Combustion versus Gasification in Power- and Biomass-to-X Processes: An Exergetic Analysis.

Area of Science:

• Chemical Engineering
• Renewable Energy Systems
• Thermodynamics

Background:

• Residual biomass presents a valuable carbon feedstock with inherent energy content for producing chemicals and fuels.
• Biohybrid or Power- and Biomass-to-X processes integrate biomass conversion with electricity-based pathways.

Purpose of the Study:

• To investigate biomass utilization in Power- and Biomass-to-X processes.
• To identify efficiency differences between biomass combustion and gasification pathways.

Main Methods:

• Modeling of process units using mass and energy balances.
• Exergetic analysis of pathways for methane, methanol, dimethyl ether, and dodecane production.
• Detailed modeling of a Power- and Biomass-to-Methanol process including practical factors.

Main Results:

• Power- and Biomass-to-X processes utilizing biomass gasification show significantly higher exergy efficiency (approx. 15-20 percentage points).
• Gasification pathways exhibit lower exergy losses in water electrolysis and higher efficiency in the gasification unit itself compared to combustion.
• Thermodynamic advantages of gasification-based routes are confirmed even when considering practical factors like side reactions and incomplete conversion.

Conclusions:

• Biomass gasification is the preferred pathway for biohybrid Power- and Biomass-to-X processes due to superior thermodynamic efficiency.
• Gasification-based routes offer a more efficient method for producing electricity-based organic chemicals and fuels from residual biomass.