Strategic petroleum reserve (SPR) and alternative fuels are both important for energy security. In this paper, a quantitative energy security model is proposed to calculate the optimized scales of SPR and alternative fuels (e.g., coal-converted methanol). The coordinated model mainly focuses on cost-benefit analysis, including the economic costs of SPR and alternative fuels, and the benefits for ensuring energy security. Demonstrating examples in China have been analyzed, and it shows that SPR and alternative fuels have coordinated effects in ensuring energy security, while alternative fuel is a supplementary method for reducing the negative effects of the raise of oil price and related economic losses. By the end of 2030, the net present value (NPV) will be considerably large with 150-200 million tons of SPR and 50-100 million tons of alternative fuels in China. Quantitative sensitivity analysis have been introduced for optimum scales and net present value (NPV) of SPR and alternative fuels, demonstrating that GDP/oil price elastic coefficient, domestic production of oil and investment of alternative fuels are key parameters for energy security. This model provides a quantitative method for the evaluations of the national energy security strategy. (C) 2017 Elsevier Ltd. All rights reserved.