Enhancing the enviro-economic viability of biogas-solar hybrid systems: Strategies for sustainable energy development in Iran

The global transition to renewable energy is essential for long-term sustainable development and climate change mitigation. Hybrid Renewable Energy Systems (HRES) offer a viable solution for reducing carbon emissions, increasing energy security, and providing reliable electricity. This study investigates the feasibility of implementing a HRES, combining biogas and solar power in a small city in Iran. HOMER software was used to analyze different scenarios, including a base model and three optimized approaches: selling excess electricity to the power grid (STPG), green hydrogen production (GHP), and obtaining government subsidies for municipal waste procurement (GSMWP). The analysis focuses on evaluating the economic and environmental performance of these scenarios, particularly their impact on NPC, and IRR. The base model shows that the biogas-solar hybrid power plant can reduce CO2 emissions by 96.8 %-97.2 % compared to the existing natural gas combined cycle power plants. Due to the high cost of equipment and the fuel and the low electricity sales price in Iran, the STPG and GHP scenarios show negative IRRs of -7% and -17%, respectively. In contrast, the GSMWP scenario, which includes a government subsidy of $100 per ton of waste, achieves a COE of $0.156 per kWh, making the project economically viable with additional revenues. The study concludes that government subsidies are critical to improving the economics and sustainability of renewable energy projects in Iran. The most effective approach integrates the optimized scenarios, reduces overall fuel costs, and maximizes revenue potential.