Where is the Fusion Power?

Ever since the early 20th century, the holy grail of energy production has been power generated by nuclear fusion. This technology held the promise of unlimited, clean energy that would take care of our planet-wide needs for a supposed fraction of the cost. It even promised the power to take us beyond Earth and to the stars. So, where are the fusion reactors?

The short answer is they don’t exist — at least not at the capabilities that were initially promised. At first, researchers imagined fusion without the huge amounts of heat that conventional fusion reactions (such as in stars) use: termed cold fusion. But cold fusion technology proved to be a dud, and has practically been written off by the scientific community. So nowadays complete focus of fusion reactor concepts are essentially on hot reactions, which take enormous amounts of temperature and pressure to sustain.

Proofs of concept for hot fusion reactions have existed in isolated laboratory experiments for decades, some costing billions of dollars to create. Yet over the decades of research, no fusion experiment succeeded in the first step of establishing fusion power as economically viable: being net energy positive. In other words, the energy put in to start the fusion reactions was always more than was actually produced by the reaction, effectively making fusion reactors a very expensive power drain. Of course, hundreds of researchers haven’t given up, and they see it only as a matter of time until our methods are refined enough to meet the net energy positive target.

Notable efforts in the field center around the concepts of using magnets to contain and pressurize high temperature plasma to effect fusion reactions, often in a tokamak (torus shaped) design. Currently, most efforts along this route have been creating ever larger tokamak reactors. This trend follows from the fact that the larger the reactor, the more plasma can be contained, therefore the more fusion reactions take place, and thus the more energy can be produced. ITER (the International Thermonuclear Experimental Reactor) is the latest and greatest among those reactors, slated for completion in 2025, with with 10 times the plasma volume of the largest reactor today. If projections for its capabilities hold, it may be the first fusion reactor to produce net positive energy. If true, the field would be revolutionized and humanity would be on the first steps widespread use of fusion power. However, ITER would by no means be the end of fusion research. For one, the cost of the project is currently estimated at $25 billion. Clearly, for fusion reactors to be truly economically viable, they should be able to compete with other sources of energy in terms of cost. Perhaps future large tokamak reactors will achieve this, but likely nowhere near the present day.

But researchers at MIT are offering another approach that just might address the concerns of being net energy positive and cost effective fusion reactors. Put simply, MIT is a proponent for the “smaller-faster-cheaper” approach through their SPARC reactor experiment. Like ITER, it utilizes the tokamak style of reactor, with the important addition of new high-field, high-temperature superconducting (HTS) magnets. The HTS magnets allow for a more compact reactor design, that should result in a much cheaper project than the traditional approach. If it realizes its promises on its projected launch in 2025, nuclear fusion will have become leaps and bounds closer to being economically viable.

Of course, ITER and SPARC are just the tip of the iceberg when it comes to tokamak reactor projects, let alone the many other experimental fusion reactors. They do however prove to be among the most eye catching and promising projects. Perhaps the holy grail will never be completely realized and fusion power will become economically viable but not unlimited, or with incredible upfront costs in capital. Or perhaps it will be everything we want and more — but decades away down the road. I know I will be watching with optimistic anticipation come 2025. Will ITER and SPARC, and other experiments like them, succeed and prove to an ever more desperate world that fusion power is the future, or will they fall short like all of the previous attempts?

Image courtesy of MIT News.