Green Consumption and Green Manufacturing

Or where does the (green) buck stop?

Recent postings have been discussing the connection between the use phase impact of a product and the manufacturing phase impact and what influences these. This was in the context of both looking at means to reduce consumption (meaning giving the consumer products that deliver the required functionality or service but at a lower environmental impact or energy/resource consumption.)

There are a number of places along the product development chain that critical decisions are made that have a positive or negative influence on this impact. Last time we were talking about whether or not the rule of thumb that 20% of the design influences 80% of the cost of a product also applies to the energy/resource impact. I thought that, in many cases, it didn't work that way.

There is, by the way, a great study on this from 1993 written by some MIT researchers (Karl Ulrich and Scott Pearson) titled "Does product design really determine 80% of manufacturing cost?"  and they tease this comment apart with some case studies and analysis. The report attempts to determine how much product design influences the manufacturing cost of a product. They study this for a class of high-volume, electromechanical consumer products — automatic drip coffee makers - and they find "that for coffee makers, the variation in manufacturing costs attributable to differences in product design is slightly smaller in magnitude than the variation in costs attributable to differences in manufacturing systems, for a specific range of assumed manufacturing system parameters." They note that the "rule of thumb" is specially flawed where the dominant cost contributor is the cost of materials. Further, they note that "There is also a basic logical flaw in the argument that if the minimum possible manufacturing cost is 80% of the maximum possible manufacturing cost then product design is a critical activity of the firm. The flaw arises from the assumption that much of the 80% of the cost of the product is under the control of the product designers."

I was not going to get into that but I agree. But, for now, we are concerned with the influence of design vs manufacturing on the life time product energy or resource impact.

So, back to use vs manufacturing impacts. You might recall this discussion recall blogs ago. We can actually visualize this use vs mfg impact space in terms of what needs to be done depending on where the product sits in that space. In the figure below, we can see four quadrants of "sustainable product" characterization.

The axes are the same as in the use vs manufacturing discussion and indicate, from low to high, the consumption or impact of that phase of the product's life cycle. Then the "low-low" quadrant indicates the most sustainable product. The "high-high" quadrant contains products that are to be avoided or, in another sense, offer the most potential for improvement. The two "high-low" quadrants represent products where we need either to increase the efficiency of the product (with respect to design or using manufacturing leveraging) or we need to improve the efficiency of the manufacturing process relative to use and manufacturing phases, respectively.

This figure does not, however, discuss the relative importance of all the phases of the product life referring back to the earlier discussion about the role of design. I've tried to capture this in the figure below. The figure shows the contribution to lifetime impact or energy/resource use of the various phases of a product, from first concept through design and production to end of life.

First, please note that this is a conceptual drawing (even a cartoon) trying to represent reality. There are lots of examples where this likely does not represent real product performance. And, you might be able to adjust the location of the high and low parts of a particular pattern relative to the phase somewhat as well. But, having said that, we can identify at least four patterns of impact shown in the figure as A. B, C, and D.

Pattern A, in blue, is what I think is a typical impact cycle with the major contributions to impact coming in the manufacturing and use phases. Pattern B, in red,  reflects design decisions that more aggressively affect product impact - things like inefficient use of energy based on design decisions/component selection, materials choice, etc. Pattern C, in yellow, reflects an introduced manufacturing process/system efficiency that reduces the manufacturing contribution but has little impact on the rest of the product performance. This might be due to a more efficient process chain for manufacturing.

Finally, pattern D, in green, represents an example of "leveraging" manufacturing. Here the assumption is that a more capable manufacturing process is introduced in the production plan that may consume more energy or resource in itself but offers product advantages in that it improves the performance of the product over its lifetime. The example given in an earlier posting about improvements in automobile engine efficiency due to aggressive use of precision manufacturing is in this category.

An important point to note is that it is the area under the curve that is the cumulative impact of the product - basically the product of impact x time. Meaning, Pattern D is the best in this example since the area under the line representing that pattern is the smallest of all the examples. The worst case illustrated here, in terms of cumulative impact, is pattern B - poor design decisions.

It is possible to have improved manufacturing offset, somewhat, poor design. Pattern C does that to some extent.

Think about these two figures and the decisions that can be made along the product phase from design through end of life that will have an effect on where the product is located in the use vs manufacturing space. There is a lot of potential for reducing the impact of the product.

And, you can tell from the way I've composed these examples that I come from the manufacturing side of the engineering profession! I don't mean to "dis" my design friends in any way. I just want to make sure we are all aware of the tremendous potential manufacturing offers to address the sustainable consumption challenge.

We will continue to work on these "potentials" more in the future.

Everyone wants a label

More on sustainable consumption

Last time we started to introduce the issues around sustainable consumption - from a manufacturing perspective. I know this sounds a bit strange, consumption from a production viewpoint, but the idea was motivated by the need to reduce the demand for un-necessary products (or, at least, to minimize the waste created by their consumption) and how manufacturing might play a role in this.

