Oil and natural gas production at Alaska’s North Slope may have been declining since 1988 but the region holds promise if energy prices stay high and Congress opens key areas to exploration, the U.S. Energy Department is arguing.

The North Slope could yield up to 36 billion barrels of oil and 137 trillion cubic feet of natural gas under optimistic assumptions, the Energy Department said.

But for that to happen parts of ANWR would have to open, so would parts of the National Petroleum Reserve, as well as greater access given to the Beaufort and Chukchi seas.

Even if all that happened, it would only be enough to meet current U.S. oil demand for about five years and natural gas for a year and a half.