European Union lawmakers have backed plans to reform the EU's vast greenhouse gas emissions trading scheme to protect it from fluctuations in the economy.
The system sets limits on certain greenhouse gases that factories and power plants can emit and allows companies to trade allowances if they cannot avoid more emissions.
Heavy fines are imposed on those who break the rules.
The European Parliament's environment committee voted Tuesday to introduce a "market stability reserve" into the scheme by the end of 2018.
The proposed reserve would bank unused emissions allowances, and release them in times of heavy demand.
The proposals must now be negotiated with EU member countries.