Combined heat and power (CHP)—sometimes called cogeneration—is an integrated set of technologies for the simultaneous, on-site production of electricity and heat.
A district energy system is an efficient way to heat and/or cool many buildings from a central plant. It uses a network of pipes to circulate steam, hot water, and/or chilled water to multiple buildings.
A microgrid is a network of electricity sources and loads that is typically connected to and synchronous with the grid, but is also able to operate independently in “island mode.”
CHP is often an integral part of district energy systems and microgrids. CHP, district energy systems, and microgrids improve energy efficiency, reduce carbon emissions, facilitate integration of renewable energy sources, lower operating costs, and improve resilience of critical infrastructure and the electric power system.
As the grid evolves and includes more different types of distributed energy resources, there is an increased need to ensure the stability and reliability of the electric power system. Flexible CHP systems that can provide needed grid support services―such as ramping capability, frequency response, and voltage control―hold significant potential.
To ensure that the CHP and district energy R&D portfolio is focused on needed technology development areas, the Advanced Manufacturing Office regularly convenes stakeholders to discuss priority needs:
- Fall 2020 Combined Heat and Power Virtual Workshop (September 2020)
- R&D for Dispatchable Distributed Energy Resources at Manufacturing Sites Workshop (February 2016)
In June 2022, approximately 50 researchers from industry, national laboratories, and research institutes met with the Advanced Manufacturing Office to understand the performance of the projects being sponsored through the CHP program and the status of the technology development, which informs future program planning:
CHP and district energy R&D portfolio focus areas are:
- Flexible CHP Systems
- High Efficiency Turbines for CHP
- High Power to Heat Ratio CHP Systems
- District Energy
- Tools and Analysis for CHP in Microgrids and District Energy Systems
FLEXIBLE CHP SYSTEMS
These projects develop flexible CHP systems that can provide support services to the electric grid. The projects are divided into two topic areas: (1) power electronics and control systems that enable seamless interconnection of CHP systems with the grid; and (2) prime movers to enable CHP systems to be more responsive to the demands of the modern grid.
Clemson University – North Charleston, South Carolina
The project will develop and test a modular control system architecture to enable flexible CHP systems with advanced grid support functionality. The distributed control system architecture will enable facilities to more effectively utilize innovative power electronics equipment and controls to seamlessly interconnect CHP systems with the power grid.
GE Global Research – Niskayuna, New York
The project will develop a full-size grid interface converter and control solution to interconnect small and mid-size CHP engines to a low or medium voltage electric grid. All control functions to meet interconnection requirements will be developed and packaged with a substation microgrid controller.
University of Tennessee, Knoxville – Knoxville, Tennessee
The project will develop a power conditioning system converter and a corresponding control system for flexible CHP systems. The power conditioning system converter and controller will support different types of CHP prime movers and be scalable to serve as the interface connector between CHP systems and a medium voltage grid.
Virginia Polytechnic Institute – Blacksburg, Virginia
The project will develop a modular, scalable medium voltage power converter featuring stability-enhanced grid support functions for flexible CHP systems. The converter will use a modular circuit topology that is scalable both in voltage and current to flexibly meet the needs of CHP systems in the 1- to 20-MW range.
ElectraTherm – Flowery Branch, Georgia
The project will enable a novel flexible CHP system concept by developing an Organic Rankine Cycle system that can be integrated with a reciprocating engine to achieve total CHP system efficiencies of 85% or more at both its rated electrical capacity and at 50% capacity. Such a CHP system will be able to provide additional power to the grid when needed without sacrificing system efficiency under different operating conditions.
Siemens Corporation – Charlotte, North Carolina
The project will integrate a supercritical carbon dioxide bottoming cycle with a 5.3-MW gas turbine to develop a CHP system that is able to transition rapidly between 50% and 100% load by engaging or bypassing the bottoming cycle while maintaining electrical system efficiency above 30% at all times.
Southwest Research Institute – San Antonio, Texas
The project will develop new combustion system solutions and technologies that will enable a gas turbine to maintain high efficiency and low emissions during high turndown operation. Increasing the efficiency of the turbine at part load conditions and expanding the lean operating envelope of the turbine will significantly enhance the ability of a gas turbine-driven CHP system to provide advanced grid services.
HIGH EFFICIENCY TURBINES FOR CHP
These projects are developing advanced materials, combustion system improvements, and new airfoil designs to improve the efficiency of turbines used in flexible CHP systems.
National Energy Technology Laboratory – Morgantown, West Virginia
Oak Ridge National Laboratory – Oak Ridge, TennesseeThe project will evaluate how a combination of new materials, additive manufacturing technologies, and airfoil cooling design can raise the efficiency of turbines used in CHP systems by demonstrating how to increase the turbine firing temperature by 100°C compared to a 2015 baseline. The project team will also estimate the economic benefits from these efficiency gains in CHP systems that use turbines smaller than 20 MW.
Oak Ridge National Laboratory – Oak Ridge, Tennessee
Argonne National Laboratory – Lemont, IllinoisThe project will evaluate advanced materials and develop lifetime modeling tools to enable a greater than 100°C increase in gas turbine inlet temperature compared to a 2015 baseline, and improve the durability and reduce maintenance costs of high temperature components in current CHP systems. The targeted components include heat exchangers, combustion liners, and hot corrosion-resistant coatings for disk applications with high sulfur opportunity fuels.
