Optimal Capacity Planning of Power-to-gas in the Integrated Electricity and Natural Gas Systems Considering Hydrogen Injections

Power-to-gas (P2G) provides a novel pathway improving the accommodation of renewable energy source (RES) by converting excessive electricity to natural gas in the integrated electricity and natural gas systems (IENGS). Aiming at the hydrogen injection problem due to high P2G penetrations in the future as well as the capacity planning problem of P2G, this paper diversifies the investment costs and energy conversion of the electrolyser and methanation of P2G device, and models the hydrogen injections in the natural gas network to capture the altered gas constant, heating value and system operation due to gas mixtures. On the basis of that, a P2G capacity planning model is proposed by minimizing the summation of investment cost and operation cost in the planning horizon. The proposed model is assessed by a typical IENGS test system. The results prove that the effectiveness of the proposed model in terms of capacity planning of P2G and analyzing IENGS with gas mixtures. By introducing the proposed model as the decision-making tool and hydrogen injections in the network, a higher overall energy efficiency of renewable energy utilizations is achieved. Furthermore, the main drivers governing the capacity ratio of electrolysers and methanations are discussed. © 2021, Power System Technology Press. All right reserved.