Factbox: What are Europe's options in case of Russian gas disruption?

LONDON, Feb 15 (Reuters) - Concern has mounted over the possible disruption of supplies from Russia, Europe's biggest gas provider, following the buildup of Russian troops near Ukraine and heightened tensions between Moscow and the West.

Russia said on Tuesday some of its troops were returning to base after exercises near Ukraine and mocked repeated Western warnings about a looming invasion, but NATO said it had yet to see any evidence of de-escalation. read more

The U.S. administration and the European Union have asked other countries such as Qatar and Japan to help provide extra liquefied natural gas (LNG) shipments should Russia attack Ukraine and sanctions be imposed on Russia.

Russian gas flows to Europe have been lower than usual for several months already. European politicians say Russia is using high gas prices as leverage in a dispute over the Gazprom-backed Nord Stream 2 pipeline project.

Gazprom says it is meeting commitments to European customers. read more

WHERE ELSE CAN EUROPE GET SUPPLY FROM?

Europe relies on Russia for around 35% of its natural gas. Most comes through pipelines including Yamal-Europe, which crosses Belarus and Poland to Germany, Nord Stream 1, which goes directly to Germany, and via Ukraine.

Europe's gas markets are linked by a network of pipelines. Most countries have cut reliance on Russian gas over the years and there are also more supply routes that bypass Ukraine.

The Center for Strategic and International Studies (CSIS) said Ukrainian transit of Russian gas has been reduced by 70%, from over 140 billion cubic meters (bcm) in 1998 to less than 42 bcm in 2021.

By last year Ukraine was a transit corridor largely for gas going into Slovakia, from where it continued to Austria and Italy, the CSIS added.

The threat of sanctions if Russia invades Ukraine could impact flows through pipelines such as Yamal-Europe, Nord Stream 1 and TurkStream. Nord Stream 2 is awaiting certification before Russian gas can flow through to Germany. read more

The U.S. government has said Nord Stream 2 will not move forward if Russia invades Ukraine. Russian President Vladimir Putin said on Tuesday the pipeline is a purely commercial project which will strengthen Europe's energy security. read more

Other possibilities are that Russia suspends sales of gas to Europe in retaliation for sanctions, or military conflict causes damage to one of the pipelines which cross Ukraine bringing gas to Europe, said analysts at the Oxford Institute for Energy Studies.

Some countries have other options. For example, Germany, the biggest consumer of Russian gas, can also import from Norway, the Netherlands, Britain and Denmark via pipelines.

But Norway, Europe's second largest supplier, is delivering natural gas at maximum capacity and can't replace any missing supplies from Russia, its prime minister has said.

Southern Europe can receive Azeri gas via the Trans Adriatic Pipeline to Italy and the Trans-Anatolian Natural Gas Pipeline (TANAP) through Turkey.

Neighbouring countries can transfer gas via interconnectors, but nations may be unwilling to part with gas they might need and importers would have to pay a high price.

On top of all this, European gas storage levels are very low for winter, when demand is traditionally highest.

"Cushion gas" held in underground storage to maintain pressure levels could theoretically be used in emergencies, analysts say.

Longer term, the European Commission has proposed a system for EU countries to jointly buy strategic stocks of gas. read more

LNG imports to north-west Europe, particularly from the United States, have climbed this year as the price of Dutch gas, the European benchmark, is higher than its Asian LNG counterpart.

But there is a limit to how much LNG suppliers can produce and transport. Global liquefaction capacity is almost fully utilized and so are LNG vessels, think-tank Bruegel said.

Qatar, one of the world's top LNG producers, could send some additional gas to Europe, but spare supply is scant as most volumes are under contract. read more

Last week Japan said it could divert some LNG cargoes to Europe. The vessels would come from ports in the United States, rather than directly from Japan. read more

NON-GAS OPTIONS

Several nations have options to fill the gap with power imports via interconnectors from neighbours, or increased power generation from nuclear, renewables, hydropower or coal.

But nuclear availability is declining in Germany, Britain, Belgium and France due to ageing plants, decommissioning, phase-outs and frequent outages.

Under pressure to meet climate targets, several EU countries have shut down old coal-fired power plants or are not building new ones.

Some countries retain coal plants for back-up supply. Europe has been switching to coal from gas since the middle of last year due to high gas prices. read more

In past crises, countries have introduced measures to reduce industrial production at certain times, pay back-up generators to switch on supply, order households to curtail energy use, or enforce temporary power cuts.

HAS SUPPLY TO EUROPE BEEN DISRUPTED BEFORE?

The past 15 years have seen several disputes between Russia and Ukraine over gas, mostly to do with prices paid.

In 2006, Gazprom cut off supplies to Ukraine for one day. In the winter of 2008-9, disruptions to Russian supply rippled across Europe.

In 2014, Russia cut off supplies to Kyiv after annexing Crimea. Ukraine stopped buying Russian gas in November 2015.

Ukraine has reduced reliance on direct gas imports from Russia via a reverse flow mechanism, allowing Ukraine to import from EU countries.

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