Hydrogen does not produce CO₂ when burned. If it is produced using renewable energy, it can therefore be a climate-friendly energy source. However, according to the current heating plan, hydrogen is not expected to play a major role in Wiesbaden’s heating supply.

One major reason is the high cost: Heating with green hydrogen is expected to be significantly more expensive than heating with a heat pump or via a district heating network. Consequently, it is expected that only a few households would opt for this option. Building a separate hydrogen network would therefore be very costly. Converting the existing natural gas network to hydrogen is only feasible if all consumers in the network switch from natural gas to hydrogen. Due to the higher costs for consumers and the organizational effort involved, this option is also unlikely.

Biogas is produced when biomass is fermented. The methane produced in this process can be processed and fed into the gas grid as biomethane. For consumers, switching is generally simple. Similar to green electricity, the biomethane does not have to be delivered directly to their homes. It is sufficient for the utility provider to feed the purchased share into the natural gas grid. Biomethane can replace a portion of natural gas consumption, but it will not be sufficient to cover the entire heating supply.

One key reason is limited availability: A biogas plant is currently under construction on the site of the Dyckerhoffbruch landfill. Starting in 2029, it is expected to process approximately 60,000 metric tons of organic waste annually from Wiesbaden and the Rheingau-Taunus district, generating about 5 million cubic meters of biomethane. However, this would theoretically cover only about two percent of Wiesbaden’s current gas consumption for heating.

In addition to waste, plants grown specifically for this purpose can also be used to produce biogas. This is controversial because these areas are then unavailable for food cultivation. Furthermore, the large-scale cultivation of energy crops in monocultures can harm biodiversity.

Synthetic methane is produced from hydrogen and CO₂. It is no different from methane derived from natural gas or biogas and can therefore be fed into the existing natural gas grid. If it is produced using renewable energy, it can be considered a climate-neutral fuel, since combustion releases only as much CO₂ as was previously captured during production. Theoretically, synthetic methane can be produced in large quantities. Nevertheless, its role in heat supply is minimal.

One key reason is the high cost and complexity involved: The production of synthetic methane is technically complex, expensive, and requires a great deal of electricity. First, hydrogen must be produced and CO₂ captured from the air in order to then produce methane from these components. This makes its production more expensive and energy-intensive than that of other climate-friendly gases. In Germany, production capacity is currently very limited. It is therefore still difficult to estimate what quantities will be available in the future and at what price.

Overall, renewable gases are not a suitable long-term alternative for replacing gas heating systems on a large scale. They are often available only in limited quantities and are significantly more expensive than the natural gas used to date. Furthermore, the future use of the gas grid remains uncertain.

For the heating sector, heat pumps and district heating networks offer good climate-friendly technologies. There are therefore strong arguments for using climate-friendly gases where other solutions are not feasible, such as in industry or in shipping and aviation.