Page 299 - Sustainable On-Site CHP Systems Design, Construction, and Operations

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Given the poor current state of operations in many commercial buildings, integrating
distributed generation (DG) technologies with existing building systems presents a
challenge. Although no reliable nationwide estimates are available, many case studies
in limited geographic regions over the past decade or more have shown that a signifi-
cant fraction (as much as 30 percent) of the energy consumed in commercial buildings
is unnecessarily wasted (Ardehali et al. 2003; Ardehali and Smith 2002; Claridge et al.
2000, 1996, and 1994). Much of the waste can be related to the inability to control and
maintain building systems, and detect, diagnose, and correct operational problems when
they occur.
The emergent CHP industry must face the challenge to reliably integrate controls
for the various CHP components to maximize system efficiency, optimize system per-
formance, prevent damage to equipment, and integrate CHP with existing building
controls. As discussed in previous chapters, CHP components are available in various
sizes and models from various manufacturers. Engineers, contractors, and integrators
assemble these components into integrated packages where capacities and operation
match those of individual building load profiles. The capability to assemble controls for
these systems automatically and error-free in a plug-and-play manner, with embedded
diagnostic capabilities, would provide a huge advantage to this new technology entering
the buildings market.
For CHP technologies to work at near-optimal and fault-free conditions, facilities as
well as CHP plants need supervisory control systems that coordinate the operation of the
entire CHP asset and integrate the CHP system with existing building systems. Challenges
in integrating CHP systems with existing building systems include sizing the equipment
and systems to optimally match the building’s requirements; smooth and seamless inter-
face between CHP controls and existing building controls; regular and frequent assess-
ment of building loads (electric and thermal) as well as equipment and system performance;
and coordination of building demands and grid needs to match CHP system outputs and
to determine how much and when to throttle back the CHP system or to sell power back
to the grid. Many buildings lack a control infrastructure suitable for seamless integration
of a CHP system with existing facility systems.
Why Supervisory Controls and Diagnostics Are Relevant
The key challenge facing the emergent CHP technologies is the integration and bundling
of today’s unitary equipment into turnkey packages where components are sized and
controlled for optimal performance for a specific building’s energy usage profile. This
suggests that suppliers will assemble CHP packages from various types and sizes of
components from original equipment manufacturers (OEMs) and provide the associ-
ated controls and control strategies, so that the heating, cooling, and electrical outputs
of the package can be matched to the building loads as they change from hour to hour
and season to season.
Realizing the potential energy savings and societal benefits from CHP will require
its rapid acceptance and penetration into the buildings sector. To accomplish this,
suppliers must produce flexible, integrated systems quickly, inexpensively, and reli-
ably, while honoring the OEMs’ suggested ranges and absolute limits for equipment
operating conditions. Therefore, there is as great a need for plug-and-play controls as
there is for physical compatibility among equipment.
Ensuring a high level of performance that will guarantee continued consumer accep-
tance requires continuous, on board performance diagnostics for both component-level