Oxymethylene dimethyl ethers (OMEn) are potential compression ignition fuels or blend components that enable drastic reductions in pollutant formation. By combining multiple conversion steps, OMEn can be produced from carbon dioxide (CO2) and hydrogen (H-2) and hence from renewable electricity. However, established processes for OMEn production are challenging to model and detailed analyses of OMEn production from H-2 and CO2 are not yet available in the open literature. In the first part of our two-part article, state-of-the-art models for the formaldehyde-containing mixtures involved in OMEn production are implemented in AspenPlus and used to analyze a process chain for production of OME1 from H-2 and CO2 via methanol and aqueous formaldehyde solution. The exergy efficiency of the process chain is 73%. Tailored processes aiming at improved heat and mass integration as well as novel synthesis routes leading to reduced process complexity or avoiding oxidative intermediate steps hold significant promise for future efficiency improvements.