• Energy Research
• 11. Sustainability close

Abstract Background Due to climate change and the rising world population, sustainable energy and fertilizer production faces many challenges. The utilization of organic waste fractions is one possible solution for promoting sustainability. Organic waste fractions have a high potential for biomethane production, which could positively contribute to the current energy mix. Furthermore, organic waste fractions could be used for nutrient recovery (i.e., the recovery of N and P) concurrently to their use in biomethane production. This study examined the theoretical potential of organic waste fractions for valorization in Austria. Further, it provides a theoretical overview of biomethane production and nutrient-recovery potential. Results This analysis revealed a total substrate potential of 13 Mt per year in Austria, with the highest contribution from manure. Over 900 million Nm3 of biomethane could potentially be produced from organic waste fractions. Furthermore, developing organic waste fractions as an energy source could improve the impact of the natural gas consuming sectors on climate, reducing 2.4 Mt of CO2 emissions annually. Regarding nutrient recovery, more than 60 kt of N and 20 kt of P could potentially be recovered per year. Conclusion The study shows a high potential for producing biomethane from organic waste fractions in Austria. The overall production potential could substitute up to 11% of the Austrian natural gas demand, which could highly decrease the CO2 emissions from fossil energy carriers. Furthermore, a high nutrient recovery potential was identified for an inclusive implementation of an efficient recovery.

Abstract Since the European Union's target a domestic greenhouse gas emission reduction of 80% till 2050, as compared to the value of 1990 (European Commission, 2011), there has been an increasing interest in greening large industrial processes. Thus, gas greening and alternative emission reduction processes are gaining importance. In this study, a gas greening system for an integrated steel plant, producing synthetic natural gas serving as a substitute for the fossil fuel-based gas, was investigated. The analysed system consisted of a Power-to-Gas unit combined with a biomass gasification plant, where carbon rich steel gases were used as a CO2 source for methanation. To analyse the system, three extreme value scenarios and three constrained scenarios were defined and evaluated. The biomass gasification plant, set to a maximum nominal power of 105 MWth, was the main limiting factor for the constrained scenarios. The assessment included a basic mass and energy balance, techno-economic analysis, sensitivity analysis, and CO2 potential impact analysis. It was found that the main cost influencing factor throughout all six scenarios was the energy supply cost (electricity and biomass).