Achieving Sustainability Through Green Engineering
Sustainability Requires Objectives at the molecule, product, process, and system levels.
Abhinav Dhaka- 19 September 2018 ID: 2017A1PS0787P
Sustainability is a critically important goal of human development. To achieve overall sustainability, its achievement in the field of engineering is of foremost importance given the (1) importance in economic development and standards of living, (2) significant impact engineering processes have had and will continue to have on the environment Factors that need to be considered and addressed to achieve this issue are presented extensively in this report. Some of them being appropriate selection of resources keeping in mind the sustainability criterion, enhancement of efficiency of engineering purpose processes and resource use. Economics, land use, lifestyle people, political factors and population are some other sustainability measure. Report is concluded by providing pathways for engineering sustainability and it’d broader ultimate objective.
Keywords: Engineering; sustainability; sustainable development; efficiency
Numerous countries have taken up sustainability as their primary goal towards development. Sustainability has 3 distinct components:environment sustainability, economic sustainability, social sustainability. Engineering is indirectly linked to each one.All resources used in engineering be it fuel, mineral are obtained from environment, and waste of processes is released into the environment. Given the intimate link between eng’g and the components of sustainable development requires accomplishment of sustainability in eng’g as a crucial aspect to gain overall sustainability. From local to global scale, all countries use eng’g services, that impacts the environment. Engineering sustainability goes much beyond the search for sustainable resources, and implies sustainable system , i.e, systems and processes use sustainable resources, store, transport & utilise them sustainably.
Sustainability and Sustainable Development
Brundtland’s 1987 report defines it as “development that meets the requirement of present generation without compromising the needs of future generations needs.” Degree to which it can be achieved varies among countries, and depends on size, wealth, living standard, culture, political and administrative system
Engineering and sustainability
Engineering is used in almost all facets of life and in nearly every habitable place on Earth. Standards of living are functions of eng’g related activities. Efforts have been increased in past few decades to make eng’g activities more green and sustainable. Concept of eng’g sustainability employs the principles of general definition of sustainability but are much more involved and intricate. Engineering related sustainability definitions have been given for specific areas like waste, energy, mass1,2 but no general definition exists. Although there are some general guidelines that are valid for any sort of eng’g process to make it green and sustainable.
Principles of Green Engineering
Designers must ensure the non-hazardous nature of all inputs and outputs.
Though the dire consequences of hazardous materials can be stripped to minimum, but it requires the input of energy, resources, and money making it a less sustainable and feasible approach. Instead, inherent nature of selected materials and energy input should be evaluated by designers to make it as benign as possible. Likewise, molecular designers must innovate technology to create inherently benign material and energy sources.3
Prevention of waste products is better than its treatment afterwards.
Concept of waste is human i.e. there is nothing intrinsic about energy or substance that qualifies it as waste; it’s the inability of humans to effectively exploit the so called waste material or energy. Whether the waste generated is harmful or not it treatment consumes energy, time, and money. Hence, innovative technologies are developed to get a waste free design at any scale based on the concept: inputs are designed to be a part of desired output. This concept at molecular level is called “atom economy”3 and “material economy” at design level.
This is demonstrated in the design of current power plant that use fossil fuel and produce hazardous waste at every stage of use4. Instead, fusion energy should be used as it neither produces hazardous products nor it uses fossil fuels and is very clear.
Separation and purification processes should be designed to minimise material and energy input.
In manufacturing process the separation and purification processes consume the most resources. Traditional methods are not at all sustainable some requires harmful chemicals others require large quantity of energy. Proper up-front design can allow for the self separation of materials using their inherent physical or chemical properties like solubility, volatility rather than using the induced conditions and hence reduces the amount of energy and time consumed.
For eg: At molecular stage processes like chromatography and distillation shouldn’t be employed as they use harmful solvent and large amount of energy hence rendering the process unhealthy and unsustainable5. However, if products are designed in a way that they are self separable strikes off the need of additional resources making the process sustainable at all design scales.
Processes and systems should be designed to maximise the efficiency of mass, energy, and time.
A process or system whose output is poor, consumes a lot of time is not at all economically feasible and sustainable. If a system or process underperform i.e applied at less than its max efficiency leads to wastage of resources, energy and time. For instance large batch reactors use only a part of available volume, whereas on the other hand micro reactors operate at small volume hence being highly productive from a small amount of input. Strategies that lead to max efficiency should be applied at macro, micro, and molecular levels.
For eg: spinning disk reactors are rapidly taking the place of large batch reactors6; powder coatings are replacing paints; digital media in place of print media.
Products and Processes should be “product pulled” rather than being “reactant pushed”.
Le Chatlier’s principle says that a reaction at equilibrium when subjected to a stress will move in the direction which results in the relief of stress. This stress could be temperature, volume, pressure, and concentration change. Employing this principle the products should be continuously removed to make the reaction outward pulled, hence rendering the process to become more productive for a given amount if reactant. In this manner resource use can be minimised, making the process sustainable.
This principle is used extensively in various chemical manufacturing processes.
Complexity of products should be viewed as excessive expenditure of resources.
Whether the complexity is at macro, micro or molecular level is an outcome of disbursement of material, energy, and time. If a product is such that it’s inevitably complex, its design should be such that it’s reusable multiple times as recycling such types of products require plethora of energy and time making the process highly unsustainable. In contrast, products with low complexity are favourable for recycling process.
For eg: Silicon electronic chip are highly complex and intricate hence it’s not feasible to recycle them to obtain the starting materials.
Design goal of material should be its durability not immortality.
Products lasting beyond their lifetime become a threat to the environment. They can lead to bio accumulation and bio hazards. Hence, a product must be designed for a give lifespan to avoid immortality. But the product must be designed so as it requires minimal amount of care and repair during the intended lifespan. For eg. Single use disposable diapers have very short lifespan but high immortality rate, for being non biodegradable and hence pose threat to environment7. Biologically based polyactics to form plastics must be used in place of petroleum based which are non biodegradable and harm the environment in numerous ways.
Production should be ample to meet the requirements and not surplus to meet the greed.
If the amount of produce is more than the requirement this surplus produce will require care which means putting in energy, resources, and time which in a way is wasteful. For eg. Large amounts of grains stored in granaries are either rotting due to lack of care or are consuming energy, resources, and time in the name of care.
Material diversity should be kept to the minimum.
A given product is formed by assembling numerous components. Each component is further formed by putting together many sub components. This diversity of material poses an issue after the end of life of product as it affects the ease and ways through which recycle and reuse can be carried out. Lesser is the material diversity, greater are the number of ways for final disposition. For eg. Components can be made from a single material having necessary design properties.
Material and energy sources used in engineering processes should be renewable rather than non-renewable.
The nature of material and energy being put to use for the implementation of engineering processes has direct link to sustainability of products and processes. Not only on this it also directly affects the surrounding and environment. So as much as the processes allows renewable energy sources must be used.
There is no denying that engineering has revolutionised the human world. Humans can’t think of spending a second with these engineering marvels that we have acquainted over the past 50 years. But everything comes with a cost, and in this its over planet is paying. Engineering processes require a lot of resources and energy, and with the race among nations to become a superpower it has become the need of hour to make these processes green and sustainable. Not only is sustainability required to meet the demand of future human generation but also the flora and fauna of the planet both at terrestrial and aqueous level.
So it’s high time that our governments, communities, NGO’s take steps to prevent the destruction of Earth or it’ll become like every other planet of The Universe i.e. incapable of supporting lifeforms.
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