“In cities, piping exhaust steam to closely packed buildings can make sense. But trying to impose CHP in typical American suburbs where there are no industrial uses, or to where buildings are widely spaced, is irrational.”
“Combined Heat and Power has become a political football in the service of government energy planning to cut CO2 emissions. CHP can be used effectively in specific applications where it can be justified economically, but it shouldn’t be forced on Americans by government edict.”
Combined Heat and Power (CHP) is dragged out periodically by anthropogenic global warming (AGW) activists who want to replace central-station electricity with distributed power from wind and solar. Power Magazine recently highlighted this movement in the section, “Global Developments Giving CHP a Much Needed Boost,” with two articles devoted to CHP installations. The UNFCCC COP 21 Paris agreement to cut CO2 emissions, the feature argued, could provide the needed boost to CHP growth.
Typically, promoters of CHP start by saying that CHP improves efficiency–even to the point of 90%. Greenpeace made this claim in its plan, the “Energy [R]evolution” which is riddled with hype and misinformation.
The Basic Fallacy
CHP uses exhaust gasses, or steam from power plants that generate electricity, to provide heat to buildings or industrial processes. This results in more energy being used for work, but it doesn’t dramatically improve efficiency.
The mistake arises when people assign the same value to the heat extracted from exhaust gasses with the electricity produced by the power plant. The exhaust gasses have low heat (i.e., energy) content and therefore less value than the electricity (i.e., energy) produced by the power plant.
A good analogy is one suggested by the former editor of Power Magazine:
An automobile’s engine using gasoline has considerable horsepower and also heats water in the engine’s cooling system. The hot water is then used to heat passengers during the winter. While this takes advantage of the heat in the water, the water doesn’t have the power to drive the automobile. Gasoline has high energy density, while hot water has a low energy density.
Figure Depicting Heat Value and Uses
Obama’s CHP Push
The Obama administration promoted CHP with an executive order. The EPA, under the Obama administration, issued a 22 page report touting the benefits of CHP as a “clean energy solution”. It has also maintained a database (http://bit.ly/2jACeNT) to provide information supporting CHP. For example, CHP qualified for a 10% investment tax credit in 2016.
Historically, there has been a role for CHP in industrial complexes and refineries since the steam, or exhaust heat, could be used to heat buildings or be used in industrial processes. Europe has used exhaust steam to heat residential buildings. Consolidated Edison used CHP to heat buildings in New York City.
In cities, where buildings are closely packed, piping exhaust stem to these buildings can make sense. But trying to impose CHP in areas where there are no industrial uses, or where buildings are widely spaced, such as in typical American suburbs, is irrational.
(Suburbs with free-standing residential buildings are an anathema to city planners and to those promoting CO2 induced climate change, so CHP fits a strategy that promotes mixed use development.)
Europe’s energy efficiency directive (http://bit.ly/2jZQ0FL) requires member states to promote CHP and remove barriers to its deployment. In addition, European countries have used policy tools such as feed-in tariffs to support CHP.
Combined Heat and Power has become a political football in the service of government energy planning to cut CO2 emissions. CHP can be used effectively in specific applications where it can be justified economically, but it shouldn’t be forced on Americans by government edict.
Also see Donn Dears, “Bogus High Efficiency of Combined Heat and Power Plants” (June 22, 2012).