Operational Energy, Cost and Carbon Optimisation Pathways for a Newly Constructed Off Grid City in The Kingdom of Saudi Arabia

Abstract

Saudi Arabia has committed to achieving net-zero carbon emissions by 2060. King Abdullah Economic City (KAEC) is a newly built port city comprising residential, retail, leisure and industrial sectors. The long term aim is for the city to reach 1 million residents from its current population of 10,000. It has the potential to serve as a leading model for achieving net-zero carbon emissions. This research was aimed at investigating low-carbon pathways for KAEC to mitigate its current carbon emissions, focusing on energy supply and energy efficiency to reduce consumption and hence emissions. A combination of top-down and bottom-up approaches to assess the transition pathway towards net-zero emissions was undertaken. The top-down approach involved analysing the city's (25MW) electrical supply and (114 GWh per annum) electrical consumption profiles. The bottom-up approach involved using simulation to model the interaction of different building elements, such as HVAC systems, insulation, appliances, and occupancy to assess energy efficiency approaches needed to support the research aim. It was found that actions such as upgrading the coefficient of performance (CoP) of the HVAC system from 2.5 CoP to 5 CoP , increasing AC set temperature (by 3Co) and occupancy change behaviour were predicted to reduce the electrical consumption in buildings by 44%, 8% and 13% respectively. In the absence of a local energy benchmark, the research also developed a building energy benchmarking scheme to evaluate and rank KAEC electrical consumption in relation to other global cities with similar climates. The benchmarking results showed that there is a substantial variation in buildings electrical consumption within KAEC. That is, the city's electrical usage in buildings is notably higher than that of global cities with similar climates, despite being recently constructed. II Commercial sector buildings in the KAEC were found to be around 16% higher on average than in Dubai, Singapore, Orlando and Los Angeles. Residential and education sectors are 57% and 50% higher than the average consumption in the benchmark cities. This contrast prompted an investigation of the identified performance gap and the COVID-19 lockdown provided a natural experiment to identify the reasons for this. The results showed that the operational strategy is occupancy-independent in many sectors in the city (i.e. similar consumption to non-lockdown periods) with the exception of the education sector, where a significant reduction in electricity consumption (80%) was observed during the lockdown. In terms of carbon emissions, the main driver of carbon emissions in KAEC is use of diesel for electricity generation with 90,503 tonne per year. The research analysed a set of scenarios to replace the diesel supplied electricity and identified that a 76.3 MW PV system connected to the national grid (when this connection becomes available) with option to export electricity at (USD 1.8c/kWh) as the most economical and emissions efficient solution for replacing the current diesel generation. This scenario in addition to upgrading HVAC system from 2.5 CoP to 5 CoP , increasing AC set temperature by 3Co and occupancy change in behaviour( to achieve 10% reduction) were found to be the optimum path towards net-zero emissions in KAEC.