CANCUN, Mexico - China, the most coal-reliant country in the world, will face a few hard decades to raise its clean energy to 50 percent by 2050 but the prospects are good, a senior climate change expert said on Monday.

Among a diversified package of energy solutions, nuclear power will play a key role in the long term, which is expected to account for about 15 percent of China's energy consumption by 2050, according to Du Xiangwan, chairman of China's National Climate Change Expert Commission.

"The country will face a critical transformation period in the next 20 to 40 years," Du said in an exclusive interview with China Daily.