Application to smart multi-energy system for supply-demand side management of a building based on power-to-gas-to-power concept: Technical, environmental, and economic assessment

Utilizing new concepts for the production and conversion of energy carriers leads to progress in reaching carbon neutrality targets. Green energy-integrated systems exposed to attention of energy scientists in recent years. In this study, a smart multi-energy system is proposed based on the hybrid utilization of solar and wind resources for producing green hydrogen. The produced green hydrogen is then blended with natural gas and used as an enviro-friendly fuel for internal combustion engine. Afterward, the heating potential of engine's exhaust and jacket water are recovered to run some equipment for producing extra power, heat, and cold. A powerful techno-economic and environmental framework is developed in EES software to assess the feasibility of the proposed system. Also, to make the modeling even more accurate, the engine is simulated in GT-Power software and its outputs are linked with EES. Furthermore, to make the proposal applicable, a case study hotel building is considered and system's effectiveness is demonstrated. The building is simulated with a full-detailed model and sustainable architectural elements are also considered in the simulation (green wall and photovoltaic facade). The analyses are done for three models (Model 1: 5 vol% hydrogen blended into NG, Model 2: 10 vol% hydrogen blended into NG, Model 3: 100 % NG). Analyzing the system illustrated that R123 is identified as the most efficient fluid for ORC with energy and exergy efficiencies of 18.03 % and 26.58 %, respectively. Also, dynamic modeling results indicated that hybrid utilization of solar/wind ensures a reliable and consistent supply of clean energy, significantly reducing reliance on fossil fuels. So that, 7.05 ton/year of CO₂ emission is prevented by the hydrogen blending (in models 1 and 2) compared to the case where only methane is used as fuel. The payback period of the proposal, based on the discounted NPV approach, is obtained as 4.2 years proving its feasibility.