Hydrogen (H2) is a promising renewable energy source, and this study focused on developing technology for biological H2 production from formate using the archaeon Thermococcus onnurineus NA1. Through adaptive evolution, an engineered strain showed enhanced growth, formate consumption, and hydrogen production. The study identified genomic mutations responsible for this enhancement and optimized fermentation processes to further increase productivity. Additionally, formic acid from CO2 electroreduction was found to be an effective feedstock for biohydrogen production. This research showcases the potential of integrating CO2 electroreduction and biohydrogen production for a sustainable hydrogen economy. The study contributes to the shift towards renewable energy sources and highlights the feasibility of biohydrogen production as an environmentally friendly and cost-effective alternative. Liquid organic hydrogen carriers, specifically formate/formic acid, offer advantages for H2 storage and transportation, making hydrogen a more viable option for a green energy future.