The 21st Century SPR Act directs the Secretary of Energy to request that the National Petroleum Council conduct a comprehensive study on modernizing the Strategic Petroleum Reserve, the nation's emergency oil stockpile. The report, due within one year of the request, must analyze improvements to the reserve's physical infrastructure and operations, including options to expand its geographic distribution, store refined petroleum products in addition to crude oil, increase storage capacity, and enhance pipeline infrastructure for faster filling and withdrawal. The bill also requires an evaluation of the Life Extension II project, which involves upgrades to the reserve's facilities. This legislation affects the Department of Energy, Congress, and ultimately American consumers and energy security, as the Strategic Petroleum Reserve serves as a buffer against oil supply disruptions. The report will be made publicly available and may inform future policy decisions on how the government manages its emergency energy supplies.