During several recent years an increasing interest concerning behavior of various gaseous or liquid hydrocarbons mixtures with neat gaseous hydrogen is observed. The phase equilibria as well as flow properties have been studied and some practical implementations indicated. The main practical idea consists in a possibility to use such mixtures as a replacement for pure hydrocarbons actually used as the energy source. Application of hydrogen enriched mixtures seem to be a temporary solution for gradual decarbonization of energy resources. The advantage of such approach may consist in much smaller requirements for investment in various aspect of infrastructure needed for handling the fuels. The present work is devoted to computer simulation of carbon dioxide emissions for several scenarios based on different compositions of hydrogen mixtures with hydrocarbons. The simulations include estimation of calorific value of the mixture and composition of exhaust gases emitted after its combustion. The simulation, based on s.c. logistic function, evaluates several variants of time dependence of new fuels implementation, and consequently time dependence of changes in composition of emissions to atmosphere. The simulation can be used for choosing the ways of practical implementation management.