Energy efficiency is crucial in meeting the unprecedented energy and environmental challenges faced by Europe in the coming decades. Energy efficiency improvements in Europe could lead to a reduction in the direct cost of energy consumption of more than €100 billion annually by 2020. Efficiency improvements will also lead to the reduction of over 780 millions tons of CO2 annually in the European Union (EU). Among the many potential methods for reducing losses and improving generating efficiency among the generating assets of the EU, there is a small measure that can lead to significant results: The reduction of windage friction losses within a generator by increasing the hydrogen purity and improving hydrogen pressure stability can lead to the reduction of more than 1.5 million tons of CO2 yearly. This estimation is based on an average improvement of 3,000 MWh/year for each of the greater than 500 hydrogen cooled coal fired steam generators located throughout Europe.
Windage loss, accounting for 30-40% of generator losses in hydrogen-cooled generators, is caused by fluid friction between the hydrogen gas, enclosed in the generator for cooling purposes, and the rotor. This loss increases as the purity of the gas decreases. The purity of the hydrogen gas has traditionally been maintained by feeding high-purity hydrogen into the generator from a high-pressure hydrogen gas cylinder, tube trailers, or liquid tanks. However, these methods can only maintain the purity level at 96-98% at best /2/.
ENDESA Generación, S.A., together with Distributed Energy Systems and BESEL, S.A., have carried out a project at ENDESA’s Compostilla Power Plant whose aim was to increase and maintain the purity of hydrogen gas above 99% and therefore, improving generator efficiency, capacity, and longevity, by installing a HOGEN® onsite hydrogen generation system and an innovative StableFlow™ hydrogen control system that controls the quality of the hydrogen cooling gas within the generator casing. The evaluation was conducted as part of a Research and Development project named EFIALTER: FIT-120000-2006-73, funded by the Spanish Department of Industry, Commerce and Tourism in the frame of the Research and Development PROFIT Program.
Evaluation of the systems was conducted on Compostilla’s generator group# 3, a 330 MW steam turbine generator. The evaluation confirmed that the equipment enhanced hydrogen purity in the generator from 97.5% to greater than 99%, thereby reducing windage loss by 3,000 MWh/year at 6,000 hours of operation.