Economy
Economic activites include energy production, transportation,
material extraction, transformation and disposal. A simple taxonomy
consists of four sectors can be used to conceptualize the relationship between material use, economic
activities and environmental impacts. They are:
- Primary Sector
- Extraction of of raw materials, such as mining, quarrying,
agriculture etc.;
- Physical processing of raw materials to concentrate crude materials,
such as distillation of crude petroleum, peeling of fruits etc.;
- Thermal and chemical processing, such as electrolytic or oxygen
refining, dehydrogenation or baking of food products etc. and;
- Disposal of wastes
Outputs of this sector are metals, wood, paper, food products,
finished fuel and electricity etc..Primary activities are considered as
the `dirtiest' because it separates useful from nonuseful materials. The
leftover, unwanted materials become wastes and pollutant. However,
'Clean Production' are becoming popular recently.
- Secondary Sector
- Conversion of finished materials into manufactured products, such as
fine chemical, pharmaceutical, cosmetics etc.
Less waste is generated here than the primary activities. Since
waste here are mostly intermediate materials, such as catalyst, solvent
etc., clever engineering which minimizes dissipative losses and maximizes the use of finished materials
can eliminate more waste.
- Tertiary Sector
- Generation of final services by consumer goods, such as
transportation, communication, retail and wholesale sales etc.
Waste from this sector are mostly comsumption-related such as
fuel. Institutional rather than engineering innovations
are needed to eliminate these wastes.
- Quaternary Sector
- Pure services, such as entertainment, education etc..
This sector is comparatively waste-free.
Compiled by
Christine Leung cwl1@cec.wustl.edu Last updated 10/26/94.