lecture 5 Flashcards
What are the 4 principle steps of an LCA?
- Goal and Scope
- Life Cycle Inventory
- Impact Assessment
- Interpretation
What does the goal in an LCA describe?
The most important choices which are often subjective.
What does the scope in an LCA describe?
It sets the system boundaries, which describe what is taken into the assessment and what is left out
What does the inventory analysis step consist of?
It is based on the scope and possible uses of LCA, it lists and quantifies the inputs and outputs of the processes at each stage in one life cycle
What does the impact analysis step consist of?
Determines the environmental impact of each input and output identified in the inventory
What does the improvement analysis step consist of?
Identifies what can be done to reduce environmental impacts by changes in product or process design
This is the key step for engineering design decisions
What are the environmental impacts of automobiles?
Land use decisions (constructing roads and parking lots) and engineering design decisions that influence release of pollutants to the environment
What 3 air pollutants are emitted from automobiles
- Hydrocarbons (HC, aka VOCs)
- NO (nitrogen oxide) gases
- CO (carbon monoxide)
What is the main source of CO and HC’s?
Incomplete combustion of fuel
How are HC’s emitted?
They are emitted in the form of gasoline vapours from incomplete combustion of fuel, hot engines, from the venting of the engine crankcase and from the venting and refilling of fuel tanks
How are nitrogen oxides formed?
During combustion by chemical reactions between nitrogen and oxygen in air that occur at high temperatures
What 3 factors make actual on-road emissions generally higher than federal test cycle values?
- Higher average speeds cause higher NO2 emissions
- Improper maintenance or tampering with emission control systems leads to higher emissions
- A clogged air filter or dirty spark plug can increase hydrocarbon and carbon monoxide emissions above their normal design limits
True or false: Heavier vehicles do not consume more gasoline than a passenger car
False
True or false: Heavier vehicles emit more CO2, HC and NO per mile of travel than a passenger car
True
What are most motor vehicles worldwide powered by?
Gasoline or diesel
What do petroleum and its derivative fuels consist mainly of?
Carbon and hydrogen compounds
What happens to carbon every time fuel is burned?
Carbon is converted to CO2, the natural product of combustion
True or false: Automobiles are a major source of lead emissions to the atmosphere
True
Why do many countries around the world continue to use leaded gasoline?
Lower costs
How are CFCs used in automobiles?
Automotive air conditioners
How do CFCs in automobiles impact the environment?
They are associated with depletion of stratospheric ozone and enter the atmosphere via leaks in AC systems
What are 4 possible methods to design cleaner cars?
- Designing for energy efficiency and reducing fuel consumption
- Understanding and aiming to reduce pollutant formation
- Alternative fuels
- Alternative vehicles
How do electric vehicles differ from gasoline cars?
EV’s have a battery instead of a gasoline tank and an electric motor instead of an internal combustion engine
What are PHEV’s?
Plug-in hybrid electric vehicles are a combination of gasoline and electric vehicles. They have a battery, electric motor, gasoline tank and internal combustion engine
