Europe's rush to fill its storage facilities with gas before winter has called for maximum use of alternative sources, from Norway to the United Arab Emirates, at wartime prices, Bloomberg reports.

A preliminary calculation by Ben McWilliams of the Brussels-based think tank Bruegel, using average gas prices of 140 euros per megawatt hour, puts the total cost of excess gas in EU storage between April 1 and October 31 at 107 billion euros.

That’s a big number, equivalent to about double the US’s total aid to Ukraine so far. The danger is that the bill for next year will be even higher. A cold winter could completely deplete existing storage facilities and start a new race to fill the reservoirs, only this time potentially without the 15-20% supply from Russia. "Prices for next summer are very high, reflecting the risk that storage will be used up this winter,” says Anise Ganbold, head of research for global energy markets at Aurora Energy Research in the UK. (Only about 10% of stored gas is under direct control of public officials.)

Much also depends on the ability to reduce demand, which comes at a cost. Countries are trying to soften the blow to households and businesses, but rising interest rates and financial market volatility are forcing countries like France and Poland to roll back financial support.

Worse, replenishing gas storage diverts resources away from longer-term needs to improve energy security. Investments in additional storage capacity, in expanding alternatives to fossil fuels, and in more energy-efficient technologies are all big budget items for the future.

“We shouldn’t rest on our laurels,” says Jacob Kierkegaard, of the Peterson Institute For International Economics.