LECTURE: 33

COURSE INSTRUCTOR: PROF. ABU TALEB KHAN

GREEN CHEMISTRY AND TECHNOLOGY

COURSE CODE: CH 426

CREDIT: 6
 LECTURE 21: APPLICATION OF GREEN CHEMISTRY IN ENGINEERING

 The learning objectives today’s lecture are as follows:

 Become familiar with the basics of engineering and its main branches.
 Learn about the 12 principles of green engineering.
 Compares principles of green chemistry and green engineering.
 Learn essentials of sustainability and how it relates to green engineering.
 Learn about types of thinking which are useful in green engineering.

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 SUSTAINABILITY AS RELATED TO GREEN ENGINEERING

Sustainability is a broad term that denotes meeting the needs of the

present without compromising the ability of future generations to meet
their own needs. Sustainability has economic, social, and environmental
aspects. Sustainability goals are embedded in various disciplines. We have
seen this already though the analysis of the principles of green engineering,
and also green chemistry.

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 SUSTAINABILITY AS RELATED TO GREEN ENGINEERING

Sustainability is an integral and critical part of these principles, and of the

entire green movement. This is especially noted in green engineering,
which is more oriented towards applications.
We briefly describe three common approaches to sustainability, aspects of
which are put into practice in green engineering. They are the natural step
(TNS), biomimicry, and cradle to cradle (C2C).

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 THE NATURAL STEP

In the TNS approach to sustainability, the economic profitability and

environmental and social accountability are weighted equally.
TNS seeks a sustainable capital, which consists of natural, human, social,
manufacturing and financial capital.
Its goals are: (1) to avoid systematic increase in concentrations of
substances in ecosphere, such as those that are extracted from the Earth’s
crust or produced by society;

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 THE NATURAL STEP
(2) to prevent systematic deterioration of the physical basis for the
productivity and diversity of nature;
(3) to implement a fair and efficient use of resources in meeting basic
human needs.
Goal 1 is in response to the pollution of ecosphere by human activities,
goal 2 is in response to human interference the nature, and
goal 3 is related to wasting resources.
There are also goals of green engineering, but in a more narrow and
specific way.

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 BIOMIMICRY

The biomimicry approach uses nature as a model for sustainability and

green engineering. In this approach, one observes, seeks to understand,
and finally mimics natural solutions by inventing similar but manmade
designs.
Examples of observations of these natural solutions to engineering
problems include capturing solar energy by leaves or purple bacteria,
making strong fibers such as spider silk, making strong adhesives by
mussels, and analyzing sustainability properties exhibited by the mature
ecosystem, among many others.

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 BIOMIMICRY
A particular instructive example of sustainability is that of redwood
forests’, mature ecosystems. Organisms in such systems use the output of
other organisms as a resources, gather, and use energy efficiently; use
materials sparingly, optimize rather than maximize; do not deplete
resources; remain in balance with the biosphere; and utilize local
materials.

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 BIOMIMICRY

Especially inspiring is the way these ecosystems use the output of one
species as a resource for the second. This closes the cycle of
transformations of organic materials within the ecosystem. In human
societies, often there is a linear path of products to waste, which then
becomes a problem. Let us recall the citation by Anastas and Zimmerman
for the very beginning of this lecture: “An important point, often
overlooked, is that the concept of waste is human.”

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 CRADLE TO CRADLE

The C2C concept was developed in 2002 by William McDonough, an

architect, and Michael Braungart, a chemist. It introduces a new paradigm
to replace that of cradle to grave, which dominates modern
manufacturing and which is based on one-way flow of materials, from
products to their “grave,” such as a landfill. In the C2C method, materials
flow back to the system and thus form a closed loop. C2C shares with
biomimicry a concept that the output of a system is a valuable resource.

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 CRADLE TO CRADLE

Waste, a human concept, needs to be thought of as a resource or “food,”

by analogy with the natural ecosystems. C2C designs the products and
processes in such a way to ensure that traditional waste is not formed;
instead, what is created is “food.” This is summarized in the first tenet of
C2C: “Waste equals food.”
C2C introduces two types of foods, namely, biological and technical
nutrients:

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 CRADLE TO CRADLE

Biological nutrients are materials or products that are designed to return

to the biological cycle. For example, textiles made from the natural fibers
represent biological nutrients. They will biodegrade and will end up in soil
as nutrients for various organisms.
Technical nutrients are materials or products that are designed to go back
into technical cycles from which they originated. Examples include
synthetic polymers that are designed in such a way to allow for repeated
depolymerization and repolymerization. Thus, they will generate no
waste, only food for the repeated polymer production.

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 CRADLE TO CRADLE

The second tenet of C2C is also nature inspired. It is summarized as

follows: “Use current solar income.” Nature uses solar energy as its
primary energy source, as evidenced by photosynthesis in which plants
produce complex organic molecules by utilizing solar energy.
The third and final tenet of C2C is also of a biomimetic nature. It is stated
as follows: "Celebrate diversity.” This tenet reflects observation that
diversity makes ecosystems resilient in their response to changes.