In the impact equation (also called IPAT) the demand is driven by population and consumption per unit of population (usually referred to as GDP/capita). It is this piece that, if reduced, would have a big effect on the overall societal impact on the environment - make consumption more sustainable (or, at least, less impactful).

Previously we discussed how manufacturing helps with the Impact/GDP piece of the impact equation - meaning, manufacturing provides the where-with-all to reduce that piece.

It is not a simple task - but ideas are emerging.

A recent International Herald Tribune article (29-30 Jan 2011) had a page of coverage about the World Economic Forum at Davos and talked about wind energy company Vesta and the wind energy association introducing a special label for products made with wind energy. The label is being promoted by a consortium of international organizations and companies interested in promoting the use of clean energy and they've come up with a symbol, consisting of three blue "swooshes" around the word “WindMade,” as their way of promoting products made with clean energy.

Companies are seeing a slow down in the movement towards reducing climate change due to the economic downturn, new political realities and questioning about the urgency. So, some groups and companies are picking up the torch themselves.

The idea is that if the consumer sees that the product was made with renewable energy they are more likely to purchase it - it aligns with their personal commitments to sustainability, etc.

Never mind that in the last posting I quoted the study by Enviromedia about the current 350 different labels that already confuse the consumer.

But this one, wind energy produced, has the potential to take root. The promoters also indicated there could be labels for other sorts of energy sources for producing the product as well, hydro, bio-fuel, solar, compost methane, etc.

The question is, to rephrase the comment from Professor Lanza in the last posting, do we want to encourage people to buy products they don't need with money they don't have to impress people they don't like and that are made with energy that is better used somewhere else (or not at all)!?

This is the quandary … if you have a renewable source of energy should you be able to "waste it" and still claim to be advancing the cause?

Now, certainly, all the products made with renewable energy are not wasteful and un-necessary - not by a long shot. But it is the mentality that is potentially problematic.

So, how about a label for products made with "green manufacturing" technology (hopefully powered by renewable energy)? Why can't we have a label to represent products that are made with the minimum expenditure of resources (materials, water, other consumables), energy and with benign or, better, positive social impact to the folks making the products? And produced on systems that optimize both production efficiency and energy and resource utilization as discussed in the last posting.

I don't have a specific proposed label here. But we could call it "GreenMade" perhaps.

If you have some ideas send me a sketch! I'll include some of the better ideas in the blog in the future! Maybe a factory made of green leaves? Or a smokestack blowing smiley faces? Go for it!

And what about product design? It is often stated that design is 20%  of the product development cycle but fixes 80% of the cost (see, for example, the article by David Anderson for a reasonable summary of this). The implication is that decisions made early in the concept and design phase for a product will dictate features/requirements that will control 80% of the lifetime product cost. The logic then follows then that it is difficult, if not impossible, for manufacturing to reduce costs since "design determines manufacturability" thus locking in costs.

But this does not necessarily translate to fixing 80% of the energy consumption (or other material/resource consumption). Let me explain.

Manufacturing processes differ in terms of their abilities, and efficiencies, to create functional products or components from raw materials. That is, transforming materials from one form to another - the definition of manufacturing - can be done in many ways. Even for the same design.

Further, the energy a product uses may depend a lot, or only minimally, on design decisions. For example, a designer may pick components for use in the product - say an electronic device -that individually consume a lot, or little, energy and together make the product function. That would count for a design driven energy product profile. Choosing correctly at the design phase would reduce product lifecycle impact.

But, there are many situations where this link doesn't work.

Going back to our "leveraging" discussion some postings ago we saw some examples of manufacturing enabling a design (which was not specifically dictating a process chain to produce the component) that had a tremendous effect on reducing the lifetime consumption, and impact, of the product. In that case the example was an automotive engine.

So, I think we can "decouple" design from manufacturing in many cases in term of energy or resource impact over product lifecycle and consider manufacturing an "independent" variable when it comes to determining life time product impact.

How we do that is a subject for additional discussion - let's continue this next time!

Sustainable consumption

I am writing this from a technical meeting in Europe I've been attending on manufacturing where the flames of green manufacturing have been flamed and are burning brightly! A separate session on energy efficiency and resource effectiveness saw a group of presentations ranging from more detailed analysis of energy use patterns in production processes (think machining or heat treatment) to more esoteric issues of process planning with energy utilization in mind.

The process planning discussion was interesting. If you are familiar with process planning you already know the complexity of just trying to make sure all machines are used to the fullest extent. Process planning is, basically, how to order the production steps of a product through a number of machines.  It includes how this is optimized to handle the production of a number of different parts (that is, several different sets of parts moving a number of production stations in a sequence - each set of different parts with a different quantity (called batch size)).

Think of the cartoons of production processes shown before here  - a series of boxes linked by transfer mechanisms to move a workpiece from process (box) to process in a sequence. Now think of how a batch of parts of the same component move through this. The first part starts in the first  box where an operation takes place for a set time. Then the part moves to the second box for a second operation and another similar part starts in the first box. With each "cycle" the parts move from box to box until the first part in the batch exits the final box and it is called a "finished product."  Over time, all the parts in the batch move through the production line and the line "falls silent" as the last part moves through the system.

