Solar energy for sustainable heating and cooling energy system planning in arid climates

Despite the high potential of renewable energy sources in Iran, the current energy system in the country is highly dependent on fossil fuel resources because the abundance of oil and gas resources in the country has made it less feasible to harvest renewable energy. Nowadays, climate change and the increase in greenhouse gases (GHG) emissions have led to measures such as determining CO2 taxes that make renewable-based energy systems more profitable. Southern Iran, with its arid climate, has a high potential for the integration of solar energy into the existing energy system in order to maximize its share on the energy system; therefore, in this research, five scenarios were defined and applied to model the energy system for 2025 and 2030. Each scenario was assumed to maximize the solar energy share for the supply of heating, cooling, and electricity demand, such as photovoltaics (PV) and concentrated solar power (CSP). The bottom up EnergyPLAN was applied to model the energy system and scenario computations. The results of the scenarios were compared based on annual CO2 emissions, costs, total primary energy supply, and critical excess electricity production. Based on the results, all scenarios were able to reduce the CO2 emissions; however, the PV based scenario had the least costs and utilized 1954 MW of PV power plant to supply the demand with 599 M€/year costs. Natural gas was largest energy resource of the system; due to the 17% reduction in the total primary energy supply compared to BAU and Best Scenario (S5) for 2030, about 20 TWh/year of the natural gas was saved and was ready for export. According to the Paris Agreement, the permissible amount of CO2 emissions for this province in 2030 is about 9.76 Mt, which is 5.59 Mt in Best Scenario (S5). Furthermore, sensitivity analysis was run for the costs of the business as usual and PV based scenarios under different natural gas prices and emissions tax rates from 0.025 to 1.92 €/Gj and 4 to 20 €/kg of CO2, respectively. According to the findings, when the natural gas price increased to 0.521 €/Gj, the renewable-based plans became feasible, and increasing the CO2 tax caused the cost differences to rise.