Life Cycle Assessment of Synthetic Natural Gas Production from Different CO2 Sources: A Cradle-to-Gate Study

Abstract

Fuel production from hydrogen and carbon dioxide is considered an attractive solution as long-term storage of electric energy and as temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology and, ultimately, on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aimed at modeling a Power-to-Gas (PtG) plant and assessing the most suitable carbon sources from a Life Cycle Assessment (LCA) perspective. The PtG plant was supplied by electricity from a 2030 scenario for Italian electricity generation. The plant impacts were assessed using data from the ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron, and steel plants). A detailed discussion on how to handle multi-functionality was also carried out. The results showed that capturing CO2 from hydrogen production plants and integrated pulp and paper mills led to the lowest impacts concerning all investigated indicators. The choice of how to handle multi-functional activities had a crucial impact on the assessment.

Comparative Life-Cycle Assessment Analysis of Power-to-Methane Plants Including Different Water Electrolysis Technologies and CO2 Sources While Applying Various Energy Scenarios

“…In comparison to the study by Bargiacchi et al that analyzed PtM-AEL and PtM-PEM plants with CO 2 delivered from various point sources, the base-case values for PM and carcinogenic effects are higher than the results in Table S30 and S31 (see Supporting Information). Furthermore, the base-case value for freshwater eutrophication is lower, while the result for ionizing radiation is close to 2050’s results of PtM-AEL and PtM-PEM plants with air as the CO 2 source.…”

“…Moreover, the value published by Bargiacchi et al for the base-case scenario of PtM-AEL and PtM-PEM plants is approx. 6 kg CO 2 equiv/kg SNG using a FU of 1 kg of SNG and a scenario of the Italian energy mix in 2030 with a high share of NG (38.5%), PV (24.3%), hydro (16.1%), and wind (13.1%) power . The value is within the lower range of the results of PtM-AEL and PtM-PEM plants by applying the energy scenario in 2050 (see Figures –).…”

“…Moreover, these values are limited for comparison purposes since different scenarios and methods have been applied in the studies. However, a rough classification of the results published by Parra et al and Bargiacchi et al is carried out. The values by Parra et al have been converted using a factor of 65 (as described above), while the values by Bargiacchi et al have not been modified since they relate to the FU of 1 kg of SNG.…”

Limits to Paris compatibility of CO2 capture and utilization

“…We found that energy requirements for CO 2 capture and their associated emissions differ between specific CO 2 sources and capture processes, in line with M€ uller et al 128 and von der Assen et al 159 Whether a CCU process is Paris compatible can thus depend on the capture process itself (e.g., a DAC process based on natural gas 143 rather than renewable electricity 145 may render the entire CCU product non-Paris compatible). Our research has focused on available CO 2 source-CCU technology combinations in the LCA literature, and further research could harmonize CO 2 sources and capture processes to provide additional insights into remaining CO 2 source-CCU technology combinations.…”

Review on Energy Storage Systems in Microgrids

“…These processes happen for remote consumers, so H 2 ESS is considered a clean technology [4]. (b) SNG: As natural gas has a lower sulphur and nitrogen content than coal and hydrocarbons, thus synthetic natural gas is a lower environmental impact than fuel because of the energy involved in the gas's creation [112].…”