Page 154 - Sustainable On-Site CHP Systems Design, Construction, and Operations

CHAPTER 8

Fundamental Concepts

Itzhak Maor

T. Agami Reddy

Types of Studies—Screening to Detailed Feasibility
Successful on-site CHP projects require careful evaluation of the feasibility of the CHP
system to the site under investigation. The process of performing the feasibility study
for a CHP is a phased process starting from a preliminary screening study and ending
with a detailed and comprehensive study. A feasibility study essentially consists of
(1) obtaining information on existing or proposed facilities including electrical, heating,
and cooling load data; (2) developing technically feasible solutions to effectively and
efficiently meet the facility’s load requirements; and (3) conducting economic analysis
which involves calculating estimated energy usage and cost, preparing budget cost esti-
mates, and calculating life-cycle costs to determine the recommended plant size and
configuration. The various phases in a feasibility study are shown in Table 8-1, while
Table 8-2 provides an indication of the time, effort, information required, and typical
cost.
The feasibility study types shown in Tables 8-1 and 8-2 are typical for existing instal-
lations and are discussed in more detail in the next sections. For new installations, the
integration of a CHP system is like any other mechanical and electrical system (such as
hybrid chiller plants and air side systems). The feasibility of CHP systems in new instal-
lations should be part of the project design process, which is typically performed
during the programming or planning stage. With the increasing availability and popu-
larity of building energy simulation programs (e.g., DOE 2.1, eQuest, and TRACE), the
applicability and cost-effectiveness of CHP systems can be evaluated in the early stages
of the design. The end of this chapter elaborates the procedure of analyzing a CHP system
for new construction.

Tools and Software for Feasibility Study
As discussed in previous chapters, detailed sizing of CHP systems is often not straight-
forward since it involves considering the variability and concurrent occurrence of
thermal (heating and cooling) loads as well as electric demand, along with plant-level
equipment performance specifics and the time-variant electric and gas price signals.
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