Benefits of chrysopoeia to the economic value of fusion

Using Hg-198 as a neutron multiplier in a D-T fusion plant allows the production of 2 tons of Au-197 each year per thermal GW of fusion power [1]. This would have an economic value similar to, or greater than, that of the generated electricity. The production of gold (chrysopoeia) and electricity would increase the marginal value of fusion plants and their net value to society. It would ease the business case of FOAK plants, encourage larger fusion fleets, and allow it to enter markets where selling electricity alone would be insufficient.

We model fusion plants in a future (circa 2050) US Eastern Interconnection. In a fully-decarbonized system an electricity-only fusion plant could require a capital cost of $7/W or less to enter the market (assuming a 4.5% weighted average cost of capital and 30 year lifetime); but with chrysopoeia acting as a subsidy of order $60/MWh, the cost threshold would increase to $13/W. An electricity-only plant costing $6/W would have an addressable market of 20 GW, with a fleet-wide societal cost savings of $1.3 B/year; but a co-producing plant costing $10/W would have a market size of 245 GW and the fleet would provide a cost savings of $20 B / year. Additionally, chrysopoeia would lower the incentive to decrease production when electricity prices are low, potentially simplifying plant engineering by reducing cyclic thermal fatigue.

[1] Rutkowski, A., Harter, J. and Parisi, J., 2025. Scalable Chrysopoeia via (n, 2n) Reactions Driven by Deuterium-Tritium Fusion Neutrons. arXiv:2507.13461.