The southern Bulgarian city of Plovdiv is benefiting from a national district heating rehabilitation program that will make heating more affordable.DATUM 2023-11-28 AUTOR Violeta Simeonova
During the last few years many Bulgarians have found their incomes falling and district heating unaffordable, despite heavy government subsidies. A rehabilitation program now in progress has two primary goals. The first is to increase efficiency and cut per-unit costs because heat losses from the existing systems are high: 17 percent in production and about 20 percent in transmission.
The second is to put consumers in control of their consumption – and their bills – by installing meters and thermostats. In the existing system, houses and some public buildings are not yet equipped with meters, so bills are based on an average price for a cubic meter of heated area. Even though bills are high, there is no incentive to conserve heat. Nor is there any means to do so, because there are no thermostats to control heat and reduce consumption.
Bulgaria’s heating problems stem partly from an aging infrastructure. The nation has 22 district heating systems that supply heat to households, industry and government institutions. The existing distribution systems and substations are more than two decades old, and many components are operating well beyond their expected life span. Supply pipes are corroded, breakage is common and the downtime for repairs can be significant.
Plovdiv’s thermal power plant was opened in 1970. In 1979, it launched a district heating system by connecting two residential buildings to its network. In 1983, another district heating station was built: Plovdiv South.
The company also owns two local heating stations in the downtown area and one district heating station in the nearby city of Asenovgrad. It serves 70,000 households and 35 enterprises that receive both heat and steam for processing needs.
Restructuring was initiated last May by the state energy agency, and the company is now called District Heating Plovdiv plc (DHP).
Important to regulate heat
Restructuring was clearly needed, says Mirko Ugrinov, executive director. “The connecting stations and the automatic control are old-fashioned,” he says. “They are 30 years old and do not provide adequate control. That, of course, results in a loss of energy. The heat supply shrinks – and so does our good relationship with customers.
“Regulating heat is the most important problem we face. That’s why we asked the state energy agency to review policies applying to district heating systems and to put a new philosophy into place. Our main priority is the consumer.”
From 1996 to 1999, customers in the southern area of Plovdiv alone dropped by 50 percent. “That sent a really strong signal,” Ugrinov says.
In terms of volume, the total decrease was 38 percent in Plovdiv. Many customers turned off the heat in parts of their apartments or houses. Another 5,600 households – 8 percent of DHP’s customers – gave up district heating altogether. “We realized that we needed to change the entire structure of the heating supply,” Ugrinov says.
Under the existing structure, about 10 percent of heat generated was being lost for technical reasons at the source, Ugrinov says. 15 to 17 percent more was being lost in transmission and 2 percent in the connection stations. As little as 70 percent of the original heat generated actually makes it into buildings, but customers must pay all the costs involved in generating it. “The result is very high bills,” Ugrinov says.
Unusually short heating seasons recently in Plovdiv also have contributed to the problem. The heating season in 1995–96 was 165 days. Last winter it was only 126 days. In Sofia, the heating season also has been abnormally short in recent years.
A gradual upgrade
Over the last year, DHP started the gradual rehabilitation needed to address the system’s problems. First it upgraded the direct district heating stations that operate with hydro pumps, outfitting its old connecting substations with new efficient plate heat exchangers.
“The quality and the results are very good,” Ugrinov says. The changes are complete in the Adata district of Plovdiv. The complete substations supplied by Alfa Laval, Sweden in 1996 operate very well. “The new stations are very compact. They are small compared to our old ones, which used to fill rooms,” Ugrinov says.
The current project will also include installation of new thermostats in 1,500 stations under a contract that was finalized in October. The two-year project is financed by the World Bank, which has loaned more than USD 6.6 million (7.5 million euros) to rehabilitate district heating systems in Bulgaria.
“Because of the higher efficiency in heat transmission and the gradual introduction of individually controlled thermostats, we expect customers’ bills to drop up to 25 percent. Although they pay less, customers will enjoy the same comfort, because they will be able to control and adjust the heating in their dwellings,” Ugrinov says.
The DHP itself is available for privatization and at least five western investors have expressed interest, he said. But privatization is not imminent because of the need to first alter regulations and laws. The state energy agency still must define who can be approved as a strategic investor and under what conditions. “But there is more at stake than money in Bulgaria’s district heating systems,” says Victor Nikolov thermal manager of Alfa Laval’s Sofia office. Access to reliable and affordable heat, especially in light of the country’s economic crisis, has great social significance, he says. “The rehabilitation and technological upgrades help lower the social price paid by the people.”
Making district heating in Bulgaria more efficient
Since 1996, Alfa Laval has supplied District Heating Plovdiv with a large number of heat exchangers, complete substations and spare gaskets.
In the project financed by the World Bank, Alfa Laval supplied only components for about 500 connecting stations. More than 100 stations have already been replaced. The current contract is for 462 brazed heat exchangers in total.
The new heat exchangers, despite their smaller size, have a higher capacity than the old ones and are more energy efficient, leading to lower fuel consumption. They also avoid leakage and decrease maintenance costs.
A contract was also signed with Alfa Laval for replacement of the brazed heat exchangers used in its hot water supply system. That work will proceed parallel to the heating system upgrade. Alfa Laval also helped to arrange the financing.