BEIJING - China's largest oil refiner, Sinopec Group, announced Monday it has signed a framework agreement with Icelandic geothermal developer Orka Energy Ltd to expand cooperation in developing geothermal resources.

Sinopec said the two will seek to grow their joint venture, Shaanxi Green Energy Geothermal Development Co Ltd, aiming to expand geothermal energy heating to at least 100 million square meters of house floor by 2020 in China.

The two are also bidding to build their joint venture into a world-class technology provider that integrates research, development and applications, according to Sinopec.

Geothermal energy is a clean energy that can be used for heating homes and generating electricity. China is rich in geothermal energy resources, the development and use of which will be crucial for the nation's energy savings and its building an environmentally friendly society.