The "falling silent" part is the issue here.

When the next batch of parts (of a different component requiring different times at each of the boxes due to the operations that are needed) starts the production line, the planner has to allow enough time between batches so that the second batch does not "run into" the batch that precedes it. This occurs when the cycle time of some of the boxes is shorter for the second product than for the first one. That is, for a given process applied to a given part, it may require different times to complete the work on a part based on the requirements of the part. And the requirements will change from batch to batch for the parts in the production line.

Further, in such a production line there is always one process that takes longer than the others (called the "bottleneck"). Then, the time in the other steps following the completion of the tasks in that box while waiting for the bottleneck to complete its work is referred to as idle time. The bottleneck may occur at a different station for each batch of parts.

Still with me?

Now, recall the discussion we had in a previous posting on "green at the process level". This identified machines that used energy pretty much independently of the process that was being performed (referred to as "tare heavy") as opposed to machines that used little energy except when performing productive work ("process heavy"). If the production line described above has a lot of stations waiting for a part to appear in order to operate on the part, and the process in the station is "tare heavy", then a poorly planned production process chain will waste a lot of energy while not doing anything productive. Not a desirable situation.

It turns out that a lot of manufacturing processes fall into this category unfortunately for a variety of reasons we won't go into yet.

So, back to the meeting, if one can include in the process planning the consideration of not only delay times (or idle times) in the sequence of starting batches of products (with varying cycle time requirements) but the energy value of that wasted time (do to the machine energy use even if not processing - which will vary from process/machine to process/machine (or box to box in this example), then one could try to find a sequence of production of several batches of products that would insure both minimum production time (or makespan - the time difference between start and finish of a sequence of jobs) and minimum energy used.

This is an industrial engineer's dream problem (and a nightmare to solve).

But, for an existing production facility, for which the processes are well characterized from the energy perspective, this is a realistic goal. A presentation at the meeting by Professor John Sutherland of Purdue University went into some of the details. We can discuss this more at a later time.

So, what about the consumption title of this posting?

At the meeting, following this (and several other) interesting presentations, a discussion started about how if we could just get people to buy more sustainable products, we could produce less overall, and manufacturing would be reduced (although the value of manufactured products would likely be the same or greater) and this would be a better solution than trying to squeeze wasted energy  (or other resources) out of the manufacturing process.

Or as Professor Gisela Lanza of Karlsruhe Institute of Technology put it to me - we need to encourage people not to buy products they don't need with money they don't have to impress people they don't like!

The assembled engineers quickly agreed that we are not into "social engineering" and that this "behavior change" is better left to experts (rock stars, politicians, marketing consultants, other bloggers, etc.)

But, trying to improve the longevity of products by design and manufacturing is something we can aspire to. And maybe the people will follow.

I am encouraged by the fact that Americans seem to be looking for help to do this. Unfortunately they are not getting much assistance from the market place. A recent article posted by Enviromedia commenting on the Federal Trade Commission (FTC) closing its public comment period for its Green Guides states that research that shows 65 percent of Americans would prefer just one seal for green products over the hundreds that are now causing confusion. They note that it is increasingly hard to determine if a product is "truly green" or not based on available information. They are presently overwhelmed with the 350 product certifications that currently exist.

So, the consumer may come around.

In the meantime, there is much to be done to reduce the impact of manufacturing  on the individual process level (and to reduce tare consumption).  This relies on such planning schemes as discussed above. If you have sufficient time between products coming into each box you may actually be able to shut off the process/machine (or essentially put to sleep major components) when the processing is done for that part. Then, if you can restart and warm up the process/machine before the next product appears at that station (box),  to some extent you can "decouple" (a word engineers like to use to mean separate the effect of one thing on the other) the energy optimization problem from the wasted time problem.

And, of course, we can always try to reduce the tare consumption by design of the machine and its control and operation.

We are going to talk more about design and energy efficiency and longevity in the next posting - also motivated by discussions at this meeting.

"Resolution motivators" for the New Year

Thoughts about green New Year's resolutions

With the turn of the calendar announcing a new year I remembered, as a kid, the flurry of activity in my house around the development and pronouncement of New Year's resolutions - those idealized goals for the next year which, if watched but not too closely, made the start of a new year enjoyable.

So I was thinking about this while reviewing a lot of material in preparation for this posting. And, it occurred to me, there are "resolution motivators" that we can use to help each of us craft our resolutions with respect to sustainability and green manufacturing for 2011.

So, here goes.

In no particular order, my top 10 "motivators" are:

1- "You snooze … you loose": The standard phrase employed when someone is not keeping their eye on the ball and gets bested, scooped, left behind or otherwise trumped by someone else. Think large lethargic corporations comfortable in their business practices while their competitors watch the trends and changes and respond resulting in increased profitability, market share and, at least, continuity in business. Reading any of the sources of green technology and business practices shows us that our competitors are not sleeting. Stay competitively awake.

