A city gearing up to the future

Research in focus June 2014

Frankfurt am Main has specific and ambitious targets to meet. In fact the city – home of the Alte Oper concert hall and the Goethe House as well as of modern buildings such as the Main Tower and the headquarters of Germany’s leading stock exchange – has defined a range of both short and long-term climate protection targets that the city intends to meet by 2050. Type ‘climate protection’ into Google and it returns more than 34 million hits. These cover topics ranging from the melting of glaciers and polar ice caps to references to companies and products that aim to prevent or at least minimize further global warming. Yet Frankfurt’s plans are not just another drop in the Internet ocean – they are an energy concept that is designed to turn the metropolis on the river Main into a “green city” and to gain recognition in the European Green Capital Award. With the funding obtained through the project “Masterplan 100% climate protection” run by the German Federal Government, the city was ready to meet the challenge of moving towards a greener, more sustainable energy economy and had the resources it needs to develop a concrete action plan. 

In order to make progress on issues of energy efficiency and the use of renewable energies in the power, heat and traffic sectors, the Energy Agency of the cityhad coorporated with external experts. Part of the team had been the scientists of the Fraunhofer Institute for Building Physics IBP in Kassel. The researchers were specialists in the efficient energy supply of buildings, building complexes, districts and entire cities. A differentiated view at all energy flows in the cities‘ energy systems under thermodynamic aspects helps to identify efficiency potentials. “By applying exergetic principles we can coordinate and optimize demand and supply aspects in the city energy system,” explains Fraunhofer IBP project manager at that time Patrick Schumacher. “We are hoping to develop measures in Frankfurt that will allow the city to reduce end-user energy consumption by 50 percent and to cover remaining requirements using renewable sources of energy.” The researchers had focused on their efforts on the three sectors of heat, electricity and traffic.

The starting point was a detailed analysis of consumption patterns for each of the three key sectors. This was based on figures provided by the city’s Energy Agency and by companies and associations in the City of Frankfurt. Schumacher and his group used this information to extrapolate how much energy is currently required and how much is actually consumed in each specific area – for example in data centers, business enterprises, industry, retail outlets and, of course, private households. Their calculations included everything from the square meterage of photovoltaic systems and solar power plants to the number and distribution of passive and energy-plus-houses, biomass power plants and district heat connections in the various parts of the city. This stock-taking process also took into account economic and organizational barriers such as the lack of cycle paths and charge spots for e-bikes in certain areas.
Frankfurt’s traffic situation also came in for investigation with the team investigating the percentage of trips made by public transport, in private vehicles, by bike and on foot. “Based on this comprehensive analysis we were able to determine the status quo of the current energy supply situation and develop a whole raft of measures that can be used to reduce both energy consumption and CO 2 emissions,” Schumacher explains.
One of the strategies used by the researchers to develop suitable measures was to draw on natural resources specific to the City of Frankfurt. For example, some 100 to 140 meters below the center of the city there is a "bubble" of heat at temperatures of over 20 degrees Celsius. This heat, which is stored in an accessible part of the Earth's crust, is referred to as geothermal energy. In combination with heat pumps it can be used as an indirect source for heating or cooling . The project team estimates that it would be possible to use geothermal energy to cover 15 to 20 percent of the heating energy demand by 2050. Frankfurt also features a significant number of data centers in both the city center and surrounding areas. In 2010 data centers occupied a total floor space of 400,000 square meters, and this figure will probably rise to 800,000 square meters by 2050 if the current trend continues on its present course. Data centers consume significant amounts of energy to keep the servers running, and even larger quantities of energy to dissipate the heat the servers generate. Instead of using air-conditioning systems to cool and dissipate this valuable waste heat, future plans could see this energy fed into the district heating network in order to heat the water in nearby buildings. Similar synergy effects can be achieved in other areas, for example by using the waste heat recovered from underground train tunnels.
These are just a few examples taken from the list of measures designed to reduce energy consumption and CO 2 emissions. “On top of this we’re also developing a fully-fledged heat supply concept – a kind of heat roadmap for the city – as well as a mobility concept and a plan aimed at saving electricity. We’ll be presenting three different scenarios that can be used to help the City of Frankfurt achieve its climate protection targets by 2050,” says Schumacher, outlining the scope of the project. There is also significant latent potential that could be exploited in the tertiary sector (trade, commerce and services). Improvements in energy management efficiency could achieve as many savings in this area as in the field of short-range mobility. According to the Fraunhofer researchers, initiatives designed to encourage citizens to walk more, use car-sharing services and switch to steadily expanding networks of rapid bike lanes instead of using their cars will have a clearly positive effect on the balance of energy use and emissions.
In addition to this general, city-wide concept, the researchers are also helping to develop three detailed concepts for specific districts. The first step in this process is to conduct an analysis of energy use on a neighborhood, building and infrastructure level. Fraunhofer IBP's job is then to use this as a basis for developing solutions to reduce heat requirements in the respective districts and elaborate tailored heat supply strategies. Its tasks also include identifying concrete pilot projects and preparing them for implementation as well as deriving synergy effects and mapping out targets for concrete scenarios. Once again the focus is on finding ways to reduce the consumption of heat energy and to supply heat more efficiently. Successfully transforming Frankfurt into a truly green city will require innovative approaches and future-oriented solutions. (taf)

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