U.S. gas reserves won't be enough to fill the gaping hole left by Russia in Europe, BloombergNEF strategists say.

The U.S. has become the world's largest exporter of liquefied natural gas, with much of that supply going to Europe as Russian gas flows have dwindled and the continent faced a serious energy crisis this winter. The International Energy Agency warned that even with a near-full supply of gas, the European Union is still at serious risk of supply shortages.

Gas supplies from the U.S. currently cover 40 percent of Europe's LNG consumption, according to a BloombergNEF report, compared to 45 percent of European consumption supplied by Russia before the war in Ukraine. But U.S. gas production is starting to dry up: exports are expected to fall below expectations over the next two years, with an increase of just 12% a year.

The year-over-year increase is not enough to offset the overall decline in Russian pipeline supplies, as less than half of those volumes are accounted for by the increase in LNG, said BNEF analyst. This means that gas exports to Europe are expected to be only a fraction of what will be consumed next summer, creating even more problems due to skyrocketing energy prices. Europe's base price for electricity, which is largely supplied by natural gas, has jumped by more than 1,000 percent compared to prices from a year ago.