Environmental and energy benefits assessment of alkali-activated concrete (AAC) energy pile

Abstract

Energy piles provide an innovative strategy for exploiting geothermal energy in low-energy buildings, as they simultaneously provide energy for space conditioning and support structural loads. In addition to research efforts aimed at improving the energy efficiency of energy piles, a significant amount of CO2 emission from concrete production has been overlooked in energy piles’ application. This study proposes an innovative energy pile utilizing alkali-activated concrete (AAC) to reduce CO2 emissions and meanwhile improve energy extraction capacity. A systematic investigation of the energy and environmental benefits of AAC energy pile is conducted. After characterizing the material properties of AAC and traditional Portland cement concrete (PCC), the CO2 emission is evaluated. Furthermore, a numerical model for energy pile is established to study the energy harvesting potential of AAC and PCC energy piles under different operating conditions. The results show that the AAC energy pile is a promising technology that will not only extract approximately 17% more thermal energy due to its improved thermal properties, but also reduce CO2 emission by 32% compared to PCC energy pile. This study demonstrates the feasibility of AAC for energy pile construction and will provide support for the design and implementation of AAC energy piles.