Serving Critical Infrastructure with Microgrids, Combined Heat & Power and Solar PV


A recently released report, “Combined Heat and Power: Enabling Resilient Energy Infrastructure for Critical Facilities[1] offers examples of critical infrastructure facilities that maintained onsite electric and thermal services during Superstorm Sandy with combined heat and power (CHP).  Critical infrastructure (CI) collectively refers to those assets, systems, and networks that, if incapacitated, would have a substantial negative impact on national or regional security, economic operations, or public health and safety.  While Superstorm Sandy caused extended power outages along the east coast of the United States, these and other critical facilities in the affected area with CHP were able continue their operations despite the emergency status of the power grid. The report was prepared for Oak Ridge National Laboratory by ICF International and several of the U.S. Department of Energy’s Regional Clean Energy Application Centers (CEACs), including the Southeast CEAC managed by the N.C. Solar Center.  Besides offering examples of how actual CHP facilities performed, the report contains information on the strategic application of CHP systems to provide CI facilities with reliable power, as well as state and local policies that promote this application.

Along with enhanced disaster resiliency, CHP systems for CI facilities deliver energy efficiency and cost savings to end users, local utilities, and the electric grid on the whole.  During normal operation, combined heat and power systems operate at an average efficiency of 80% or higher, compared to an average of 45% for utility grid power and onsite thermal generation.  An independent localized grid, termed a microgrid, enables CHP-powered CI facilities to island from the utility grid in anticipation of an emergency.  During such times, microgrids with CHP can maintain utilities for CI facilities without demand for grid power, freeing utility power resources to serve other needs until the grid is restored to full capacity.  Development of a CHP based microgrid for a CI facility, such as a hospital, institutional campus or government facility establishes reliable onsite base load infrastructure that can be complemented with intermittent distributed energy resources, such as solar photovoltaics (PV).  A district energy system provides the infrastructure necessary to distribute heating and cooling to CI facilities in a campus setting.  Great care must be taken to analyze the facility’s electric and thermal needs, and select the combination of CHP, district energy and other DG resources to reliably and cost-effectively provide the desired CI energy infrastructure.

Several of the facilities described in the report “Combined Heat and Power: Enabling Resilient Energy Infrastructure for Critical Facilities” utilize the effective design and technological benefits of an integrated CHP and solar PV microgrid system.


  • South Oaks Hospital is a 245-bed healthcare facility located near Long Island in Amityville, NY, that operates a 1.25 MW CHP system coupled with a 47 KW PV solar system.  On During Superstorm Sandy South Oaks isolated itself from the Long Island Power Authority (LIPA) grid on and remained disconnected from the grid for approximately fifteen days.  During this time, the Hospital admitted patients from other sites that had been displaced by the storm and offered refrigeration for vital medicines to those who had lost power and had no means of keeping medicines refrigerated.  At the request of the utility, the Sandy Oaks remained islanded, despite the partial restoration of local power, affording the utility time to restore the grid to normal.


  • Princeton University operates a 15 MW CHP system integrated with a 5.3 MW solar PV system.  The CHP system produces electricity, steam, and chilled water for the campus, and during Superstorm Sandy the University was able to continue normal operations by disconnecting from the grid and relying on its CHP microgrid district energy system to power the campus.  Non-critical loads around campus such as administration buildings and some classrooms were shut off to keep the CHP system within its generating capability.  The CHP based microgrid system supplied campus with needed energy for three days until the University was able to receive power from the macro utility grid.


  • The Marine Corps Air Ground Combat Center, Marine Air Ground Task Force Training Command in Twentynine Palms, CA  (MCAGCC) operates a 7.2 MW CHP system that is complimented by a 4.8 MW solar PV system and 1.0 MW of fuel cells. By the end of 2013, an additional 9.2 MW of CHP will be operational, for a total of 16.4 MW of CHP.  “Strategic energy planning is a key component of our master plan,” says Commander Rob Tye, head of the facilities management division at Twentynine Palms.  “[The CHP system] is helping us treat energy as a resource rather than as an expense.” (cite CI CHP report) Since the installation of the CHP system, capable of operating independent of the grid, the base has had to disconnect from the utility grid to operate in “island mode” a number of times due to curtailment by Southern California Edison.


State and local policymakers in the Northeast and other areas are considering CHP and solar PV-powered microgrids as a strategic resource for strengthening CI facilities against future storm events.  An example of recent legislation supporting the use of CHP as CI was recently passed by the Texas Legislature and signed by Governor Rick Scott on June 14, 2013.  HB 1864[2] instructs the Texas Energy Conservation Office to issue guidelines for conducting feasibility analysis of CHP for government facilities meeting the definition of CI.  These analyses are already required under legislation passed in 2012, and these new guidelines will establish clear criteria for decisions on whether to implement CHP based on cost / benefit ratios.

The N.C. Solar Center’s Clean Power and Industrial Efficiency (CPIE) team supports advanced deployment of microgrid powered CHP and other distributed energy resources through it’s work on the DOE Southeast CEAC and other strategic initiatives.  At the 2012 N.C.  Sustainable Energy Conference, the N.C. Solar Center’s Clean Power team organized a panel session describing the roles and capabilities of CHP systems in microgrid systems.  This year, at the same conference, the session topic grew into a separate, pre-conference Smart Grid Forum that focused heavily on microgrid applications.  The CPIE team works increase awareness of market opportunities to develop this transformative technology by working alongside the N.C. Solar Center’s Renewable Energy program on technical assistance efforts, and working with the Research Triangle CleanTech Cluster[3] on awareness of policies that promote applications of microgrids with CHP.

[1] Oak Ridge National Laboratory, ICF International and DOE Clean Energy Application Centers, March 2013; available at

[2] “An Act relating to certain energy security technologies for critical governmental facilities”, Texas Legislature;