Joint optimal sizing and operation scheduling of a power-to-gas hub based on a linear program

With rising challenges of greening the gas sector and decreasing wasteful curtailment of renewable energy sources, power-to-gas hubs seem to be a suitable solution for mitigation of both. Power-to-gas hubs can act as energy storage and as sector coupling solution between electricity, gas, heat, and water grids, but also agricultural markets when using biomass and/or biochar. However, the economic viability and adequate operation of such hubs is crucial in order to make a difference. The optimization procedure developed tackles the complex problem of finding the optimal structure of a power-to-gas hub and simultaneously optimizing its operation. The unique aspects of the proposed procedure include: i) finding the optimal system structure across a large number of possible technologies, processes and storage components, rather than optimizing a power-to-gas hub with a single mass/energy conversion pathway; ii) collocation of a power-to-gas hub with an existing renewable energy plant and/or an existing industrial plant; and iii) viable computational complexity while short-term intermittence of renewable sources is included. After comprehensive techno-economic modelling of the overall setup, the developed optimization procedure is used on three case studies showcasing the strengths of the procedure. The case studies show how the optimal system configuration and optimal components’ sizes change depending on prices of electricity and natural gas, and on possibility to sell digestate and/or biochar. Also, the case studies show the influence of electricity sources, or rather the intermittence of renewables, on optimal operating schedules.