2- Avoid "technical dickies": Definition - when I was in high school there was a "dickie craze." Dickies are faux turtleneck sweater necks (and a bit of shoulder) that you can wear under a shirt to give the appearance that you are wearing a full turtleneck sweater. They are the sweater equivalent to the clip on tie. Whereas they may appear to fool some … they eventually are apparent for what they are (a fake item). Green washing is, to me, the equivalent of a "technical dickie" - something that is not what it appears to be and only fools other "dickie" wearers. Don't green wash. (If you are not familiar with the greenwashing term see the July 10, 2009 posting)

3- "Every one wants to drink milk … but no one wants to milk the cows": This is a saying I got from my old friend Professor Dick DeVor of the University of Illinois. And he got it from his late father-in-law, farmer Herb Luedtke. Country wisdom. We all have to put something in to get something out. That is the reason for the social element of the triple bottom line of sustainability and, frankly, just common decency and good sense. A corollary to this is the familiar "no such thing as a free lunch."

4- The golden rule - "them with the gold makes the rules"; This was a well worn saying of one of my old, now departed, Berkeley colleagues Joe Frisch. It can actually be a positive concept. Consider Walmart (or any other very large corporation with a lot of sway over their suppliers).  Walmart has embarked on a mission to green up their supply chain. Working with the Sustainability Consortium at Arizona State University and the  University of Arkansas they are using their marketing leverage to drive the creation of eco labels for products sold in their stores so consumers can make decisions about what to buy. And they've been proactive about reducing packaging waste. Using your leverage to make things happen.

5- "Why worry about future generations? What have they ever done for us?" Attributed to Groucho Marx. This is the mantra of the "me generation" and has contributed to much of the situation we find ourselves in today. Sustainability, as we have discussed many times, is insuring the future has the same, or better, opportunities that we have. Same opportunities for education, life style, health, freedom, leisure, employment, nourishment and so on. Tall order. But that's what this is all about.

6- "Lead, follow or get out of the way": (and see number 1 above). There is probably nothing more frustrating about someone who is intellectually, or competitively, asleep than if, also, they are blocking your way. I had a friend who used to refer to a mythical "intellectual hat pin" (another relic from the past) that they would employ to poke someone to get someone to start taking some action or, at least, wake up and get out of the way. Leaders have special responsibilities (see numbers 1, 2 and 5 above). Maintaining an open and responsive attitude towards new drivers for reducing impacts in their operations and enterprises is at the top. And then taking action is next.

7- "Live life like a pizza … one slice at a time": I never quite understood this one but it is on a billboard along Interstate 80 outside of Dixon Ca advertising an Italian restaurant. I have other versions of "living life like a pizza" but won't bore you with those. This reminds me of technology wedges. These tech wedges (see September 15, 2009 blog) if this does not ring a bell) are designed to make small, but measurable, reductions in impact or consumption in a process or system. Rather than trying to eat the whole pizza in one bite, take small slices and make measurable, but consistent, progress.

8- "You cut and I pick": This has to be one of every mother's standard instructions in the face of siblings trying to divide like a pie or donut or something else they'd both rather eat all of. One slices and the other then gets first pick of their piece of the pie, or whatever. This insures that the "divider" will do their best to cut the item as close to equal in half as theoretically possible to insure the "chooser" gets a fair shake.  Or, unless the chooser is asleep, the divider loses out. Be fair in your appraisal of any new concept or idea … just as if you were the divider.

9- "This will come in handy if we never use it": This was a phrase often employed by my father, reflecting his depression era "save it" mentality when any item or object came up for disposal but it seemed to have some inherent value or usefulness. He was not a hoarder by any means. But he did know how to get the most out of anything. The "low hanging" (if you will) energy or resources in any factory or facility ripe for saving/reducing/reusing is usually very large indeed. Find it and save it. As Ben Franklin would have said "A kilowatt saved is a kilowatt earned."

And, finally

10- Don't rely on the "magic 8 ball" or similar schemes for your planning.  Read, think, ask, try. There are a lot of resources out there, specially now on the web, put together by folks who spend a lot of time scouring the world looking for innovation, examples, etc. - read them! Some of these sources are listed at the bottom of this page. Google search is an amazing tool. But read, think/analyze, then act.

Thanks for reading along. I hope this provide some stimulation for your resolutions this year.

And, Happy New Year!

Humbug?!

Or, considering our future

One of the things that forms part of our holiday routine is watching the Alastair Sim's version of Dicken's classic "Christmas Story" (see You Tube). Scrooge (the character Sims plays) is visited by three spirits on Christmas Eve (in his dreams) who show him the errors of his past, present and potential errors of his future if he doesn't "wise up" to the value of looking out for others. Scrooge, as you may recall, is a wealthy self-centered business man who was representative of some folks in Dicken's time in London in the 1850's. As a result of his spirit interactions Scrooge comes around to the betterment of all he comes into contact with (specially his clerk Bob Cratchit and his lame little boy 'Tiny Tim') and doesn't really lose much as the cost is not large compared to the benefits in his generosity and kindness.

