or other exothermic processes, the process had net neutral carbon footprint. This caused the carbon footprint of synthetic diesel to decrease by 250% and have a negative footprint even with 2015 Finnish grid. From the models it was found SOEC for hydrogen and FGC for carbon would yield the lowest carbon footprint and was seen to have a negative carbon footprint of (-)440 gCO2e/kg or (-)120 gCO2e/MJ of fuel produced.
It was found that synthetic diesel had 85% less carbon footprint from vehicle emissions than traditional diesel but had 2% to 40% more carbon footprint than traditional diesel when the whole process was considered. SOEC had the highest carbon footprint followed by AEC. Both carbon capture methods had negative footprint while DAC had higher energy consumption than FGC. Synthetic diesel had 75% higher carbon footprint when German grid (2015) electricity was used instead of Finnish grid (2015). When renewable energy sources were used, synthetic diesel had a negative carbon footprint. Usage of wind based grid had a lower footprint than solar PV based grid.
With modifications to SOEC to use waste heat from FTS or other exothermic processes, the process had net neutral carbon footprint. This caused the carbon footprint of synthetic diesel to decrease by 250% and have a negative footprint even with 2015 Finnish grid. From the models it was found SOEC for hydrogen and FGC for carbon would yield the lowest carbon footprint and was seen to have a negative carbon footprint of (-)440 gCO2e/kg or (-)120 gCO2e/MJ of fuel produced.