10.3 Controls on Idling – Idle Reduction Technologies

Reduce vehicle idle emissions through the use of idle reduction technologies.

Description

This measure achieves emission reduction through the use of idle reduction technologies for heavy duty vehicles and equipment including trucks, buses, construction equipment, and other heavy-duty on-road vehicles in the nonattainment area. Idle reduction technologies can include:

• Diesel- and battery-powered auxiliary power units (APUs);

• Direct-fire heaters (DFH);

• automatic engine shut down and start-up (ESS); and

• Truck stop electrification (TSE).

The equations provided here may be used for projects in which heavy-duty vehicles shut down the main engine and apply power using an idle reduction technology. The equations quantify the reduction in heavy-duty vehicle emissions and adjust the emissions for the emissions produced by fuel-operated idle reduction technologies.

The primary attraction of this measure is that it provides emission reduction benefits while also providing a cost savings through reduction in motor fuel consumption. A limitation of this measure is that it is equipment dependent, requiring either the heavy-duty vehicle to be equipped with an idle reduction technology, or the facilities that idling occur provide TSE option.

Application

Medium-sized and large urban areas with significant number of heavy-duty vehicles and equipment operating in the area.

$$\text{Daily Emission Reduction (grams/day)} = \sum A \times (B - C - D)$$

$$A = N_{V\ T}$$

The number of vehicles equipped with each type of idle reduction technology T (APU, DFH, ESS, and TSE)

$$B = \mathit{EF}_{I} \times t_{T}$$

The reduction in idling exhaust emissions from reduced time spent idling as a result of operating idle reduction technology T

$$C = N_{\mathit{RSt}} \times \mathit{TEF}_{\mathit{TRK}}$$

The increase in start exhaust emissions resulting from engine restarts

Applicable to automatic engine shut-off and restart

For other technologies, C = 0

$$D = \mathit{EF}_{T} \times t_{T}$$

The increase in emissions from operating idle reduction technology

Applicable to APU and direct-fired heaters

For TSE and battery-powered APU, D = 0

Variables	(Unit)	Definitions
$\mathit{EF}_{I}$	(grams/hour)	Idling emission factor for trucks (NOX, VOC, PM, or CO)
$\mathit{EF}_{T}$	(grams/hour)	Running emission factor for idle reduction technology T (NOX, VOC, PM, or CO)
$N_{\mathit{RSt}}$		Average number of times vehicle is restarted
$N_{V,T}$		Number of vehicles equipped with idle reduction technology T
$t_{T}$	(hour)	Average time per heavy-duty vehicles that idle reduction technology T is used instead of engine idling
$\mathit{TEF}_{\mathit{TRK}}$	(grams/trip)	Engine start emission factor (NOX, VOC, PM, or CO)

Source: Texas A&M Transportation Institute