Where 𝑏 [-] is the learning exponent, 𝐿 𝑟 [-] is the learning rate, 𝑦 [$ t-CO2 -1 ] is the current capital or operating cost, 𝑎 [$ t-CO2 -1 ] is the FOAK capital or operating cost, and 𝑥 [-] is the ratio of existing capacity to the initial capacity of the technology. 𝐶 𝑁𝑅 = 𝐶 𝐺𝐶 1 -𝑋