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Scoping is arguably the most important step for conducting an LCA. It is here that the rationale for carrying out the assessment is made explicit, where the boundaries of the system are defined, where the data quantity, quality, and sources are specified, and where any assumptions that underlie the LCA are stated. This is critically important both for the quality of the resultant analysis, and for comparison among LCAs for competing or alternative products.

Inventory analysis

The inventory analysis step involves the collection of information on the use of energy and various materials used to make a product or service at each part of the manufacturing process. If it is true that scoping is the most important step in an LCA then the inventory is probably the most tedious since it involves locating, acquiring, and evaluating the quality of data and specifying the sources of uncertainties that may have arisen. For products that have been produced for a long time and for which manufacturing processes are well known, such as making steel, concrete, paper, most plastics, and many machines, data are readily available. But for newer products that are either under development or under patent protection, data are often considered proprietary and are generally not shared in open sources. Uncertainty can arise because of missing or poorly documented data, errors in measurement, or natural variations caused by external factors (e.g., weather patterns can cause considerable variation in the outputs of agricultural systems or the ways that consumers use products and services can cause variability in the emission of pollutants and the disposition of the product at end of life). Often the manufacturing chain of a process involves many steps resulting in a detailed inventory analysis. Figure Detailed System Flow Diagram for Bar Soap , for example, shows the manufacturing flow for a bar of soap (this diagram is for making bar soap using saponification—the hydrolysis of triglycerides using animal fats and lye). The inventory requires material and energy inputs and outputs for each of these steps, although it may turn out that some steps contribute little to the ultimate impact analysis. For example, the inventory associated with capital equipment for a manufacturing process, i.e. machines that are replaced at lengthy intervals such that their impacts in the short term are minimal, are often omitted from the analysis.

There are two additional aspects of LCA that should also be addressed during inventory analysis: the functional unit    of comparison, and the allocation    of inventory quantities among co-products or services. The functional unit is the basis for comparing two or more products, processes, or services that assure equality of the function delivered. This may seem like a straightforward task. For example, for the soap produced by the process of Figure Detailed System Flow Diagram for Bar Soap , one might choose “one bar of soap” as a functional unit of comparison. But then how would a LCA comparison be made with, say, liquid hand soap or a body wash product (which combines the functionality of soap and shampoo)? Perhaps “number of washings” would be a better choice, or maybe concentration of surfactant made available per average use (in the latter case an “average dose” would need to be defined). Furthermore, soaps have other additives and attributes such as scents, lotions, colors, and even the functionality of the shape – factors that may not affect cleaning effectiveness but certainly do have an impact on consumer preferences, and hence quantity sold. Since it is quite likely that essentially all soaps purchased by consumers will eventually be washed down the drain, such marketability factors may indeed have an environmental impact.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Sustainability: a comprehensive foundation. OpenStax CNX. Nov 11, 2013 Download for free at http://legacy.cnx.org/content/col11325/1.43
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