District heating: cities that generate their own heat
A central heating system as any community of neighbors, but big. In the case of district heating, a city or neighborhood has a facility that produces heat and is channeled through the streets to reach all households, like water or gas . Several cities and districts of countries around the world, including Spain, have this type of network.
The heat production is based, in general, cogeneration plants, but increasingly used renewable energies such as biomass, solar and even waste heat from nuclear power plants and municipal waste incinerators.
The district heating is based on a power close to consumers that produces heat. Through a system of insulated pipes, usually underground, heat is distributed to buildings of a neighborhood or city that are part of the network. The most common means to distribute the heat is water, but steam can also be used.
To meet demand situations more intense, with storage systems that store energy in times of low consumption. The heat is distributed not only can be used to heating, but also to produce hot water and air-conditioned cool in summer.
The most common is the central cogeneration. These facilities use fossil fuels, particularly natural gas, but to produce and use of electricity and heat together, achieve a significant energy savings. However, increasingly used plants based on renewable energies like biomass, geothermal and solar, even nuclear power.
Faced with individual heating systems, the urban district or distinguished by several advantages.The heat production is more efficient because less is wasted and, therefore, pollution is also lower. A study by research group Claverton Energy, district heating based on cogeneration is the cheapest method of reducing coal use and has one of the lowest carbon footprints of all generating plants based on fossil fuels. For their part, consumers save money on energy and facilities should be for your own heating systems.
As for drawbacks, the implementation of central heat production and the pipeline network requires a large initial investment, but pays for itself over time. Due to its characteristics, is not an ideal system for areas with low population density or for communities with many small buildings.
The vapor distribution is most suitable for industrial processes that require a higher temperature, but because it loses more heat quantity. In addition, this modality can be dangerous if the pipeline network is not well cared for.
Therefore, before thinking of installing a district heating system should perform a study to determine if the best solution. An expert should analyze how to install it in the most efficient and economic, so that heat supply meets demand throughout the different months of the year.
District heating in the World.
Several Spanish cities have small district heating systems. In Barcelona, the company Districlima has launched a network for more than 50 buildings. Meanwhile, Nova Energy has installed several of these facilities, as in Oviedo Mining Orphanage Foundation of Asturias, in Bellver de Cerdanya (Lleida) for various public buildings from fuel chip, or in Guadalajara for the Foundation Sponsor a Tree. In Madrid, the Ministry of Environment plans to launch a network within the Bridge Ecobarrio Vallecas. The system will combine heating and hot water for about 30 buildings.
Factors such as weather, proximity to energy sources or technological development have assumed that greater implementation of district heating has occurred in the Nordic countries, Russia and Eastern Europe.
Iceland leads the global use of district heating. 95% of all households, mostly in the capital, Reykjavik, enjoy this system. Most of the heat comes from the three major geothermal plants in this country.
After Iceland, the Scandinavian countries are the largest consumers of district heating. In Denmark, more than 60% of the production of heat and hot water is based on this system. Most large cities have significant Danish district heating networks. Copenhagen has the largest network: 275,000 households (nearly 95% of populated areas) receive heat through a network of 54 kilometers. Its energy source is based on 80% in cogeneration plants, while the remaining 20% comes from the use of heat recovered in the municipal waste incinerators.
In Finland, 50% of heating needs are met by this system. In large part, is based on the cogeneration technology, but also uses renewable biomass and energy recovered from incineration of municipal solid waste.
Sweden has a long tradition of use of district heat. 90% of the energy used for this purpose has renewable sources, and also uses garbage as fuel (Swedish law prohibits landfills), or nuclear energy, as the case of central Agesta. Thanks to a heating system based on biomass, eco-city of Växjö has reduced the use of fossil fuel energy by 30% in recent years and hopes to reach 50% in 2010.
Russia is another major consumer of this kind of heat. In most cities, CHP plants produce more than 50% of the country's electricity and simultaneously hot water supplied to citizens.
In the rest of Europe, countries like Estonia, Poland, Slovakia, Hungary, Austria and Germany also an important advantage of this heating system. The examples are very different: in Vienna serves more than 250,000 homes, with a substantial basis in the heat of the three major municipal waste incinerators, in Flensburg (Germany) covers 90% of the needs of their neighbors in Switzerland , NPP Beznau supplies heat to about 20,000 people, in Italy, cities such as Bergamo, Ferrara and Turin have such networks, and so on.
Outside Europe, district heating is also used in various countries. In the United States and Canada, several private companies have made this their livelihood system. Some major Canadian cities and U.S. cities like New York, San Francisco, Minneapolis, San Diego or Pittsburgh have such networks. Several U.S. college campus also base their heating system, such as the University of Notre Dame of Maryland.