Digital reflections of physical energy plants can help support and optimize energy technologies within their lifecycle. So far, no framework for the evolution of virtual representations throughout the process development lifecycle exists. Based on various concepts of virtual representations in different industries, this review paper focuses on developing a novel virtual representation framework for the process development environment within the energy sector. The proposed methodology enables the continuous evolution of virtual representations along the process development lifecycle. A novel definition for virtual representations in the process development environment is developed. Additionally, the most important virtual representation challenges, properties, and applications for developing a widely applicable framework are summarized. The essential sustainability indicators for the energy sector are listed to standardize the process evaluation throughout the process development lifecycle. The virtual representation and physical facility development can be synchronized by introducing a novel model readiness level. All these thoughts are covered through the novel virtual representation framework. Finally, the digital twin of a Bio-SNG production route is presented, to show the benefits of the methodology through a use case. This methodology helps to accelerate and monitor energy technology developments through the early implementation of virtual representations.

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.

This analysis estimates the technically available potentials of renewable gases from anaerobic conversion and biomass gasification of organic waste materials, as well as power-to-gas (H2 and synthetic natural gas based on renewable electricity) for Austria, as well as their approximate energy production costs. Furthermore, it outlines a theoretical expansion scenario for plant erection aimed at fully using all technical potentials by 2050. The overall result, illustrated as a theoretical merit order, is a ranking of technologies and resources by their potential and cost, starting with the least expensive and ending with the most expensive. The findings point to a renewable methane potential of about 58 TWh per year by 2050. The highest potential originates from biomass gasification (~49 TWh per year), while anaerobic digestion (~6 TWh per year) and the power-to-gas of green CO2 from biogas upgrading (~3 TWh per year) demonstrate a much lower technical potential. To fully use these potentials, 870 biomass gasification plants, 259 anaerobic digesters, and 163 power-to-gas plants to be built by 2050 in the full expansion scenario. From the cost perspective, all technologies are expected to experience decreasing specific energy costs in the expansion scenario. This cost decrease is not significant for biomass gasification, at only about 0.1 €-cent/kWh, resulting in a cost range between 10.7 and 9.0 €-cent/kWh depending on the year and fuel. However, for anaerobic digestion, the cost decrease is significant, with a reduction from 7.9 to 5.6 €-cent/kWh. It is even more significant for power-to-gas, with a reduction from 10.8 to 5.1 €-cent/kWh between 2030 and 2050.