Integrated energy system modeling perspectives for future decarbonization pathways based on sector coupling, life-cycle emissions and vehicle-to-grid integration

The impending environmental crisis has propelled the global energy sector into radical transformation. Variable renewable energy necessitates unprecedented flexibility, transcending energy needs. Decarbonization is critical to achieving sustainable development goals on clean energy and climate action, creating a healthier planet for all. This critical review of current energy system modeling advocates integrated-whole-energy-system models as vital tools for generating diverse energy and policy-related insights. Sector-coupling is investigated, exploring the complex interplay between power, gas, transport, and heating. Nine challenges are delineated: Uncertainty, Renewable integration, Transparency and open-access, High-resolution modeling, Sector-coupling, Flexibility, Technological representation, Life-cycle emissions, and Social and human factors, while offering strategies for their resolution. This review envisions a future powered by renewables, achieving 50 % emissions and 30 % water usage reductions within a decade. The life cycle assessment integration can result in up to 80 % reductions in emissions; however, the cost may increase up to 40–60 %. Emerging technologies like green hydrogen and vehicle-to-grid (V2G) are vital drivers. Green hydrogen offers flexible storage and distribution while V2G transforms electric vehicles into prosumers, enabling grid flexibility and demand management, with studies demonstrating 20–50 % cost reductions and 65 % peak load reduction. A case study for the future decarbonization of the Indian power sector is presented in 19 scenarios based on recent studies, demonstrating the dominant role of solar and wind energy with around 55 % and 22 % share in 2050. This review pinpoints crucial research gaps, identifies successful strategies, and proposes new avenues to guide the energy sector toward a sustainable, low-carbon future.