The article delves into the journey of lab-scale nanotechnologies, specifically focusing on thermophotovoltaics (TPV) and proton exchange membrane (PEM) electrolysers. TPV technology shows promise with its compact and durable modules, efficient heat-to-electricity conversion, and affordable costs ranging from US$10–75 per kWh. Start-ups are working on scaling up TPV technology, mainly focusing on design robustness and material durability. On the other hand, PEM electrolysers for green hydrogen production have gained momentum, supported by global decarbonization efforts. However, a recent study highlights the need for substantial subsidies to support green hydrogen projects, with challenges related to operational infrastructure and rising costs. Research is ongoing to enhance the efficiency of water electrolysis by finding cost-effective alternatives to iridium as the oxygen evolution reaction electrocatalyst. Despite the potential of green hydrogen as a sustainable option, its competitiveness against grey and blue hydrogen, especially in regions with abundant fossil fuels, poses a challenge. Policy support is deemed crucial for the successful commercialization of green hydrogen technology, emphasizing the importance of ongoing research and innovation in the field.