Decision-making methodology for managing photovoltaic surplus electricity through Power to Gas: Combined heat and power in urban buildings

Abstract

Power to Gas technology, which converts surplus electricity into synthetic methane, is a promising alternative to overcome the fluctuating behavior of renewable energies. Hybridization with oxy-fuel combustion provides the CO 2 flow required in the methanation process and allows supplying both heat and electricity, keeping the CO 2 in a closed loop. The complexity of these facilities makes their management a key factor to be economically viable. This work presents a decision-making methodology to size and manage a cogeneration system that combines solar photovoltaic, chemical storage through Power to Gas, and an oxy-fuel boiler. Up to 35 potential situations have been identified, depending on the surplus electricity, occupancy of the intermediate storages of hydrogen and synthetic methane, and thermal demand. For illustration purposes, the methodology has been applied to a case study in the building sector. Specifically, a building with 270 kW of solar photovoltaic installed power is analyzed under nine energy scenarios. The calculated capacities of electrolysis vary from 65 kW to 96 kW with operating hours between 2184 and 2475 hours. The percentage of methane stored in the gas grid varies from 0.0% (no injection) to 30.9%. The more favorable scenarios are those with the lowest demands, showing temporary displacements beyond the month between injection and utilization.

Renewable energy sources and power-to-gas aided cogeneration for non-residential buildings

“…According with the results presented previously [37]. Power to Gas facility is properly The lowest amounts of stored electricity are presented when electricity is mostly generated by wind power.…”

“…The influence of the ratio of thermal/electricity demand, taking constant the maximum electricity production calculated with the roof area, was analysed in a previous paper [37]. This study is borne out from a thorough decision-making methodology developed by the authors.…”

“…Equipment sizingThe information in this subsection includes the corresponding size and hours of operation of the electrolyser which will store the surplus electricity from RES, the annual energy consumption and required sizing of the air separation unit, the corresponding size of the oxyfuel boiler and the size and number of hours of operation of the methanizer.ElectrolyserThe electrolyser power is dimensioned maximizing the hours of operation at nominal load by means of the load duration curve[37]. It manages the electricity surplus from renewable sources and stores the maximum possible amount of energy.…”

Methodology for Dimensioning the Socio-Economic Impact of Power-to-Gas Technologies in a Circular Economy Scenario

“…Currently, the stability of the grid can be affected by mismatches between demand and electrical supply, and the security of the grid limits the technical and economic exploitation of RES. To some extent, it also limits PtG expansion [26]. Other limits to PtG could be related to the availability of CO 2 , the scarcity of water, the low efficiency of these systems, other processing steps, or the economic and financial issues related to this technology [11].…”

Techno-Economic Assessment of Demand-Driven Small-Scale Green Hydrogen Production for Low Carbon Agriculture in Sweden

“…Also, H 2 refueling stations with electrolysers smaller than 500 kW to supply the demand of H 2 cars, and the optimization of an electrolyser operation employing wind, electricity prices, and H 2 demand have been investigated elsewhere (Grüger et al, 2018;Grüger et al, 2019). Furthermore, the feasibility of stationary power-to-gas systems to store excess electricity from renewable sources in buildings with different heat and power requirements have been assessed combined with oxy-fuel boilers to produce concentrated CO 2 stream and facilitate further methanation of H 2 (Bailera et al, 2018;Bailera et al, 2019). Even though previous studies addressed H 2 production from solar PV to fuel an all-wheel drive vehicle on a winery (Carroquino et al, 2018;Roda et al, 2018), to the best of the authors' knowledge, techno-economic assessments of on-farm H 2 production based on wind power to supply the fuel demand of heavier agricultural machineries like tractors and harvesters have never been reported.…”