Page 414 - Sustainable On-Site CHP Systems Design, Construction, and Operations

CHAPTER 24

Case Study 6:

Eco-Footprint of On-Site

CHP versus EPGS Systems *

Milton Meckler

Lucas B. Hyman

Kyle Landis

his chapter compares the eco-footprint of three sustainable on-site CHP system
alternatives with a representative 30 percent thermally efficient conventionally
Tdesigned remote electric utility/merchant power generation station (EPGS) serving
a 3.5-MW gas turbine installation proposed for a central California university campus.
It has been demonstrated (2007 ASHRAE Transactions # DA-07-009) that sustain-
able on-site combined heat and power (CHP) systems for large multibuilding projects
employing a simplified design approach from that of a conventionally designed
miniutility-type CHP systems employing large volume/footprint, costly, high thermal
mass heat recovery steamgenerators (HRSGs), and 24/7 stationary engineers, can result
in lower annual owning and operating costs.
The above peer-reviewed 2007 paper illustrated the use of prefabricated, skid-mounted
hybrid steam generators with internal headers, fully integrated with a low-pressure drop
heat extraction coil (in lieu of an HRSG) located in the combustion gas turbine (CGT)
exhaust. Subject CGT extraction coil utilized environmentally benign heat transfer fluid to
redistribute extracted CGT exhaust waste to serve campus multibuilding annual space
cooling, heating, and domestic hot water loads with system thermal balance facilitated via
maintenance of a high year-round log mean temperature differential at the CGT extrac-
tion coil, also resulting in a lower CGT backpressure, and significant life-cycle-cost (LCC)
savings. This chapter also takes an alternative look at the earlier referred CHP plant

∗ This case study is reprinted with permission from ASME, and originally appeared as ASME paper
ES2008-54241 presented at the ASME International Conference on Energy Sustainability, August 2008.
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