From coal to natural gas to hydrogen

Climate-neutral by 2035 – based on this promise, EnBW is committed to playing its part in mitigating climate change in line with the 2015 Paris Agreement. With this aim in mind, EnBW will continue to systematically expand renewable energy capacity and phase out the use of coal as an energy source in the medium term. In doing so, the number-one priority is to ensure that the supply of electricity and heat is never under threat. EnBW is therefore embracing the fuel switch principle at its Heilbronn site and initially replacing coal with more climate-friendly natural gas by constructing a new combined cycle gas turbine (CCGT) plant. This switch to natural gas represents a bridge on the way to green gases, such as hydrogen produced from renewable sources, with which complete climate neutrality can then be achieved by 2035.

A combined cycle gas turbine (CCGT) plant is one in which the principles of a gas turbine power plant and a steam power plant are combined. It involves a gas turbine generating heat, which in turn is converted into steam for the turbine in a downstream waste heat boiler. The gas turbine is connected to the generator that produces the electrical energy. A higher degree of efficiency – up to 60 percent – can be achieved by combining these two principles, with the fuel being used particularly efficiently.

Following expansion via the gas turbine, the flue gas still has a temperature of between 550 and 620°C. The hot flue gas is then used to generate electrical energy. For this purpose, it is passed through a heat recovery steam generator. This is a heat exchanger that transfers the energy present in the flue gas to the water or steam from the steam turbine process. Once almost all of the absorbed energy has been extracted from the steam, it must be recondensed in order to close the cycle. The condensate is then fed back to the heat recovery steam generator at high pressure via the condensate and feedwater pumps. From there, flue gas is discharged into the environment via the chimney.

• The new CCGT plant has a maximum electrical output of 750 MW_el
• Through district heating extraction, including heat storage facility, the CCGT plant has a thermal output of approx. 190 MW_th
• The new heat storage facility has a capacity of 600 MWh
• The planned hot water boiler plants used to secure the district heating deliver a thermal output of 160 MW_th

• The new gas-fired CCGT plant can be controlled more flexibly than a coal power plant and can therefore better complement the fluctuating production of electricity from wind power and solar energy.
• As a fuel, natural gas is much more climate-friendly than hard coal and will more than halve greenhouse gas emissions from 2026.
• Airborne pollutants are also significantly cut: NOx emissions by approx. 80%, total dust by approx. 44% and SOx by approx. 93%. Heavy metal emissions are eliminated entirely.
• Replacing the coal power plant with the new CCGT plant thus plays an important role in achieving climate change mitigation goals and improving air quality in the Heilbronn region.
• Following the construction of the CCGT plant on the Heilbronn site and the decommissioning of the coal blocks, the existing coal storage facility will no longer be needed, thereby completely eliminating its dust and noise emissions.
• The new plants will reduce the volume of traffic, because coal will no longer need to be supplied after the decommissioning process and the disposal of residues and delivery of additives linked to flue gas cleaning will no longer be necessary.
• Once the new plant has been built, the coal boilers, the associated flue gas cleaning system and the coal-fired auxiliary steam generators will be decommissioned. This eliminates noise sources that were significantly louder than the new plants will be with their modern noise reduction technology.