How much can
district energy help?
Mark Spurr, IDEA Legislative Director
production is estimated to be 26 million
MWh, or 8. 2 percent of all CHP generation.
The majority of district energy CHP is classified as Commercial NAICS, with the balance split between NAICS- 22 and Electric
CHP has already contributed significantly to holding greenhouse gas emissions
down. Based on detailed analysis of EIA
data on more than 9,000 power generation
units, figure 3 shows that Commercial and
Industrial CHP emit half the CO2 per MWh
compared with all U.S. generating plants
including nuclear, and only 41 percent of
the emissions compared with non-nuclear
plants. NAICS- 22 CHP plants, which are
designed primarily for power sales, are less
efficient but still significantly better than
District energy has already helped reduce greenhouse gas emissions worldwide. As the U.S. Congress
continues its work on climate change legislation, this is a good time to tackle the
question, “How much can district energy
contribute to achieving future U.S. carbon
dioxide emission reductions?
A Look at U.S. Emissions
First, let’s look at the total U.S. greenhouse gas picture. According to the U.S.
Energy Information Administration (EIA),
greenhouse gas emissions totaled 7,147
million metric tons of carbon dioxide
equivalent (MMTCO2E) in 2005. Of this
total, 5,945 MMTCO2E, or 83 percent,
were energy-related CO2 emissions, with
the remainder other greenhouse gases.
Power generation accounts for 40 percent
of energy-related CO2 emissions. As shown
in figure 1, with only 31 percent of power
plant fuel converted to useful electric energy,
power generation waste heat represents a
startling 27 percent of total CO2 emissions!
plants. CHP provided 8. 2 percent of all U.S.
electricity generated in 2005. As shown in
figure 2, of the total 325,000 MWh of CHP
power generated in 2005, 56 percent was
generated in facilities classified by the North
American Industry Classification System as
NAICS- 22, defined as plants “whose primary
business is to sell electricity and heat to the
public.” Industrial and Commercial CHP
accounted for 41 percent and 2 percent,
respectively. These facilities are classified as
using CHP “primarily for own-use generation, but which may also sell some power
to the grid.” A small portion ( 1 percent)
of CHP generation was by Electric Utilities.
Total district energy CHP electricity
Based on U.S. EIA data,
Commercial and Industrial CHP
emit half the CO2 per MWh
compared with all U.S. gener-
ating plants including nuclear.
Annual U.S. greenhouse gas emissions would be 120 MMTCO2E higher if
the 325 million MWh generated by CHP
were instead generated with a typical fos-sil-fueled, power-only power plant. These
savings exceeded 2 percent of total U.S.
energy-related emissions in 2005.
District Energy Today
District energy systems represent a
substantial ‘heat sink’ for further CHP
Figure 1. Electricity Generation Waste Heat as Percentage of Total Energy-Related Greenhouse Gas
Emissions, United States, 2005.
How CHP Has Already
Combined heat and power is a demonstrated strategy for reducing greenhouse
gas emissions by recycling the heat that is
normally wasted in power-only generating
27% Electricity generation waste heat
13% Delivered electricity
Source: U. S. Energy Information Administration, Energy Market and Economic
Impacts of S.280, the Climate Stewardship and Innovation Act of 2007.
Other energy- related GHG 60%