20 research outputs found
Pre-transplant risk factors predicting post-transplant cytomegalovirus infection in liver transplant recipients
Energy analysis of hydrogen production from a hybrid wind turbine-electrolyzer system
In this study, the energy performance of hybrid wind-hydrogen system is investigated. In addition to energy performance, a cost analysis of hydrogen production is also carried out for stand-alone system for different PEM electrolyzer capacities. Monthly efficiency variations for wind turbine operation for the total system are calculated and maximum efficiency values obtained as 22 % and 11.9 %, respectively. Energy efficiency of the PEM electrolyzer is determined for different temperature and electric current values. The results show that increasing the working temperature from 35 °C to 75 °C increases the energy efficiency of PEM electrolyzer from 62 % to 70 % at 30 A current. Hydrogen cost is calculated by economic analysis of wind-electrolysis-hydrogen production systems using the present-value method. The lowest cost at 6 m/s wind speed is calculated as 23.6 US/kg. Furthermore, economics of wind-hydrogen system not only depends on the cost of wind turbine and electrolyzer but also on the configuration and resources. © Springer International Publishing Switzerland 2014