12.11.21 Heat pumps are not the only solution” Interview with Oliver Koukal • Reading time: 4 min.

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Buildings should be climate-neutral, but according to Oliver Koukal, Senior Vice President and head of the Residential Heating division at Bosch Thermotechnology, heat pumps are not suitable for most of the existing building stock. He is calling for the installation of gas boilers that are designed to burn hydrogen.

Heat pumps are generally regarded as the best solution for achieving the energy transition in buildings. Why do you think the situation is not as simple as that?

Oliver Koukal, Senior Vice President and head of the Residential Heating division at Bosch Thermotechnology

Heat pumps are definitely an important technology, but not the only one. We need an approach that uses multiple technologies in the building sector. More than 50 percent of new buildings are now being fitted with heat pumps and this percentage will continue to rise. This is because the efficiency standard of new buildings makes them ideal for heat pumps. But we must not forget that around 70 percent of all the buildings in Germany were built before 1980 and they are generally not very efficient.

Are heat pumps simply a waste of time for buildings like this?

A large amount of investment, for example, in insulating the outside walls, replacing the windows, and installing underfloor heating, would be needed to enable heat pumps to be used efficiently in older buildings. Some house owners could afford this, but it is not a socially acceptable option. And there is something else that we need to remember: heating systems are generally used in the winter and often in the early evening and the morning when the sun is not shining and we cannot rely on wind power. At the same time, a lot of electricity is being used for other purposes, including charging electric cars. Because of the increased demand for electricity, there may in the future be predefined shutoff times that will have to be covered by local storage facilities.

What alternatives to heat pumps do you suggest for existing buildings?

Oliver Koukal, Senior Vice President and head of the Residential Heating division at Bosch Thermotechnology

No one disputes the fact that future heating systems will have to be climate-neutral. The industry must be prepared to offer a range of different solutions to suit the various types of buildings. The ideal solution for the existing housing stock is H2-ready gas boilers that have been designed for use with green hydrogen. As soon as the hydrogen is available, it will be possible to switch over in the space of an hour from fossil fuels to renewably produced hydrogen. There is also the option of combining a heat pump and a hydrogen-ready gas boiler to form a hybrid unit. During peak loads the gas boiler would be used and at other times the heat pump. This would be an efficient solution even in buildings that have not been renovated.

Is it possible to buy gas boilers now that are designed for use with hydrogen as well?

The gas boilers that are currently available can be operated on 20 percent hydrogen. Pilot projects are already underway to evaluate gas boilers that can run on 100 percent hydrogen. We are aiming to bring these boilers onto the market by 2025. Initially they can operate entirely on natural gas, but they can be converted to hydrogen as soon as it is available via the gas network. They will represent a climate-neutral alternative to heat pumps that is ideally suited to the existing building stock. The H2-ready boilers will cost the same as conventional gas boilers.

How expensive will green hydrogen be in comparison to natural gas?

The key factor here is the relationship to the electricity price, in other words, the question of what a kilowatt hour of green hydrogen will cost in comparison to renewable electricity. I can say with certainty that hydrogen will initially be more expensive. We need to bridge this gap with help from government subsidies and the regulatory authorities. The network operators and the hydrogen manufacturers need security for their investments, for example the construction of large electrolyzers. For this reason, we are supporting the plan to blend hydrogen with natural gas. This will guarantee the producers that they will be able to sell a certain quantity, so that they can ramp up the production of hydrogen. As a result, it will be possible to make green hydrogen available at a competitive price by 2030 or 2035.

You have referred to the United Kingdom in connection with hydrogen. How does the approach there differ from that of Germany?

Oliver Koukal, Senior Vice President and head of the Residential Heating division at Bosch Thermotechnology

The British government is requiring all boilers installed after 2025 or 2026 to be ready to run on hydrogen. They have recognized that heat pumps cannot be the only solution, in particular for the existing housing stock. We would like to see Germany taking the same approach.

Oliver Koukal, Senior Vice President and head of the Residential Heating division at Bosch Thermotechnology


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