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Highlights • Increasing variable renewable electricity sources has shown to lower market prices. • Researchers have investigated this effect using historical data electricity markets. • Here holistic energy system analyses are done with an energy system simulation tool. • The analyses are used to quantify the effect on a specific case. Abstract Variable renewable electricity sources have been shown to reduce wholesale electricity market prices. This is expected to reduce the incentive for investments in new electricity production capacity, and might even make these investments infeasible, if relying only on the income from trade on the current electricity market paradigms. In this paper, a novel approach for quantifying this effect in future energy systems is developed using a holistic energy system approach. The approach is applied to the case of Denmark in 2015, which is part of the Nordic and Baltic wholesale electricity market Nord Pool Spot. A holistic energy system model is created and verified according to both the Danish energy balance and the Nord Pool Spot system price in 2015. Using this verified model, the Nord Pool Spot system price is quantified at increasing amounts of onshore wind power, offshore wind power and photovoltaic in Denmark. It is found that regardless of which variable renewable electricity source is implemented, including a combination of the three, the Nord Pool Spot system price decreases as the amount of energy produced by these sources increases, and this effect occurs immediately as more is introduced. [ABSTRACT FROM AUTHOR]

• Electrification and electric vehicles increase peak electricity import in the energy community. • Revised tax and tariff structures can incentivise flexible operation. • Capacity payments prove an effective measure in reducing peak electricity imports. • Heat pump operation in the energy community is well-aligned to a national 100% RE system. • Electric vehicle peak charging requires proper incentives to align to a national 100% RE system. Energy communities are often referred to as a potential source of flexibility to energy systems. However, the extent remains uncertain and is dependent on both the technologies and market structures present. This study models an energy community under different technical system configurations subject to different electricity tax and electricity grid tariff schemes to determine flexibility potentials and effects on the surrounding energy system. It is found that unless incentivised to reduce electricity grid imports, or that import capacity is otherwise restricted, the electrification of energy communities will significantly increase the electricity import from the surrounding electricity grid and thus increase the required electricity grid capacity. This can largely be negated by restructuring tax and tariff schemes to incentivise flexibility and a more temporally distributed consumption pattern. Most notably, capacity payments prove an effective measure in this regard. The operation of the energy community was generally found to be well-aligned with the operation of a future national 100% renewable energy system, indicating that there are no inherent critical contradictions in the expected operation of this kind of energy community and a surrounding national energy system. [ABSTRACT FROM AUTHOR]

• Focusing on the trade-off problem between industrial excess heat and heat pumps in DH system. • A novel hybrid framework for optimal DH strategy in 100% renewable smart energy systems. • The real energy system of Aalborg, Denmark is employed for technical–economic analysis. • Sector synergies between the DH network, power grid, and gas grid are revealed. • 40% IEH and 20% HP in DH bring Aalborg a balanced near carbon–neutral system with minimum cost. The literature emphasizes the important role of industrial excess heat (IEH) and heat pumps (HP) in future 4th generation district heating and smart energy systems. However, they can potentially have negative or positive effects on the integration of renewable energy sources (RES). It is necessary to find a trade-off between IEH and HP in the transition towards a 100% renewable energy system yet has not been discussed in the literature. This paper presents a comprehensive techno-economic analysis for the optimal district heating (DH) strategy in a 100% renewable energy system. It is conducted based on a novel hybrid methodology framework that couples hourly smart energy system simulation, multi-objective optimization, and multiple-criteria decision making. The optimal share between IEH and HP and associated RES capacity can be determined considering the preferences of policymakers. A scenario for 2050 for Aalborg Municipality in Denmark is used as a case study. Results show that an appropriate mix of IEH and HP, 40% and 20% respectively in the DH supply, should be employed to obtain a balanced near carbon–neutral system with the least cost. Also, the cross-sector effective interactivities between the DH network, power grid, and gas grid are revealed in the smart energy system context. The proposed framework is designed in a general way that can be used in other cities, regions, or countries. [ABSTRACT FROM AUTHOR]