Stuttgart, Germany, is the first city in Europe to launch its own bioeconomy strategy. Il Bioeconomista has interviewed Dr. Max Schuchardt, who developed the bioeconomy strategy of the City of Stuttgart, and Dr. Elisabeth Saken-Braunstein, who is leading the bioeconomy team at the Ministry of Environement, Climate and Energy and the strategic development of the urban and industrial bioeconomy strategy section in the Amendment of the bioeconomy strategy of Baden-Württemberg.
Interview by Mario Bonaccorso
Dr Schuchardt, Stuttgart is the first federal state capital in Europe to launch its own bioeconomy strategy. What are the main pillars of this strategy and what are its objectives?
Schuchardt: The City of Stuttgart has developed its urban bioeconomy strategy in the framework of a funding by the Ministry of Environment, Climate Protection and Energy Sector. This funding suited for the City of Stuttgart very well, as we consider it as part of our climate protection agenda and to reach our sustainability targets. As city administration we are not in first instance a biomass producer, but organizing the daily lives of our residents, including the management of large material flows, such as waste and waste water, the management of city trees and park areas and initialization of climate adaptation measures. For this reason, we found the concept of an urban bioeconomy strategy very much in line with our core competences and used this unique opportunity. Before going into detail about our strategy and concrete measures, I believe it would be interesting if Dr. Saken-Braunstein briefly introduces the concept of urban bioeconomy.
Saken-Braunstein: Thanks for the introducing words, I’m happy to share some thoughts about urban bioeconomy. While Bioeconomy is often understood in the context of biomass utilization from forestry or agricultural areas, urban bioeconomy focusses on activating sustainability potentials in urban areas. Generally,urban areas are hot spots for material consumption, as many goods, like food, building material, textiles, but also all kind of consumer goods are transported into such areas. To achieve a truly circular economy, we need to recycle these materials after their use phase completely and use such secondary raw materials for the recovering of resources and for the production of new products. Biotechnology and biological approaches are offering a very promising portfolio helping us to close these material cycles by extracting valuable substances from secondary material streams, like for example plant nutrients from waste water or gold and rare earth metals from electronic waste. As Mr. Schuchardt mentioned already urban administrations and municipalities are at least in Germany managing large parts of these secondary material streams and for this reason we consider them as key actors to facilitate the implementation of the bioeconomy in urban areas. We are very happy and proud that the city of Stuttgart took over this idea and developed a tailored urban bioeconomy strategy, which will be introduced by Mr. Schuchardt.
Schuchardt: The urban bioeconomy strategy of the City of Stuttgart consists of4 main pillars. First of all, we focused on the wastestreams. We want to reduce waste, successively leave behind the word “waste” and replace it with “raw material source” or “resource” depending on the particular case. Secondly, we want to make local use of such resources that, till today, are mainly exported from our city. Examples are organic waste from Stuttgart’s households, green waste from i.e. parks and roadside green or phosphorous and nitrogen from sewage water. Making local use of these material flows does not only safe money, but also generates added value for the city. We can produce green energy, but even more importantly in many cases allows for material utilization. A bioeconomical approach would be to use fibers from fermentation plants to produce insulating material for our strong local car manufacturers. Another example is extracting phosphorus and nitrogen before sewage sludge incineration and avoid transforming valuable fertilizers into low-value ash). Material utilization approaches regularly offer higher value productsbesides the energetic use.
Thirdly, we can reduce GHG emissions by stopping the export of our local material flows or optimizing our wastewater treatment plants. In the latter case, a Stuttgart based Start-up has confirmed measures from Switzerland where Nitrous Oxide emissions are by ~50% higher than originally thought. As the city of Stuttgart is operating the biggest wastewater treatment plant in Baden-Württemberg, the optimization of the aeration tanks would be promising. And we are convinced, it is better to produce nitrogenfertilizer than nitrous oxide emissions.
