Evaluation of the potential emissions reductions from the use of CHP systems in different commercial buildings

Combined heating and power (CHP) systems generate electricity near the site of use and capture the waste heat for space heating or hot water. Under the right conditions, a CHP system can reduce the harmful emissions resulting from power production, causing less greenhouse gases to be released than a reference system where power is purchased from the electricity grid. Different building types may be more or less likely to save emissions with CHP systems based on the electrical and thermal needs of the building. This investigation evaluates seven different types of buildings located in Chicago, Illinois for their potential to reduce CO2, NOx, and CH4 emissions using a CHP system. The CHP system modeled is sized to provide 30% of the average hourly electricity needs of each building. The total carbon equivalent emissions, primary energy consumption (PEC), and operational cost of a CHP system are presented along with those of a reference system. In addition, the CHP system efficiency is analyzed with respect to the fraction of the thermal load that is satisfied by the CHP system (Rh). Results show that a CHP system would reduce emissions for all buildings studied, with more than 21% of carbon equivalent emissions reduced for an outpatient health care building. PEC and operational cost would be reduced with the use of a CHP system for some of the buildings. In general it is beneficial to have high Rh values to provide better emissions, cost and PEC reduction from the CHP system operation.