I've often thought about how this movie might be remade with the concept of a sustainable world and the impacts individuals and companies make on all around them and their environment. Corporate sustainability reports are one way in which companies try to show, as Scrooge did, that they "get it" and it is not too late to embrace this bigger view of the world.

Lester Brown compares the change in thinking needed to that akin to the notion that the earth revolves around the sun and not the other way around - he is called "an environmental Paul Revere" (see Wikipedia). He notes that we used to consider the environment as part of the economy but it is really that the economy is part of the environment. Wikipedia quotes him from a speech in 2008 stating ' "indirect costs are shaping our future,' and by ignoring these, "we're doing exactly the same thing as Enron- leaving costs off the books. Consuming today with no concern for tomorrow is not a winning philosophy."

He could very well be one of the spirits of the future to visit our modern day Scrooge.

Other "spirits" include Paul Hawken (and his book The Ecology of Commerce, Collins, 1993 - a book I assign for reading in my sustainable manufacturing class). He gives (p. 139 of that book) as a definition of sustainability "an economic state where the demands placed upon the environment  by people and commerce can be met without reducing the capacity of the environment to provide for future generations...your business must deliver clothing, objects, food or services to the customer in a way that reduces consumption, energy use, distribution costs, economic concentration,soil erosion, atmospheric pollution, and other forms of environmental damage. Leave the world better than you found it."

Our modern day Scrooge wakes up to realize that if you are NOT presently at a sustainable state … then you need to meet the demands  of today without compromising our ability to meet the demands of the future by reducing the environmental load/unit of commerce to offset any increase in unit production so as to achieve a sustainable state over time.

If you are presently at a sustainable state…then you can meet the demands  of today without compromising our ability to meet the demands of the future. This is a net zero impact.

That is, in the words of Hawken, your business must deliver clothing, objects, food or services to the customer in a way that reduces consumption, energy use, distribution costs, economic concentration, soil erosion, atmospheric pollution, and other forms of environmental damage at a rate greater than the normal growth in consumption would require. Business must have a “net positive impact.”

That is a challenge to do while staying profitable but, as we've seen in postings in the past, not impossible and the tools to help do this, specially with respect to manufacturing, are growing in number and capability. Our so-called technology wedges are one set of tools.

Hawken and Lovins, in Natural Capitalism (Little Brown, 1999, another book I assign for class reading) state in the preface p x-xi. “The best solutions are based not on tradeoffs or “balance” between these objectives [economic, environmental and social policy] but on design integration achieving all of them together - at every level, from technical devices to production systems to companies to economic sectors to entire cities and societies.”

They go on to state that, ala Scrooge and his spirit visitors, “Without a fundamental rethinking of the structure and the reward system of commerce, narrowly focused eco-efficiency could be a disaster for the environment by overwhelming resource savings with even larger growth in production of the wrong materials, in the wrong place, at the wrong scale, and delivered using the wrong business models.”

That's what we've been talking about.

One way to "rethink the structure and reward system of commerce" to bring the external costs firmly into play is cap and trade.

As I heard on NPR the other morning while going to my office on campus "the whole world is watching California."

This is part of the 2006 Climate Law, called AB32, designed to give companies who generate large volumes of green house gases the "incentive" to emit fewer of those. And, interestingly, this is designed to move from impacting the big emitter, like oil refineries and some factories, "downstream" to the consumers of the products of those industries. Like me driving my car if it uses gasoline from a refinery that emits green house gas in this fuel production.

Which means I'll pay for this. Which means, I expect, I'll have even more incentive to look for vehicles that have improved performance in fuel economy or use none at all (but power companies are also on the list so be careful - who is most efficient in creating energy with least impact will be the question?! Remember the "impact equation"? Impact/GDP - this is it in practice!). This will impact automakers and many others in the supply chain as well.

And, although some take issue with this, the impact on the economy of California (eighth largest in the world if California was considered an independent country) is expected to encourage job growth and technology development.

More to come on this next time.

For now, my best to you for the holidays and a happy new year to all or, as Tiny Tim says, "God bless us every one!"

Tools for assessing impact

Or, are we "doing the right thing?"

The last couple of postings have focussed on how to insure we can measure, and then take credit for (or get some credit for) changes made in a process that create a positive impact in terms of life-cycle impact or consumption.

This came up with reference to a discussion on net present value (or NPV) which is a way to estimate the the degree to which an improvement today leverages benefits into the future. The goal is to identify investments that can be leveraged in the future for big returns.

This brings up the question - what are some methodologies for making these assessments? In earlier postings (very early, in fact, see August, 2009 posting) we discussed rates of return for reductions in green house gas emissions, or water use, or energy use.  But, how can we identify where to apply technologies (and, more importantly, what technologies to apply) for driving these reductions?

