Author: Dragan Stanković, Director of the Iron Gate Company Ltd. Kladovo

Introduction

The Iron Gate I hydropower and navigation system (km 943+600 of the Danube) was commissioned on 6 August 1970.

This gigantic facility, resulting from joint efforts of Yugoslavia and Romania, comprises two power plants whose overall power output is 2,280 kW, two navigation channels (l=310 m, b=34 m, h=5 m) and overflow dams, as well as other related facilities and riparian protection against backwater resulting from operation of the system. The backwater, or increase of water level of the Danube, is felt all the way to Novi Sad (km 1225+000), of the Sava to Šabac (km 105+000), and of the Tisza to Bečej (km 61+000).

The design of Iron Gate I was entrusted by the former governments of Yugoslavia and Romania to Energoprojekt of Belgrade and ISPH of Bucharest. On the basis of this design the works commenced on 7 September 1964 and the first cubic meters of concrete were cast on 15 May of 1966. The first kilowatts began to flow on 6 August 1970, and the giant was officially commissioned at a ceremony held on 16 May 1972.

The Importance of Iron Gate I HPP in Terms of Energy

Each power plant, Serbian and Romanian of the same size, includes six power units with Kaplan turbines of 190 MW nominal power per unit. During the design and construction phases, these were the largest units of the kind in the world, with a diameter of 9.5 m and a constant flow rate of 850 m3/s. Rotor diameter of the generator is 14.9 m, and the weight more than 60 tons.

• Maximum drop 34.5 m
• Calculated drop 27.16 m
• Minimum drop 21.90 m
• Installed flow rates 10,000 m3/s
  Installed power 2,280 MW
• Average annual production 11 billion kWh

To date the Iron Gate I HPP, which accounts for more than 20% of overall production in Serbia, has achieved the following:

• Produced about 232,000,000 MWh;
• Exceeded planning by 13.3%, meaning four annual outputs;
• Highest annual output 7,214,583 MWh in 1980;
• Highest monthly output 729,510 MWh in May of 1985;
• Power units on line 84% of possible time (after deduction of overhaul downtime), with a power of 137 MW.

Navigation Channels

The effect of Iron Gate I on navigation, relative to the natural condition of the Danube in the Iron Gate sector, was alleviated by two dual-stage navigation channels (Serbian and Romanian) of the following characteristics:

• Average chamber length 310 m;
• Width 34 m;
• Water depth at threshold of Serbian channel 5 m; and
• Available size 13.5 m.

These navigation channels and the increase of water level of the Danube upstream in the reservoir have improved navigation conditions since:

• Depth is not a limiting factor for vessels, and heaviest navigation is possible even under low flow conditions;
• It is possible to increase vessel tonnage and thus permit traffic of river and sea faring ships;
• It is no longer necessary to pilot vessels through the Iron Gate sector;
• The navigation season is extended;
• Significantly lighter means of tugging are used for the same tonnage.

Following is a rough comparison of navigation through the Iron Gate sector:

Prior to construction of Iron Gate I HPP		Following construction of Iron Gate I HPP
12,000,000 t	Rate of passage	50,000,000 t
800 t	Average vessel tonnage	5,000 t
120h	Average duration of passage through Iron Gate sector	31h
6.12 USD/t	Navigation costs through Iron Gate sector	0.62 USD/t

And here is some additional information on the Serbian navigation channel:

During the period from 1970 to 2011:

• 68,171 passages
• 356,540 vessels
• 203,741,595 tons of goods
• 417,984,154 tons of vessel capacity

Significance with Regard to Watercourse Regulation, Defence Against Flooding, and Adverse Effects of Water Level Increase on the Riparian Zone

Utilization of the hydropower potential is conditional upon construction of a protection system for the riparian zone of the Iron Gate I reservoir and timely prevention of adverse consequences resulting from changes of the natural regime due to long-term slowdown of the Danube and its tributaries.

The riparian protection system comprises:

• New and reconstructed embankments with protective liners;
• Protection of riverbanks and roadways;
• Protection of populated areas, cities, and industrial zones against external water and groundwater;
• Countless separate drainage systems;
• More than 60 pumping stations;
• Six partition dams and a navigation channel on the Tamis;
• Relocation and reconstruction of railroad tracks, roads, ports, power lines, cultural and historical buildings;
• Relocation of population;
• System of observation and monitoring of the reservoir and protection system;
• System of management, recording, and transmission of data and forecasts.

