The move followed a wave of anti-nuclear protests sparked by the disaster in Fukushima, Japan.
German Chancellor Angela Merkel said that power use would be cut 10% by 2020 and renewables such as wind and solar energy would be further expanded.
But Polish Prime Minister Donald Tusk saw an opportunity for Poland's dirty coal plants.
"From Poland's point of view, this is a good thing," he said . "It means coal-based power will be back on the agenda."
European energy traders report that Germany is already making up for its energy shortfall by importing lignite coal from Poland and nuclear power from France.
According to the energy commissioner, Günther Oettinger, other energy sectors could soon enter the fray.
"We need more gas," he stated earlier this week (30 May). "After Berlin's decision, gas will be a driver of growth."
Tusk agreed. "If [Poland's] shale gas reserves turn out to be possible to extract on a large scale, we could also shift to gas-fired power plants," he said.
British curve gas prices rose to their highest level in six weeks on news of the planned German nuclear shutdown yesterday (31 May).
Traders reportedly expected more "flexible gas plants" to fill energy gaps left by intermittent renewables.
Sources in Brussels told EurActiv that while Poland was looking to export more fossil fuels, no energy "masterplan" yet existed in Berlin and it was too early to predict outcomes.
"In general we need a number of new power plants - preferably gas - probably also coal and these will have to be built in a relatively short period of time," a diplomat told EurActiv.
"For this reason, a Planning Acceleration Law will prepare the way for the new conventional power plants, which will balance out the nuclear energy, as fast as possible," he added, stressing it would be a huge challenge.
But campaigners claim that differences between Germany's ministries of environment and finance have been accentuated by pressure from power companies.
Jan Haverkamp of Greenpeace, talking to EurActiv, cited one firm as an example. "They generate less than 4% of their electricity from renewables," he said.
"They have bet on the wrong horse for the last decade and a half and their links are closest to the Ministry of Finance, so I'm not surprised to hear different tones coming from the Ministry of Environment, which is more independent."
Greenpeace have been strong supporters of a nuclear phase out in Germany, which they believe could be implemented by 2015 without endangering power supplies or raising CO2 emissions.
But the potentially climate-damaging nature of the nuclear-replacement fuels which were being talked up around Europe yesterday also sparked calls for reflection.
Sweden's environment minister, Andreas Carlgren, told the TT news agency that Berlin's decision was "unrealistic" and risked missing a vital issue. "How are we to meet the dual challenge of both cutting nuclear power dependency and of climate emissions?" he asked.
One Japanese diplomat, speaking in a personal capacity, raised a further issue. "Germany should have taken more time to consider all the aspects of energy security involved before making a decision," he told EurActiv.
