That's a great question. So I'll lay out some statistics, first.
According to the EU official website, the following is stated about their energy sources: In 2019, the EU produced around 39% of its own energy, while 61% was imported. In 2019, almost two thirds of the extra-EU's crude oil imports came from Russia (27 %), followed by Iraq (9 %). A similar analysis shows that almost three quarters of the EU's imports of natural gas came from Russia (41 %), Norway (16 %), Algeria (8 %) and Qatar (5 %), while over three quarters of solid fuel (mostly coal) imports originated from Russia (47 %), the United States (18 %) and Australia (14 %).
Effectively, the European's entire energy grid is utterly dependent on Russian energy provisions. But that's not all.
I am going to speak about Germany, because it's EU's biggest economy.
Germany imports nearly half of it's energy. Of that, 20-50% of the energy it imports comes from Russia Germany isn't alone in this, Italy, Belgium and Netherlands also import about 25-50% from Russia.
Now let's talk about Russia's energy exports. While it is true that Russia's energy exports are it's major bread and butter for it's federal budget, the EU isn't it's only major market. China is a massive importer of Russian energy. If the pipeline to Europe goes dead, it doesn't mean production will – and China is energy starved and more than happy to buy it from Russia.
Here is the map of all the Russian pipelines that go to Europe: so as you can see, there are even some that go through the Caucasus mountains, and Turkey. Which means bombing one a pipeline that shuts down all the arteries, means that you're also affecting the export/import structure of countries like Georgia, Armenia, Azerbaijan, and Turkey.
It's true that EU has pipelines from Algiers, and the ME that bypass Russia:
But, here's the thing. It's not a short-term couple of day thing for Europe to switch it's entire energy infrastructure to import more and more from the ME, and Norway. First off, you're also forcing these countries to the following: massively ramp up their oil producing capabilities, which means building more wells, pumping larger, harder, or, selling more to EU than to other places, which brings even more countries into the conflict. Second, Russia can live without pumping energy to Europe for a long time. The EU – being largely Democracies – would face civil and political unrest from an energy crisis that would absolutely devastate it internally.
The EU, effectively, has far FAR more to lose from losing energy from Russia, than Russia has from Europe. If those pipelines are bombed you're literally effecting the entire world's energy supply systems, and everyone will be involved.
And neither recommissioning, infrastructure, demanding and paying for more energy from other sources is going to be an overnight solution. It would be a minimum of years before it can ramp up the demand for energy it suddenly got cut off from. Months to switch the infrastructure supply lines, months more to recommission plants – hire the crew – make sure new supply lines are met, while months for exporting countries to either ramp up production (which is a major investment), or switch trade.
The question here is: will the general EU voter (keep in mind they are Democracies) be willing to live with several months, if not years, with extreme energy crises? Daily blackouts, rationed energy use, effectively live like they do in North Korea? Are they willing to pay the kind of prices even when they do switch?
Now here's even a bigger issue. Without energy supply, how do you even run a modern military? Without oil, how does your modern mobile infantry function? Without energy how does your technological statetigic apparatus handle? Russia will still have that energy, they will still have that oil to use for their own military. The Polish, the Latvians, Finnish, Estonians, would be even bigger targets due to their military unable to function like Russia. The EU would not be able to help either because again – their military also relies heavily on oil, energy, to function. The entirety of the EU strategic systems, it's militaries capabilities would be instantly crippled while Russia – who, at this point, would have every reason to do whatever land-grabs it wants to rebuild the USSR, would be at it's fullest supply might.
This will give impetus for a global conflict if Russia takes advantage of a crippled European power.
As far as Gunther is concerned, Gunther isn't switching from gas heating to electric heating. Because there is no electricity for Gunther to switch over to. The gas they use isn't just for heating homes, the gas imports from Russia is to power their electricity.