Page 403 - Sustainable On-Site CHP Systems Design, Construction, and Operations

376 Ca s e S t u d y 5

As with many U.S. regulatory issues, interconnection is seriously complicated
because utility regulation resides, in large part, at the state level. A CHP project would
be responsible for the reliability effects and costs of all utility system upgrades associ-
ated with its particular interconnection. These effects are determined by the utility’s
studies of each project, based on assumptions made with regard to the timing of any
other distributed resource projects ahead of it in the queue.
Final reliability requirements and cost responsibility depend on which projects are
ultimately built. As these often may not be the same projects assumed in the study, this
condition adds to uncertainty and delays. Some public service commissions have queu-
ing management protocols (such as clustering or class-year studies) that aim to mitigate
the problems caused by the project-by-project queue approach.
The mother standard for micro- and macrogrid interconnection is the IEEE 1547-
series of documents, some of which are still in draft mode. During IEEE 1547 develop-
ment, industry thought leaders recognized that islanding parts of the macrogrid’s
distribution system could improve reliability of the major control areas of the U.S. grid.
The 1547-series of standards provide alternative approaches and good practices for the
design, operation, and integration of the microgrids and covers the ability to separate
from and reconnect to part of the utility while providing power to the islanded local
power systems. 10

Other Considerations
• Local enforcement authorities determine whether the natural gas supply is
available enough to be treated as an “on-site” fuel source.
• Any COPS feasibility study should include information about other generators
in the area. Sometimes information about other backup generators are registered
with the fire department rather than the buildings or air quality/permitting
departments.
• Most urban areas limit the hours that diesel generators can be operated each
year because of their NO and SO emission levels. Peak-shaving may require a
x x
separate air quality permit.
• Backup fuel supply chains share with the electric and gas network, the basic
feature of congestion. When primary fuel supply chains bind, the same will be
seen in the prices of backup fuel supplies.
• Dual-fuel generators are ideal for COPS and are the thin end of what could be a
big wedge for CHP. A number of tests are underway around the country using
dual-fuel diesels fired with 80 percent natural gas and 20 percent diesel oil.
Some European manufacturers offer gas/diesel packages capable of continuous
operation on a 90/10 mix. 11

Electrical Load Classes
Throughout this chapter the term “backup” has been used to describe a family of tech-
nologies which carry load when the normal (primary) source of power is absent. When
the backup source can carry full load, the term “alternate” source is used. A common
vocabulary for the subtle differences in electrical load classes, however, has eluded
thought leaders in IEEE and NFPA leading practice committees. There is ambivalence