(228b) Operational, Economic, and Environmental Analysis of Hybrid Renewable Energy Systems

The global push to achieve 100% renewable future energy system by 2050 is a key focus for sustainable development. To achieve this goal, previous studies have extensively investigated the potential transition to a renewable energy system by equating the electricity demand of a region with its available renewable energy resources. However, these studies often overlook the dynamic nature of energy systems and the intermittent characteristics of renewable sources. Furthermore, many studies predominantly focused just on the possibility of transition to 100% renewable energy system and lack a thorough economic analysis of such a transition. Notably, a 100% renewable energy system cannot be achieved without the elimination of natural gas consumption and using electricity instead, which puts extra load on the electric grid due to heating purposes during colder months. Our study conducts a detailed techno-economic analysis on an hourly basis to assess the cost implications of transitioning to 100% renewable energy. Additionally, we examine the impact of building electrification in residential and commercial sectors (which account for 62% of total electricity consumption in the U.S.) on the entire energy system. There have been large efforts to address the challenges of moving towards a 100% renewable energy system, yet challenges remain, particularly regarding transmission losses, environmental considerations, land use, and societal acceptance, which warrant further investigation.

In this study, using HOMER software tool, we performed a comprehensive techno-economic analysis of hybrid renewable energy systems (HRESs) to evaluate the technical feasibility and economic viability of integrating renewable energy sources into existing energy systems. In an HRES, as shown in Figure 1, Renewables are integrated with a battery system and there is a natural gas power plant as a back-up to help the energy system to meet the electric load when renewables are not available and battery is emply. Additionally, we investigated the impact of building electrification in residential and commercial sectors on the entire energy system. To simulate this electrification scenario, illustrated in Figure 2, we employed building simulations using EnergyPlus and OpenStudio, analyzing the electrified load of an entire city. Notably, in our simulations, we replaced conventional fossil fuel-powered heating, ventilation, and air conditioning (HVAC) systems with heat pumps, which operate solely on electricity. Our analysis yielded insightful results regarding the optimal renewable fraction necessary to minimize the levelized cost of electricity (LCOE) across different regional contexts. We found that the value of the optimum renewable fraction is heavily influenced by the regional availability of renewables, varying substantially between different case studies. Moreover, as we approached a 100% renewable fraction, we observed a remarkable exponential increase in the LCOE. This trend was mirrored in the sizing of renewable components such as photovoltaics (PVs) and wind turbines, as well as battery systems, all of which increased exponentially to meet peak electric demand. Additionally, our sensitivity analysis, examining the impact of carbon taxes, fuel prices, and renewable component costs, revealed significant shifts in the optimal renewable fraction. For instance, increasing the carbon tax from $0 to $120 per tonne of CO₂ led to an increase in the optimum renewable fraction from 5% to 26%. Similarly, an increase in natural gas prices from $0.26/m³ to $0.7/m³ and considering estimated renewables costs for 2050 resulted in notable rise in the optimal renewable fraction from 5% to 60% and 56%, respectively. A summary of sensitivity analysis is shown in Figure 3. Overall, our study underscores the importance of a cost-aware approach, urging policymakers to strike a balance between mitigating carbon emissions and ensuring economic feasibility when adopting renewable energy solutions.