Optimizing Low-Carbon Economic Scheduling for Hydrogen-Integrated Energy Systems with Enhanced Supply-Demand Response and Vehicle-to-Grid Integration

Low-Carbon Economic Scheduling of Hydrogen-Integrated Energy Systems with Enhanced Bilateral Supply–Demand Response Considering Vehicle to Grid Under Power-to-Gas–Carbon Capture System Coupling

Abstract: Hydrogen-integrated energy systems (HIESs) are crucial for the transition to a low-carbon energy structure. This paper presents a low-carbon economic scheduling strategy aimed at enhancing operational efficiency and reducing carbon emissions in HIESs. The strategy begins with a stepwise carbon trading framework designed to limit carbon output. Following this, a joint operational model is developed that integrates hydrogen energy usage with carbon capture technology. To increase the energy supply flexibility of HIESs, modifications to traditional combined heat and power (CHP) units are introduced, incorporating waste heat boilers and organic Rankine cycles. This results in a flexible CHP response model capable of adjusting electricity and heat outputs. Additionally, a comprehensive demand response model is created to optimize both electric and thermal load capacities, improving demand-side responsiveness. The study analyzes the integration of electric vehicles (EVs) into the system, focusing on their energy consumption patterns and dispatch capabilities, thereby enhancing their scheduling flexibility and optimizing the synergy between demand-side flexibility and system operations. Ultimately, a low-carbon economic scheduling model for HIES is developed, aiming to minimize system costs. Results indicate that the proposed scheduling method effectively enhances the economic viability, low-carbon performance, and operational flexibility of HIESs while promoting clean energy consumption and the deep decarbonization of the system.

Keywords: hydrogen-integrated energy systems; economic scheduling; operational efficiency; supply flexibility; CHP; demand response; electric vehicles; low-carbon performance; V2G

1. Introduction

The increasing tension between economic growth and environmental protection has become a pressing issue, exacerbated by severe energy depletion and ecological degradation. To combat the energy and environmental crises, particularly the excessive carbon emissions linked to fossil fuel dependency, the Chinese government has established dual-carbon development goals. The energy sector, a major contributor to carbon emissions, is a primary focus for regulatory efforts aimed at reducing emissions. There is an urgent need to enhance the efficiency of clean energy utilization and accelerate the transformation of the energy structure.

To facilitate green and sustainable economic development, it is vital to adopt advanced communication technologies that aggregate renewable energy and efficient hydrogen energy, leveraging the synergies of various energy technologies and the advantages of multi-energy complementarity. Establishing an energy internet system with HIESs as a pivotal component will maximize the flexibility of scheduling resources across both supply and demand sectors, significantly improving system efficiency and reducing carbon emissions.

Traditional energy storage technologies, while stable and efficient, face limitations in scalability due to energy density and space requirements. In contrast, hydrogen-based power-to-gas (P2G) technology offers higher energy density and greater long-term storage potential, making it advantageous for stabilizing the grid and facilitating the integration of substantial amounts of renewable energy. Various studies have demonstrated the economic and environmental benefits of integrating P2G with carbon capture systems (CCSs), enhancing the system’s low-carbon economic performance through CO2 capture and utilization. However, existing models often rely on conventional P2G systems, necessitating further refinement to fully exploit hydrogen energy’s potential.

Combined heat and power (CHP) systems have been widely recognized for their efficiency in energy supply. Nevertheless, their fixed electro-thermal output ratios present challenges in meeting the variable energy demands of different loads. Various strategies have been proposed to enhance the flexibility of CHP systems, including integrating heat pumps and organic Rankine cycles. Despite these advancements, the complexity and variability of demand-side loads often hinder the supply side’s ability to adequately address excess heat or power generation.

Integrated Demand Response (IDR) serves as an effective measure to stimulate resource utilization on the demand side, mitigating fluctuations between peak and off-peak loads and improving the clean energy consumption rate of HIESs. Recent developments in EV charging demand models and time-of-use pricing strategies have shown promise in optimizing system performance regarding carbon emissions and economic efficiency.

Building on this research context, this paper proposes a low-carbon operational strategy for HIESs, considering the integrated operation of P2G and CCS and the dual responsiveness of supply and demand. The proposed framework includes multiple energy forms that complement one another, a stepwise carbon trading scheme, and a refined coupling of CCS with two stages of P2G to explore hydrogen energy’s varied applications. The flexibility of electricity and heat output is enhanced through the incorporation of waste heat boilers and organic Rankine cycles on the energy supply side.

2. Operational Framework for HIESs

The operational framework for HIESs includes energy supply from photovoltaic (PV) systems, wind turbines (WT), the power grid, and the gas grid. Energy conversion processes involve CHP units, gas boilers, hydrogen fuel cells (HFCs), and P2G devices. The energy storage system comprises electrical storage, gas storage, thermal storage, and hydrogen storage. Energy demand encompasses electricity, heat loads, and EVs.

2.1 Stepwise Carbon Trading Model

To incentivize carbon emitters to reduce emissions, a carbon trading mechanism allows for the free trade of carbon emission rights. If actual carbon emissions exceed allocated allowances, entities must purchase additional permits. Conversely, surplus allowances can be sold for profit.

3. Bilateral Interaction Framework for Supply and Demand

The dual supply and demand response model consists of constructing a CHP response model on the supply side and establishing a regulated EV charging and discharging framework on the demand side. By coordinating and optimizing the dual response, the dispatchable potential of each sector can be fully utilized, enhancing the flexibility and economic efficiency of the HIES.

4. Optimization Framework for HIESs Incorporating P2G-CCS Integration and Bilateral Supply–Demand Response

The objective of this study is to enhance the cost-efficiency and low-carbon effectiveness of HIES operations. The model aims to minimize the overall cost, which includes energy purchase costs, equipment operation costs, carbon trading costs, wind and solar energy abandonment costs, and response subsidy costs.

5. Case Analysis

A simulation case of an HIES system in western China is used to validate the proposed model and operational strategy. The case features a 24-hour dispatch cycle with one-hour intervals. The analysis includes benefit assessments of the P2G-CCS coupled model and evaluations of supply and demand flexibility.

6. Conclusions

This study presents a regulation strategy for HIESs that emphasizes low-carbon and economic performance by integrating P2G-CCS operations and enhancing supply-demand responsiveness. The findings indicate significant improvements in both carbon emissions reduction and operational costs, demonstrating the benefits of the proposed dual-response optimization strategy.

This paper highlights the importance of refining hydrogen energy utilization and enhancing system flexibility through integrated operational strategies, paving the way for sustainable energy practices. Further research will explore the impacts of renewable energy fluctuations and user incentives on the effectiveness of V2G scheduling.