Enhancing grid flexibility under scenarios of a renewable-dominant power system in China

Renewable energy is poised to play a major role in achieving China's carbon neutrality goal by 2060; however, reliability and flexibility are a big concern of a renewable-dominant power system. Various strategies of enhancing flexibility are under discussion to ensure the reliability of such a system, but no detailed quantitative analysis has been reported yet in China. Here we combine the advantages of a capacity expansion model, SWITCH-China, with a production simulation model, PLEXOS, and analyze flexibility options under different scenarios of a renewable-dominant power system in China. We find that a larger balancing area offers direct flexibility benefits. Regional balancing could reduce the renewable curtailment rate by 5%-7%, compared with a provincial balancing strategy. National balancing could further reduce the power cost by about 16%. However, retrofitting coal power plants for flexible operation would only improve the system flexibility marginally.

To Prevent or Promote Grid Expansion? Analyzing the Future Role of Power Transmission in the European Energy System

Future energy supply systems must become more flexible than they are today to accommodate the significant contributions expected from intermittent renewable power sources. Although numerous studies on planning flexibility options have emerged over the last few years, the uncertainties related to model-based studies have left the literature lacking a proper understanding of the investment strategy needed to ensure robust power grid expansion. To address this issue, we focus herein on two important aspects of these uncertainties: the first is the relevance of various social preferences for the use of certain technologies, and the second is how the available approaches affect the flexibility options for power transmission in energy system models. To address these uncertainties, we analyze a host of scenarios. We use an energy system optimization model to plan the transition of Europe’s energy system. In addition to interacting with the heating and transport sectors, the model integrates power flows in three different ways: as a transport model, as a direct current power flow model, and as a linearized alternating current power flow model based on profiles of power transfer distribution factors. The results show that deploying transmission systems contribute significantly to system adequacy. If investments in new power transmission infrastructure are restricted—for example, because of social opposition—additional power generation and storage technologies are an alternative option to reach the necessary level of adequacy at 2% greater system costs. The share of power transmission in total system costs remains widely stable around 1.5%, even if cost assumptions or the approaches for modeling power flows are varied. Thus, the results indicate the importance of promoting investments in infrastructure projects that support pan-European power transmission. However, a wide range of possibilities exists to put this strategy into practice.

Optimal Energy Portfolios in the Electricity Sector: Trade-Offs and Interplay Between Different Flexibility Options

The expansion of renewable energy sources (RES) and the electrification of demand side sectors raise the need for power system flexibility. The following model-based analysis illustrates the complexity of the European energy system transformation with pathways regarding the RES expansion, sector coupling, and different levels of flexibility provision. Differences occur concerning the optimal mix of flexibility options between the moderate and ambitious climate target scenarios. Dispatchable back-up capacities are necessary, also in presence of high RES shares. Here, CO2 prices influence the role of low-carbon technologies. Due to cross-sectoral interactions, energy storages have a limited value. For the ambitious scenarios, the emission reductions come close to the Green Deal targets of the European Commission, while levelized costs of electricity increase moderately compared to the less ambitious scenario.

Introduction

The future energy system in Europe needs to be decarbonized and thus be based almost exclusively on renewable energy sources. Therefore it is challenged by the intermittent nature of renewables and requires several flexibility options. The interaction between different options and the impact on environment and society are in the focus of this contribution. It is the core objective of this book to analyze and evaluate the development toward a low-carbon energy system with focus on flexibility options in the EU to support the implementation of the Strategy Energy Technology Plan. The analyses are based on a bottom-up modeling environment that considers current and future energy technologies, policy measures and their impact on environment and society while considering technological learning of low-carbon and flexibility technologies.

Model Coupling Approach for the Analysis of the Future European Energy System

In REFLEX ten different bottom-up simulation tools, fundamental energy system models, and approaches for life cycle assessment are coupled to a comprehensive Energy Models System. This Energy Models System allows an in–depth analysis and simultaneously a holistic evaluation of the development toward a low–carbon European energy system with focus on flexibility options up to the year 2050. Different variables are exchanged among the individual models within the Energy Models System. For a consistent analysis, relevant framework and scenario data need to be harmonized between the models.