Apparently Germany dipped into their gas reserves last week for the first time this winter. Same chatter I was listening to said that countries like Hungary and Slovakia are most at risk while Netherlands, Denmark, Germany etc aren't though it would only take one really bad week to test the reserves.
Central European countries are most at risk. Indeed, Hungary, Slovakia, Austria, Croatia, the Czechs, Switzerland and a few others either have almost no (internal/own) gas reserves in the ground or have no infrastructure (pipes) connecting them to other sources, so they depend on the Russian gas pipelines.
Every country close to the North Sea (Germany, Poland, Norway, Sweden, the Neanderlands...) have access to gas from the sea. There's plenty of it and there is plenty of pipelines.
Today I read Hungary is buying gas from Oman (LNG, of course) and earlier they were talking about the construction of a pipeline connecting the country to Turkey and the Caspian region. This might take years to develop.
The EU wants to sell the North Sea gas (this is why Germany, the NeanderDutch, Denmark etc.) at galactic prices to everyone. This could make the northern richer European countries even richer. Non-EU member Norway could become even richer by selling its gas to most of Europe, but there aren't enough pipelines.
Europe should have become independent from Russian gas years ago. Now they cut themselves off without any backup infrastructure.
I think the Caspian and Mediterranean gas fields would be good options for Central Europe and the Balkans, Italy.
Luckily for Croatia, they have seaports and can import LNG. Yet, LNG comes in smaller quantities, costs more and only those near the post cities can benefit from "acceptably expensive" prices. Transporting LNG inland would have to be done via rail and that would make it too costly.
Italy imports mostly Russian gas (from what I've heard recently) and a bit from Algeria. Luckily Spain has stronger connections to Algeria.
The REALLY cold months in Europe usually come in January and can last all the way up to April. Wait and see what happens. A harsh winter could demolish half of Europe's economies, but would make the other half very prosperous (countries like Spain, Poland, Norway, the Dutchhollenders, Portugal, Romania, Denmark have almost no issues).
Some European countries are already running out of gas, I've heard.
This winter will be very expensive and dangerous for Europe. Let's hope for warm weather. Hope that global warming comes sooner!
