Balancing renewable energy systems in Saudi buildings

Newswise — An analysis of the influence of weather fluctuations on the structure and function of sustainable energy systems for Saudi Arabian office buildings investigates the balance between the competing goals of minimizing both total cost and CO2 release.

The incorporation of renewable energy systems is crucial for the forthcoming provision of low-emission electricity. However, the planning and functioning of these systems must account for the impact of weather fluctuations on the accessibility of renewable energy sources and energy requirements.

Scientists from KAUST and the University of Sharjah have examined a standard office building in three Saudi Arabian cities: Riyadh, Jeddah, and NEOM. In their study, they explored the utilization of renewable energy sources for electricity supply to the building, along with the ability to tap into the power grid for additional flexibility. Additionally, they analyzed a scenario where the building had no connection to the grid. [1]

The scientists utilized diverse weather datasets with varying degrees of variability to optimize the configuration of renewable energy systems for the office buildings and evaluate their operational efficiency. They conducted an in-depth analysis of factors such as the quantity of photovoltaic (PV) panels, wind turbines, batteries, and grid-supplied power. Their aim was to find a balance between minimizing both lifecycle cost and CO2 emissions.

According to Postdoc Farah Souayfane, the study highlights the significance of having access to a power grid. It demonstrates that the influence of weather variability and extreme weather events on the design of renewable energy systems can be mitigated when there is the availability of a power grid.

Souayfane states that considering the complete range of weather variability, especially extreme weather events, leads to higher costs in implementing a fully renewable energy system. This is primarily due to the need for increased battery storage to accommodate these variations in weather conditions.

"However, Souayfane emphasizes that neglecting the consideration of extreme weather events during the design phase can result in a notable performance gap. To bridge this gap, grid integration can be employed, which does not incur additional system costs but may contribute to overall CO2 emissions," she explains.

The analysis reveals a trade-off between CO2 emissions reduction and lifecycle costs. On one end of the spectrum, there is a system with maximum CO2 emissions but the lowest lifecycle cost. This system is characterized by minimal renewable energy supply and heavy reliance on the power grid. On the other end, there is a solution with zero CO2 emissions but the highest lifecycle cost, which entails a fully renewable energy system without any reliance on the power grid.

Co-author Ricardo Lima suggests that the influence of weather variability on the lifecycle cost of fully renewable energy systems can be mitigated by implementing a CO2 emissions budget. By setting a specific limit on CO2 emissions, the system can be designed and operated in a manner that takes into account weather fluctuations while still managing to control the overall lifecycle cost.

Lima explains that when considering a cap of 50 tons of CO2 emissions over a span of 21 years, the disparity in lifecycle costs among various weather datasets is relatively insignificant compared to the substantially higher cost associated with implementing a fully renewable energy system in all three cities. This suggests that imposing a CO2 emissions limit can help alleviate the impact of weather variability on lifecycle costs, making the overall cost of the system more manageable.

The researchers delved into the effects of a carbon tax and discovered that, based on the specific buildings and locations examined, a relatively substantial carbon tax would be necessary to stimulate the adoption of fully renewable energy systems that achieve zero CO2 emissions. This finding suggests that implementing a higher carbon tax can serve as a potential incentive to encourage the transition towards cleaner energy alternatives.

During the summer season, the demand for electricity is at its peak in all three locations primarily because of the widespread usage of air conditioning. In Jeddah, the need for cooling persists throughout most of the year, whereas in Riyadh and NEOM, heating is frequently required during cold days.

An additional observation is that extreme weather events took place in December and January, coinciding with cloudy days and high energy demand, rather than the periods of peak energy demand in the summer months. These findings suggest that the decision on the appropriate PV capacity to install should be based on the periods of lower solar irradiation.

The authors of the study assert that the overall findings have global relevance. For instance, energy systems that are connected to a grid are less susceptible to weather extremes. However, in fully renewable energy systems, the design and operation of such systems are significantly influenced by weather variability.

Group leader Omar Knio suggests that another avenue of research is to examine how climate change and extreme events affect the design and operation of energy systems. He proposes considering climate change trends and variability in future studies to assess the likelihood of disruptions in renewable energy supply. Furthermore, he emphasizes the importance of exploring countermeasures to mitigate potential negative impacts that may arise under different scenarios.

Saudi Arabia is known for having one of the highest rates of energy consumption and CO2 emissions per capita globally. This is primarily driven by the country's rapid economic development, which has led to a significant increase in electricity demand over time.

The Vision 2030 target set for Saudi Arabia aims to achieve a renewable energy share of 30 percent by 2030. This target is crucial in fulfilling the Kingdom's commitment to generating 50 percent of its electricity from renewables and natural gas. By incorporating renewables into its energy mix, Saudi Arabia can significantly reduce its carbon emissions, with an estimated reduction of 130 million tons by 2030. This ambitious target aligns with the country's sustainability goals and contributes to global efforts in combating climate change.