ANALYSIS-To tackle climate change, China must overhaul its vast power grid Reuters 4 hrs ago * China to peak carbon emissions by 2030, neutral by 2060 * Pledge could have major impact on global warming * Upgrading China's electricity grid is a major hurdle By Muyu Xu and John Geddie BEIJING/LONDON, May 19 (Reuters) - One of the most pressing challenges for China to meet its pledge to cap carbon emissions this decade and pivot toward renewables is overhauling its electricity grid, the world's largest, officials and analysts say. Beijing's surprise announcement last year that it would hit peak emissions by 2030 and become carbon neutral by 2060 could presage the biggest reduction in projected global warming of any climate commitment to date, researchers say.