Almost two-thirds of the thermal energy output in 1970 was based on natural gas fuel, and one-third, on coal--mostly coal of very low quality. Less than 3 percent of the fuel used was accounted for by oil. The proportion of natural gas in the fuel balance was roughly the same as in 1960 but ten percentage points lower than in 1965. The share of coal, particularly of low-grade coal, has been rising, in line with the government's policy of conserving natural gas for use in the petrochemical industry. In 1971 construction was virtually completed of a huge hydroelectric station at the Iron Gate on the Danube River, built jointly with Yugoslavia and equipped, in part, with turbines made in the Soviet Union. The station's twelve turbines have a total capacity of 2.1 million kilowatts and are planned to produce about 11 billion kilowatt-hours of electricity per year. The output is to be evenly divided between the two participating countries. Nine of the twelve turbines were reported to have been in operation in September, and six were reported to have been connected to the Romanian national power grid in November. Completion of the Romanian portion of the project almost doubled the country's hydroelectric capacity and increased its power output potential by about 15 percent. A second, much smaller, hydroelectric station with a capacity of 400,000 kilowatts and a planned output of 1.5 billion kilowatt-hours per year is to be built jointly with Yugoslavia on the Danube River below the Iron Gate plant. Plans for this station were to be initialed by the negotiators before the end of 1971, but information on the dates for the start and completion of construction is not available. Plans for the construction of yet another power station on the Danube River, as a joint venture with Bulgaria in the Cernavoda-Silistra area, were announced in the fall of 1971. This station is to have a capacity of 760,000 kilowatts and an annual output of about 3.8 billion kilowatt-hours. Construction is apparently scheduled to begin in 1975. An agreement with the Soviet Union to build a 440,000-kilowatt nuclear power station, using a Soviet reactor, was signed in May 1970. Construction of the plant is to begin in 1972, and completion is scheduled for 1978. The agreement culminated extensive negotiations with the Soviet Union and several noncommunist countries. The ultimate choice is believed by Western observers to have been dictated primarily by political considerations.