China must invest about 220 billion yuan in natural gas distribution networks over the next 15 years if a planned fourfold increase in usage of the clean fuel is to be achieved, according to a senior researcher at the country's largest producer. Huge overseas gas supply contracts have been signed but the country needs to build an estimated 50,000 kilometres of pipelines by 2020 in order to lessen the reliance on heavily polluting fuels such as coal, according to Liu Keyu, vice-president of China National Petroleum Corp's research centre. Natural gas production was projected to rise from 34 billion cubic metres (bcm) last year to 130 bcm in 2020, he said at an industry forum. Beijing has allowed foreign firms to hold majority stakes in gas distribution ventures since March 2002 and granted generous tax breaks for firms in natural gas-based projects. These are part of a long-term scheme to increase households' share of the natural gas market to 35 per cent by 2020.