Europe imported more natural gas from Russia in the first 10 days of the war than before the invasion. Keeping it flowing is a crew of intrepid Ukrainians.

Minutes after explosions rocked the southern town of Mykolaiv early on Feb. 24, Yevhen, a pipeline engineer who leads the region’s main pipeline divisionarrived at work and drew up plans to operate potentially explosive natural-gas pipelines in a warzone.

Yevhen sent his wife and two children westward to safety. A skeleton crew had extinguished fires caused by Russian artillery, occasionally ducked into a bomb shelter—and coordinated gas flows both to local residents and customers of Russia west of Ukraine in Europe. The Wall Street Journal agreed to use only his first name.

“They’re ready to react to any turn of events,” Yevhen said of his staff.

About a third of the gas the European Union imports from Russia hurtles down a clutch of pipelines that thread their way through Ukraine. Massive Soviet-era pipes strike from east to west and spit Russian gas into the heart of Europe. Other pipes run diagonally from northeast Ukraine, past Yevhen’s station in Mykolaiv, through Moldova and into EU members Romania and Bulgaria.

It is left to Ukraine to keep the gas flowing. Ukraine itself doesn’t directly consume the gas Russia pumps through its territory. After Moscow annexed Crimea in 2014, Kyiv stopped buying gas from Gazprom. Ukraine meets its needs with home production supplemented by imports from Poland, Slovakia and Hungary, much of it gas that originated in Russia, was resold, and then returned to Ukraine through pipelines from the West.

The amount of gas shipped through the pipelines has surged since the invasion because of a quirk in the structure of Europe’s gas market. Under deals struck years ago with Gazprom PJSC, Russia’s state producer, customers pay according to the level at which gas traded a month ago when prices were lower.

Russian natural-gas flows from Ukraine to Europe via key checkpointSource: EustreamNote: Flows are through Veľké Kapušany on Ukraine-Slovakia border. Volume for March 7 is a forecast.
Russia invades Ukraine.Jan. 2022Feb.March0102030405060708090million cubic meters

As prices in northwest Europe rocketed, hitting a record of more than 300 euros a megawatt-hour Monday, it became more profitable for companies to max out imports from Russia.

Europe’s reliance on Russian gas is at the heart of awkward power dynamics between Moscow and the West. The mismatch between sanctions imposed on Russia’s financial system and Europe’s hunger for Russian gas shows the limitations of the push to make Mr. Putin to back down.

Many in Europe fear Mr. Putin will at some point turn off the gas taps as retaliation for the sanctions, a threat spelled out by Russia’s Deputy Prime Minister Alexander Novak on Monday.

Main natural-gas pipelines into Europe

About 109 million cubic meters of Russian gas shuttles through Ukraine a day. Eventually, that fuel arrives in home furnaces, power stations and factories across Europe, keeping the region’s economy humming and voters warm.

Inside Ukraine, more than a million residents are going without gas after fighting caused extensive damage to domestic pipelines. Districts of Kyiv and entire towns including Mariupol have no gas, according to the Transmission System Operator, or TSO. The dearth of fuel is contributing to a humanitarian crisis caused by Russia’s bombardment of residential areas in cities.

“Nobody feels safe,” said TSO Chief Executive Sergiy Makogon from a reserve dispatching station in western Ukraine, to which the company’s headquarters decamped from Kyiv a day after war broke out.