Energy managers at the Essen headquarters of Ruhrgas, a subsidiary of E.on and Germany's largest gas importer, played out crisis scenarios: What would they do if the break in gas supply didn't end? How many days would their reserves last? And where could they find so-and-so many millions of cubic meters of natural gas in a matter of weeks?

This was no test: It was the real thing. Hour by hour, technicians nervously watched as pressure fell in German pipelines after the Russian monopoly Gazprom shut off natural gas taps for Ukraine on Jan. 1. The sudden decision in Moscow sent ripples of panic across Europe, and spot-market prices for gas climbed to unanticipated levels -- until the Russians gave in and repressurized the pipes.

Soon, Ruhrgas gave the all-clear. The gas supply was secure again, and the message of the day was: Don't worry. Everything's OK.

But the fact is that nothing is OK. Ukraine and Russia may have put their natural-gas dispute behind them, but in Germany the debate has just started. The cold-blooded way the Russians used their natural resource as a blackmail tool has made a lot of Germans realize, suddenly, just how vulnerable the national energy supply is -– and how dependent they are on the good graces of foreign suppliers.

Germany's energy consumption has grown quickly in recent years; the nation now imports roughly three-fourths of its fuel resources. Almost every liter of petroleum used in Germany comes from abroad (97 percent), and the national demand for foreign coal and natural gas has also grown. Roughly 83 percent of the gas used by Germans comes from abroad, and the imported fraction of coal used here has risen to over 60 percent -- up from 18 percent only 10 years ago.

A natural resources superpower

Of course, German utility firms do business with a number of different international suppliers. But one stands out: Russia is easily Germany's biggest supplier of natural gas, bigger than Norway or the Netherlands. The largest nation in the world also leads oil exports: Russia sells 10 times more petroleum to Germany than Saudi Arabia. Germans increasingly buy coal from Russia, too -- imports have multiplied ten-fold in five years. Russia has assumed third place in the world, after South Africa and Poland, for coal exports, and third place for exports of Uranium 235, the fourth most important fossil fuel. Russia, in other words, is a natural resources superpower.

And Germans survive on an IV drip. No other western European nation is quite so thoroughly under the former Soviet Union's sway as Germany. Politicians wonder how long things can continue to be "OK" when the nation is so reliant on an increasingly authoritarian regime . And, above all, do they have any choice?

All of official Berlin seems to have gone hunting for a "new mix" of energy sources. Everyone agrees it should be broader and more well-balanced –- tilted away from reliance on both fossil fuels and supplies from the east. An energy expert from the left-leaning Social Democratic Party (SPD), Hermann Scheer, sees the new energy debate as a clear signal in favor of renewable energy sources. "It's a wake-up call," he says.

On the other hand, Germany's economics minister, Michael Glos, from the right-leaning Christian Social Union, took the opportunity to rekindle the debate over nuclear power. Germany is the only industrialized nation with a (very popular) plan to phase out its nuclear energy program. The country intends to abandon nuclear power by about 2020, when the last German reactor is expected to finish its mandated 32-year lifespan. Glos wondered aloud if it wasn't time to "go back and think again" about extending the legal operating periods of Germany's nuclear power plants until he was whistled back to the bench by Chancellor Angela Merkel.

For years, of course, politicians have talked about re-jiggering German energy policy. Helmut Schmidt's cabinet gave up on the last platform of bright ideas in 1980. Since then, no German government has dared to lay out a complete and decisive strategy to answer the most pressing questions.

For example: What if the world's oil supply peaks in a few years? Can Germany really give up nuclear power? Would a coal renaissance make sense? And how can Germany spark real competition in its domestic energy markets?

These are the delicate questions raised here by the Ukraine crisis. Besides, Germany's growing dependency on Russian natural gas is only one example of the plight of German energy politics.

Since Russia began supplying gas to the Federal Republic of Germany in 1970, the country has relied on the natural resource pumping through pipelines with names like "Union" and "Brotherhood," which would also, in theory, provide for rising demand in the future. Three-quarters of newly built German homes have gas heating. Meanwhile, all of Europe uses more and more natural gas to generate electricity.

