b'Engineer Innovation | Power & EnergyA clean energy future Figure 1: The Siemens SGT-800 Gas Turbine LES Simulations hold the key to cleaner fuel flexible gas turbinesBy Stephen Ferguson, Siemens Digital Industries SoftwareGas turbines play an increasingly criticalcoal, it releases much less carbon role in delivering energy security,dioxide during combustion. In dynamically evening out the peaks andcomparison with a brand-new coal-troughs in production from intermittentbased power station, modern gas power sources such as wind, solar andturbines generate 50 to 60 percent less hydroelectricity. However, efforts toCOper MWh of electricity generated. 2reduce NOx emissions have theThe International Energy Agency potential to introduce thermo-acousticestimates that coal-to-gas switching has oscillations that can limit the range ofsaved over 500 million metric tons of operation of low-emissions gasCOemissions in the past decade, which 2turbines. is equivalent to the savings that would have been generated by putting 200 I spoke with Dr Daniel Moll, amillion electric vehicles on the road Combustion Engineer with Siemensduring the same time period. Energy, who has been pioneering the use of CFD simulations with large EddyFrom an air pollution point of view, gas simulation (LES) models forturbines are also running cleaner than understanding and predicting theever. With the almost universal adoption formation of thermo-acoustic waves inof lean premixed combustion gas turbine combustors. technology (in which the fuel is mixed with air to reduce the temperature of The changing role of gas turbines in acombustion), modern gas turbines clean energy future routinely deliver so-called single-digit Although natural gas is obviously aNOx emissions when operating at full fossil fuel, when compared with oil andload. 6'