Petrotel Lukoil Refinery is one of the largest Romanian oil refineries and one of the largest in Eastern Europe, located in Ploieşti, Prahova County. Its main activity is the processing of Romanian and Russian oil, but a separate unit is specialised in biodiesel production and another unit specialises in energy production. Russian oil is transported by oil tankers from the Novorossiysk Commercial Sea Port, unloaded at an oil terminal located in the Port of Constanţa, and transported to the refinery by rail or by a 250 kilometres (155 mi) underground pipeline that links the refinery to the port. In 2004, the refinery underwent a major modernization that reduced the production capacity of 3.5 million tonnes/year to 2.4 million tonnes/year but made the refinery more efficient, with a higher