Feasibility Analysis and Design of Gas-Electricity Integrated Transmission System

An increasing number of large-scale renewable plants are generating abundant electricity. As power-to-gas and power-to-x technologies become promising ways to utilize surplus electricity to enhance the flexibility of energy systems, an innovative gas-electricity integrated transmission system (GEITS) to co-transmit electricity and hydrogen or other gas products is proposed, with the foreseeable advantages of compact structure, lower installation cost, and larger energy capacity. This paper investigates the feasibility of GEITS, suggests a design guideline, and gives the operation technical parameters of GEITS in different application scenarios. The dimensions and operating pressures of GEITS benchmark natural gas pipelines and then the nominal voltages of GEITS are calculated based on the electrical strength of high-pressure hydrogen. The nominal ampacities of GEITS are evaluated by temperature-rising simulations, which are larger than those of other transmission lines. Furthermore, high-pressure flowing hydrogen acting as an electrical insulator is a novel topic, and it is investigated via experimental validation on a scale model. Although the effect of 0.4 m/s flowing hydrogen on discharge characteristics has not been observed compared to static hydrogen, the discharge is impaired in 2.4 m/s flowing nitrogen. Future works will investigate the electrical strength of high-pressure long-distance hydrogen gaps under lightning impulse tests and the discharge phenomenon in higher flowing-velocity hydrogen. Methane and methane blended with hydrogen with higher insulation performance can increase the nominal voltages.