HIGH POWER TO HEAT RATIO CHP SYSTEMS
These projects are developing CHP technologies with increased electricity generation efficiency while maintaining high overall system efficiency.
Georgia Institute of Technology – Atlanta, Georgia
The project will develop a hybrid fuel cell/gas turbine system concept and cyberphysical demonstration as a combined heat and hybrid power (CHHP) system for both robust and high power-to-process heat ratio cogeneration. The system maintains distinct, elevated electrical efficiencies while simultaneously supporting a broad span of heating needs.
Noble Thermodynamic Systems – Berkeley, California
The project will expand the application of the Argon Power Cycle―a closed loop internal combustion engine cycle that uses argon as its working fluid―to develop an ultra-efficient CHP system capable of single-cycle efficiency greater than 65% and overall CHP efficiency more than 75%, delivering emission-free electricity from natural gas.
University of Wisconsin Madison – Madison, Wisconsin
The project focuses on the design, development, and fabrication of two major system subcomponents―a turbine wheel and the electrical generator and associated power electronics―to be used in a supercritical CO2 (sCO2) heat to power solution system. The use of sCO2 provides the advantages of small size, high efficiency, and lower capital cost compared to conventional steam cycles.
Fact sheet coming soon.
DISTRICT ENERGY
These projects are developing innovative technologies and approaches to integrating flexible CHP into district energy systems.
Caterpillar Inc. – Peoria, Illinois
The project will develop and demonstrate a 2-MW flexible natural gas/hydrogen CHP system in a municipal district energy system. The project will also evaluate the greenhouse gas emissions profile, reliability, durability, and barriers to adoption of a natural gas/hydrogen CHP system.
Clemson University – North Charleston, South Carolina
The project will demonstrate the capability to use an Organic Rankine Cycle in multisource heat recovery applications utilizing a single turbo expander and a flexible electrical generation system. The heat recovery system will be able to aggregate multiple heat sources, including geothermal, into a single collection heat stream that can then be controllably proportioned between electrical generation and district heating and cooling requirements.
Fact sheet coming soon
The George Washington University – Washington, D.C.
The project seeks to determine how to effectively integrate and enhance electricity generation and energy storage components of an urban district energy system. The project will focus on an urban district energy system with a combined heat and power plant, solar thermal heating, rooftop photovoltaic generation, and battery and thermal storage.
Paragon Robotics, LLC – Bedford Heights, Ohio
The project will develop improved control technology architecture and algorithms for district energy systems. Most current community-based district energy systems only employ basic controls optimization, drastically reducing the overall efficiency of the systems and hindering the addition of CHP and other district energy assets.
TOOLS AND ANALYSIS FOR CHP IN MICROGRIDS AND DISTRICT ENERGY SYSTEMS
These projects are conducting analysis and developing tools for the application of flexible CHP systems in microgrids and district energy systems.
Houston Advanced Research Center – Houston, Texas
The project will develop a cloud-based user-friendly tool for stakeholders with very limited engineering knowledge to expedite feasibility analyses of CHP-based district energy systems, stimulating the integration of efficient CHP systems, renewable energy sources, and thermal energy storage into innovative community-based district energy systems and microgrids.
International District Energy Association – Westborough, Massachusetts
The project will increase stakeholder awareness of the role of district energy, CHP and microgrid assets in supporting and participating in the grid of the future. The project team will verify, validate and analyze performance metrics of district energy, CHP and microgrids compared to existing baseline technology.
Fact sheet coming soon
National Renewable Energy Laboratory – Golden, Colorado
The National Renewable Energy Laboratory, working with project partners, has extended the DOE’s REopt Lite tool to include CHP modeling capabilities. REopt Lite provides technoeconomic optimization and resilience analysis for grid-connected solar photovoltaics (PV), wind, and battery storage at a site. The recent addition now adds CHP, absorption chillers, and thermal energy storage to the mix. The tool analyzes hourly data across the project lifecycle and evaluates the trade-off between capital costs, operating costs, and savings to find the most cost-effective mix of technologies.
National Renewable Energy Laboratory – Golden, Colorado
Lawrence Berkeley National Laboratory – Berkeley, CaliforniaThe project will develop a tool that can quantify the value of a district energy system and its potential for waste heat recovery. The new software analysis platform will evaluate and optimize district energy systems to better utilize low-temperature waste heat from nearby commercial and industrial buildings. The tool will help project developers and engineers easily quantify the potential value and cost savings of community energy systems for both producers and consumers of waste heat.
University of Colorado Boulder – Boulder, Colorado
The project will create a holistic open-source modeling and optimization platform for the design and retrofit of grid-interactive efficient district energy systems by extending the National Renewable Energy Laboratory’s Urban Renewable Building and Neighborhood optimization (URBANopt) platform.
Fact sheet coming soon
Find information about past CHP R&D projects funded by DOE. Previous R&D efforts focused on advanced reciprocating engine systems, packaged CHP systems, high-value applications, fuel-flexible CHP, and technology demonstrations.
Learn more about CHP in DOE's Onsite Energy Program.