<Tr> <Td> 2015 </Td> <Td> 3,527 </Td> <Td> 199 </Td> <Td> 3,726 </Td> </Tr> <Tr> <Td_colspan="4"> Excludes Hong Kong </Td> </Tr> <P> Coal remains the foundation of the Chinese energy system, covering close to 70 percent of the country's primary energy needs and representing 80 percent of the fuel used in electricity generation . Coal has grown rapidly in importance in recent years along with the rising demand for electricity . In 2011, according to the IEA, Chinese coal production was equivalent to 3,576 Mt * 0.522 toe / Mt * 11.630 TWh / toe = 21,709 TWh . Assuming the same caloric value for the imported coal, the net coal energy available would be 22,784 TWh . Equally calculated available coal was 17,000 TWh in 2008 and 22,800 TWh in 2011, with increase of 5,800 TWh in three years . Total renewable energy in China was 3,027 TWh in 2008 and 2,761 TWh in 2005, with increase of 266 TWh in three years . Same period from 2005 to 2008 annual coal use increased 3,341 TWh . </P> <P> China's coal supply was in 2009 18,449 TWh which was 47% of the world coal supply . </P>

What is the leading source of energy used in china