The effects of operation of the Iron Gate I HPP are reflected in many areas that have been addressed separately during the design, construction, and more then 40 years of operation. Today it is clear that the overall effects of construction and operation of the system have been favourable in the following basic domains:

• Economic energy effect (cost-effectiveness);
• Demographic effect;
• Effect on navigation;
• Effect on employment;
• Effect on tourism;
• Effect on public infrastructure; and
• Overall effect on economic development.
• Industrialization;
• Effect on transportation (roadways and railways);
• Effect on archaeology;

Modernization of the Iron Gate HPP

Production of Electrical Power

In the 21st century the Iron Gate I HPP will still represent the focal point of the power supply systems of Serbia and Romania, as well as the focal point of navigation on the Danube with its navigation channels falling within the framework of development of European Corridor VII.

In this regard, and in the sense of power supply, after various reviews by international and national specialists, both countries have initiated refurbishment and modernization of power units and hydro generators with a view to increasing their ratings. After the onset of operation (1970-1972), the power units have on the average been subjected to about 200,000 hours of operation each. The calculated operating life of the equipment has elapsed, and testing shows clear signs of ageing.

In order to avoid operation with increased frequency of failure and downtime, resulting in significant production losses and increased maintenance costs, as well as to prevent possible damage, it is necessary to refurbish the power units and vital ancillary equipment in a timely fashion.

Refurbishment of power units implies complete disassembly, replacement of a number of most vital parts, and detailed inspection and repair of other parts.

Following refurbishment, the status of the power units will equal that of brand new units and will secure their reliable operation over the next 30 years. This is the main goal of refurbishment.

An additional effect of refurbishment will be the increase of installed power from 180 to 190 MW per unit, made available by up-to-date technology. The annual output of the plant will increase by 130 GWh due to a reduction of overflow and a higher degree of efficiency of refurbished units.

Navigation Channel

After 42 years of operation of the Iron Gate I HPP, the standard operating life of the overall navigation channel equipment has elapsed. In addition to the efforts of Serbia and Romania, the construction of navigation channels was supported by Pan-Danubian countries at the time: USSR, Austria, Germany, Czechoslovakia, and Hungary. These countries secured the benefit of not having to pay the Iron Gate passage fee, which is still not charged. For this reason it is necessary to resolve the issues of capital equipment replacement and modernization of the navigation channel as the most significant node along the navigation route of the Danube, Rhine, and Main, or the navigation route along the Danube to the Black Sea. This would be in accordance with EU planning related to the Danube as Corridor VII, the Danube Commission, and other interested parties.

Above all, the aforesaid shows that there are significant and serious problems and opening issues due to the fact that the production of electrical power can no longer sustain the costs of maintenance, production, and overhaul of the navigation channel, as was the case in the preceding period of 42 years.

In this regard the Iron Gate Company Ltd. has asked the Federal Government and the competent Federal Ministry to proceed with an initiative that would secure the required financial support of the international community, European Navigation, and the Danube Commission, in order to guarantee safe navigation in the future, increased transportation along the Danube, and better co-operation between Pan-Danubian countries. This would further contribute to rapid development of tourism and other areas envisaged by EU planning.

Navigation Route Downstream of the Lower Pre-Port of the Serbian Navigation Lock at the Iron Gate II HPP

The program of construction of a navigation channel on the Serbian side of Iron Gate II HPP, in accordance with agreements and contracts between Yugoslav and Romanian parties, defines downstream navigation along the existing route entered in the navigation chart of the Danube. It is a known fact that this route was degraded in terms of traffic while still in the natural regime of the Danube.

Former Yugoslav navigation authorities have prepared designs of two new routes that represent a permanent solution but, of course, require specific regulation works and removal of a large number of shipwrecks dating back to World War II.

The Serbian side has photographed the shipwrecks by suitable methods, so that accurate documentation is available with locations and related technical measures.

On the basis of the above, it is clear that there are obvious problems relative to the Corridor VII program and initiatives on navigation safety and regulation of the navigation route in this sector of the Danube, that need to be resolved with the assistance of the Danube Commission and other European organizations.