And - apologies in advance - I've been slow to get this posting ready due to end of the year academic activities and this will be along one!

One neat technique that came to our attention for meeting this challenge is called a "pinch analysis." (see wikipedia for a good description). This came up in a recent project we were doing for a major European automotive manufacturer and the very energy intensive process they were using to clean precision components (including engine blocks and heads) after production to remove contaminants. These contaminants could lead to assembly problems and performance issues in use.

First let's look at what pinch analysis is, then the process we applied it to and then the results. (And put your thinking cap on as this will get technical fast!)

Wikipedia describes a pinch analysis as "a methodology for minimizing energy consumption" that was originally developed for the chemical industry. Wiki includes this nice summary of the technique -

"… process data is represented as a set of energy flows, or streams, as a function of heat load (kW) against temperature (deg C). These data are combined for all the streams in the plant to give composite curves, one for all hot streams (releasing heat) and one for all cold streams (requiring heat). The point of closest approach between the hot and cold composite curves is the pinch temperature (pinch point or just pinch), and is where design is most constrained. Hence, by finding this point and starting design there, the energy targets can be achieved using heat exchangers to recover heat between hot and cold streams. In practice, during the pinch analysis, cross-pinch exchanges of heat are [often] found between a stream with its temperature above the pinch and one below the pinch. Removal of those exchanges by alternative matching makes the process reach its energy target."

This example comes from the MS Thesis of Mr. Saurabh Garg, titled "Solid Particle Contaminant Cleaning in the Automotive Industry",  and done in my lab at Berkeley in Spring 2010. The motivation for this project was the large amount of energy consumed by the cleaning process that is not only a production cost constraint for the automotive industry in the wake of ever increasing energy prices, but also leads to a significant environmental footprint in terms of indirect greenhouse gas emissions. Garg noted that the severity of this impact depends on the energy mix of the geographical area and the impact created by the sources of energy production.

The objectives of the work that form the basis of applying the pinch analysis were:

- characterize various fluid flows in the process and in external circuits in terms of important parameters such as steady state flow rates, and temperature
- optimize the energy flows in the system to ensure maximum process-to-process heat recovery potential
- propose distribution of the net load on external utilities to minimize the overall heating and cooling costs, and
- analyze and compare the energy requirements of a standalone system of cleaning machines vs. that of centrally heated and cooled machines in a manufacturing assembly line.

So we are dealing with flows of fluids at different temperatures - a relatively common process characteristic in manufacturing (think painting, heat treating, washing, etc.) Not surprisingly, this will involve some simple thermodynamics.

The basic concept of a pinch analysis (as defined above) is represented by the diagram below, showing the temperature - enthalpy rate for a process stream in manufacturing. If you need some brush up on your thermodynamics, check the wikipedia discussion on enthalpy. Enthalpy is, basically, the  measure of the total energy of a thermodynamic system. Wikipedia explains that since "the total enthalpy, H, of a system cannot be measured directly … change in enthalpy, ΔH, is a more useful quantity than its absolute value. The change ΔH is positive in endothermic reactions, and negative in exothermic processes. ΔH of a system is equal to the sum of non-mechanical work done on it and the heat supplied to it."  The figure below summarizes the basis of the analysis.

The analysis starts by representing all the process streams in the domain of analysis on a temperature-enthalpy rate (T- ΔH) diagram where the vertical (y) axis represents the temperature scale while the horizontal (x) axis represents enthalpy rate. Each process stream is represented by a straight line on this diagram running from the stream inlet temperature (Tin) to the stream target temperature (Tout). For a process with a series of process streams that comprise the whole operation, you make one straight line for each stream in the series. The term ΔT stands for the difference between two temperatures.

Since any horizontal distance on the x-axis represents a difference of enthalpies in which we are interested, the absolute values on the x-axis are insignificant. It is precisely for this reason that the composite curves can be translated horizontally on a T-ΔH diagram, without affecting the process stream.  The slope of any line representing a process stream on a T-ΔH diagram is given by 1/(mass flow rate x Cp). Here Cp is the specific heat of the fluid.

For heat exchange to occur, the hot stream cooling curve (hot composite curve) must lie above the cold stream heating curve. (cold composite curve). Because of the ‘kinked’ nature of the composite curves, they approach each other most closely at one point defined as the minimum approach temperature (ΔTmin). The point of minimum temperature difference represents a bottleneck in heat recovery and is commonly referred to as “pinch” as defined earlier by the Wikipedia reference. The area of overlap between the composite curves represents the potential for process-to-process heat recovery. As stated before, horizontal translation of the curves will vary ΔTmin such that at one particular value, the overlap shows the maximum possible scope for heat recovery within the process. At this value the requirement for external hot and cold utilities, as represented by the hot and cold end overshoots of the composite curves, is minimum. However, the maximum process recovery is only a theoretical concept and practical design challenges and cost considerations limit this value as illustrated below.

