China's top oil company has taken over a major ethanol maker as it tries to expand in the renewable energy sector.

China National Petroleum Corp (CNPC) has signed a deal with Tianguan Group, based in Henan Province, to invest in the ethanol producer, Tianguan said yesterday.

Tianguan did not disclose the size of CNPC's stake. But according to China Business News, CNPC has taken a 55 percent share of Tianguan to become the controlling stakeholder.