Page 333 - Sustainable On-Site CHP Systems Design, Construction, and Operations

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individual piece of plant equipment. CHP plant personnel should be able to discuss
how individual pieces of equipment and the main components that make up that equip-
ment function. Various pieces of plant equipment are tied together in plant systems,
and CHP plant personnel should

• Trace out all plant systems (i.e., follow the piping through plant from start to
finish).
• Draw, from memory, a schematic diagram of each plant system showing all
major equipments and key system components including all major valves.
• Discuss with the lead operator each piece of equipment in each system and how
the system functions efficiently as part of the overall CHP plant.
The various CHP plant systems combine to form a working CHP plant that often has
various equipment strategies and equipment operational choices. The equipment/system
operating choices can be analyzed and understood and CHP plant personnel should have
this information in order to make good economical decisions (e.g., operate the duct burn-
ers and steam turbine generator during the summer on-peak periods, or take the electric-
drive chillers off-line and use the absorption chillers during the on-peak period).
Sustainable on-site CHP operations require a team effort by CHP plant management,
plant operations, and often by outside consultants (engineering, energy-purchase,
financial) with each team member playing an important role. While each team member
has a role to play and a certain level of expertise, all CHP plant team members should
be familiar with all the basic aspects of the operation and maintenance of the CHP
plant.
The typical main goal of the sustainable CHP plant is to maximize the return on
investment (ROI) in the plant itself, to payback investments, to fund plant operations
and maintenance, and hopefully to provide for a reserve fund for equipment replace-
ment. The ROI is maximized, when the annual CHP plant utilization is maximized, for
example, when the electric generators are fully loaded and the waste heat–generated
steam is fully consumed, for example. Assuming that the CHP plant was properly sized
and configured for the facilities varying electric and thermal load profiles, CHP plant
output is maximized by maintaining a high plant availability, which results from good
operation and maintenance procedures, but is also very much a function of equipment
quality and plant design.
The ROI is also maximized by minimizing plant operating costs, with fuel costs
usually being the major cost driver. Depending upon CHP plant location, fuel purchase
options vary from “the only option is to buy fuel from the local utility” to “buying differ-
ent term (spot, short-term, long-term) fuel contracts on the open market.” Knowledge,
experience, expertise, and some luck are required to minimize fuel costs when buying
fuel in the futures markets. CHP plant management must make decisions with conse-
quences based on unknowable futures. Will fuel prices rise or fall, and if so, by what
escalation or de-escalation rate? Other decisions must be made: What is the appropriate
breakdown between spot-market, short-term, mid-term, and long-term fuel contracts? Is
it better to lock in (or hedge) using a guaranteed long-term, known fuel cost, or take a
chance on saving money in the spot market should fuel prices fall with the chance that
one could have to pay more, possibly substantially more, for their fuel than they would
have otherwise had to pay? Some facilities have a full-time energy manager to work on
the above issues, while other facilities hire outside consultants for professional advice.