## 1 Introduction  
Integrating renewable energy sources is essential to address global energy demands while minimizing environmental impacts. The need for innovative and sustainable energy solutions is even more critical in regions like Idlib, Syria, where energy infrastructure has been severely disrupted. This study explores the potential of a solar-biogas hybrid renewable power plant, which combines the benefits of solar energy and biogas production to create a more reliable and sustainable energy supply. In this hybrid system, a unique approach is proposed: using the condenser of a steam turbine cycle to heat the anaerobic digester (AD), which is a key component in biogas production. The excess heat from the steam turbine is redirected to maintain optimal temperatures in the digester, improving the efficiency of biogas generation. This integration not only enhances energy production but also maximizes the use of available resources, making it a highly efficient and eco-friendly solution. By focusing on Idlib, Syria, this study highlights the potential for renewable energy systems to support regions with limited access to conventional power sources,contributing to energy resilience and environmental sustainability. The hybrid solar-biogas model represents a step forward in addressing both energy needs and the challenges of climate change, offering a blueprint for similar regions worldwide. This study examined the technical and economic feasibility of a hybrid solar-biogas power plant in Idlib, Syria; Greenius 4.9.0.1 software was used for the simulation, and the supposed system includes an AD for producing biogas and solar parabolic trough collectors. A traditional steam turbine power block uses heat to produce electricity. Five identical digesters running at five different temperatures were used in a practical biogas generation experiment as part of this study. Using this hybrid system in the Idlib region may provide in several benefits, including the following:  
* Ensuring the stability of the electricity produced;
* Disposing of waste in a clean and energy-producing way;
* Producing bio-fertilizers;
* Creating new job opportunities for the local community. Hybrid plants can generate electricity from renewable energy, utilizing two or more renewable energy sources. Hybrid power plants are classified according to the way energy sources are connected into two systems [1]:  
* Hybrid power plants with electrical connection: where there is no direct relationship between energy sources, and none affects the other, and each energy source has its own independent generator; the plant requires a synchronization system between the two electrical currents to operate simultaneously, such as a wind turbine or photovoltaic (PV) system;
* Hybrid power plant with energy source connection: there is a relationship between energy sources before reaching the generation units. Table 1 illustrates the advantages and disadvantages of both types of conjunction. One of the most famous hybrid systems that follows this configuration is the hybrid power plant that combines solar thermal energy and biogas (generated from an AD). Improving the performance of these systems represents a significant benefit for enhancing the utilization of the plant and reducing the cost of the electricity produced. Syria falls within the economically acceptable range for establishing concentrated solar power (CSP) plants [3], and the city of Idlib can provide wastewater (WW) and municipal food waste to operate a biogas plant, where the population is approximately one million, the average daily solid waste is 260 tons, of which 47.4% is biodegradable organic material, and the average daily sewage is 40,000 m\({}^{3}\)[4]. The amount of biogas from sewage daily per person is 0.018-0.026 m\({}^{3}\)/person, which is an average of 0.022 m\({}^{3}\)/person according to the International Energy Agency [5].