The ‘green’ in green urban infrastructures is not only foliage and flora, it may also be seen as technical and organizational structures, which allow urban areas to substantially cut their fuel input and reduce emissions caused by the demand for heating. District heating makes available unused ‘waste’ heat from industry or power stations. It allows using renewable energy resources outside economic reach for individuals, such as deep geothermal heat or large scale solar heating. It may help societies to achieve 100% renewable energy systems by offering flexibility. And it may offer resilience to societies by means of feasible and democratic energy.
Aalborg University has a long tradition in researching smart energy systems, which encompass all sectors: housing, services, business, industry and transport; and which are characterized by zero fossil fuel input. In order to make these systems work we need a high degree of flexibility to meet demand at all times from variable production of energy from renewable sources. This flexibility may be accomplished by first seeing heat and electricity as connected through co-generation and district heating, using heat pumps in the short run to efficiently convert surplus wind and solar energy to heat, which can be stored. Consumer ownership and efficient public regulation are cornerstones of smart energy systems. These measures allow us to reduce fossil fuel input roughly by half. However, in the long run towards 100% renewable energy we need to substantially reduce our end-use energy demand, be aware on the limitedness of biomass resources, and use advanced biochemical conversion to make transport fuels from wind energy and carbon sources. Various studies from Denmark (www.ceesa.plan.aau.dk) and other countries have shown that this is feasible within the next four decades.
A central element in these smart energy systems is district heating of the next generation, which will be the fourth after steam, high temperature centralized systems, and the current approach used in Scandinavian countries. These 4th generation district heating systems (see www.4dh.dk) supply heat from sustainable sources using low temperatures to low energy buildings. To find out if these systems work, how much they cost, and how they can be planned and managed, Aalborg University is doing a case study for the municipality of Aalborg.
The case study is a working example for assessing the effects of efficient district heating infrastructures but also for the development of geospatial data infrastructures. The Heat Atlas is a central element that maps the current building mass on the crossroads between restorations to high efficiency levels, and the burying of pipes to deliver heating from central waste heat and renewable energy sources.
Each single building is mapped with its basic energy properties: annual heat demand, current supply, investments in the climatic shield, consumer details, the possibility and the costs of connecting to district heating, and the supply chain from primary energy to end-use demand. The aim is to model individual house owners’ choices for a sustainable energy system under the umbrella of strategic municipal energy planning. The means to do this are full access to what is probably the best building database on a national scale, the use of advanced energy systems modeling, and the location of Aalborg, where the famous Aalborg Charter for local sustainable development was initiated in 1994.