CONVERSION TO RENEWABLE ENERGY MEANS INCREASED DEMAND FOR WELL-FUNCTIONING DISTRICT HEATING SYSTEMS In recent years we have seen an increasingly focused transition from fossil fuels to renewable energy in both the electricity and the district heating sector. In many countries, an increasing share of the electricity production is now based on the utilization of solar energy in the shape of solar cells and utilization of wind in the shape of large wind farms both off-shore and on land. Since there is often no correlation between the time of production of renewable electricity and the current consumption, there is a need to store the produced electricity. However, this remains a major challenge as the costs of storing electricity on a large scale are very high. If we are to succeed in the transition of our societies to more renewable energy, it is essential that we ensure well functioning district heating systems. Without such systems, we will not be able to utilize waste heat from companies on a large scale; we will not be able to store solar heat from summer to winter and we will not be able to integrate the electricity system and the district heating system in the shape of large electric heat pumps, which utilize cheap wind-based power generation.