Our fourth pillar is an entirely new topic for Stuttgart and the urban bioeconomy. It’s about negative GHG-emissions and the circular economy of urban green waste. We have an ambitious climate target: Net Zero 2035. To reach it, we are avoiding and reducing emissions wherever possible but there is a need to compensate a certain amount no matter how successful we are. Residual emissions are estimated to be 0.2mio t/year in Stuttgart if we meet all other climate targets. From our perspective it doesn’t make sense to only buy external CO2 certificates from 2035 onwards but rather to try to compensate as much as possible locally with available material flows on our territory. We have already gathered experience with several bioeconomical stakeholders within Stuttgart. Our Municipal Landscaping, Cemetery and Forestry Authority is providing green waste from roadside trees to another Stuttgart based Start-up which is producing certified biochar. This local biochar is not only a „granola bar“ for our city trees but also offers green energy and permanent carbon sequestration (including CO2 certificates). The produced biochar is then used as substrate for planting new roadside trees or improving already existing tree habitats. With this project we are closing local material cycles, transform parts of our city into a sponge (e.g. Stockholm tree pits) against flooding, create an awesome habitat for climate resilient urban trees and collect first experiences on negative emissions. In general, this is a very sexy bioeconomical topic with large scaling potential and direct impact on many levels due to the many co-benefits.”
The updated EU bioeconomy strategy was focused on the concept of biocities. As far as you’re concerned, why is the role of cities so relevant in the framework of EU Green Deal? And what are your expectations related to the announced review of the European bioeconomy strategy by the end of 2025?
Saken-Braunstein: The city of Stuttgart is a very good showcase to show the importance of our concept of the “urban bioeconomy”, as with ongoing urbanization cities and urban areas are more and more developing towards huge resource hubs. For example, residents in the City of Stuttgart are importing more than 14 million tons of materials and Products each year. As mentioned above: Instead of wasting products after their usage, we need to close material cycles and recover the resources, such as rare elements or gold, which are in secondary material streams. For this we identify smart options for high-value recycling of even high tech materials in our urban und industrial biorefineries. This will help us not only improving the ecological footprint, but also contribute to strengthen our strategic autonomy in critical substances, e.g. phosphorus or rare earth elements. However doing this requires robust and environmental-benign technologies and we see here some promising biotechnology routes. For this reason, we clearly expect that in the review of the European bioeconomy strategy the importance of environmental and industrial biotechnology and the recycling of secondary streams such as waste, sewage water and air emissions using biological technologies will be more emphasized. For sure this needs to be aligned with surrounding legislation and in this context we certainly need to pave the way for a truly circular and sustainablebioeconomy and remove barriers for its implementation.
How can the concept of biocities be connected with the one of smart cities e.g. in Stuttgart?
Schuchardt: Climate smart cities are an interesting topic which is handled by several departments in Stuttgart. First, such a topic relies on innovative approaches where people from different departments need to talk to each other in interdisciplinary groups. This means to overcome silo thinking and also sometimes bureaucracybarriers. As an example: we want to improve our blue-green infrastructure which involves the expertise from many of our departments. It is not only important to water our urban trees but even more important to know which tree needs how much waterand when. Especially in times of heat waves and increasing water scarcity the answer can’t be “random 200 liters per tree within 5minutes will do the job” (with 80% runoff straight into the canal as the dried-out urban soil can’t handle the amount of watering). There is AI based technology available that tells us where to water how much and in the end, this saves us money due to less kilometers travelled by irrigation trucks and a reduced tree mortality. Furthermore, while taking care of our trees, we generate data on which basis future decisions can be taken instead of the gut feeling of individuals. Surely such projects need initial investments but they amortize quickly – especially when hard to monetize topics such as micro climatic benefits and heat deaths are taken into account. In Stuttgart, we have a Climate Innovation Fund where stakeholders can apply for funding for innovative projects.
Saken-Braunstein: This is a very good example which shows the importance of urban bioeconomy strategies. The collaboration with and within the administration cannot be implemented by bioeconomy strategies on European, national or federal state level. It can only be implemented by the local authorities themselves and needs to evolve from a process on the local level. This was exactly the basic intention for funding the development of such urban bioeconomy strategies.
There is a huge potential of new raw materials for the bio-based economy in the collection of organic wastes. Are there specific plans in Stuttgart to improve the use of these specific wastes?
