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.
Studying daily data from India's national grid, analysts found that coal-fired power generation fell 15% in March and 31% in the first three weeks of April, while renewable energy generation increased by 6.4% in March and decreased by 1.4% in April.
Oil consumption has also been slowing since early 2019, researchers found, but noted that Covid-19 lockdown measures have had a "dramatic impact" on transport oil consumption, which fell 18% in March 2020 compared to the previous year.
Though oil consumption grew 0.2% during the fiscal year, this was the slowest growth in at least 22 years because of coronavirus, researchers said, adding there had already been slower demand in the sector earlier in the year.
Meanwhile, natural gas consumption, which increased 5.5% in the first 11 months of the fiscal year, is expected to fall by up to 20% during the lockdown, analysts said.
Though they note that the coronavirus pandemic is only affecting India's emissions in the short term, analysts said the disruption caused by coronavirus could "catalyse, reinforce or accelerate the factors that have already been driving Indian policymaking in this area."