Assessing and exploiting the interaction between ventilation and geothermal systems in an underground data centre

Abstract

Digitalization and population growth lead to the development of underground data centres, while simultaneously current climate goals stimulate the development of renewable energy sources. In this framework, this study evaluates the so far unexplored domain of geothermal activation of an underground data centre using numerical modelling. Computational fluid dynamics simulations are used to properly represent the air domain. The focus of the work lies on the analysis of the interaction between ventilation and geothermal systems in the data centre, a topic that has never been evaluated for energy geostructures in general. This leads to the possibility of suboptimal air ventilation system design and thus a potential for optimization, especially in underground data centres where daily ventilation requirements are determined by air temperature limitations. The analysis first explores the sensitivity of geothermal potential to varying ventilation conditions (airflow velocities), heat release conditions in the data centre and fluid velocities in the pipes of the geothermal activation. The impact of geothermal activation on air temperature in the underground data centre cavern is then assessed and thus the consequent impact on the ventilation system. Geothermal activation of a section of the cavern leads to a regional decrease in air temperature, which allows optimization of the whole system by reducing mechanical ventilation requirements while still respecting the temperature limitations within the data centre. The economic and environmental benefits of this optimization are also explored. Overall, it is proven that ventilation conditions have an influence on the geothermal potential that can be extracted, and optimization of the complete system is possible when considering the effect of geothermal heat extraction in underground data centres while determining their ventilation requirements.