An economic slowdown, the growth of the country's use of renewable energy and the impact of the coronavirus pandemic have all contributed to the fall, analysis from environmental website Carbon Brief has found.
Over the past year, India had already been seeing weakened demand for thermal power generation because of lower demand and competition from renewable energy, researchers said.
However, lockdown measures introduced to curb the spread of coronavirus caused a further, steeper "drop off" in March, pushing thermal power generation growth below zero for the first time in three decades. Carbon emissions fell by an estimated 15% in March, and a likely 30% in April, analysts said.
Studying oil, gas and coal consumption, researchers estimate that CO2 emissions fell by 30m tons in the fiscal year ending March, in what they say could be the first such annual decline in four decades.
Analysts from the Centre for Research on Energy and Clean Air (CREA) noted that demand for coal was already down in the country, with coal deliveries falling by 2% in the fiscal year ending March -- a first in two decades. However, this trend steepened in March, with coal sales falling 10% and imports falling 27.5%.
India imposed a nationwide lockdown on March 25 to stop the spread of coronavirus, closing factories, markets, shops, and places of worship and suspending most public transport and construction work.
Already, data has shown that cities are recording much lower levels of harmful microscopic particulate matter known as PM 2.5, and of nitrogen dioxide, which is released by vehicles and power plants.
Studying data from India's national grid and main coal producer, analysts said that disruption caused by coronavirus has cut India's demand for electricity, which has reduced appetite for coal.