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 CRADLE TO CRADLE
A detailed description of incorporation of C2C tenets into the principles of
green engineering is provided by McDonough et al. The C2C concept has
been further developed and expanded by its authors, in which they cover
“upcycling,” which is reuse of discarded objects or materials in such a way
to create a product of a higher quality or value than the original. This
would be the opposite of “downcycling,” in which the quality of value of
the product is less than the original.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

We have discussed various types of thinking as appropriate for green

chemistry, such as deductive, inductive, critical, linear, nonlinear, lateral,
vertical, and complex. We have evaluated each type of thinking and have
concluded that all of them are useful for green chemistry, but especially
complex thinking may be needed to cover the simultaneous
considerations of all 12 principles.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

The same types of thinking are relevant to green engineering. However,

we notice additional challenge that are posed by green engineering when
networks and their integration are considered. One example was given in
principle 10 of green engineering, which requires integration of HENs and
MENs. Methods that are particularly useful for considering networks are
systems thinking, and holistic thinking, in addition to complex thinking,
which was previously covered. These three types of thinking are related.
Also, there is a substantial overlap between them.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

We represent here a brief and simplified summary of the system and

holistic thinking, for more complete treatment. We start with some basic.
A system may be defined as an interconnected set of elements that are
coherently organized in a way that achieves a purpose. Thus a system
consists of elements, interconnections and purpose. Systems can be
embedded in other systems, which further may be embedded in yet other
systems. We can think about a chemical reactor as a system, which is
embedded in a chemical factory, which is further embedded in an
industrial park.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

It is easier to learn about a system’s elements than to learn about the

interconnections that hold the system’s elements together. However, it is
precisely the presence of interconnections which requires an expansion of
our thinking. Although, we may know a chemical reaction, once a reaction
becomes a part of a system, such as a chemical reactor, or factory, or an
industrial park, we find out that knowledge about the reaction or the way
of thinking about the reaction does not longer suffice. We must be able to
view the system in terms of their interconnections.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

System thinking provides us with a useful way to think about

sustainability. Let us consider a presumably renewable resource consisting
of a plant material, from which some important chemicals, such as drug,
is extracted. If we take into account the entire system, comprising the
plant material and including all other elements of the process all the way
to the final extraction of the drug, we realize the inherent limitation of a
natural plant based source. If the flow of the plant extract into the system
is higher than the regeneration rate of the plant, we shall exhaust our
plant source, which then will not be renewable.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
System thinking helps us to understand better the ecosystem. Ecosystems
exhibit the resilience, which is the ability to restore or repair itself.
However, there are always limits to the resilience of any system, and if we
go above the threshold of the resilience, the system will break down. As
green engineers and chemists, we must be aware of this and make sure
that the system is maintained within its inherent limits of self-repair.
From there brief examples, we realize that our thinking type must match
the problem that we are dealing with. More useful tips about thinking in
general, systems thinking, and a new type of thinking are provided by
Kasser.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
In the following text, we represent different types of thinking, as
described by Kasser. Then, we introduce the need for the systems thinking
and finally holistic thinking.
Types of thinking can be absorptive (the ability to observe), retentive, (the
ability to memorize and recall), reasoning (the ability to analyze and
judge) and creative (the ability to visualize). Thinking can be top-down
(analysis) or bottom up (synthesis). Analysis consists of breaking down a
complex problem into smaller ones, and then thinking about the latter.
This thinking type is also known as reductionism, because it is used to
reduce a complex problem to a number of smaller and simpler ones.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

In contrast, synthesis combines thinking about two or more phenomena,

to form a more complicated question. For green chemistry and green
engineering, we need all these types of thinking, and we need to combine
analysis and synthesis. As mentioned earlier, the green movement
requires creative thinking, which will generate ideas, but also needs
critical thinking, which will analyze, compare and choose the best
solutions.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
As instructive example of analysis is given as a series of steps: (1) take
apart the phenomenon that needs to be understood, (2) try to
understand how the individual parts functions independently, and (3)
apply the understanding of the parts into an understanding of the whole.
This is a reductionist way of thinking, as mentioned before, because it
reduces the phenomenon to smaller parts.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

Unfortunately, this type of thinking does not give good results when the
phenomenon under study is a system. Instead, one needs systems
thinking. Such thinking looks at a system as a whole and seeks to identify
relationships, connectedness, and pattern within the system, rather than
focusing on its parts. The system thinking focuses on understanding
relationships and their context in the system.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING

 Still, there are more ways to improve our thinking about complex
systems. Kasser describes the concept of “holistic thinking perspective”
(HTP). A clear description of HTP is provided via nine anchor points
within four different perspectives. This is presented in below.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
 Holistic Thinking Perspective
External perspectives
 Big picture: the context of the system
 Operational: what the system does
Internal perspectives
 Functional: what the system does and how does it do it
 Structural: how is the system constructed and organized

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
 Holistic Thinking Perspective
Progressive perspectives
 Generic: the system is perceived as an instance of a class of similar
systems
 Continuum: the system is perceived as one of many alternatives
 Temporal: considers the past, present, and future of the system
Other perspectives
 Quantitative: consider numeric and other quantitative information
associated with the system
 Scientific: generates hypotheses about the system

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
In this chapter, we have described the 12 principles of green engineering,
sustainability principles, and their selected methods. We have also
discussed the methods of thinking, which are well suited for the analysis
of systems and networks that are characteristic in engineering. It is
important to realize that the field of engineering is broader than that of
chemistry.

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 TYPES OF THINKING USEFUL IN GREEN ENGINEERING: SYSTEMS AND
HOLISTIC THINKING
Still, green chemistry and green engineering are related in many respects.
As we move into the further applications of green chemistry, we shall find
it necessary to revisit some of the principles of green engineering and
related sustainability. The interdisciplinary nature of chemistry will
become even more apparent, because we shall bring into play industrial
chemistry, pharmaceutical chemistry, and other fields.

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