Distributed Energy Resource Basics
Distributed energy resources (DER)—also called distributed generation, distributed energy, and distributed power systems—are small, modular, decentralized, grid-connected or off-grid energy systems located in or near the place where energy is used. They are integrated systems that can include effective means of power generation, energy storage, and delivery.
As the single largest energy user in the nation, the Federal Government stands to gain many benefits by using DER and combined heat and power (CHP) systems at its facilities.
DER and CHP systems can be applied in a variety of applications to:
- Improve power quality and reliability.
- Provide efficient, low-cost heat and power to a facility.
- Provide energy to off-grid or remote facilities.
DER systems can also enhance energy security at a site by helping diversify the energy supply and by providing prime power to mission-critical loads. In addition, these systems benefit the local utility infrastructure by offsetting the need for capacity increases and by reducing congestion in transmission and distribution systems.
- Improve power quality and reliability
- Provide standby power for critical loads
- Provide peak power and low-cost energy where electricity rates are high
- Generate power for remote and off-grid facilities
- Permit efficient use of waste heat in combined heat and power applications.
Where should Federal agencies use DER systems to get the greatest benefit? To answer this question, FEMP conducted market studies of Federal opportunities for DER and CHP systems. The results indicate tremendous potential for cost-effective DER and CHP systems in the Federal sector.
Several technologies can be used in DER projects. The right choice is determined by application, cost, environmental considerations, and system size. The following DER technologies are described across the Department of Energy (DOE) Industrial Distributed Energy Web site:
- Reciprocating Engines
- Combustion Turbines
- Fuel Cells
- Photovoltaic Systems
- Concentrating Solar Systems
- Wind Energy Systems
- Small Modular Biopower
- Energy Storage Systems
The summary table below provides some preliminary cost, size, and emissions estimates for these DER technologies:
|Summary of Cost and Performance Parameters for Distributed Generation Technologies|
|Technology||Size Range (kW)||Installed Cost ($/kW)b||Heat Rate
|Approx. Efficiency (%)||Variable O&M ($/kWh)||Emissionsa (lb/kWh)|
|Natural Gas Engine||1-5,000||450-1,100||9,700||35||0.025||0.0059||0.97|
|Natural Gas Engine w/ CHPc||1-5,000||575-1,225||9,700||35||0.027||0.0059||0.97|
|Dual Fuel Engine||1-10,000||625-1,000||9,200||37||0.023||0.01||1.2|
|Microturbine w/ CHP c||15-60||1,100-1,850||12,200||28||0.014||0.00049||1.19|
|Combustion Turbine w/ CHP c||300-10,000||700-2,100||1,100||31||0.024||0.0012||1.15|
|Photovoltaics||Limited by Available Space||7,000-10,000||--||N/A||0.002||0.0||0.0|
a Nationwide utility averages for emissions from generating plants are 0.005 lb/kWh of NOx and 1.2 lb/kWh of CO2.
b The high end of the range indicates costs with NOx controls for the most severe emissions limits internal combustion technologies only.
c Although the electric conversion efficiency of the prime mover does not change, CHP significantly improves the fuel utilization efficiency of a DER system.
d Storage devices have virtually no emissions at the point of use. However, the emissions associated with the production of the stored energy will be those from the generation source.
e Same as generation technology selected.
f Add cost of component technologies.
The applicability of renewable energy technologies for DER systems depends on a number of things, including:
- Local renewable resources
- Cost of energy at the site
- Available financial incentives
- Specific application factors
Non-renewable DER technologies (e.g., reciprocating engines, combustion and microturbines, and fuel cells) are largely fueled by natural gas, but can also use diesel and biodiesel fuels, anaerobic digester gas, biomass fuels, and even hydrogen.
DER systems can be used as retrofits in existing facilities, or designed specifically for a new facility. In either scenario, DER should be used with energy-efficient products and practices, to maximize the benefits and reduce costs. The more energy requirements are reduced; the smaller (and less expensive) the needed DER system.