East China city pilots central cooling using water from abandoned coal mine

(ECNS) -- As outdoor temperatures approached 36 degrees Celsius this summer, Xuzhou City in east China's Jiangsu Province has piloted an innovative cooling project for residential compounds, using mine water from the abandoned Woniushan coal mine to keep homes comfortable.

Launched in the Rongshengcheng Phase V residential compound in June, the system uses 19-degrees-Celsius water from the abandoned Woniushan mine, circulating it through underfloor heating pipes — a network normally reserved for winter warmth — to lower indoor temperatures.

The four-month cooling season runs from June 1 through Sept. 30. Residents received free service for the first two months, and for the remaining two months, they are charged 4 yuan (about 56 U.S. cents) per square meter of floor space.

On Tuesday afternoon, with the mercury approaching 36 degrees Celsius and the heat index reaching 41 degrees Celsius, a wallmounted thermometer in one apartment in Quanshan District recorded a steady 26 degrees Celsius and 54% humidity.

"The cooling feels very gentle and comfortable, and there's absolutely no noise," said a resident surnamed Wang. She said nearly 100 households in her compound have signed up for the service.

The system pumps mine water to a surface heat-exchange station, where it is treated and circulated through the existing floor pipes. After heat exchange, all the water is reinjected into the mine, with no net consumption or discharge, said Zhang Tao, who oversees research at Jiangsu Xukuang Thermal Power Co, a subsidiary of Xuzhou Coal Mining Group. 

"The system reduces the heat-island effect caused by outdoor air-conditioning units and aligns with national energy-saving goals," Zhang said.

To tackle condensation, a common problem with floor-cooling systems, the company works with Yunlong Lake Laboratory of Deep Underground Science and Engineering to develop a dedicated water-cooled dehumidifier that maintains indoor humidity at around 50 percent, a level considered comfortable for occupants.

The pilot currently taps only a fraction of the Wolushan mine's geothermal water. Zhang said the company plans to expand the model to more residential compounds in Xuzhou, aiming to bring the underground "cold resource" to a broader population.

(By Zhang Dongfang)