European directives require that 20% of energy must come from renewables by 2020. But, while policymakers have helped drive down the price of emissions permits in the ETS by mandating and subsidizing renewable energy, the supply of permits has not been reduced.
欧洲的方针要求在2020年时必须有20%的能源来自于可再生能源。政策制定者们通过批准和补贴可再生能源使得排放交易系统中的许可价格降低，但这类许可的供应却下降了。结果对许可的需求低到无法附加任何捆绑条款。到了2013年4月，许可价格已经跌到3欧元每吨，导致排放交易市场基本停滞。