Professor Zeng Rongshu flew back to Beijing on New Year's Eve with something rather unusual in his suitcase: rocks.
They were no ordinary rocks. Black and covered in oil, they were the fruits of two years spent trudging across some of the remotest parts of the country in search of an answer to a question that could have huge economic consequences.
Can carbon dioxide emissions be used to dramatically increase oil production on the mainland?
That is what Zeng, a geologist from the Institute of Geology and Geophysics, Chinese Academy of Sciences, is trying to find out.
Zeng's research, into the suitability of mainland oilfields for storing carbon dioxide, is part of an ambitious national research programme, funded by the China National Petroleum Corporation (PetroChina), on carbon capture and storage (CCS) technology.
CCS is one of the most talked-about methods of cutting greenhouse gas emissions. While hugely expensive, its implications for extracting the rest of the world's oil supplies makes it highly significant.