IGCC/CCS power plant
In IGCC power plants, the coal is not burnt in a conventional steam power plant, but is initially dried and supplied to a gasifier, in which high temperatures prevail. Here, the dried coal is subjected to pressure and is converted into combustible or reactive gas using air or pure oxygen. The resulting gas, mainly consisting of carbon monoxide (CO) and hydrogen (H2), is subsequently cooled down and purified from particulate matter and other unwanted components. With the help of water vapour, the CO can be converted into carbon dioxide (CO2) and further H2 in the so-called "shift stage". There is also the option to separate and condense the CO2 in a downstream purification stage required for sulphur capture, and feed it into the Carbon Capture and Storage/Usage (CCS/U) system. The remaining gas – after it has been diluted with nitrogen, if required – can be utilised in a gas turbine combined cycle plant (GTCC), which is a highly efficient power-plant technology to generate electricity. Here, gas is burnt in a gas turbine driving a generator to produce electricity. In the case of CO2 capture, the resulting hot flue gases are composed of atmospheric nitrogen and pure water vapour and are used for steam generation. The steam drives a steam turbine connected to a generator to produce electricity. The overall power-plant concept is referred to as Integrated Gasification Combined Cycle (IGCC) or as IGCC-CCS if the CO2 is also captured and stored.
As an important contribution to climate protection, RWE systematically promoted the developments and planning required for the erection of an IGCC-CCS plant at Hürth.
For the implementation of this IGCC-CCS project, an appropriate regulatory framework and the promotion of acceptance of the CCS technology by policy-makers were required. Unfortunately, the German Carbon Storage Law (KSpG), which is to enable the construction of demonstration plants in principle, considerably tightened the existing CCS Directive of the EU. This development makes CO2 storage seem impossible for RWE in Germany.
Without CO2 storage facilities, it seemed neither viable nor reasonable to erect a power plant designed for CCS or an associated pipeline for CO2 transport. For this reason, RWE had to defer further steps in connection with the specific implementation of the IGCC-CCS project at Hürth and has discontinued this project until further notice.
The IGCC power-plant concept is primarily based on the gasification of coal. The gas created in this process cannot only be used for electricity generation (as in the IGCC power plant described above), but can also be utilised for producing chemical products and fuels. For this reason, RWE will continue its activities in the field of coal gasification, with the objective to open up alternative ways to make use of lignite.