Stefan Heyne

Integration Study for Alternative Methanation Technologies for the Production of Synthetic Natural Gas from Gasified Biomass

This paper analyzes the integration of two different methanation technologies – fixed bed adiabatic and fluidised bed isothermal - in a SNG production process and the consequences for the overall process energy conversion performance. The different operating conditions of the two methanation technologies lead to a change in temperature levels and quantities of recoverable heat, respectively, but also to differences in the overall processes’ power consumption. Using pinch methodology for optimal internal heat recovery in combination with flowsheeting software (ASPEN Plus), the two methanation alternatives are fitted into the SNG production process. The potential power production from recovered process heat is analysed based on the Carnot efficiency and compared to the overall power consumption within the SNG process. Both methanation alternatives perform equally within the given boundary conditions, resulting in an output of SNG of 63.3 MWLHV per 100 MWLHV dry fuel input and a ratio of about 1.22 between theoretical power production and overall power consumption.

Integration opportunities for substitute natural gas (SNG) production in an industrial process plant

This paper investigates opportunities for integration of a Substitute Natural Gas (SNG) process based on thermal gasification of lignocellulosic biomass in an industrial process plant currently importing natural gas (NG) for further processing to speciality chemicals. The assumed SNG process configuration is similar to that selected for the ongoing Gothenburg Biomass Gasification demonstration project (GoBiGas) and is modelled in Aspen Plus. The heat and power integration potentials are investigated using Pinch Analysis tools. Three cases have been investigated: the steam production potential from the SNG process excess heat, the electricity production potential by maximizing the heat recovery in the SNG process without additional fuel firing, and the electricity production potential with increased steam cycle efficiency and additional fuel firing. The results show that 217 MWLHV of woody biomass are required to substitute the site’s natural gas demand with SNG (162 MWLHV). The results indicate that excess heat from the SNG process has the potential to completely cover the site’s net steam demand (19 MW) or to produce enough electricity to cover the demand of the SNG process (21 MWel). The study also shows that it is possible to fully exploit the heat pockets in the SNG process Grand Composite Curve (GCC) resulting in an increase of the steam cycle electricity output. In this case, there is a potential to cover the site’s net steam demand and to produce 30 MWel with an efficiency of 1 MWel/MWadded heat. However, this configuration requires combustion of 36 MWLHV of additional fuel, resulting in a marginal generation efficiency of 0.80 MWel/MWfuel (i.e. comparing the obtained electricity production potentials with and without additional fuel firing).

A COMPARATIVE ASSESSMENT OF CURRENT AND FUTURE FUELS FOR THE TRANSPORT SECTOR

To facilitate the transition to a sustainable and less fossil dependent transport sector in the short to medium term, the current fuel mix needs to be enriched with renewable fuel alternatives. The present work aims to assess and highlight the opportunities for current and future biomass based fuels to be utilized. Seven fuels and fuel blends fulfilling the EN590 diesel fuel standard have been selected and are compared using qualitative and quantitative criteria covering technical, environmental and economic attributes of the fuels. Mature fuels such as dimethyl-ether (DME) and hydrotreated vegetable oils (HVO) are ranked higher in the assessment due to the increased possibility for environmental gains at moderate costs. For future fuels to be competitive stricter regulation in terms of GHG emissions savings are needed.