The amount of electrical energy produced over the lifetime of the ARIES-RS and UWMAK-I DT-fusion power plants is compared to the total amount of energy required to procure the fuel, build, operate, and decommission the power plants. The energy payback ratio varies slightly for the two power plants; 23 for ARIES-RS and 26 for UWMAK-I. By knowing the magnitude of the energy investment and the source of the various energy inputs, a CO2 emission factor is calculated. This number is similar for both fusion power plants with ≈8 tonnes of CO2 per GWeh for UWMAK-I and ≈9 tonnes of CO2 per GWeh for ARIES-RS. These fusion plants are compared to other existing electrical producing power plants.