Carbon dioxide emissions could fall by up to 12% in 2020 as a result of the Covid-19 outbreak.
The Sustainable Energy Authority of Ireland (SEAI) says early data received indicates a large drop but warns it will probably be temporary.
The SEAI says a reduction in petrol and diesel emissions so far could lead to a massive drop in CO2 emissions overall.
Fewer cars are on the road due to various COVID-19 restrictions.
The news comes after carbon emissions for electricity use fell by just under 4% last year, which is the equivalent of 1.5m tonnes of CO-2.
Head of data and insights at the SEAI, Jim Scheer, says this fall is down to a reduction in coal, with more focus on renewables. For example, the coal power station at Moneypoint is generating less electricity.
Mr Scheer says: "We've made great strides in the use of renewables for electricity generation mainly from wind and there is significant opportunities to do more there,
"So a huge effort in offshore wind, for example, could mean that Ireland could reach a stretched target of 70% renewables in electricity by 2030.
"We have a lot more work to do in renewables for heat and also in transport."