The energy quay wall: Results from a full-scale field test

Energy Quay Walls (EQWs) are innovative energy geostructures which exchange thermal energy with both soil and open water while providing a structural function. A full-scale EQW with thermally activated sheet piles was tested, measuring 8.4 m in length along a 1.75m deep canal, with the sheet piles embedded 13m into the underlying soil. Two different length heat exchangers were used: shallow (3 m length) loops primarily extracting thermal energy from the open water, and deep (15 m length) loops extracting energy also from the soil. The shallow loops demonstrated a high heat extraction rate per activated surface area (∼200 W/m2 at 8 °C water temperature, compared with ∼60 W/m2 for the deep loops), with their performance closely linked to the open water temperature. The shallow loops did not require time to restore surrounding temperatures, indicating stable long-term performance, yet can extract the least energy at the coldest time periods. In contrast, the deeper loops exhibit greater stability across varying open water temperatures and achieve the highest total energy extraction per quay wall length (∼900 W/m at 8 °C water temperature, compared with ∼600 W/m for the shallow loops). Realistic operation of the deep loops lowered the soil temperature by ∼2 °C.