IGCC/CCS power plant

CC with CCS technology viable on an industrial scale

In implementing the climate-friendly coal-fired power plant including carbon capture and storage (CCS), we are pinpointedly backing IGCC technology (Integrated Gasification Combined Cycle). Among all the options for climate-friendly power plant technology, the IGCC technology is the only one that can already be implemented on an industrial scale today. This technology is by no means new to RWE Power. It was already being researched in depth by the company in the 1980s and 1990s. At that time, efficiency improvements were to the fore. Today, we are developing the IGCC technology primarily in view of the requirements of sustainable climate protection since, unlike other processes, carbon capture is comparatively easy using the IGCC process, so that the effects of carbon capture and storage on efficiency can be kept relatively low.

 

Coal gasification including carbon capture

In our IGCC process, the gasification of lignite is combined with carbon capture, and electricity is generated in downstream gas and steam turbines. To this end, coal is not burned in a conventional steam power plant, but first converted into a combustible crude gas in a gasifier at high temperatures and a pressure of approximately 35 bar. The gas, which consists mainly of carbon monoxide (CO) and hydrogen (H2), is purified and the carbon monoxide converted into CO2 and more H2 in the CO shift. Following desulphurization, the CO2 is captured, compressed and transported to a storage site.

 

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The remaining hydrogen is then burned in a gas turbine driving a generator to produce electricity. The hot flue gases, consisting in the main of atmospheric nitrogen and pure water vapour, are used to generate steam. This steam drives a steam turbine and a second generator to produce electricity. Since the electricity is being produced using a particularly effective combination of gas and steam turbines, this power plant principle is referred to as a “combined-cycle power plant”.

 

Application and product flexibility

The technology employed in the IGCC-CCS project in principle offers the opportunity to produce electricity in a flexible fashion. This is important especially in light of the increasing feed-in of renewable energy sources, such as wind and solar power, into the electricity grid. The energy yield from renewables, the predictability of which is limited, could be supplemented in a sensible manner by employing the virtually zero-CO2 IGCC-CCS technology.

The synthesis gas produced during the process may basically be used either energetically, as in the IGCC power plant described above, or materially to produce various chemical products or fuels, for instance hydrogen to be used as a fuel in the transport sector. Further material use requires additional conversion steps. Methanol and synthetic natural gas (SNG), among others, but also motor fuels such as diesel and petrol can be produced from synthesis gas using well-known processes that are commercially available today. The wide variety of possible uses is shown in the diagram below. 

 

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This flexibility on the product side for future applications is one more important motivation for the use of coal gasification.

 

"2015" deadline cannot be met

The implementation of the IGCC-CCS project requires that the Carbon Storage Law (KSpG) be passed and that policy-makers promote acceptance of the CCS technology. Without this framework, the exploration of suitable storage sites is not possible. Without a CO2 storage facility, the route for the pipeline cannot be planned. Without the pipeline and storage facility, on the other hand, the construction of a power plant designed for CCS is neither viable nor sensible from the perspective of climate protection.
Thus, RWE has to defer the first steps necessary to implement the IGCC project in Hürth and put the brake on the engineering activities for the power plant. RWE banks on the speedy creation of a legal framework and the improvement of the acceptance situation in particular as regards CO2 storage and transport.

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