Russia may have to start selling natural gas to Europe again - but that would maximize Moscow's revenue, Citi's commodities chief says

Citigroup's global head of commodities research said that Russia could make more money if it restarts natural gas flows during the winter.

The state-run energy giant stopped gas deliveries to Europe. The ability of Russia to sell gas to other countries is mostly limited to former Soviet republics, which aren't large enough to offset the volumes that went to Europe.

He said that Russia is going to run out of places to sell gas soon.

Russian officials have said that gas flows will not resume until European Union sanctions are lifted.

It may be in Russia's best interests to resume gas deliveries to Europe.

He said that there was only a small amount of switches Russia could make to sell gas to other countries. Russia might one day want to maximize revenue from natural gas.

He said that he wouldn't be surprised if Russia resumed gas flows after European countries ended their efforts to store gas for the winter.

He predicted that Europe would have to wait until the middle of the decade or later to be able to replace Russian natural gas with supplies from the US and Qatar.

A total Russian gas shutoff would plunge Europe into a years-long emergency according to the global commodity chief of the Royal Bank of Canada.

In an interview with CNBC, Croft said that this may not be a crisis just for this winter. Europe is going to have a huge supply problem if there is no gas in the future.