As seen in the figure, external energy costs increase linearly as the ΔTmin increases. This is because at low temperature difference, the energy transfer process is more efficient and the in-process energy recovery potential is high because the hot and cold composite curves align nicely with each other. In other words, the potential for energy recovery decreases as the composite curves move apart (increasing ΔTmin).

Ok, so how was this used in the automotive cleaning example? The T-ΔH diagram depicting the hot and cold composite curves for the existing cleaning process (flows of hot and cold fluids at various temperatures) is shown in the figure below. Temperature is along the vertical axis (degrees C) and enthalpy (in kW) is along the horizontal axis. The figure was constructed following the procedure described above (and you may need to 'click' on the figure to see all the detail.)

The figure shows that there is a good potential for energy recovery through process-to-process heat exchange, as shown by the green shaded region. The pinch, in this case, is defined by an extended region and not a single position, having a minimum temperature difference of 3 degrees C.

The next step is to propose solutions to "recover" this energy and evaluate whether or not they are feasible economically and, also, what the potential environmental impact will be. A suitable heat exchanger was determined based on the area of heat exchange needed to accomplish the energy recovery. Then, using an economic analysis the potential return of the investment was determined. The figure below compares the total annual energy costs (based on heating and cooling alone) for the proposed retrofit design of the cleaning process based on an improved process-to process

heat exchange optimization vs. the current costs based on the existing design of the process. It can be seen from the figure that beyond the initial 3 years when the capital cost will be completely paid, the net difference between the operational energy costs of pinch-optimized retrofit design and the existing design is worth a savings of 84,500 Euros annually.

Further analysis resulting in considering adding a heat pump to recover some energy due to changes in fluid pressures also. That was good for another 20,000 euro savings annually after the payoff (3 years).

Finally, what about the environmental payback?

Garg includes this analysis as well. The use phase emissions for the existing cleaning process can be attributed directly to the impact created by the consumption of process electricity, and the heating and cooling energy. The total impact for each of these three forms of energy consumption can be calculated by simply multiplying the total energy requirement in each case, with a conversion factor that expresses the impact (kg CO2) per unit kWh based on the source and quality of that energy generation. For example, for a unit (kWh) electricity consumption, the corresponding GWP impact is roughly 0.649 kg CO2 equivalent based on the energy mix of Germany where this facility is located. The same is true for cooling energy, as the cooling is achieved through a refrigeration cycle that involves electricity consumption. For the heating, high temperature steam is used, whose production is linked to an equivalent impact of 0.204 kg CO2 eq./kWh.

Based on the above numbers, the use phase impact generated by the existing cleaning process is found to be 2335 MT CO2 per year. Because of the reduced energy consumption due to pinch optimization, the net impact due to the optimized process is much lower, about 1388 MT CO2 eq. per year - a "savings" of almost 1000 MT CO2 eq. per year!

However, the capital investment in the form of heat exchanger devices will also cause a one-time (fixed) impact, which can be evaluated using, for example, an Economic Input-Output Life Cycle Assessment (EIOLCA) database (e.g. from Carnegie Mellon University).  The EIO-LCA analysis for the heat exchanger was used for the given application and predicted an impact of 100 MT CO2 eq. So that is the "embedded" impact of the proposed switch and any improvement needs to be greater than that at the minimum.

Since the reduced impact, almost 1000 MT CO2 eq. per year, is substantially greater than the one time 100 MT CO2 eq. hit due to the production and installation of the heat exchanger we can safely say the GHG return on this investment is pretty good!

There is even better news. This is one cleaning station of dozens in this large automotive facility and, perhaps, hundreds throughout the company. The potential for larger impacts as more are retrofitted, with the same economic and environmental impacts, is tremendous. Talk about a great technology wedge!

And you can use this in your net present value evaluation also.

I'll let you chew on this long and detailed discussion a bit! But, the point is that there are a lot of existing tools out there that, carefully applied with solid engineering logic, can make a big impact on both bottom lines - cost and environment.

Leveraging all your resources

Future planning/future rewards

A number of items passing across my computer screen (or my ears from the radio) have prompted an additional posting on "leveraging" following our last blog on leveraging manufacturing.

These are, in no particular order, the continuing development of the Chinese high speed rail network (as reported on NPR the other morning), recent e-mails among a few "green friends" on the need for, and feasibility of, inclusion of influences other than economic terms in net present value (NPV) calculations, and a discussion I had recently with some "design" folks at a meeting on how a major company can include green manufacturing "awareness" in its products and get some recognition of this from the consumer.

These sound unrelated - but, I will now try to string them together! And apologies in advance if this sounds like rambling to you.

Let me start with the NPV discussion. This came up due to an article in a trade press basically stating that, since "green technologies" really only have positive net present value due to subsidies they cannot really drive economic recovery or create "high value jobs." This was presented as part of a discussion as to why we will be better off without cap and trade.

