Assessing urban heat island intensity and emissions with compressed natural gas in non-commercial vehicles

The paradigm to shift toward cleaner fuel in vehicles and upgrade emission norms is a frequent discussion. The current study is a narrative of comparing fuels (gasoline, diesel, and compressed natural gas) in non-commercial four-wheel vehicles on the urban heat island (UHI) and their effects on emissions of greenhouse gases (GHG) and pollutants. We assume all such vehicles are single-fuel driven at a time in the densely populated urban city of Delhi, corresponding to the fiscal year 2017. We estimate that CNG can potentially raise the local temperature due to vehicular heat released and increased power plant load during summer by 1.09 °C and produces ∼1.6 times more heat than gasoline and diesel vehicles for the same distance traveled. CNG lowered the PM2.5 emissions by 81%, NOx by 45%, and VOC by 3%, while CO emissions increased by ∼14% and GHG emissions increased by 15%. For natural gas to become more effective, CNG vehicles' efficiency needs to improve, and the dependence on electricity should be more on cleaner resources. The analysis is based on estimates for Delhi, although the results would apply to other cities in India and globally.