Jan 12 (Reuters) - The U.S. Energy Department said it has approved a fourth exchange of 870,000 barrels of crude oil for release to Shell Trading (US) Co (RDSa.L) from the Strategic Petroleum Reserve (SPR). Combined, the Energy Department has provided about 8 million barrels of SPR crude oil to boost the nation"s fuel supply, including three previous exchanges awarded last month, the department said in a statement on Wednesday. Late in December, the department had approved a release of 2 million barrels of crude oil to Exxon Mobil Corp (XOM.N). In November, U.S. President Joe Biden"s administration announced it would release about 50 million barrels from its reserves in conjunction with other consumer countries, including China, India and South Korea, to combat the rising cost of fuel. read more Companies that receive SPR crude oil through the exchange agree to return the amount of crude oil received, as well as an additional amount, depending on the length of time they hold the oil, according to the Energy Department.