SGIP subsidies are supposed to go to projects which emit greenhouse gases below a certain threshold. At the moment, that limit is at 836 pounds of carbon dioxide per megawatt hour of electricity generation. As the California grid gets cleaner and more efficient over time, the SGIP limit is supposed to decrease.
The California Public Utilities Commission is now proposing to lower the emissions maximum by 5%. Many organizations in the energy industry have submitted written comments asking for a different number. Part of what's at stake is whether or not projects which rely on natural gas will make the the new cutoff.