Hydrogen is often called the energy carrier of the future. In fact, it is very versatile and can also supply our flats and houses with heat. This can be done through hydrogen heating based on combined heat and power. Electricity is generated in a fuel cell. The resulting heat can be used for heating. Actually, the principle is the same as for any other CHP unit. The difference to conventional CHPs is that no emissions are produced when green hydrogen is used. The following information is intended to serve the reader as a small guide for the use of hydrogen heating systems.
What is a hydrogen heating system?
A hydrogen heater provides heat to a building just like any other heater. Only that a hydrogen heater uses hydrogen as fuel. In this case, however, we are talking about a special kind of heating, namely a fuel cell heating.
Unlike conventional heaters, no fuel is burned there, but the heater has a fuel cell at its heart. In this, the hydrogen reacts with the oxygen from the ambient air and generates electricity and heat. It is therefore not just a pure heating system, but a cogeneration plant that makes use of combined heat and power.
Image: Stationary application: The fuel cell CHP inhouse5000+.
What is a CHP unit and what is CHP?
The abbreviation CHP stands for combined heat and power. A CHP unit is a power plant that supplies objects with heat and electricity. With CHPs, this is usually done in smaller, more compact plants. These are used to supply apartment buildings, production facilities or similar objects.
This uses combined heat and power (short: CHP) and the heat generated during electricity production is made usable. This technology is also used for smaller properties by micro or mini CHP units. These generate electricity in power classes between five and 50 kW.
How does hydrogen heating systems work?
Hydrogen heaters use a fuel cell as an energy converter. In conventional heaters, gas or oil is burned to generate heat. In fuel cell heaters, hydrogen is used as the "fuel". The only difference is that hydrogen is not burnt in the fuel cell, but it reacts with oxygen and generates electricity and heat.
This is also an advantage over gas heaters, as these do not generate electricity. A fuel cell heating system, or rather a fuel cell CHP unit, uses combined heat and power. This can also be done conventionally with a natural gas engine. However, the combustion of natural gas produces soot, fine dust and other CO2 emissions.
Image: Functioning of the fuel cell CHP powered by natural gas inhouse5000+ (Source: inhouse engineering GmbH).
What types of hydrogen heating systems are there?
There are different types of hydrogen heaters on the market. But they all have one thing in common: they use a fuel cell as an energy converter to generate electricity and heat. The differences lie in the type of fuel cell used and the way in which the hydrogen to power the fuel cell is produced.
Currently, most hydrogen is produced by steam reforming. In this process, the hydrogen is split off from the natural gas. Disadvantage of this method is that CO2 emissions are still produced. However, much less than when the natural gas is burnt in an engine. So in the hydrogen heaters there is a steam reformer which extracts the hydrogen from natural gas and converts it in a fuel cell. In the fuel cell, without the steam reforming, only water is produced as an emission. This is currently the best-known mode of operation of a fuel cell heating system.
The types of hydrogen heaters differ in at what temperature the fuel cell is operated and what electrical and thermal output results.
What are the advantages of hydrogen heating systems?
The biggest advantage of a hydrogen heater is that it can generate electricity and heat in one device. However, this is not a unique selling point. The high electrical efficiency, i.e. how much of the energy from the supplied hydrogen can be converted into electricity, is a particular unique selling point.
This is over 50% percent for a fuel cell CHP powered by hydrogen. By comparison, natural gas engines have an electrical efficiency of a maximum of 30 percent.
In summary, hydrogen CHPs have the following advantages:
- Lowest noise emission
- Highest efficiency
- No soot, no fine dust
- Low CO2 emissions
- Low maintenance
- Use of natural gas, bio natural gas, liquefied petroleum gas and hydrogen
It should be noted that the natural gas engine is almost completely mature. This is not yet the case with fuel cells or hydrogen technology in general. The efficiency can therefore be further increased through intensive research.
Where does the application of such a system make sense?
The use of such heating systems makes sense if the building has a whole-year high heat demand. By generating electricity in the system, heat is produced that has to be given off. This means that electricity is generated only if the heat can also be removed.
In order to use the technology as sensibly as possible, it should be ensured that there is also a heating demand in summer. In this way, it can be ensured that the heating system or the CHP unit has sufficient operating hours to achieve a good payback.
Possible areas of application for hydrogen-based mini or micro CHP units are:
- Single and multi-family houses with high heat demand
- Small businesses
- Trade and service buildings
- Swimming pools
- Small industrial buildings
This is only a selection of applications. This narrows down even further when the necessary infrastructure is included in the decision. For example, if hydrogen is produced directly on site near the plant, this can be a significant advantage for the application. On the other hand, a building without a gas connection cannot use hydrogen heating.
For whom is the use of a CHP worthwhile?
In order for the use of a CHP unit to be worthwhile, the investment costs should be recovered as quickly as possible through the consumption of the self-produced electricity, the electricity purchase costs thus avoided, and the heating costs avoided through the heat generated during electricity production. This is referred to as the amortisation period. After that, the CHP produces money for you. And this is exactly the point that you as a user want to reach as early as possible.
What these payback periods look like cannot be defined in a generally valid value. Because every building, every application is different. And thus the payback periods also differ considerably. As a rule of thumb it can be assumed that the system should pay for itself within its useful life. The sooner this happens, the sooner the system generates money for the owner.
Can I usefully combine a fuel cell heating system with other technologies?
A combination of the hydrogen heating with other devices is possible in different variations. You can combine the CHP with a heat pump to use the electricity generated to operate the heat pump. Another option is to combine the CHP with a photovoltaic system and thus cover even more of your own electricity needs without drawing much electricity from the grid. Depending on the area of application and the object to be supplied, further combinations are possible. An overview of different hydrogen heaters and their combinations can be found on the page brennstoffzellensystem.de.
What is the potential for the future?
For the future, there is substantial potential in the area of hydrogen heating. Depending on how the problem of producing green hydrogen is solved by other hydrogen technologies, heating systems or CHP units can be built in larger power classes. This would then also enable the supply of large residential complexes or quarters .When using green hydrogen even completely without CO2 emissions . There is also further potential in the area of sector coupling .
DiLiCo engineering offers various consultations on the use of hydrogen technologies. Feel free to contact us if you are interested!