Will Fusion Become Commercial?
The road to fusion energy is now in its third stage. Between 1970 and 1980 the first reactors, such as the United States’ TFTR, Europe’s JET, and Japan’s JT-60, demonstrated the scientific feasibility of fusion making it clear that the concepts developed by researchers were valid and functioning. Second, a large machine had to be built to demonstrate technological feasibility by producing large quantities of energy and testing certain technologies essential to building a fusion reactor. This is the milestone that ITER represents. Third, a machine should demonstrate the commercial viability of an industrial prototype and produce electricity. This will be a demonstration fusion power reactor (DEMO). Each ITER member has already defined the broad lines of what its own DEMO might be. It may open the door to industrial exploitation. What does this mean exactly? ITER is expected to produce 500 MW of thermal fusion power compared with about 50 MW that will be injected for the purposes of heating plasma. This represents a “gain factor” of 10. However, if we want to estimate the energy efficiency of a tokamak and its potential use as an energy source on the industrial scale, we should consider not only the heating power injected into the plasma but the power that will be supplied to all its equipment and systems during the experiment (all necessary to keep the plasma at a given temperature). The industrial viability of fusion energy will only be proven if the output power exceeds the power consumed by the complete installation. What would be the point from an economic point of view of ITER producing 500 MW if it turns out that the average electricity consumption on site is the same, or perhaps even more? Before fusion can become an industrial source of energy yet another major challenge is to identify the best economic conditions for its industrial exploitation. This involves, in particular, finding new structural materials for tokamaks. Last but not least the supply of some existing materials might be an issue in the industrial age of fusion.