The inventory of energy resources has been examined many times in past years. It is evident that the fossil and light water reactor fuels, as our present energy resources, cannot be relied upon for ever as they will eventually disappear. Therefore, it is indispensable to seek alternatives. However, the difficulty of forecasting future energy resources come from the fact that either in case where the technical feasibility is adequate, the amount of supply is scarce, or in case where abundant resource is anticipated it is often accompanied by technical difficulty. In the present situation, it is in principle impossible to specify a single energy resource which mankind could rely on in the future.
Fusion energy is one of the options.
In order to evaluate the feasibility of fusion energy as one of the options, I would introduce two important viewpoints here. One is the safety and the other is the cost, whereas in general the technical feasibility and the cost are the fundamental issues for evaluating new technologies. As to the safety considerations, inherent safety of the fusion reactor as well as safety of specific reactors are addressed by the scientific experts. In regard to the cost estimate, on the other hand, we first have to clarify the significance of making a large amount of investment on fusion as one of the options, which does not guarantee its feasibility. However, we wili not be able to verity quantitatively that the amount of investment is appropriate.