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World class performance and made to last

Posted: 28 July 2014 By: Kyle Nicol

World class performance and made to last, I am of course referring to German engineering. On 22 July 2014, Knut Stahl of RWE Power took the time to exchange information with me on my latest research topic, and show me around the Niederaussem Coal Innovation Centre. The new fleet of lignite-fired pulverised coal combustion power plants, known as BoA, operate with net electrical efficiencies greater than 43% (LHV) and there are detailed designs, integrated fluidised bed lignite drying, for BoA+ plants operating within 45-47%! 

Surprisingly, I was there to talk about another technology which operates at 50% efficiency with unrivalled flexibility, which does not use nickel-based alloys to increase steam temperatures or is a new concept. Coal-fuelled diesel engines have been investigated many times since the 1890s, predominantly in Germany, Switzerland, the USA and now in Australia and Germany (again). Each attempt has failed to commercialise such technology, due to lack of financial incentive with persistently low-cost petroleum fuels. 

Today, however, the energy market has changed, creating a need for coal-fuelled diesel engines. It is not so much that petroleum fuels are drastically increasing in price, but with the increased utilization of renewable energy, the demand for flexible power generation is much greater than that for base-load. The feed-in tariff in Germany has increased photo-voltaic solar power, largely located on roof and in farms, to 36 GW and wind power to 30 GW. Therefore solar power meets the majority of peak demand, and sometimes even more, and wind power intermittently contributes all day. Therefore, the traditional energy supply curve of base-load nuclear/lignite, flexible-load black coal/combine cycle gas turbines, and peaking open cycle gas turbines and pumped storage hydro-electricity no longer functions. This makes peaking power plant redundant and places narrow or negative, profit margins on load following and base-load power plant. Therefore, energy companies, such as RWE and E.On, who have large fleets of thermal power plant are in financial difficulty. To further complicate matters, the Fukushima nuclear power plant accident caused record sales of Geiger counters in Germany, and subsequently the German Government has enforced a staged de-commissioning of their fleet of nuclear power plants by 2017.

RWE see that coal-fuelled diesel engines, using German lignite, could compete with open cycle gas turbines for balancing intermittent renewable energy. More information on this topic will be in my draft report titled ‘Coal beneficiation for the direct injection carbon engine’, which should be out on 1 August.

The Niederaussem Coal Innovation Centre, is home to a pilot post combustion carbon capture plant, a pilot flue gas desulphurisation plant with improved performance (now in construction for a commercial lignite plant) and a fluidised bed lignite pre-dryer (WTA process, reviewed in reports by Colin Henderson and Nigel Dong). 
The main point I took home with me is that, in the power generation industry, the market can change well before a technology is commercialised. Once the market places a need for a new technology, it takes 20-30 years to bring it to full-scale operation with good performance. However, the market can change in shorter time frames. For example, lignite drying technology for higher efficiency power plant took 30 years to develop. The solar power in Germany has increased by 26 GW in the last five years, reducing the need for high efficiency thermal power plant, and increasing the need for more flexible thermal power plant. However, the market could change again to favour newly developed technology. So, having a wide range of technologies allows quick adaption, and therefore no research is wasted.

One last interesting fact is that the cooling tower for the newest unit at Niederaussem power plant is 200 metres tall and is big enough to enclose Essen cathedral. 

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