China's first independently developed ocean thermal energy conversion facility has been tested in the waters of the South China Sea, according to the Guangzhou Marine Geological Survey, the facility's developer.

The relatively small 20-kilowatt OTEC facility was tested for 4 hours and 47 minutes and reached a maximum power output of 16.4 kW, but more importantly, it was the first time that China had achieved principle verification and engineering operation of an OTEC facility in actual sea conditions.

OTEC has been used in commercial electricity generation since the 1970s, with Japan and the United States playing major roles in its development. The process involves utilizing the difference in temperature between cooler deep and warmer shallow water in the ocean to run a heat engine to produce electricity.

"This offshore test verified the theoretical viability of the indigenously developed ocean thermal energy power generation system, as well as its practicability, marking a crucial step in China's journey to develop and harness ocean thermal energy, from the land test stage to offshore applications," said Ning Bo, a senior engineer at the Guangzhou Marine Geological Survey.

Guangzhou Marine Geological Survey cooperated on the project with the National Energy Research Center for Natural Gas Hydrate Exploration and Development, Guangdong Provincial Laboratory of Southern Marine Science and Engineering, and other research institutes.

"The device was independently developed, according to actual sea conditions in the South China Sea," said Ning.

A three-dimensional model of water temperatures in the South China Sea, based on previous investigations and research into ocean geology, currents and hydrology, was established before the launch of the OTEC facility.

The marine geological survey authority also uated and selected advantageous sea areas suitable for the development of OTEC in the South China Sea, according to Ning.

The OTEC facility was tested in a 1,900-meter-deep sea area of the South China Sea in August, completing the verification of thermoelectric power generation technology, with an effective power generation utilization rate of 17.7 percent, according to Ning.

After the test, the marine geological survey conducted comparative tests on the circulating pressure and temperature of cold and heat sources under different displacements using the already-constructed sea trial system.

"Collection of rich test data helps provide references for optimization of the system configuration, development of high-power engineering prototypes, large-scale applications and demonstration of power generation costs in the later stage," said Ning.