The 1000 MWe USC turbine of Niederaussem Unit K
A memorandum of understanding between IEA Clean Coal Centre and VGB allows us to attend the English speaking VGB Technical Group: Power Plant Concepts. In return, VGB attends our ExCo meetings. This meeting was hosted by RWE, at their Schloss Paffendorf office and Niederaussem power generation sites, in Germany, 13-14 November 2018.
The first main business consisted of a discussion of VGB’s plans to merge some Technical Groups, including this one, in order to provide greater value from the sharing of more information and assist in catering for future uncertainties. The plan was welcomed, and the merged body, which will meet for the first time in the Spring of 2019, will have the higher status of a Technical Committee.
The next agenda item consisted of presentations by members. These were:
- Developing Power Plant Concepts for the Scholven Site (Karsten Riedl, of Uniper)
- New application of gas turbines on Avedore Power Station (Carsten Hendriksen, of Ørsted (Chairman of this TG)
- Energy Storage options at two plants in the Czech Republic (Hynek Lang, of CEZ).
The Scholven site has seen a dramatic fall in capacity as many units have closed. There are now three units remaining, of 890 MWe in total. These will close soon. The site provides steam to industry and district heating heat, but uncertainties due to ambiguities within the German CHP Act plus flexibility in power requirements and minimum reliable steam supply needs have meant that various concepts have been considered for the future. One potential system is two CCGTs with the option for firing with natural gas or coke oven gas plus a gas-fired boiler for reliable steam supply and a steam turbine to take excess steam, plus hot water generators for 140°C hot water for DH. The project is at the basic engineering stage, with a view to commissioning in 2021.
The Avedore unit 2 already has a straw boiler which was retrofitted 17 years ago. The current plan is to add two CCGTs to be integrated into the existing plant’s feedwater preheating system. Matching temperatures, including stack temperature limits, is a challenge.
The CEZ presentation covered conceptual studies of liquid air and liquid hydrogen energy storage at the Prunerov 1 site after the existing unit is decommissioned in 2020 and possible battery storage at the Tusunice plant. Both are preliminary examinations, and other possibilities may be considered.
RWE’s Niederaussem lignite-fired power plant
The second day’s main agenda item was a presentation by Peter Moser, of the Coal Innovation Centre at Niederaussem, followed by a tour of the Niederaussem BoA USC lignite-fired USC unit that I described in detail in a report for the IEA in 2006-7 (https://webstore.iea.org/fossil-fuel-fired-power-generation). The view from the top of the boiler house was fine, with billowing clouds from the cooling towers at the Niederaussem site a dramatic sight. There is concern for the towns in this area because of the gradual closure of significant amounts of the older generation capacity and lignite production. There is limited other employment locally. Continuing the same level of production from the Hambach mine, which supplies a significant part of Niederaussem’s lignite, is now prevented by a court order won by an environmental group (to preserve bats). Increasing the balance of fuel from the Garzweiler mine will thus be needed, and this will bring issues of changes in ash behaviour, with increased fouling that will necessitate more sootblowing.
The emphasis in the Innovation Centre’s work is on CCU, with sector coupling through CO2 to DME and OME for energy storage while reducing the CO2 emissions from transport fuels. There is a water electrolyser for hydrogen production at the site, and CO2 captured from the BoA unit’s flue gases in the ALIGN project will be used to demonstrate such a system.
Electric vehicles are not regarded as practical for large vehicles, ships, or for long distances because of the mass of Li-ion batteries needed. A need was perceived to make politicians and the public properly aware of the fallacy of simplistic views on implementing the Energiewende, examples of which are ignoring hourly movements in power availability and only looking at average contributions from wind and solar compared with fossil generation. Germany’s solar PV capacity is 100 GWe, and maximum simultaneous system demand is 80-90 GWe, yet less than 3% of electricity supplied comes from PV, illustrating the difficulties. Another message that is not being heeded, according VGB, is that there would be insufficient storage capacity to balance an 80% renewables-based grid using just electric cars for the purpose, even if all Germany’s cars were replaced by electric ones. Such an assumption is being made by policymakers.