Sustainable living in the cities of tomorrow – Part 2

Energy in the City of Tomorrow 

Our “Sustainable living in the cities of tomorrow” series continues with a deeper look at the topic of energy and the Morgenstadt initiative – a wide-ranging joint research project
carried out by the Fraunhofer Society to determine how the cities of the future will work. In an interview with Prof. Dr. Eicke R. Weber, Head of the Fraunhofer Institute for Solar Energy Systems (ISE), we asked what sustainable urban energy generation and supply may look like in the future.

Supplying energy to the Cities of Tomorrow

Sun, wind and biomass as sources of energy

The Morgenstadt vision of a sustainable, liveable city involves energy processes that are largely CO2-free and completely forgo the use of fossil fuels. This ambitious objective requires both a substantial reduction in energy consumption and the ability to sustainably generate the needed energy. In the cities of the future, sun, wind and biomass will represent important sources of electricity and heat.
Furthermore, Germany is increasingly shifting towards renewable energies as part of the national “Energy Transition” programme: according to figures from the German Association of Energy and Water Industries, renewable resources accounted for some 30 percent of the country’s energy in 2015, making them the most important source in Germany‘s overall energy mix.
In order to ensure cities and municipalities reliance on sustainable energy supplies from renewable sources over the long term, there is the need for a forward-looking shift in energy systems – away from fossil fuels, towards efficient use of renewable energies. The Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg – Europe’s largest
solar research institute – is carrying out pioneering research in the field.

Fraunhofer Institute for Solar Energy Systems

Application-oriented research on the key technologies of the future

The Fraunhofer Institute for Solar Energy Systems (ISE) researches and develops new technologies for supplying environmentally-friendly energy to the cities of the future. The solutions and concepts undergo practical testing in programmes such as the Morgenstadt initiative.
Focusing on the key research areas of energy generation, efficiency, distribution and storage, the Institute works with partners from the fields of economics, politics and society around the world to develop products, processes and concrete technical solutions for a sustainable, economical, secure and socially equitable energy supply system.

Expert interview

In an inverview with energy expert Prof. Dr. Eicke R. Weber, we discussed sustainable energy generation and supply in the cities of tomorrow, and how this could benefit the cities and municipalities themselves.

1. Mr Weber, how do you envisage the energy systems in the Morgenstadt – the City
of Tomorrow?

The Morgenstadt will use sustainable energy supplies based on renewable sources. The supplies will be safe and protect the climate. This will be achieved by making energy generation, distribution and consumption highly efficient, for example by using cogeneration of heat and electricity, ensuring buildings are  well-insulated, and by using electric vehicles. The cities will use renewable energy capacities to their full potential. Solar energy will be the principle source of electricity and heat generation, though geothermal, biomass and water power will also be used where possible.
Larger cities with insufficient energetic capacities will work with neighbouring regions to source solar, wind and biomass energy. The Morgenstadt’s intelligent energy system will involve the use of “smart grids” which will coordinate generation and consumption locally and intelligently using controllable loads and energy and heat storage facilities, as well as through targeted charging and discharging of electric vehicles. "Smart homes" - which not only provide electricity, heat, cooling and temperature-controlled air to their inhabitants, but also offer convenient operation, security and communication systems - will be commonplace.

2. The topic of energy is a central research field for the Fraunhofer Gesellschaft’s Morgenstadt initiative. Its vision of the future is based on the concept of a “CO2-neutral, energy-efficient and climate-friendly city,” as the government states in its High-Tech Strategy 2020. What does this mean for tomorrow's cities?

Cities are becoming increasingly aware that they are responsible for some three quarters of our energy consumption and greenhouse gas emissions, and they are beginning to recognise that the realisation of sustainable energy systems – such as by installing solar panels on roofs and façades, by establishing smart grids and building smart homes – will predominantly take place within the cities themselves.
For this reason, they are increasingly concerning themselves with the question of what a master plan for a transformation like this could look like, how they can design ultra-low energy and plus energy buildings and districts, and how they can drive the shift towards electric vehicles on a local, city-wide level. The Fraunhofer Institutes are supporting them in this process.

