The biogas as produced in a generator is roughly a 50:50 mix of methane and carbon dioxide;  it is fine for use for on farm energy.  To produce RNG (renewable natural gas), the biogas is processed to remove most of the carbon dioxide.  Why do this?  It is required to put the gas into a natural gas pipeline system.  Why does the Climate Action Council not support RNG?  Because it takes a lot of energy, and so has lower efficiencies than using the biogas on site, and because it is very difficult technically to fully separate the methane and carbon dioxide, resulting in a substantial increase in methane emissions over simply using the biogas.

It would be a mistake to pass legislation that would lead to RNG production from dairy manure, and so should there be subsidies and encouragement for biogas digesters, the legislation should clearly discourage this.