Recent scientific investigations have revealed a correlation between nutrition habits and the environmental impacts of agriculture. So, it is obviously worthwhile to study what effects a change in diet has on land use patterns, energy demand, and greenhouse gas emissions of agricultural production. This study calculates the amount of energy and emission savings as well as changes in land use that would result from different scenarios underlying a change in diet. Based on the healthy eating recommendations of the German Nutrition Society, meat consumption in Austria should decrease by about 60%, and consumption of fruits and vegetables has to increase strongly. This investigation showed that compliance with healthy eating guidelines leads to lower energy demand and a decrease in greenhouse gas emissions, largely due to a decrease in livestock numbers. Furthermore, arable land and grassland no longer needed for animal feed production becomes redundant and can possibly be used for the production of raw materials for renewable energy. The scenario examination shows that in the self-sufficiency scenario and in the import/export scenario, up to 443,100 ha and about 208,800 ha, respectively, of arable land and grassland are released for non-food uses. The cumulative energy demand of agriculture is lower by up to 38%, and the greenhouse gas emissions from agriculture decrease by up to 37% in these scenarios as against the reference situation. The land use patterns for the scenario demonstrate that animal feed production still takes up the largest share of agricultural land even though the extent of animal husbandry decreased considerably in the scenarios.

The current work investigates the feasibility of a novel Carbon Capture and Utilization (CCU) approach—also known as Underground Sun Conversion (USC) or geo-methanation. The overall objective of the current work is a comprehensive assessment on the technical, economic and legal aspects as well as greenhouse gas impacts to be concerned for establishing USC technology concept. This is achieved by applying multidisciplinary research approach combining process simulation, techno-economic and greenhouse gas assessment as well as legal analysis allows answering questions about technical, economic feasibility and greenhouse gas performance as well as on legal constraints related to large scale CCU using geo-methanation in depleted hydrocarbon reservoirs. CO₂ from the industry and renewable H₂ from the electrolyser are converted to geomethane in an underground gas storage and used in industry again to close the carbon cycle. Process simulation results showed the conversion rates vary due to operation mode and gas cleaning is necessary in any case to achieve natural gas grid compliant feed in quality. The geomethane production costs are found to be similar or even lower than the costs for synthetic methane from Above Ground Methanation (AGM). The GHG-assessment shows a significant saving compared to fossil natural gas and conventional power-to-gas applications. From a legal perspective the major challenge arises from a regulative gap of CCU in the ETS regime. Accordingly, a far-reaching exemption from the obligation to surrender certificates would be fraught with many legal and technical problems and uncertainties.

Isobutene (IBN, C₄H₈) is widely used in industry. Currently, IBN production relies on petrochemical processes. The current work assesses the comparative environmental sustainability of bio‐based IBN production routes based on first‐ and second‐generation sugar compared with fossil IBN by applying the ISO 14044‐based Life Cycle Assessment methodology. In total nine scenarios are examined. Scenarios 1–6 used first‐generation sugar for IBN fermentation and scenarios 7–9 use cereal straw‐based second‐generation sugar. The scenarios also differ in their process energy source. The savings in Global Warming Potential for first‐generation IBN are up to 68% (scenario 1); for second‐generation IBN, the savings reach 105% if an avoided burden approach for utilizing lignin as an energy source is applied (scenario 8). It is found that applying renewable process energy is a prerequisite to maximizing greenhouse gas savings. Special attention has to be drawn to the eutrophication potential, were none of the scenarios show savings. This is driven by sugar crop cultivation owing to fertilizer usage, thermal energy from solid biomass or natural gas due to NO_x emissions and nutrient use for fermentation (e.g. ammonia). Scenarios 4, 7 and 8 show savings in the acidification potential compared with fossil IBN. A driver of acidification is biomass‐based process energy generation, mainly due to SO₂ and NO_x emissions from biomass combustion. In contrast, all scenarios show a better environmental performance concerning the freshwater aquatic ecotoxicity potential, the abiotic depletion and the photochemical ozone creation potential. Process development should focus on conversion efficiencies and a fully renewable process energy supply. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

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.