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One of the important targets of the economic planning is economic growth via enhancement of the labor productivity. In this regard, education expenditures play a crucial role. This study aims at investigating the effect of education expenditures on the level of human capital and economic growth through a computable general equilibrium approach. The data on economic variables and social accounting matrix belongs to the year 2001. Three scenarios on education expenditures are defined and their effect on human capital and economic growth are estimated. The results show that education expenditures have positive effects on economic growth and human capital. A 50% increase in education expenditures in the first period causes 3.81 and 5.8 percent increase in human capital and economic growth respectively. In the second period, the same increase in education expenditures affects human capital and economic growth positively by 5.4 and 7.3 percent respectively. Although separating the economic growth into human and physical factors in the first period shows that there is no relationship between human capital and economic growth, but in second period this separation causes a relationship between the two factors.

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Although fossil fuels consumption may causes to rapid economic growth, but due to related pollutants and its consequences, the world has suffered from climate changes. Moreover, fossil fuel resources such as petroleum, gas, coal and uranium are being exhausted rapidly in the last decades. Therefore, seeking an appropriate as well as low-cost alternative for the above-mentioned energy carriers is one of the most important research topics. Regarding this situation, the utilization of renewable energy sources especially solar and wind energies is very important. In this study, the social welfare is maximized and optimal trajectory of solar and wind energy substitution is derived by using an optimal control approach. The model is solved empirically by genetic algorithm using MATLAB software. The results show that assuming social discount rate of 5% and no reduction in solar and wind energy conversion cost during next years, transition from fossil energy to solar and wind energy must occur in 2089 while assuming a 50 % reduction in solar and wind energy conversion cost in every 10 years period, this transition must take place in 2032.