Page 41 - Sustainable On-Site CHP Systems Design, Construction, and Operations

20 CHP B a s i c s

Distributed energy resource (DER) is a term used to denote an on-site power system
involving electric generation units (typically in the range of 3 kW to 50 MW) that are
either stand-alone or in parallel with the electric distribution system strategically placed
at or near the end user facility (Shipley et al. 2001). Under this perspective, DER would
apply to categories (2) through (4) described above. Within the electric industry, the
following terms have also been used (Shipley et al. 2001):

1. Distributed generation (DG). It is defined as anything outside of the conventional
utility grid that produces electricity. DG includes nonutility CHP plants, and
backup generators. DG technologies include internal combustion engines, fuel
cells, gas turbines, and microturbines, as well as hydro and microhydro
applications, photovoltaic, wind energy, and solar energy.
2. Distributed power (DP). It encompasses all of the technologies included in DG as
well as electrical storage technologies. DP includes batteries, flywheels, modular
pumped hydroelectric power, regenerative fuel cells, superconducting magnetic
energy storage, and ultracapacitors.
3. Distributed energy resource (DER). It involves any technology that is included in
DG and DP as well as demand-side measures. Under this configuration, power
can be sold back to the grid where permitted by regulation.
4. Power-only applications:
(a) Standby power required by fire and safety codes for hospitals, water
pumping, critical loads, and other such applications
(b) Base load power or primary power that is less expensive to produce
locally than it is to purchase from the electric utility (continuous on-site
power)
(c) Demand response peaking on-site generation used in coordinated peak
shaving programs with the service utility
(d) Customer peak shaving equipment used by the customer to reduce the cost
of peak load power
(e) Premium power used for reduced frequency variations, voltage transients,
surges, dips, or other disruptions
(f) Grid support equipment used by utilities for peaking or intermediate load
5. Combined power and heat applications. Thermal energy from a single energy source
drives the DER equipment, which is meant to simultaneously meet (in whole or
in part) the electrical or mechanical energy (power) and thermal load of
(a) A single building, group of buildings, a single campus: BCHP plants
(b) Process heat and power needs of an industrial/agricultural unit: ICHP
plants
6. DER technologies. It includes the systems, equipments, and subsystems used to
support the DER applications. These include the following prime movers:
(a) Reciprocating engines (spark ignition or compression ignition)
(b) Gas turbines
(c) Microturbines
(d) Steam turbines
(e) Fuel cells