Life cycle carbon footprint assessment of coal-to-SNG/methanol polygeneration process.

The coal-to-natural gas project alleviates the shortage of natural gas in China by using the abundant coal resources, but it has the problems of single product and poor ability to deal with risks. The coal to synthetic natural gas (SNG)/methanol polygeneration process can solve this by coproducing chemicals and have the advantages of high economic benefit and energy saving. The impact of polygeneration process design on carbon emission reduction is still the key issue to be solved urgently. Therefore, for the coal-to-SNG/methanol polygeneration process, this paper explores the interactions between the polygeneration process design and carbon emissions by using life-cycle assessment method, and evaluates the environmental impact potential of the process. The fluctuations of industrial parameters are also simulated using Monte Carlo analysis, and most of the results are concentrated at ±6.5 %, which verifies the reasonableness of the results. And the carbon emission reduction effect of the polygeneration process is examined by comparing with coal-to-gas and coal-to-methanol processes. The results show that the polygeneration process will reduce carbon emission by about 7.9 % under the same output, which helps to achieve carbon emission reduction.