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Highlights • Current import of waste has a positive value, but mostly during wintertime. • Future optimized incineration capacity favoured centralized cogeneration plants. • Heat only boilers are preferred at small scale district heating grids. • Waste imports showed socioeconomic benefits in future systems with high variability. • Combustible waste replaced heat pumps, biomass fuels and wind-based electricity. Abstract This study analyses the socio-economic value of trade of combustible waste, taking Denmark as an example for importing countries with large district heating networks and already high shares of variable renewable energy. An integrated systems analysis framework allowed to assess under which circumstances import of wastes leads to less expensive waste management and energy, accounting for increasing ambitions for a circular economy and renewable energy. The dynamics of both systems are captured through two optimization models, which are solved simultaneously. OptiFlow optimizes Danish waste management and transport, and Balmorel, the Northern European energy system. Results show that waste import to cover the existing Danish incineration overcapacity during wintertime has definite economic value. Conversely, summertime import can have negative value unless a gate fee is received, with the exception of imports of waste with high calorific content (>16.2 GJ/t). In some cases, mothballing of up to 14% of the existing incineration plants is a cost-efficient alternative to decrease the level of over-capacity. In the longer term, results show a socio-economic value of importing waste, being mainly sensitive to assumptions regarding biomass prices and wind power cost, as the technologies would compete with incineration plants. The present methodology can be applied to other countries where waste-to-energy participates in district heating, and where variable renewable electricity and constraints on biomass resources are becoming important. A pan-regional approach regarding waste management planning to maximize the value from combustible waste might be desired, along with a coherent taxation to avoid competition based on tax differences. [ABSTRACT FROM AUTHOR]

Highlights • Identification of affected fuels applying regional energy system analysis. • Currently import of waste is often beneficial from a climate perspective. • Presently, imports with higher fossil-based content yields more climate advantages. • Decarbonization of the energy system makes waste import worse over time. • Heuristic identification of affected energy by imports can overestimate benefits. Abstract This work addressed the role of waste-to-energy (WtE) within the growing paradigm of the circular economy (CE), by combining long-term co-optimization of waste management and energy systems, to determine possible economic and climate impact consequences of future WtE capacity utilization. Co-optimization was realized by integration of a network optimization model for the waste sector, OptiFlow, with the partial equilibrium energy systems model Balmorel. The modelling framework allows to determine the effects of waste-derived energy production within energy systems, including induced and avoided energy (production and long-term investments). The article documents the application of this framework to an analysis of waste trade for WtE between European countries in the base year 2014 and prospectively until 2035, taking Denmark as example for an importing country. Results indicating present and long-term economic benefits for waste trade, under socio-economic conditions, were documented in a concurrent publication. Here, a broader consequential LCA approach was employed to appraise climate change impact potential in a variety of foreground and background conditions. We find that in 2014, trade of residual combustible waste was mostly beneficial from a climate perspective, as the Danish energy system still relies partly on fossil fuels. Towards 2035, climate advantages are uncertain and dependent on avoidance of higher impact waste management (i.e. sanitary landfilling), the differences in the energy carbon-intensity of importing and exporting countries, impact of global biomass supply, and the type and quantity of traded waste. In general, benefits from waste-derived energy production will be offset by direct combustion emissions as background systems decarbonize. Waste transport played only a minor role in the outcome. The study showcases integration of ESA in waste LCA to better account for affected (often referred as marginal) energy production. [ABSTRACT FROM AUTHOR]

• Novel modelling framework allow spatiotemporal optimisation of energy systems. • Co-simulating regional power market model and local biomass and district heat model. • New detailed spatial optimisation of renewable gas and fuel production. • PtX shows promising economic-viability in the future. • Excess heat from biorefineries is efficiently used for district heating. This study conducts an integrated energy system assessment to evaluate pathways for using locally distributed sustainable biomass resources in the conversion to renewable gas and liquid biofuels in future integrated energy systems. A modelling framework with a detailed spatiotemporal representation is used, optimising the usage and transportation of local biomass resources for producing renewable gas and renewable liquid fuels through the OptiFlow model, along with the comprehensive power and district heating model Balmorel, integrating short-term dynamics in the long-term planning horizon. Results for a fossil-independent Danish energy system by 2050 show that production of bio-jet fuel in Denmark would impose high pressure on national biomass resources. Electrofuels, such as biomethanol, have economic viability and promising potentials. The results regarding renewable gas production show that anaerobic co-digestion of a mixed feedstock to produce biogas, which is further upgraded to biomethane using water scrubbing for CO 2 removal, would be the preferred option. Biorefineries are located near larger cities to benefit from economy of scale and access to large district heating networks, as excess heat from biorefineries could supply up to 21% of the national district heating demand. On the contrary, biogas plants would be located in the countryside, as the costs of transporting manure are a determining factor. Therefore, our study provides a novel modelling approach, which enables optimisation of geographical distributed resources for renewable gas and liquid fuel production, while taking synergies across energy vectors in account. [ABSTRACT FROM AUTHOR]