Combined Heat and Power
Combined heat and power (CHP) systems on research campuses can reduce climate impact by 15% to 30% and yield a positive financial return, because they recover heat that is typically wasted in the generation of electric power and deliver that energy in a useful form.
The following links go to sections that describe how CHP may fit into your climate action plans.
CHP systems can take advantage of large central heating plants and steam distribution systems that are available on many campuses. CHP systems may be new at a particular facility, but the process and equipment involve well-established industrial technologies. The U.S. Environmental Protection Agency CHP Partnership offers technical information and resources that describe how campuses use CHP technologies and best practices.
Considerations for Campus CHP
- Does it have a central boiler and district heating system?
- Can it operate a complex utility plant?
- Is coal part of the fuel mix?
- Do you want one project that significantly reduces climate impact?
- Do you have a good match between heating and electrical demands?
Before undertaking a CHP assessment or installation, a research campus should consider the following to determine whether CHP is a viable option.
Central Boiler and District Heating System
Research campuses with central boilers and district heating systems can readily leverage CHP. If your campus does not have these systems, it is probably not well positioned to use CHP.
Operating a Complex Utility Plant
Operating CHP systems is an around-the-clock effort and requires plant managers, operators, electricians, and mechanics. This is nothing new if your campus currently operates a central plant. However, if you are considering a new plant, you need to bear these costs and logistics in mind.
Coal as a Fuel Source
Coal produces more carbon dioxide emissions per British thermal unit (Btu) than other boiler fuels. Replacing some or all coal with biomass or other renewable fuels greatly reduces carbon emissions and climate impact. The material handling and combustion systems used for coal are often suitable for partial, if not total, biomass mixing with little modification.
One Project with Significant Carbon Reductions
Few single projects can reduce climate impact as much as installing a CHP plant. When undertaking a CHP project, campus managers sometimes simultaneously convert from coal to natural gas, biogas, or landfill gas (read more about fuel sources). The net result is a substantial reduction of carbon emissions.
Matching Heating and Electrical Demands
Having the right balance of heating and electrical demands is important, as CHP plants have an optimal ratio of thermal energy to electricity production; in the range of 2:1 to 3:1. That said, CHP is usually not a good choice for southern climates, which have large electricity loads during the summer.
Some research campuses in such areas use "tri-power plants" that combine a CHP system with an absorption chiller. The chiller uses the heat output to produce chilled water for cooling. Here, the ratio of thermal energy used for cooling to electricity production is similar to the case where CHP is used for heating.
Leading Example: University of Missouri CHP Plant
The University of Missouri houses a CHP system that produces thermal energy and electricity at nearly twice the efficiency that it formerly obtained from its conventional power plant. The system includes gas turbine electric generators, solid fuel boilers, steam turbine generators, and centrifugal and absorption chillers.
The central plant offers operational flexibility, allowing the university to use a wide range of fuels. Campus facilities staffs have tested local waste materials, including tires, corn cobs, and wood chips, as fuels to replace coal. The university also has an award-winning energy conservation program.
Read more about the installation on the University of Missouri Web site.
Additional examples of research campus fuel source projects include:
Princeton University: Uses CHP in addition to steam-driven chillers for a total energy system.
University of Iowa: Uses oat hulls and other fuel sources to operate a CHP system on campus.
Cornell University: Recently installed a 30-megawatt CHP system. You can read about system information, construction details, and industry reference articles online.
The following resources explain the fundamentals and link to technical information about CHP:
Roughly 65% of fuel energy content entering a conventional electricity generating station is rejected as heat. CHP systems use most of this heat, increasing total system efficiency to 80% or higher. They produce thermal energy for buildings or processes and simultaneously generate electricity. Additional information is available on the U.S. Department of Energy Federal Energy Management Program CHP Basics page.
Detailed information about CHP technologies is available through these organizations:
International District Energy Association: Provides a forum for evaluating, installing, and operating central heating and CHP systems.
Northeast Combined Heat and Power: Offers CHP technical support and information resources.