Saken-Braunstein: Organic waste is certainly one important secondary raw material source and offers a high potential to utilize it for new products, including very basic applications such as extraction of plant nutrients or for replacing peat in planting substrate, but also more high-tech applications using insect biorefinery approaches to produce biobased materials or feed. Nevertheless, organic waste is not the only secondary material stream in urban areas, basically all waste streams offer potentials for urban bioeconomy approaches and to close material streams of critical raw materials for the industry. As mentioned before, electronic waste contains relevant quantities of rare earth metals, gold and other elements which can be recovered using biotechnology in urban biomining concepts. But also gaseous waste streams offer a relevant potential as our chemical industry will also require carbon in the future. Utilization of CO2 for example from waste incineration plants can help to implement a technological carbon cycle contributing to both – meeting the demand of the industry and improving sustainability.
How was the development of the urban bioeconomy strategy supported by the Land of Baden-Wuerttemberg and what was the strategic thinking behind? Will the cooperation/support continue?
Saken-Braunstein: The concept of urban bioeconomy strategies was developed together with our partners at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) in Stuttgart and is, as described before, based on the strategic thinking, that urban areas and municipalities are important driversfor the local economy and managers of the daily lives of their residents, including waste management, issuing building permits and facilitating economic activities in their community. Derived from this, the Ministry of Environment, Climate Protection and the Energy Sector has funded the development of urban bioeconomy strategies in Baden-Württemberg and it is great to seethat not only our capital city Stuttgart but also three other regions in Baden-Württemberg, namely the Technologie Region Karlsruhe, Metropolregion Rhein-Neckar and the metropolitan area region of Stuttgart has joined this program. It is an interesting side note, that with these four regions we already address more than 50% of the residents in Baden-Württemberg. All four urban regions have developed specific urban bioeconomy strategies to facilitate the implementation of the bioeconomy in line with their specific strengths and needs. In the next months, we also plan to extend this concept to smaller urban areas in Baden-Württemberg as we see a clear need to translate bioeconomy strategies developed on a higher level, e.g. EU, national or on state Baden-Württemberg level, into real actions on site. The urban bioeconomy strategy of the City of Stuttgart is a great example, as it is not only a strategy, but also contains 22 concrete measures for implementation. We are very keen to keep track upon the implementation of these measures and the strategies of all four regions and will see how we can support the implementation in future.
According to the UN, 70% of world population will live in cities in 2050. How do you think will be the city of the future?
Saken-Braunstein: As mentioned above in Baden-Württemberg already today more than 50% of the residents are living in urban areas already today and this trend is continuing. For this reason, the city of the future not only needs to provide a pleasant and healthy living environment, but also contribute to circularity and sustainability. This contribution includes an intensive exchange with surrounding rural areas, especially by the provision of nutrients for the food production in such areas. So from our point of view, future cities and urban areas cannot just be hot spots for material consumption, but we also need to make sure that relevant materials, such as nutrients for plant growth, but also rare earth metals and other metals, find their way back into new production cycles.
Schuchardt: There is no way around transforming huge parts of our cities. Mobility, energy and food supply are important topics of the future but also on the level of single districts we face challenges and opportunities. We have well established contacts to various cities with best practice examples of cities of the future. An important topic is participation of the inhabitants as these are the people that live in the respective districts and have an intrinsic motivation to make their lives climate resilient and nice for future generations.
I imagine Stuttgart as a city that incorporates the following vision:
In accordance with the Circular Economy Act, material utilizationis preferable compared to energy-related utilization. Green waste, wood chips and solid fermentation residues should be utilizedlocally in the medium term for heat, energy and substrate production (biochar) using pyrolysis technology. Not only does the limited raw material resource biomass remain in the City ofStuttgart, but there is also a great future-oriented opportunity to generate negative emissions locally.
The city of the future will include much more urban green than nowadays, plants will be increasingly used in roadside greenery, on roofs and facades, but also in parks and tiny forests in Stuttgart. Concrete and tarmac give way to urban greenery. No valuable biogenic material flow leaves the City of Stuttgart. The urban biomass is collected centrally during maintenance work and fed into a local pyrolysis plant. The resulting waste heat is fed into the local heating network, and the pyrolysis gas is treated (e.g. carbon capture). The locally produced biochar is used for planting new trees, the improvement of tree habitats as well as parks and for greening roofs and facades. The CO2 certificates for the use of biochar and urban biomass are accounted for in Stuttgart and double claiming by external service providers is ruled out. In the medium term, scaling will not only compensate for residual emissions that are necessary to achieve net zero by 2035, it will also generate the urgently needed negative emissions to survive on this planet as humans.
IL BIOECONOMISTA 