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THE TECHNICAL INNOVATION The Danish DH is not only known for its efficient ownership and large market share of CHP and waste. It is also recognized for a wide range of innovative solutions, which have already had and will also in the future have a positive impact on the energy sector world-wide.
The stable national energy policy, the transparent planning and the municipal responsibility for both DH and gas seemed important for successful implementation. It ensured strong competition between consultants, suppliers and contractors, and it created bankable projects. Moreover, municipal guarantees for loans stimulated competition among banks to offer the lowest interest on loans to DH and gas infrastructure.
THE PREINSULATED PIPES The first and most important innovative DH technology was the preinsulated pipe developed by a small company in the town of Løgstør and tested in full scale by the local DH companies searching for cheaper solutions. The first prototype developed around 1965 was only successful in permeable soil, but lessons were learned and finally, around 1980, the bonded and welded pipe technology was ready to be used at large scale for the heavy expansion of the DH system. The technology has since then been further developed with curved pipes, twin-pipes, no- dig methods etc. and has been used world-wide for DH and even DC. These direct buried pipe systems are much cheaper than pipes in concrete ducts, and we can therefore give this technology credit for a significantly larger market share of DH.
The Greater Copenhagen DH system tells the history of Danish district heating.
ELECTRONIC HEAT METERS Another important technology is the electronic ultrasonic heat meter, which can bemonitored automatically by the DH company. This meter opens for time-dependent tariffs and incentives for lower return temperature. Moreover, it is an opportunity for the DH company to offer active energy management support to the end-users, which will stimulate energy efficient consumer response on price signals and thereby improve the efficiency of both buildings and DH systems.
After year 2000 , the gas project was on safe ground, and the environmental awareness became stronger. Shortly after, a significant majority of the Danish Parliament agreed on a long-term vision - that Denmark must be independent of fossil fuels in 2050. Thereby DH became even more important as the DH system is able to integrate and store all efficient non-fossil heat sources in a cost-effective way. The first stage from 2009 of this transition was to extend the DH to replace mainly large gas boilers whenever it was cost effective. It started in districts in which the gas supply had got preference in the first planning phase with the aim to replace oil. Another later step was to shift from coal and gas to biomass at several large CHP plants. In 2017, the Climate Commission gave its recommendations for how Denmark can be independent of fossil fuels in the most cost-effective way: Wind energy should be our main renewable energy source, but the challenge will be not to produce it but to use it. That opened up for an even more important role of DH in combination with district cooling (DC) as the DH and DC infrastructure can use large amounts of electricity once it is cheap (due to strong wind), store it for later use and not use electricity or produce it once it is very expensive (due to lack of wind, even in longer periods). The DH&DC systems combining hot- and cold-water storage, heat pumps, electric boilers and CHP plants act like it was an electric battery, but much more efficient and cost effective than electric batteries. Besides, it improves the environment, both the carbon emission reduction and the local air quality. Currently, the Danish Parliament is forming the coming years’ energy policy in which DH&DC owned and controlled by local democratic society hopefully will continue to have an important role to play.
Gram District Heating demonstrates the newest innovations and forms a virtual battery.
LARGE-SCALE SOLAR WATER HEATING AND HEAT STORAGE PITS
The latest Danish DH innovation, which is important for meeting the new low-carbon objective, is large-scale solar water heating combined with an underground heat storage pit, which can store solar heat from summer to winter. These two technologies, which really take advantage of the economy-of-scale, were developed by Marstal consumer-owned DH company followed by many others in co-operation with suppliers and consultants. More than a hundred companies have now established solar water
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