Page 132 - Sustainable On-Site CHP Systems Design, Construction, and Operations

110 CHP B a s i c s

This calculator is widely used internationally by government and business leaders to
understand, quantify, and manage greenhouse gas emissions. It provides the accounting
framework for nearly every GHG standard and program in the world—from the
International Standards Organization to The Climate Registry—as well as hundreds
of GHG inventories prepared by individual companies. It can be downloaded from
http://www.ghgprotocol.org/calculation-tools/sector-toolsets.

Environmental Benefits of CHP
As discussed in previous chapters, use of a CHP system improves the energy efficiency
of natural gas utilization to as much as 85 percent compared to the approximately
50 percent energy efficiency of a conventional approach of buying electric energy
from the grid and using a conventional boiler for providing the thermal energy needs.
Therefore, for this example, the CHP system is 70 percent more energy efficient than the
conventional system and will thus, reduce carbon dioxide emissions by 70 percent.
As shown earlier in Table 7-1, the use of CHP can significantly reduce the carbon
emissions or “eco-footprint” when compared to those from the average and nonbase-
1
load electric generation. Estimates in Table 7-2 show that the use of CHP in a commer-
cial building (2.6 million square feet) located in New York, NY could reduce annual
emissions of CO by about 16,800 metric tons.
2
According to the U.S. Energy Information Administration and EPA’s eGRID, the
total installed capacity of CHP systems in the United States is about 85 GW and
2
accounts for only 9 percent of the total U.S. electric power generation in 2006. Accord-
3
ing to a report of the Oak Ridge National Laboratory, these CHP systems help reduce
annual energy consumption by 1.9 quads and reduce annual CO reduction by 248
2
metric tons (or about 68 metric tons of carbon). This quantity of reduction in CO
2
emissions is equivalent to removing 45 million cars off the road. If in the future, the
United States received 20 percent of its electricity capacity from CHP, it would be
equivalent to removing more than 154 million cars (or more than half of the U.S.
vehicle fleet) from the roads. If the installed capacity of CHP reaches 20 percent mark
in 2030, the total installed capacity would be about 241 GW. It will reduce annual
energy consumption by 5.3 quads and reduce annual CO emissions by 848 metric
2
tons (or about 231 metric tons of carbon).

CO Emissions (metric tons)
2 CO Emissions
2
Source 2004 Baseline CHP System Reduction (metric tons)
On-peak electricity 34,400 8,000 26,400
Baseload electricity 3,700 3,700 0
Steam 6,300 4,600 1,700
Natural gas 0 11,300 −11,300
Total 44,400 27,600 16,800

Source: Kelly, J., “CO Reduction by Distributed Generation,” presentation made at the Midwest Cogen-
2
eration Association Meeting, Oakbrook Terrace, IL, March 2008.
TABLE 7-2 Carbon Footprint Reduction Impact of Using CHP in a Commercial Building in New York, NY