Encyclopedia of Environmental Science and Engineering, Volume I and II

MOBILE SOURCE POLLUTION 707

between 99 and 100% of (ATFR) STO. Above this range NO x

levels increase markedly as ATFR is increased; below this

range CO and HC levels increase as ATFR is decreased.

Electric vehicles (EV’s) operated by high energy high

powered batteries are making great strides toward commer-

cialization. The near term goal is to provide over 100 miles

per recharge at accelerations capable of matching the internal

combustion engine. The California Air Resources Board has

issued a technical document in December of 1995 supporting

the concept of such vehicles. The key performance parameter

for EV’s is its specifi c energy (or energy density), measured

in watthours per kilogram, with a near term goal of 80–100

wh/kg, suggested by the US Advanced Battery Consortium

(USABC).^38 Another important measure of performance is the

peak specifi c power (or power density), which gives us an idea

of an EV’s acceleration. It is measured in units of watts per

kg with an USABC near term goal of 150 w/kg that can be

sustained for 30 seconds during discharge down to 80% depth

of discharge. A comparison of different chemical system per-

formance parameters is presented in Figure 4. All of the bat-

teries are expected to achieve the USABC’s midterm goals for

these EV parameters, which coincide with lasting about fi ve

years (-600 cycles) and costing no more than $150 per kwhr of

battery capacity. Hybrid power electric-diesel engines became

available in 1995. They alternate between diesel power opera-

tion at 2000–2600 RPM where its effi ciency is best to battery

power at other RPM.

RELATED TRANSPORTATION PROBLEMS

Diesel Exhaust Odors

Diesel engines are found in buses, trucks, off-road vehicles

and power applicators and increasingly in automobiles. Public

reaction to diesel-engine exhaust odors provides the impetus

for controlling effl uents of that type of fuel combustion.^24

A list of oily kerosene and smokyburnt odor compound iden-

tifi ed by A.D. Little, Inc. is included in Table 4. Exhaust odor

and smoke from diesel engines are more objectionable than

those from spark ignition. CO emissions are generally less

serious but NO x is troublesome (4 to 10 g/mile). Improved

fuel injection and afterburners are considered to be the most

promising of the existing control methods. The injection dif-

fers from the internal combustion engine in that fuel does not

enter the cylinder as a mixture with air, but is injected under

high pressure into the chamber in exact quantities through

low tolerance nozzles. For NO x removal the basic approaches

Without

Recycle

With

Recycle

Without Recycle

With Recycle

Without Recycle

With Recycle

CO = 0

30 60 90 120 0 30

TIME, SECONDS

60 90 120 0 30 60 90 120

1000

4

2

4

2

60

40

20

PPM NO

% O

2

% CO

MPH

BEFORE CATALYSTS AFTER MONEL AFTER BOTH CATALYSTS

~

FIGURE 3

C013_005_r03.indd 707C013_005_r03.indd 707 11/18/2005 10:42:29 AM11/18/2005 10:42:29 AM