Power beyond Coal

A full repowering entails not just changing the fuel from coal or oil to gas but converting the steam power plant to a highly efficient combined cycle power plant (CCPP) by reusing infrastructure, site permits and local personnel. Not only is this approach faster and more sustainable but it also saves up to 30% of Capex compared to building a new power plant.

There are two options to repower your plant: the indoor and the outdoor approach.

With the indoor approach, you can reuse most of the existing infrastructure such as foundations, connections, housing and piping. This saves time and costs. With the outdoor approach, you can start building in parallel when the existing plant is still running to secure critical supplies.

In principle, a "full repowering" means that one or more gas turbines with downstream heat recovery steam generators replace the old steam generator previously fired with coal or oil. In order to achieve this, various modifications of the steam cycle are necessary, as well as the exchange and retrofit of various components. 

For a full repowering, one needs to make sure that the appropriate gas capacities are available. For the final plan, other factors to be considered are the plant capacity, the heat quantities, and levels to be supplied for district heating and/or process steam applications. Also, one needs to consider the space available, and the condition of the power plant. The overall aim is to keep as much of the existing infrastructure as possible. 

While it is impressive that by converting a conventional coal power plant to a CCPP CO₂ emissions get reduced by up to 70%, it’s worth mentioning that this is a result not just from the fuel switch, but also from an increase in the power plant’s efficiency from an average of 38% to up to 63%.

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