ERUs may be generated in the following manner:

(1) Actual emissions below GHG emission reduction requirement. Covered parties (including voluntary parties) may generate an ERU when actual covered GHG emissions, as reported per the requirements of chapter 173-441 WAC for a compliance period, are below the emission reduction requirements for that compliance period. The covered party may generate ERUs in an amount equal to the difference between the reported covered GHG emissions and the higher GHG emission reduction requirement.

(2) Emission reduction projects, programs, or activities. A project, program, or activity allowed under WAC 173-442-160 may generate ERUs consistent with WAC 173-442-150.

(3) GHG emission markets external to the state of Washington. A covered party may generate ERUs consistent with WAC 173-442-170.