Global energy consumption is expected to increase significantly due to the growth of the economy and population. The utilization of fossil resource, especially coal, will likely be constrained by carbon dioxide emissions, known to be the principal contributor to climate change. Therefore, the world is facing the challenge of how to utilize fossil resource without a large carbon footprint. In the present work, a nuclear–coal hybrid energy system is proposed as a potential solution to the aforementioned challenge. A high-carbon energy such as coal is integrated effectively with a low-carbon energy such as nuclear in a flexible and optimized manner, which is able to generate the chemicals and fuels with low carbon dioxide emissions. The nuclear–coal hybrid energy system is presented in this paper for the detailed analysis. In this case, the carbon resource required by the fuel syntheses and chemical production processes is mainly provided by coal while the hydrogen resource is derived from nuclear energy. Such integration can not only lead to a good balance between carbon and hydrogen, but also improve both energy and carbon efficiencies. More importantly, a significantly lower CO2 emission intensity is achieved. A systematic techno-economic model is established, and a scenario analysis is carried out on the hybrid system to assess the economic competitiveness based on the considerations of various types of externalities. It is found that with the rising carbon tax and coal price as well as the decreasing cost of nuclear energy, the hybrid energy system will become more and more economically competitive with the conventional option, which make it a potential viable solution for the future carbon-constrained world.