Fusion Energy and Future Fusion Power Plants

Abstract Fusion energy offers clean, reliable power for future generations and is undeniably part of a fully sustainable energy mix. Fusion combines two light atomic nuclei to form a single heavier one while releasing massive amounts of energy. To fuse atoms requires extremely high temperatures and pressures, in a plasma, to overcome the nuclei’s mutual electrical repulsion — achieving these conditions on earth, which is typically achieved in stars, has a host of challenges. Within a magnetic confinement device (tokamak), plasma is heated using ohmic and a mixture of neutral beam and/or radio-frequency heating to exceed 80 million Kelvin (K) where fusion happens. Strong magnets are needed to shape and control the plasma. Generating and sustaining the extreme temperatures and magnetic conditions, requires significant amounts of energy — which is difficult to manage at scale. The technical challenge of efficiently and effectively extracting power from a fusion machine and integrating these multiple energy sources into a thermodynamic cycle is significant. This requirement is further compounded by the operational timeframes of typical tokamaks. These challenges and the scales of the next generation of fusion tokamaks will require significant thermal electrical power transfer and conversion technologies, as well as electrical infrastructure equipment. This paper illustrates these challenges by evaluating possible fusion power plant efficiencies and how this is significantly influenced by the thermodynamic efficiency of the power conversion technology. Experimental research has been in progress for nearly 70 years, but we are now at a tipping point with active private and public funded fusion power plants programs seeking to exploit fusion energy. UKAEA’s Spherical Tokamak for Energy Production (STEP) project and Tokamak Energy’s Spherical Tokamak Fusion Pilot Plant (ST-X FPP) are examples of such programs.