3. Which key factors shape sustainable energy-related urban development, in terms of the Morgenstadt concept?

The key factors are on one hand energy efficiency, i.e. achieving the lowest possible level of energy consumption per citizen in terms of energy, heating, cooling and fuel, and on the other, the proportion of renewable energies in the energy generation system. Every sector, from private households to industry, retail, services and mobility will be involved.

4. How will buildings and districts have to be designed in the future in order to meet these ambitious energy efficiency and consumption targets?

City buildings are responsible for about 40% of our energy consumption. Insulating them well can increase their comfort levels and minimise their energy consumption at the same time, whether they are new buildings or parts of a renovation project. The integration of solar energy turns the buildings themselves into energy generators, and by using storage acilities, they can play an active role in controlling the supply and consumption of electricity and heat from the grid. The increasing digitisation and integration of our energy systems is making this possible.
Energy systems will be optimised on a district level, too. For example, a cogeneration unit could be run on biogas and distribute the heat through a grid. Heat storage facilities would then enable the unit to be used to balance out the fluctuations in solar power generation and fluctuating consumption levels of buildings and electric vehicles. Additionally, the controllers for grid-reactive buildings would communicate with the district controller to help balance generation and consumption. The process would both increase supply reliability and reduce costs.

5. The wind and sun are becoming increasingly important sources of heat and energy for our future cities. What could the energy mix look like by 2020?

In Germany, solar and wind energy have the greatest potential and therefore these will be the most important sources. However, they will need to be supplemented by biomass, hydropower and geothermal power, which are necessary due to the stability of their generation profiles. The future energy mix will be different for each city, depending on their individual potential to generate renewable energies and on their consumption structures.Fraunhofer ISE has calculated that the city of Frankfurt am Main would require a mix of 22% wind, 20% solar electricity, 12% solar heat, 23% energy generated from waste and 23% biomass from the city and the surrounding area to supply enough energy for every hour of the year. However, the city would still need to use power storage facilities and import 10% of its electricity from neighbouring countries, which would also come from renewable sources.

6. A sustainable energy supply based on renewable sources would have to rely on innovative storage technologies that can capture excess energy. What kinds of solutions and concepts will be available to cities?

Electricity storage facilities will use lithium-ion and redox flow batteries. Heat and cold storage facilities will be expanded considerably, and gas storage with methane or hydrogen will also play a role.

7. Information and communication technology is playing an increasingly important role in the energy sector. In the Morgenstadt, electricity grids will be expanded to create intelligent energy information networks, so-called “smart grids”. How do these work, and how will they benefit future energy supply in cities?

As we’ve already mentioned, ICT will play a central role in the Morgenstadt. It will be used to control energy feed-in and consumption efficiently, as well as to coordinate integration with external systems. Smart grids will enable cities to make their energy supplies stable and cost-effective, with loads effectively adapted to the fluctuating energy feed-in.

8. What measures can cities and municipalities put in place to make the transition to sustainable energy easier for residents of urban areas?

Our cities are facing the challenge of completely transforming their energy supply systems, building technologies and transport, a process which will be heavily influenced by the increasing digitisation. They will also have to deal with sustainability in terms of resources and waste, and must adapt to climate change.In general, it is important to work with residents, as well as companies and institutions within the city to define an objective and determine how it can be achieved. As this is a process that will take some 20 to 40 years, there has to be a consensus about the path that will be chosen and what the steps for the next five to ten years will be. This master plan should offer guidelines for the transition, but also be flexible enough to adapt to current developments.
A master plan is particularly important in ensuring that any decision made in terms of infrastructure is the best choice to make the required developments possible. Infrastructure changes have to take into consideration long term objectives in order to be financially viable. Processes like this often see intensive public participation. But it is also important to have an expert Management team to ensure that conclusions are well-founded and plans are agreed with the widest possible consensus.
Thank you for the interview, Mr. Weber.

Further information

For more information about the business areas and research projects of the Fraunhofer Institute for Solar Energy Systems, please visit: