A glut of European Union carbon-emission permits is limiting Germany's options to meet its 2020 greenhouse gas-reduction target. This led to a 74% slump in the cost of emissions since 2008, eroding the penalty for burning coal and prompting market reforms that probably won't start for more than three years. Forcing utilities in Germany to switch to cleaner natural gas from coal would cost about six times the current carbon price, according to Bain & Company.