Instead, the Russians purposely designed Admiral Kuznetsov to utilize a dirty, cheap fuel source known as mazut. Mazut has a high sulfur content that is known for billowing black smoke emissions.

Regardless of the black-smoke-byproduct, Mazut is just inferior to nuclear power, which allows a vessel to operate indefinitely without refueling. The Kuznetsov can run for just 45 days at a time.