QUESTION:

 

What do the new hybrid buses offer in terms of public health and environmental protection?

 

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ANSWER:

 

1. Reduction of pollutants
2. Fuel efficiency
3. Noise pollution

 

 

 

1.    Reduction of pollutants

 

…        Reduction of carbon monoxide emission. Carbon monoxide forms when carbon in fuel doesn't burn completely. Although diesel vehicles produce only 4% of the total carbon monoxide emissions from on- road vehicles, this number is projected to deflate due to less diesel buses on the road and more hybrid- electric buses.Ý Carbon monoxide is harmful because it reduces oxygen delivery to the body's organs and tissues.

 

Ý(Statistics provided by NAVC)ÝÝ

Ý

…        Hydrocarbon reduced by 90 percent.Ý Hydrocarbons are aÝÝÝÝÝÝÝÝ precursor to ground-level ozone.Ý Ground-level ozone is formed by reactions involving hydrocarbons and nitrogen oxides in the presence of sunlight.Ý Hydrocarbon emission includes unburned HC (paraffins and aromatic HCís), partially burned hydrocarbons (aldehydes and ketones) and products of thermal cracking (ethylene, hydrogen and carbon).

 

…        The engine of a hybrid bus is much smaller.Ý The new buses will use electric power from their batteries even when accelerating from a stop or going up a hill, the times when regular buses emit the most pollutants.

 

…        Hybrid buses have 36 percent lower oxides of nitrogen.Ý Nitrogen oxides are precursors of ozone.

 

 

ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ (Statistics provided by NAVC)

 

…        Hybrid buses also have 50- 70 percent lower particulate matter emissions than diesel buses.Ý The reduction is a result of the utilization of regenerative breaking in the hybrid- diesel buses and the regenerative particulate trap control mechanism.

ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ (Statistics provided by NAVC)

 

…        Exhaust emissions as clean as natural gas-powered vehicles

 

 

…        Diesel particulate filters are used to either burn particulates at normal diesel temperatures as in the Engelhard DPXDPF

model or oxidize and then collect the soot as in the John Mattheyís Continuously Regenerating Technology.Ý Oxidation catalysts are used for the control of carbon monoxide, particulate matters and hydrocarbons.Ý The oxidation catalyst traps the particulates.Ý The NO is trapped and converted into NO_2. ÝThe NO₂ then oxidizes carbon particles in the trap.

 

 

The following graph is based on statistics obtained from the Environmental Protection Agency.Ý It shows the standard amount of bus emission base on the amount of pollution emitted per unit of energy in grams per break horsepower hour.Ý By 2004 the Nox and PM emission is projected to be lower because of the substitution of diesel hybrid- electric buses for many traditional diesel buses.

 

 

	Nitrogen Oxide Emission	Particulate Matter Emission
1984	10.7	0.6
1991	5	0.25
1994	5	0.10
1998	4	0.10
2004(projected)	2	0.10
2007(projected)	0.2	0.7

 

 

 

A study done by the Department of Energy came to the following conclusions after testing diesel and hybrid buses in New York City. ÝÝÝÝÝÝÝÝÝ

2.      Fuel efficiency

 

…        Hybrid buses are more fuel-efficient than regular buses reducing our independence on fossil fuels.

 

…        Approximately $10, 000 a year is spent on fuel for regular diesel buses.Ý This price is less for hybrid- electric buses because less fuel is needed for each bus.

 

…        The yearlong evaluation of 10 prototype diesel hybrid-electric buses in the Metropolitan Transportation Authority's New York City Transit (NYCT) fleet of 4,489 buses showed that these hybrid buses have a 10 percent higher in-service fuel economy.

 

…        The engines used are smaller than conventional diesel engines and regenerative breaking allows the storage of energy in the batteries that would otherwise be lost during breaking.

 

…        Hybrid buses use low- sulfur diesel fuel, less than 30 parts per million-sulfur content, leading to:

ÝÝÝÝÝÝÝÝÝÝÝ 76% average reduction in total hydrocarbons

ÝÝÝÝÝÝÝÝÝÝÝ 29% average reduction in carbon monoxide

ÝÝÝÝÝÝÝÝÝÝÝ 29% average reduction in particulate matters

when compared to regular sulfur diesel fuel.Ý While sulfate is a particulate it is not listed as a carcinogenic.

 

…        With less fuel being consumed there is also a lower emission of greenhouse gasses, cutting global warming pollutants by at least one- third.

 

A trial run of hybrid buses in California had the following results:

 

 

A study done by the EPA shows that hybrid buses use 24% less fuel per mile when compared to diesel buses.Ý For each mile traveled hybrid buses used less fuel as seen by this bar graph:

 

 

3.    Noise pollution

 

…        Hybrid buses operate with less noise.Ý

 

…        A recent test shows the acceleration noise to be reduced by over 2 dB.