Determining the optimal process configurations for Synthetic Natural Gas production by analysing the cost factors

Abstract

Producing Synthetic Natural Gas (SNG) via Power-to-Gas (PtG) is favourable for two reasons; it can be substituted for natural gas in the gas network, and it enables CO2 recycling as energy systems transition towards a low-carbon future. However, the expensive SNG production process is a barrier to being cost-competitive with other market gases. Several diverse factors influence SNG production cost, which results in several possible process configurations with varying performance which influence it. The hydrogen (H2) and carbon dioxide (CO2) required to produce SNG are available from multiple sources, while the SNG production cost is also influenced by the capital investment required for PtG process units, interim storage facilities, and operating expenses. Hence, an in-depth analysis of the factors affecting SNG production is required to understand their effect on the cost and to provide information on cost savings, economic implications, and optimal SNG production setup for decision-makers.In this paper, an optimisation algorithm is developed to model the PtG process units. The main objective of this work is to determine optimal process configurations for SNG production by analysing its influencing cost factors. A factorial design approach is integrated into the optimisation process to minimise the production cost by choosing the cost-effective process configurations. This work also determines the factors with a significant influence on the production cost using an ANOVA. The algorithm identifies the cost-effective H2 and CO2 source to obtain the least expensive SNG production setup. Based on the values of the cost factors, strategies for lowering the production cost in an existing setup are identified. The factors with the most influence on the SNG production cost are the capacity and capex of the methanator unit