Potential Air Impacts of Demand Response in New England

Geoff KeithSynapse Energy Economics, Inc.

www.synapse-energy.com617-661-3248

DR Emissions Modeling for NEDRI

• Hourly dispatch modeling with PROSYM• Modeled a hypothetical near-term year with a

system reserve margin of 20%• 500-MW DR resource in New England• 60% of DR capacity modeled as load

response and 40% generation• Modeled economic (day-ahead bidding)

demand response – not emergency programs • DR bid at five bid points: $100-500 per MWh

Synapse Energy Economics, Inc.

Overview (cont.)• Examined emissions of NOx, SO2, CO2 ,

PM2.5, PM and seven air toxics

• Explored different assumptions about:– Level of participation by diesel- vs. gas-fired IC

generators– Amount of loads shifted to off-peak periods– Whether the DR resource could be used to meet

operating reserve requirements

• Also modeled energy efficiency programs for comparison

Synapse Energy Economics, Inc.

DR Operation

0

20

40

60

80

100

120

1 11 21 31 41 51 61 71 81

Hours of DR Operation

MW

of

DR

• DR operated in approximately 90 summer hours.• It provided 3,360 MWhs of load relief (over three times as much as ISO NE’s 2002 economic demand response program).• The vast majority of the load relief was in southwest CT.Synapse Energy Economics, Inc.

When DR Is Used for Reserves

• The result is more efficient unit commitment, reduced operation of oil- and gas-fired steam units and overall emission reductions.

• The emission reductions are primarily due to the use of DR capacity to meet reserve requirements.

• Increasing the level of diesel participation in the DR program reduces overall emission reductions for NOx, SO2, CO2, PM2.5 and PM. Reductions of NOx are compromised most. Some toxics increase, some decrease

Synapse Energy Economics, Inc.

When DR Is Not Used for Reserves

• Emissions impacts are much smaller than when DR is used for reserves.

• The net impact on NOx could be positive or negative depending on the amount of DR provided by diesel-fired units.

• While overall emission impacts are small, they could pose health risks in specific locations. The most serious of these risks are probably diesel fine particulates and PAHs.

• DR emissions are likely to come from units without tall stacks located in populated areas.

• On one day in the modeled summer, total DR emissions in southwest CT are in the range of: 3.5 tons NOx.

Synapse Energy Economics, Inc.

Summer Emission Changes from New England DR

(when DR is used for reserves)

NOx

(tons)SO2

(tons)CO2

(tons)PM2.5

(tons)PM

(tons)Hg

(lbs)

All Gas -41 -220 -31,800 -13 -22 -0.3

Half Diesel -32 -220 -31,600 -13 -21 -0.3

All Diesel -23 -220 -31,400 -12 -21 -0.3

1,3 But. (lbs)

Acetaldehyde

(lbs)

Acrolein

(lbs)

Benzene

(lbs)

Formaldehyde

(lbs)

PAH

(lbs)

All Gas 4.3 120 73 10 680 2.2

50% Diesel 2.5 70 38 13 320 3.6

All Diesel 0.6 9.0 2.0 15 -44 4.9

Synapse Energy Economics, Inc.

Range of uncertainty ±10%

Summer Percentage Changes from DR (when DR is used for reserves)

NOx

(tons)SO2

(tons)CO2

(tons)PM2.5

(tons)PM

(tons)Hg

(lbs)

All Gas -0.18% -0.30% -0.13% -0.37% -0.32% -0.07%

50% Diesel -0.14% -0.30% -0.12% -0.37% -0.32% -0.07%

All Diesel -0.10% -0.30% -0.12% -0.36% -0.31% -0.07%

1,3 But. (lbs)

Acetaldhyd.

(lbs)

Acrolein (lbs)

Benzene (lbs)

Formaldehyde (lbs)

PAH (lbs)

All Gas 4.33% 0.29% 0.04% 0.01% 0.23% 0.54%

50% Diesel 2.49% 0.16% 0.02% 0.01% 0.11% 0.86%

All Diesel 0.64% 0.02% 0.00% 0.01% -0.01% 1.10%

Synapse Energy Economics, Inc.

Summer Emission Changes from DR

(when DR is not used for reserves)

Synapse Energy Economics, Inc.

NOx

(tons)SO2

(tons)CO2

(tons)PM2.5

(tons)PM

(tons)Hg

(lbs)

All Gas -3.7 2.3 700 0.1 0.3 0.0

50% Diesel 5.7 3.4 520 0.2 0.5 0.0

All Diesel 15 4.5 340 0.4 0.7 0.0

1,3 But. (lbs)

Acetaldehyde(lbs)

Acrolein (lbs)

Benzene(lbs)

Formaldehyde(lbs)

PAH (lbs)

All Gas 3.6 110 71 5.6 710 0.2

50% Diesel 1.7 57 35 8.2 350 1.5

All Diesel -0.1 0.0 0.0 11 -19 2.9

Range of uncertainty ±10%

Impacts of Efficiency vs. DR• Two efficiency programs we modeled, an energy-targeted

and a peak-targeted program.

• The energy-targeted program reduced annual energy use the most, followed by the peak-targeted program and the DR program.

• Focusing on annual emissions, the peak-targeted program reduced NOx and SO2 most, but the energy-targeted program reduced CO2 most.

• Focusing on summer emissions, the energy-targeted program reduced NOx, SO2 and CO2 most.

For DR, these results are from the scenario in which DR is used to meet reserve requirements.

Synapse Energy Economics, Inc.

Summer Impacts of Efficiency vs. DR

For DR, these results are from the scenario in which DR is used to meet reserve requirements.

-1.0%

-0.9%

-0.8%

-0.7%

-0.6%

-0.5%

-0.4%

-0.3%

-0.2%

-0.1%

0.0%DR ETE PTE

Scenario

Pe

rce

nt

Re

du

cti

on

NOx

SO2

CO2Demand Response

Energy-Targeted EE

Peak-Targeted EE

Synapse Energy Economics, Inc.

Annual Impacts of Efficiency vs. DR

-0.8%

-0.7%

-0.6%

-0.5%

-0.4%

-0.3%

-0.2%

-0.1%

0.0%DR ETE PTE

Scenario

Per

cen

t R

edu

ctio

n

NOx

SO2

CO2

For DR, these results are from the scenario in which DR is used to meet reserve requirements.

Demand Response

Energy-Targeted EE

Peak-Targeted EE

Synapse Energy Economics, Inc.