Frequently Asked Questions.
What is Combined Heat and Power?
Combined heat and power (CHP), sometimes referred to as cogeneration, is an efficient and clean approach to generating onsite electric power and useful thermal energy (e.g., steam, hot water) from a single fuel source. CHP can use several different technologies and a variety of fuels. When evaluated against comparable separate heat and power options, CHP reduces emissions of greenhouse gases and other air pollutants by avoiding the need for grid-based electricity generation, transmission, and distribution, as well as use of an onsite boiler to meet thermal needs.
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What is Cogeneration?
Cogeneration is a technology that converts natural gas into useful energy for greenhouses, which includes inside power generation to heat the greenhouses and the production of supplemental carbon dioxide that can be used to increase plant growth. The cogeneration system purifies the exhaust gases to produce carbon dioxide. The carbon dioxide can be used to supplement atmospheric carbon dioxide for the production of vegetables, ornamentals and medical cannabis. For the production of cannabis, cogeneration is being used to generate electricity to operate the grow lights.
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What are the Benefits of CHP?
The advantage of having a cogeneration system in greenhouses is the ability to have a combined supply of electricity, heat and CO2 for cultivation, as well as to be able to turn heat into cold air if needed. In countries that allow the cultivation of cannabis in greenhouses for medical purposes, cogeneration becomes a key ally, as growing this plant requires a great deal of energy and the ability to self-produce it significantly reduces the producer’s operating costs. Trigeneration and quadrigeneration applications further maximize a plant's overall energy efficiency.
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How does CHP work?
Every CHP application involves the recovery of otherwise wasted thermal energy to produce useful thermal energy or electricity. CHP can be configured either as a topping or bottoming cycle. In a typical topping cycle system, fuel is combusted in a prime mover such as a gas turbine or reciprocating engine to generate electricity. Energy normally lost in the prime mover’s hot exhaust and cooling systems is instead recovered to provide heat for industrial processes, hot water, or for space heating, cooling, and dehumidification.
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Will CHP contribute in the future?
There is an additional 149 gigawatts of onsite capacity in technical potential for new CHP installations across the United States, which could provide resilient, reliable power with lower emissions for facilities (see the U.S. 4 Department of Energy’s Combined Heat and Power (CHP) Technical Potential in the United States). Furthermore, renewable or zero-carbon fuels (e.g., RNG, hydrogen) can be used to further reduce emissions and ensure that CHP systems do not become net carbon emitters over time as future grids incorporate renewable or zero-carbon resources on the margin.
When was CHP Invented?
Thomas Edison included a CHP system when he built the world’s first commercial power plant in 1882. At the time, Edison produced both electricity and thermal heat while using waste heat to warm neighboring buildings. Today, there are more than 4,200 CHP installations in every state in the country. Combined, these projects produce nearly 83 gigawatts of clean and efficient power – the equivalent of more than 166 conventional power plants. This represents 8 percent of U.S. electric capacity and roughly 12 percent of U.S. generation.
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Is CHP widely used in the United States?
The existing 82 gigawatts of CHP capacity at over 4,700 industrial, commercial, and institutional facilities represent approximately 8 percent of current U.S. electric generating capacity. Detailed information on each of these operational CHP systems is available on the U.S. Department of Energy’s CHP Installation Database. CHP is used in every state and is primarily found in areas with high concentrations of industrial and commercial activity, high electricity prices, and policies favorable to CHP.
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What kinds of facilities use CHP?
CHP can be utilized in a variety of applications that have significant electric and thermal loads. As of December 31, 2020, 78 percent of existing CHP capacity is found in industrial applications, providing electricity and steam to energy-intensive industries such as chemicals, paper, refining, food processing, medical grow ops and metals manufacturing. Commercial and institutional applications currently represent 16% of existing CHP capacity, providing electricity, steam, and hot water to hospitals, schools, university campuses, hotels, nursing homes, office buildings, and apartment complexes.