Home appliances hanging on the wall stood out in many rural houses in Hantianling Village, northwest China's Ningxia Hui Autonomous Region.
Powered by both geothermal heat and solar energy, the appliances helped keep the houses warm -- at above 22 degrees centigrade -- while the outside temperature dropped to minus 18 degrees in the mountainous village.
The heating system was developed by engineers with China National Nuclear Corporation (CNNC), who sought to tap rich geothermal and solar energy resources to bring more green power to remote villages.
To install the system, the engineers drilled pipes 150 meters deep into the ground in villagers' courtyards and installed photovoltaic panels on their rooftops.
As part of the CNNC's aid program to less developed areas, the systems were provided to the villagers free of charge. In summertime, they can also function as coolers.
"We developed the systems powered by geothermal heat and solar energy after learning about the shortcomings of traditional ways of heating in rural homes," said Wang Yiwei, a CNNC official posted in Tongxin County, which administers Hantianling Village.
Traditionally, villagers used coal and sheep excrement for heating in winter, which was costly, inefficient, and could pose a safety hazard.
In Hantianling, over 30 households have now benefited from the new systems, which are also much less costly than traditional ways of heating.
For the family of villager Yang Yueying, the system saved about 1,400 yuan (about 206 U.S. dollars) in heating costs during the winter.
"Warm air blows into the room with a simple click of the remote control. The room is much warmer than it used to be when heated by burning coal," Yang said.
With the success of this pilot heating program in Hantianling, engineers of the CNNC plan to expand the program to more villages in Ningxia.
"We believe the heating system can provide a feasible technical solution for green heating in rural areas in north China with similar climate and geothermal resources," Wang said.