Below is a brief analysis of the beneficial effects of shifting to CNG (Compressed Natural  Gas) as fuel for vehicles, instead of of power generation plants:

1. Use of CNG as fuel for electric power generation: Since nuclear power plants have become unpopular (due to security fears after 3-Mile Island and Chernobyl nuclear power plant accidents), coal burning power plants also became unpopular (due to concerns about global warming), and hydro-electric power generation has almost reached its natural upper limit. 40 years ago the US decided to use CNG as fuel for power plants built in the future. CNG is mostly methane (CH4); when burnt, each molecule of it releases one CO2 molecule and two water (H2O) molecules, so generating power by CNG is  only about a third as damaging (in terms of CO2 releases) as generation from coal. Now a significant (about 20%) of our electricity comes from CNG.