FRANKFURT, April 30 (Reuters) - Germany’s government on Friday presented plans for so-called contracts for difference (CfDs), instruments that help companies in the steel, cement, lime and ammonia industries finance the transition to low-carbon technologies. A draft plan by the environment ministry, seen by Reuters, says that companies that commit to cutting carbon dioxide emissions by more than half using innovative technologies could be given the go-ahead to operate on the basis of 10-year CfDs. Through CfDs, the state reduces or partially finances higher operating costs than those in existing processes, decreasing uncertainty around the development of emissions permit prices and thus helping planning and access to finance. (Reporting by Markus Wacket and Vera Eckert, editing by Thomas Escritt and Veronica Brown)