The world population is increasing and has now exceeded 7.000.000.000 people. The need for good indoor climate and hot sanitary water is increasing even more.
Unfortunately, the world will run short of fossil fuels within a few generations, and we have to reduce climate gas emissions due to the risk of climate change – not to speak about the security of supply for future generations.
At the same time, more and more people prefer to live in cities. Cities grow and new cities develop.
This is a challenge, but also an opportunity to serve the population with the necessary thermal services in a smart and sustainable way. In smart energy cities low-carbon energy in general can be provided in a more cost effective way to buildings than in remote areas.
Industrialized countries should be able to reduce the dependency of fossil fuels, at least if it is done in a smart and cost effective way, and the European Community has already set objectives for emission reductions.
The European Community has adopted the idea of Smart Energy Cities in the European Energy Policy, e.g. as presented in the Energy Efficiency Plan 2011.
Moreover the EU promotes integration of smart energy grids and buildings, namely smart grids for electricity, district heating, district cooling and natural gas in interaction with buildings.
The EU directives for buildings, renewable energy and energy efficiency (proposal) outline how the member states shall plan and develop the smart cities in order to reduce the fossil fuel consumption to buildings to almost zero in a cost effective way. That is:
- to plan for district heating and cooling in order to use renewable energy and CHP through this infrastructure
- to locate new power generation with respect to the CHP potential in the district heating and cooling grids
- to supply buildings with almost zero-carbon energy in a cost effective way taking into account the opportunity of district heating and cooling
- to consider electric heat pumps in case district heating and cooling is not cost effective
It is my experience from working with these issues since 1979 in Ramboll and in the Danish Energy Authority that we have to take the following into account in the planning in order to develop smart, cost effective and sustainable cities within energy:
- Optimal zoning of the district heating and natural gas energy infrastructure for heating
- Optimal zoning of the district cooling energy infrastructure
- Combined production of heat and power (CHP) to the district heating and cooling grids to minimize power-only production (and the associated waste of thermal energy) and heat-only production
- Use of available renewable low-temperature energy sources and surplus heat from industries and in particular use the energy from waste, which else would be wasted in e.g. landfills and chillers.
- Use of the most cost effective renewable energy for power production in the region, e.g. from large off-shore or on-shore wind farms and large biomass CHP plants
- Large thermal storages for district heating and chilled water in order to optimize the efficiency of the CHP plants and integrate fluctuating renewable energy sources, e.g. wind energy.
- Natural gas grid to serve industries, CHP plants, households for cooking, traffic etc. and to utilize upgraded biogas and other renewable gasses in future
- Natural gas storages to ensure available capacity to CHP gas turbines
- Low temperature heating and “high temperature” cooling installations in buildings in order to utilize the energy renewable energy and CHP more efficient
- Optimize building envelope with respect to good thermal capacity and low heat transmission losses.
- Minimize use of electricity by natural ventilation, natural light, district cooling and low temperature heat sources for washing, drying, laundry etc.
- Optimize the remaining electricity consumption and the electricity grid to use electricity for transport and processes and to allow load management and “intelligent grid” operation whenever possible.
In new urban development areas we have the opportunity to do all this in a cost effective way from the very beginning and moreover to design the city taking into account the heavy infrastructure for public traffic, district heating and district cooling as well as natural light, nice environment etc.
In existing urban areas it is a challenge to modernize the city districts in a cost effective way for the society by co-ordinating investments in the buildings with the investments in the energy infrastructure for district heating and cooling.
In Denmark we started this strategic planning already in 1979 with the aim to reduce dependency on oil in a cost effective way. Therefore many regions have managed to develop and implement smart grid solutions by integrating the power, the natural gas and the district heating sectors. As a result, the CHP and renewable energy potential in particular from waste and biomass has been utilized to reduce the CO2 emission from heating in a cost effective way. Moreover the district heating systems and their themal storages are ready to integrate the fluctuating wind energy from the booming off-shore wind energy farms.
To study this you may find inspiration in the regional district heating systems in the Copenhagen Region (see picture below), the Århus Region and the Triangle area (Fredericia, Kolding, Vejle and Middelfart).
The integrated district heating system in the Copenhagen Region (The heat transmission companies CTR, VEKS and Vestforbrænding, Copenhagen Energy and more than 20 local distribution companies in 20 local authorities)