So, first, what is NPV? Referring to our old friend, Wikipedia, net present value  is "simply the present value of future cash flows minus the purchase price." It is a means to take expected future cash flows from an investment, usually a series of expected cash inputs over time, and convert them to an equivalent sum (present value, PV, or present worth, PW) based on an assumed interest rate or growth rate over the time of the future flows. Sort of, if you had this amount today (present value), and invested it over the same time period, it is the accumulation of value you'd realize over the amount started with.

If the NPV is greater than zero, the investment will yield positive results and may be worth the risk of investing. As Wikipedia says, "NPV is an indicator of how much value an investment or project adds to the firm." The assumption is, then, that if the NPV is zero, or less, the investment is not worth it.

So, now we throw in environmental considerations, or carbon footprint, or some other metric of impact or consumption, These are hard to monetize so the impact of these potential "rewards" cannot be easily determined. So, some say, we should not consider them in our calculations of investment and only go with those costs that can be solidly determined.

So, since we cannot estimate the "value" of reducing the carbon footprint of our process, or product, we cannot really determine whether the NPV of any investment which has the effect of reducing the carbon footprint is worth it. And, this brings cap and trade into the cross hairs. Cap and trade is a market-based approach that uses economic incentives to drive pollution reduction by steadily reducing the allowable amount of pollution that can be emitted. The idea is that if you are successful in reducing pollution below your allowable level, you can "sell" your excess allowance to someone else who has not yet been able to reduce their pollution.

And this is, to some, an artificial subsidy to some technologies that reduce pollution that cannot be justified by a reasonable economic analysis, like NPV.

The challenge is, can you include environmental metrics into NPV?

This was originally brought to my attention by Ralph Resnick of NCDMM in a note to a few of us asking whether or not we could include sustainability metrics in NPV. One response from John Sutherland, a professor at Purdue University and a leader in green manufacturing, referred to a great article in Forbes from June 2009 on "Calculating the true cost of carbon" by David Serchuck. This article offers a balanced and rational (to me!) explanation of carbon cost evaluation and the value of carbon taxes in an economy to drive CO2 reduction and technology. And the article puts an average price of $20 per ton of carbon dioxide.

The real question is - how do you value risk? And, then, how do you figure this in your NPV calculation?

Most folks I talk with, over a wide range of companies, see the potential risks associated with driving full speed off the "business as usual cliff" as real. Recall our recent discussions about water, rare earth metals, etc. This is all part of the equation. What is it worth to you to be able to reduce your carbon footprint and is the investment needed to do this worth it?

One common proxy for carbon is electricity (or rather one common proxy for electricity is carbon!). You can calculate the cost of electricity. You can determine the impact of your use based on where you are and the mix of fuels used by your local utility. So, we can use that for NPV.

You can estimate the impact of regulation on the cost of your product if we expect some areas of the world (and California) to start to track the carbon footprint of your product and, maybe (probably) tax you for excessive carbon use. This already occurs in France when you buy a car that has a gCO2 equivalent/kilometer travelled value less than a prescribed level. So, I can use that in my NPV for transportation.

There are probably more. We'll work on it.

NPV is a way to estimate the impact of future benefits in today's terms. Or, put another way, the degree to which an improvement today leverages benefits in the future.

So, what about the Chinese trains? The  NPR program talked about a new high speed train that cut the travel time from Shanghai to Wuhan to just 4 hours. It used to take 10 hours.  Wuhan is a rural area with lower costs of operation (by 50%) than in Shanghai nearer to the coast. Companies are moving there now (and these are international companies) due to the supply of labor, lower costs of operation (like living expenses for employees and, yes, local incentives) but accessibility due to the train. And they mentioned the investment in high speed train networks in China which will create a high speed rail network with more kilometers of track than the systems of the rest of the world combined.

And in US, some recently elected governors are refusing to accept Federal stimulus funding to build high speed high speed rail networks in their states.

In another e-mail exchange on some common research collaboration on energy efficiency and resource effectiveness we had a go around on the meaning of terms. John Sutherland made a simple definition that is worth sharing -  "In lay language, efficiency is "doing things right," and effectiveness is "doing the right things."

That's a great way of looking at investments that can be leveraged in the future for big returns - like high speed rail for example with big returns on impact/unit of distance travelled.

Finally, conversations with "design folks."

One of the discussions was on the motivation that companies (and societies) have for "doing the right thing" even if it is not possible to fully compute the benefits today. Sounds like the NPV discussion!

I was chatting with a particularly clever designer and we came up with a neat "app" for your smart phone or pad computer - "text messages from the future." Meaning, some algorithm for sending you, extemporaneously, a hypothetical text message from some friend (or relative) far in the future commenting on their life experience, or job or some other topic - just like you get text messages from folks today.

We thought of one - "Hi great-great-grandpa, wish you had cut down on your CO2 emissions 50 years ago; bought a new respirator today and my sister just moved to a great ocean front place in Savannah." LOL (not).

What do you think are likely text messages from the future?

We'll get back to more on green technology next time. And, let me know if you have ideas about calculating the leverage effect of your green technology wedges.