and the overall downtime of the unit during the reconstruction period is shorter as a greater amount of the works can be done while it is still in commercial operation .
On the other hand , the supplemental outdoor approach is more costly and less sustainable as it requires significantly more new construction work and material compared to the integrative indoor approach .
While other repowering concepts like topping or boosting have their justification for meeting specific customer requirements and to increase the performance and fuel-flexibility of existing coal fired power plants , only full repowering can be seen as a solution which comprises both a significant immediate reduction of GHG emissions based on available technology and a long-term full decarbonisations potential .
PREPARING FOR THE DECARBONIZED FUTURE The decarbonisations of the global power industry will be diverse , complex and depending on the different regional circumstances and needs .
Still there is agreement today that natural gas will continue to play a significant role in the energy mix during the next decade and probably longer , and that it is considered to be the bridge to the hydrogen future .
With the coal-to-gas shift of coal-fired power plants the foundation is laid for the transition of valuable , but inefficient and environmentally harmful assets into a long-term clean energy scenario , using green hydrogen as the succeeding fuel , as soon as the hydrogen economy is in full swing .
In addition , such repowered and hydrogen ready power plants can play a central role in the further hybridization of the power industry , providing the already existing infrastructure and grid access to feed electricity from renewable energy sources winto large-scale storage facilities , like battery or thermal storage and / or into electrolysers , to generate green hydrogen , which would fuel the combined cycle power plant .
Beyond that , other solutions for heating , cooling or process steam supplies , grid stability services and / or operational flexibility can be integrated to maximize the exploitation and perfecting the interplay of all hybrid puzzle pieces within a seamless system of multiple and parallel working value streams .
At the end of the decarbonisation journey , such hybrid power plants would be integrated into a larger energy landscape , comprising of energy generation , transformation and consumption sectors .
Repurposing of legacy power plant infrastructure and equipment through repowering is a technically , economically and sustainably viable option to address todays and future demands during the transition of the global energy landscape .
The full repowering of legacy coal fired power plants with highly efficient gas turbine technology provides a fast , competitive and environmentally state-of-the-art bridge solution ; and the technological foundation for the midterm transformation of legacy power plants into fully decarbonized hybrid energy centres .
All with limited negative – or even positive – socio-economic impact for the plant location .
Hartmut Oehme is Director of Brownfield Transformation for Combined Cycle Solutions at Siemens Energy