Sustainability of natural gas chemical looping combustion from efficiency, economic and emergy analyses

Exergo-environmental cost optimization of a combined cooling, heating and power system using the emergy concept and equivalent emissions as ecological boundary

“…For hourly values, the life-cycle emergy consumption is converted into hourly emergy utilization by dividing the service life and operating hours over a year: (20) where SL and OH are the service life (20 years) [55] and the operating hours over a year.…”