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The energy transition in miniature

Biogas plants process waste from agriculture such as liquid manure, sewage sludge or dung. (Credit: shutterstock)

On the way to climate neutrality, the Helmholtz-Zentrum Berlin has reached another milestone: After the power supply, a large part of the heat supply now also runs CO2-neutral. How was this achieved? An interview about the challenges and prospects of the project.

3,500 tons of CO2; that's how much harmful greenhouse gas the Helmholtz-Zentrum Berlin (HZB) saves annually because it has changed its heat supply. Since January, it has been using biomethane at the Wannsee site, and further conversion measures are being implemented at the combined heat and power plant. The new energy concept was developed by HZB together with the utility provider Vattenfall. We talk to the people who came up with the ideas for this conversion: Carina Hanke and Bernd Rech from HZB and Carolin Süß and Christian Feuerherd from Vattenfall Wärme Berlin AG.

A look inside the generation plant at Helmholtz-Zentrum Berlin. (Credit:HZB)

Ms. Hanke, you are the energy and climate manager at HZB and have driven the change in heat supply there. Why was this step necessary?

Carina Hanke: First and foremost, because HZB has set itself ambitious climate targets: We want to be greenhouse gas neutral from 2035. At the Wannsee site, we still used fossil fuels for heating, primarily natural gas. The combined heat and power plant on our site belongs to Vattenfall, so we looked for new solutions together and decided on biomethane, and the plant has been running on this since the beginning of January. Today, our energy is almost completely CO2-neutral, because we have already switched to green electricity in 2020. Nevertheless, two further steps are planned: First, Vattenfall will start up a combined heat and power plant in Wannsee that will produce electricity in addition to heat. Secondly, solar cells will be installed on the roof of the building, which will supply electricity primarily for the pumps of the boilers. The surplus will be fed into the public grid. All in all, this conversion is therefore an important milestone on our way to climate neutrality.

Carolin Süß, Head of Business Solutions Germany/Vattenfall. (Credit:E-world 2020)

Ms. Süß, you have already managed numerous energy projects at Vattenfall, where you are Head of Business Solutions Germany. Was the conversion at HZB nevertheless a challenge for you?

Carolin Süß: Technologically, we didn't break any new ground with the project. After all, we use proven applications such as photovoltaics and cogeneration, i.e., the parallel generation of electricity and heat in the combined heat and power plant. What is challenging, however, is the amount of biomethane that HZB now needs from us; enough for about seventeen gigawatt hours of heat per year. Special strategies are needed here to purchase and secure this quantity.

What is the problem?

Carolin Süß: Biogas is usually produced in rather small plants, classically located on farms. In them, manure from chicken and pig stalls, but also plant residues, are fermented, producing biogas. If this gas is processed, it can be used in the same way as natural gas. But none of these plants alone produces the quantities we now need for the HZB. That's why we had to put the volume out to tender across Europe and bundle it via our suppliers.

Christian Feuerherd, Managing Director of Vattenfall Energy Solutions.(Credit: private)

So a lot of work for you as Managing Director of Vattenfall Energy Solutions, too, Mr. Feuerherd. Is the project therefore something special for you?

Christian Feuerherd: Yes, because it shows solutions of the kind we want to develop much more frequently in the future. After all, the energy market is facing tremendous changes: Biogases, but also hydrogen, will play a much greater role in the future. In this respect, HZB is already a pioneer among our customers. If you like, together we have implemented an energy transition in miniature: We have used a whole variety of technologies and energy sources at the research center; solar cells, biogas, combined heat and power plant. In addition, we also use landfill gas, which we receive from a nearby landfill site. We need such small-scale, decentralized solutions for energy supply if we want to achieve the climate turnaround. And in Wannsee, with this mix, we are already producing surpluses that go to neighboring households in the south of Berlin. In this respect, our plant at HZB can act as a beacon: Ideally, it will encourage other organizations and companies to also become active in the spirit of the energy transition.

Scientific Managing Director of Helmholtz-Zentrum Berlin (HZB). (Credit: HZB/Phil Dera)

Mr. Rech, you are not only the managing director of HZB, but also an internationally recognized expert on energy issues. So the conversion of the heat supply was probably also a very special concern for you personally?

Bernd Rech: That's right, because we are saving a remarkable 3,500 tons of CO2 per year; that's how much a small village consumes annually. And of course, the conversion fits ideally with our research strategy. After all, at HZB we are developing numerous ideas for the production and use of biogases, but also of hydrogen, especially with our catalysts, which are needed for this. And this can be taken even further: When the photovoltaic plant goes into operation in the fall, we could test new solar cells there that we have developed and that work much more efficiently. So the conversion is turning our campus into an interesting testing ground for alternative energy sources.

What potential do biogases like biomethane generally hold for the climate turnaround?

Bernd Rech: They clearly make a valuable contribution and complement the energy mix very sensibly. However, only if they are produced mainly from waste products, i.e., manure, sewage sludge, and so on. The carbon footprint is less favorable if crops are grown specifically for biogas, such as corn. This is because cultivation consumes a lot of energy and resources, and it also damages the soil in some cases. For biogas from residual materials, however, the balance is clearly positive.

However, the percentage share of biogas in Germany's heat supply is still only in the single digits. What is the reason for this?

Christian Feuerherd: This is also a social issue; biogas is comparatively expensive. As a supplier, we have to bear this in mind, because we are currently seeing how hard rising heating costs are hitting many people. However, the price difference will weaken somewhat in the future because the CO2 tax will have to be paid on conventional heating gases in the future.

Carina Hanke: In the long term, we therefore believe that it is not only an ecological but also a financial advantage that we at HZB have switched to biomethane: Because the gas is climate-neutral, we don't have to pay a CO2 tax on it. And the costs for the basic supply have increased only insignificantly as a result of the switch. In this respect, cost-effectiveness and sustainability go hand in hand.

Bernd Rech: As a managing director who should keep a close eye on costs at HZB, I even have to say that anything that is not sustainable will not be economical in the future.

Ms. Süß, when you look back today on the project with HZB: Is it particularly easy to work with customers who are themselves experts in energy issues? Or rather particularly complicated?

Carolin Süß: It was very stimulating for us! Of course, a partner like HZB, with a lot of know-how in its own ranks, is challenging: Ideas were questioned, concepts developed anew, but together and with great openness. The exchange of ideas was also particularly valuable for us because we also do our own research and development. Vattenfall, for example, is currently trying to produce biomethane from poplar residues. In this respect, I think we will certainly continue our discussions beyond the current project. And I'm already looking forward to it.

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