But according to Latvia's Andris Piebalgs, who serves as the EU's Commissioner for Energy, nations need to be careful about using too much natural gas in their energy portfolios. "That can be dangerous," he says.

The "super-giant" gas fields of western Siberia -- Urengoy, Yamburg, Medvezhye -- lie relatively close to Europe, but they're almost exhausted. "By 2015, at the latest, we expect a significant drop in supply" from those fields, reports the German Institute for International and Security Affairs in Berlin -- "calculating forward to a point in time when Europe's import needs will grow."

Indeed, the Russians want to develop more giant fields, with European help. The planned pipeline  linking Germany to Russia through the Baltic Sea promises a huge boost in supply. This northern European pipeline could even open up one of the largest gas fields in the world, in the Barents Sea. But that would also raise dependency on Russia, at least if Gazprom fails to cut the German firms E.on and BASF a share of the fields, as promised.

But the Russians also want to capture new markets, like China. According to the German institute's study, a new shift in attention towards the Far East would reduce Russian gas exports to Europe from a level of about 70 percent (in 2000) to about 33 percent (in 2020).

To make matters worse, import demand in the EU by then "will skyrocket to a level that will overwhelm both Russia's export capacity and its intention to provide." In other words: The west needs to hurry up and find some other source of gas.

For this reason, hopes have shifted south, to north Africa or the Caspian Sea. The richest alternatives seem to lie near the Persian Gulf -- especially in Iran. Tehran has control over the second-largest gas reserves in the world, only a fraction of which has been developed. But the politics are fragile.

Germany would also have to improve its infrastructure just to receive any gas from such remote places. Beyond 3,000 kilometers, delivery by pipeline ceases being economical, and gas becomes cheaper to move in liquid form, known as as "LNG" (Liquefied Natural Gas). Special freighter ships carry the gas -- which has been cooled down to minus 160 degrees Celsius and liquefied for transport all over the world -- except to Germany. The problem here is that no German port has the equipment needed to render the gas back into its natural state so that it can be pumped into a pipeline network. However, Wulf Bernotat, the chief executive of E.on, says his company wants to develop a facility for de-liquefying gas in the northwestern port city of Wilhelmshaven by 2010. LNG will become "an important extension of pipeline gas," Bernotat told SPIEGEL. The cooling process, though, is expensive, so the costs of LNG are still about one-third higher than the costs of pipeline gas.

But in the long run, such investments could pay off. There's no shortage of natural gas. Indeed, exploration has uncovered only about 17 percent of the world's estimated potential. The oil situation is different: about 36 percent of the world's oil has been extracted from the ground. The German Federal Institute for Geosciences and Natural Resources expects a drilling peak in 10 to 20 years. After that, production will sink as demand rises -- at least if consumer behavior doesn't radically change. For the first time in history, a gap in oil supply will open, and oil will stop playing a central role in the energy mix of industrial nations. But renewable energies won't catch up in time to replace it. Right now water power, wind power, and other "renewables" meet around three percent of Germany's energy needs.

Experts lay their hopes on "biomass," which can be converted to synthetic fuel. The earth's natural heat also has huge potential; geothermal energy could make "a decisive contribution to global energy demand," according to a study by Dresden Bank. But it will be years before geothermal energy truly bubbles to life.

Coal, on the other hand, would be instantly usable -- in huge quantities, even mined in Germany, though it is outrageously expensive here. Coal from German shafts costs up to five times as much as coal imported from abroad.

However, wherever it comes, coal -- in Germany mainly brown coal -- is the most important resource for generating electricity. Of course, coal-fired power stations are still a dirty business, and emissions-free electricity production from coal is still a long way off.

"Clean" atomic energy

Operators of atomic power stations don't have the same problems. Nuclear fission does not emit any greenhouse gases. And contrary to comments recently made by Germany's new environment minister, Sigmar Gabriel of the SDP, uranium supplies won't be tapped for a long time. Uranium mining operations have been neglected in recent years only because there was so much uranium on the market from dismantled nuclear weapons. Now, since prices for the raw material have risen, companies have invested in new mines. The Organization for Economic Co-operation and Development estimates that reserves will meet demand for well over 100 years.