SHANGHAI, Oct 13 (Reuters) - China"s yuan firmed on Wednesday, as data showed September export growth unexpectedly picked up, while investors awaited U.S. data due this week for more signals on when the Federal Reserve would taper its crisis-era bond buying programme. The People"s Bank of China set the midpoint yuan rate at 6.4612 per dollar prior to market open, weaker than the previous fix of 6.4447. In the spot market, the yuan opened at 6.4509 per dollar and was changing hands at 6.4456 at midday, 16 pips stronger than the previous late session close. China"s exports in September rose 28.1% from a year earlier, beating analysts" expectations, as solid global demand offset some of the pressure on factories from power shortages and a resurgence of domestic COVID-19 cases. Overnight, the dollar hit a one-year high on expectations the U.S. Federal Reserve will taper its massive bond-buying program next month, and on concerns over soaring energy prices which would fuel inflation. Investors are waiting for U.S. Consumer Price Index data on Wednesday and retail sales data on Friday for further clues as to when the Fed might begin winding down stimulus. Three Fed policymakers on Tuesday said the economy has healed enough for the central bank to begin to withdraw its massive support. Separately, China said on Tuesday it will liberalise coal-fired power pricing to tackle a worsening energy crisis which has led to production curbs across various industries. Higher electricity prices may push up prices of Chinese exports to a certain extent in the medium term, and the resulting reduction in the trade surplus may place certain depreciation pressure on the renminbi exchange rate, investment bank CICC said. By midday, the global dollar index stood at 94.356, while the offshore yuan was trading at 6.4485 per dollar. The yuan market at 0420 GMT: ONSHORE SPOT: Item Current Previous Change PBOC midpoint 6.4612 6.4447 -0.26% Spot yuan 6.4456 6.4472 0.02% Divergence from -0.24% midpoint* Spot change YTD 1.28% Spot change since 2005 28.41% revaluation Key indexes: Item Current Previous Change Thomson 100.12 99.97 0.2 Reuters/HKEX CNH index Dollar index 94.356 94.523 -0.2 *Divergence of the dollar/yuan exchange rate. Negative number indicates that spot yuan is trading stronger than the midpoint. The People"s Bank of China (PBOC) allows the exchange rate to rise or fall 2% from official midpoint rate it sets each morning. OFFSHORE CNH MARKET Instrument Current Difference from onshore Offshore spot yuan 6.4485 -0.04% * Offshore 6.637 -2.65% non-deliverable forwards ** *Premium for offshore spot over onshore **Figure reflects difference from PBOC"s official midpoint, since non-deliverable forwards are settled against the midpoint. . (Reporting by Jason Xue and Andrew Galbraith; Editing by Lincoln Feast.)