Bio-SNG from Thermal Gasification - Process Synthesis, Integration and Performance
Doktorsavhandling, 2013

Biomethane or synthetic natural gas (Bio-SNG) produced from gasified renewable woody biomass is a promising option for replacing fossil natural gas. The complete interchangeability with natural gas in all its conventional applications such as in the power generation, transportation and chemical industry sector is of particular interest. This work presents results from a comprehensive process integration study of different process alternatives for Bio-SNG production from gasified biomass. The influence of the main conversion steps in the process chain – drying, gasification, gas cleaning, methanation, and gas upgrade – on the overall process performance is investigated. Process bottlenecks and both heat and material integration opportunities are highlighted. Using future energy market scenarios the energetic, economic, and carbon footprint performance of the investigated processes are evaluated from a system perspective clearly showing the sensitivity of the obtained results to underlying assumptions. It is shown that drying of the biomass feedstock prior to gasification using excess process heat – using steam drying or low-temperature air drying technology – is an important aspect for improving the process energy efficiency. The results also indicate that indirect and direct gasification technologies perform equally well within the overall Bio-SNG production process. Existing infrastructure in the form of biomass-fired combined heat and power plants based on fluidised bed combustion technology presents interesting opportunities for integrating indirect gasification for Bio-SNG production, with beneficial effects on the cogeneration of electricity from the Bio-SNG process excess heat. The choice of methanation technology between fixed and fluidised bed is not a critical one with respect to process integration, since both technologies allow for efficient heat recovery and consequent cogeneration. For gas upgrade, in particular removal of CO2 from the product gas, amine based separation is shown to achieve better energy efficiency and economic performance than membrane based or pressure swing adsorption processes. Preliminary estimations of Bio-SNG costs are significantly higher than current natural gas prices, thus dedicated and long term policy measures are necessary in order to stimulate Bio-SNG production. The process integration aspects presented in this thesis can contribute to reducing production costs by increasing energy efficiency and in consequence increasing economic robustness of Bio-SNG process concepts.

process integration

process modelling

performance indicators

biomass

energy systems

synthetic natural gas

gasification

Vasa C, Vera Sandbergs allé 8, Chalmers
Opponent: Prof. Tord Torisson, Department of Energy Sciences, Faculty of Engineering, Lund University, Sweden

Författare

Stefan Heyne

Industriella energisystem och -tekniker

Extending existing combined heat and power plants for synthetic natural gas production

International Journal of Energy Research,; Vol. 36(2012)p. 670-681

Artikel i vetenskaplig tidskrift

Methane from biomass: process-integration aspects

Proceedings of Institution of Civil Engineers: Energy,; Vol. 162(2009)p. 13-22

Artikel i vetenskaplig tidskrift

Impact of choice of CO2 separation technology on thermo-economic performance of Bio-SNG production processes

International Journal of Energy Research,; Vol. 38(2014)p. 299-318

Artikel i vetenskaplig tidskrift

Exergy-based comparison of indirect and direct biomass gasification technologies within the framework of bio-SNG production

Biomass Conversion and Biorefinery,; Vol. 3(2013)p. 337-352

Artikel i vetenskaplig tidskrift

Production of synthetic natural gas from biomass - Process integrated drying

22nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems,; (2009)p. 1877-1886

Paper i proceeding

I den här avhandlingen har olika processalternativ för framställning av Bio-SNG genom förgasning studerats och analyserats genom processmodellering. Med hjälp av så kallad pinchteknik kan man bedöma potentialen för att generera el och fjärrvärme från processens överskottsvärme, men även peka på möjliga processmodifikationer som förbättrar energieffektiviteten. Med hjälp av lämpliga nyckeltal kan de olika processalternativen jämföras ur energi-, ekonomi- ochmiljöperspektiv.

Avhandlingen visar tydligt att torkning av biomassa är ett viktigt steg för att öka både processverkningsgraden och genereringen av el och värme från processens överskottsvärme. Indirekt förgasning, en teknik där nödvändigt värme till förgasningsprocessen genereras i en separat panna, möjliggör integration av Bio-SNG-processen i befintliga kraftvärmeverk. Det har visats att ett sådant koncept möjliggör en effektivare konvertering av överskottsvärme till produktion av el och fjärrvärme jämfört med en fristående anläggning. Kostnaderna för att framställa Bio-SNG kan inte konkurrera med dagens pris på fossil naturgas. Kostnadsberäkningarna som har gjorts kan dock användas för att identifiera de processmodifikationer för bättre energieffektivitet som ger de lägsta produktionskostnaderna i jämförelse med varandra. Ur ett miljöperspektiv borde Bio-SNG användas främst som drivmedel inom transportsektorn.

Drivkrafter

Hållbar utveckling

Styrkeområden

Transport

Energi

Ämneskategorier

Energiteknik

Kemiska processer

Kemiteknik

Energisystem

ISBN

978-91-7385-838-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3519

Publication - Department of Heat & Power Technology, Chalmers University of Technology: 2013:2

Vasa C, Vera Sandbergs allé 8, Chalmers

Opponent: Prof. Tord Torisson, Department of Energy Sciences, Faculty of Engineering, Lund University, Sweden

Mer information

Skapat

2017-10-06