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

• Published in: Applied energy Vol. 228; pp. 1032 - 1045
• Main Authors: Bailera, Manuel, Peña, Begoña, Lisbona, Pilar, Romeo, Luis M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.10.2018
• Subjects: Cogeneration; Energy storage; Methanation; Oxy-fuel combustion; Power-to-Gas; Renewable energy; Methanation; Renewable energy; Cogeneration; Power-to-Gas; Oxy-fuel combustion; Energy storage
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2018.06.128

•A new cogeneration is proposed and analyzed: PV, Power to Gas, and oxy-fuel boiler.•A decision-making methodology is developed to manage and size the system.•A building with 270 kW of PV installed power is analyzed under 9 energy scenarios.•Low demands allow temporarily displacing the stored methane beyond the month.•Synthetic methane covers 15.5–86.5% of thermal demand depending on the scenario. 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 CO2 flow required in the methanation process and allows supplying both heat and electricity, keeping the CO2 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 h. 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.