Fuel part and mineral part of the thermoecological cost

The thermoecological cost, expressing the cumulative consumption of nonrenewable exergy per unit of the considered useful product, may be divided into the fuel part and the mineral part. The fuel part may be eliminated by the utilization of renewable exergy carriers. The mineral part cannot be eliminated. The depletion of mineral resources leads to the necessity of utilization of more and more lean natural resources. The equation system determining both parts of the thermoecological cost is formulated. Two numerical examples are included. The first one is a simple demonstration example, the second is detailed and relates to the Polish energy system