The designers of the National Energy Guarantee have warned doing nothing is "not an option", in a new paper that finds coal will not be affected by the policy in the first 10 years but the pace of the renewable energy rollout could slow without it.

The paper, which was sent to the states on Wednesday and contains the modelling underpinning the final design of the policy released last week, reaffirms that the combined average annual saving for households under the NEG will be $550.