Geothermal Exploration Through Deep Exploratory Slimholes: Singapore's Perspective

Abstract

Singapore is a small, densely populated urbanized city-state that relies on energy imports for self-sustainability and security due to the lack of natural resources. Aside from renewable energy sources, including solar energy, geothermal power could also be a viable domestic source of energy. Hot springs and anomalous regional heat flow indicate that the country have geothermal potential. Two deep exploratory slimholes have been conducted in northern Singapore to ascertain the presence of this resource. The first slimhole, located at Admiralty Lane, reached a depth of about 1.16 km in February 2023, while the second slimhole at Gambas Avenue reached a depth of 1.76 km in February 2024. The evaluated geothermal gradient at these sites exceeds the global average for continental regions, with temperatures at depths surpassing those in many other non-volcanic areas worldwide. Heat production from the granites is found to be higher than average compared to other granites worldwide. Extrapolated temperature data to depths of 4 – 5 km is high enough for various applications, including “green” electricity generation, hydrogen production, district cooling, and desalination. Geothermal heat extraction for electricity generation and space cooling are also considered. Techno-environmental results indicate that utilizing geothermal resources will significantly reduce carbon emissions even though most of the country's electricity is generated by burning natural gas, the cleanest fossil fuel. Considering that one-third of the electricity generated is used for cooling, the potential to meet a portion of this demand with geothermal energy would significantly enhance the country's ongoing decarbonization initiatives. Moreover, the levelized cost of electricity is found to be competitive with other renewable energy sources. In conclusion, the results are in favor for Singapore’s geothermal potential, warranting further exploration to depths of around 5 km. Utilization cases demonstrate their potential contribution to Singapore's decarbonization efforts, making geothermal energy initiatives significant for sustainable energy development.