A comparison is presented of the main approaches to second-law analysis (SL
A) reported in the literature. Five SLAs are considered: exergy, physical-e
xergy, exergy-consumption, negentropy and entropy analyses. The application
of the SLAs is illustrated through an example. In addition, several signif
icant implications of SLA are examined in the fields of environmental impac
t and economics. The presentation herein of the approaches to and implicati
ons of SLA is expected to enhance understanding of SLA and improve its usef
ulness. Copyright (C) 1999 John Wiley & Sons, Ltd.