Page 343 - Sustainability in the Process Industry Integration and Optimization

320 Cha p te r F o u r tee n

the complete spectrum of renewable energy sources and energy
carriers—and to evaluate the appropriate combinations of waste-to-
energy and fossil fuels—in order to deliver more complete and
practical procedures.

14.3 Conclusions
In recent years there has been much interest in the development of
renewable, non-carbon-based energy sources to combat the threat of
increased CO emissions and related climatic change. Increases in
2
the price of oil and gas have further boosted interest in such
alternative energy sources. These concerns have resulted in increased
efficiency of energy and water use in the industrial sector, although
the major industry’s use of renewable energy sources has been only
sporadic. In contrast, domestic energy supply has moved more
positively toward the integration of renewable energy sources,
including wind turbines, solar heating, and heat pumps. Yet efforts
to design a sustainable combined energy system that includes both
industrial and residential buildings have been limited and ad hoc,
since there are no systematic design techniques available for
producing a symbiotic system on this scale.
Increasing the efficiency of energy-using processes is the most
effective current method for reducing costs and emissions that affect
the stability of the world’s climate, and contributing to sustainable
growth. Increasing energy efficiency is the cleanest short-term
method to produce green energy—that is, energy that produces the
least amount of emissions. The situation is similar with respect to
minimizing the consumption of water and the generation of
wastewater. Unfortunately, these relatively mundane approaches are
often overlooked by those who are seduced by exciting new
technologies—such as renewable energy sources—that have
generated more publicity. Nonetheless, the primary sustainability
issue remains the efficient use of resources: raw materials, energy,
and water.
Two metrics have recently been developed to assess the impact
of energy-efficient methods and energy-reduction proposals. The
carbon footprint (CFP) takes account of all carbon emissions over the
entire life cycle of a process or product, and the water footprint (WFP)
indicates how much water is used during the life cycle of a product
or service.