The Keystone XL Pipeline could emit more carbon emission (CO2) because of the drop in oil prices.

In a letter to the International Energy Affairs department, the Environmental Protection Agency said the proposed pipeline would emit up to 27.4 million metric tonnes more of CO2 every year.

That’s equivalent to the annual greenhouse gas emissions from 5.7 million cars or building eight new coal-fired power stations.

The letter said while the project will be driven by long-term oil prices, the recent dip could lead to an increase in production, promoting further expansion.

This could lead to much more CO2 emissions over what would normally occur, it stated.

The letter stated: “Until ongoing efforts to reduce greenhouse gas emissions associated with the production of oil sands are more successful and widespread, the Final SEIS [Supplemental Environmental Impact Statement] makes clear that, compared to reference crudes, development of oil sands crude represents a significant increase in greenhouse gas emissions.”

Earlier this week, the US Senate passed a bill to Obama for approval of the pipeline.

President Obama, who has final decision over the pipeline previously said he would veto any bill being passed through congress that would allow the extension of the pipeline.