Energy requirements should be recognised
for their environmental and economic impacts and should be minimised.
Synthetic methods should be conducted at ambient temperature and pressure.
(Green Chemistry Principles, Dr. Paul Anastas et al)
All manufacturing processes need energy to convert raw materials into
useful products. In the chemical industry it is used in several ways:
- Heat to raise the temperature of reactants so a reaction begins
or continues
- Electrical energy for electrolysis
- Heat for distillation to separate and purify or concentrate desired
products
- Heat to dry product material
- Energy for waste treatment
The energy used in separation, drying and waste management may be more
than that used in the reaction stages.
Chemical production is much more energy-efficient than in the past.
The average energy required per tonne is less than half that needed
50 years ago, and there are economic and environmental reasons to continue
this trend.
Energy Sources
Heating is often done with natural gas or other fossil fuels, either
using the heat of combustion directly or by making super-heated steam.
Electrical energy, needed for electrolysis to produce aluminium and
chlorine,
is generated using fossil fuels and nuclear energy, with some contribution
from renewable sources like wind.
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