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The bigger picture: Professor Tim Gutowski's group at MIT researches environmentally benign manufacturing. It's about equipping engineers with a broader view of the consequences of their decisions.

Manufacturing industry worldwide has had a difficult relationship with public perceptions over the past century or so. Recent surveys of young people's attitudes towards manufacturing show discouragingly little progress from the stereotypes of yesteryear, and the distance between the perception and the reality is growing.

Tim Gutowski gets some of the backwash from this problem. Professor of mechanical engineering at the Massachusetts Institute of Technology (MIT), Gutowski heads a research group looking at "environmentally benign manufacturing".

"A lot of people say 'isn't that an oxymoron' and I use the name because yes, it might be a self-contradiction, but in any case it's intriguing," he says. Some of the intrigue comes for him as an engineer because concepts of sustainability stretch the engineering view of the world, where "you can set goals and you can meet them".

In the area that he is dealing with, he says, there are "all kinds of unintended consequences, rebound effects that take you to some place that you hadn't originally expected". What looked like a straightforward logical decision ends up unexpectedly; the conventional tools in an engineer's toolkit don't give all of the answers.

He cites as an example the demand, particularly strong in Europe, for the microelectronics industry to move away from lead-based solders. "So when we looked for alternatives we were all over the place and we included things like copper and boron and bismuth, and there was an interesting study looking into bismuth and they found that bismuth tended to be comined with lead and the upshot was that if there was going to be a greater need for bismuth then it would lead to more mining of lead."

The group that Gutowski heads at MIT is known for making some fairly challenging pronouncements about the environmental performance of products and technologies. It has recently, for example, been in the news for wondering publicly why it is that "environmental" products such as solar panels seem to be rather less environmentally benign in terms of their manufacture than established 44 unenvironmental" products such as cars.


Gutowski has many answers to this apparent anomaly and they're not unhopeful. Cars and steel and many other products have been made for a very long time: methods of manufacture have been continually optimised and the manufacturers are often fairly aware of their energy usage and their environmental image. And, as well, the full lifecycle is pretty much known: "Trends change a bit, but we know that in the US people keep their cars for about 10 years and they drive about 12,000 miles a year."

So the environmental effects and the sustainability of a well-established product can be worked out fairly readily. This isn't entirely good news, Gutowski says. "If you look at manufacturing as a whole its been paying attention to energy usage for a long time and they're much better at looking at it than you and I are in our own personal lives. So you look at industries like steel and aluminium and their use has been coming down year on year over decades. But in some ways for some of the processes we've come to the point where there isn't going to be much more room for improvement."

New products are different and more difficult, though, which explains why some apparently environmentally benign products like solar panels still have some way to go before realising the full benefits. Even more challenging is trying to work out what the lifecycle will be for a product that hasn't even been brought to life at all yet. But that's what Gutowski and his colleagues want to encourage business leaders and their engineering students to try to do.

There are some general rules. "Use less toxic materials, use less energy, make it recyclable: nothing very surprising there," he says. At times, though, these laudable aims will conflict with each other. And in many instances, of course, there are other conflicts: "Toxic materials are often toxic specifically because they have special properties that greatly facilitate what it was that we wanted to get done, so when we move away from toxic materials we often find that we end up with less efficient processes or less effective products. People don't like saying that out loud, but it's the truth."

The law of unintended consequences operates in product development too, so innovations such as the replacement 50 years ago of "nasty" ammonia and sulphur dioxide as refrigerants by the chlorofluorocarbons that then chomped their way through the ozone layer brought consequences that were perhaps not foreseeable.

It's a truth too, Gutowski believes, that much of manufacturing industry--all human activity, in fact--has been based on seeing lifecycles and performance in financial terms rather than in terms of environmental cost or material cost. "A good general statement is that energy and materials have been a really good deal and we've learned how to exploit them," he says. "We routinely substitute energy and materials for human labour. We've exploited these opportunities because they've been cheap."

Some of that legacy of a mismatch between the economics and the environment is not going to be easy to eradicate. Across the world, motorists are complaining because the price of fuel has risen and shows little sign of diminishing. In financial terms, however, the motorist pays on average a lot less for the fuel that the car will consume across its lifetime than for the original cost of the car. But in terms of the energy cost, the balance is very different: fuelling the car will consume a huge amount more energy, both directly and in terms of the energy needed to get the filel into the car, than the energy that was needed originally to make the vehicle.

Maybe that's because the automotive industry is a mature one, but Gutowski points to a similar mismatch in terms of cost versus energy in a much newer industry, solar power. "Off the top of my head, I reckon most solar panels will pay back from the energy point of view in somewhere between one and three years," he says. "But in terms of the cost, the payback could well he 15 to 20 years. It's not even in the same ball park."

On the materials side, it may be easier to square financial costs with the environmental factors. A highly promising photovoltaic material, for example, is cadmium telluride. "You can apparently deposit it in very thin films and make these PV cells that use far less material than conventional ones," Gutowski says. The downside, though, is that telluride is found as a mineral in only minute quantities: "For large-scale production of it even at this point we can say that it looks like there will be a problem." The problem will manifest itself as cost: though in fact it's the scarcity of the substance which is the real problem that causes the high cost.


That link between material scarcity and high financial cost is much less well-established with energy prices, and it doesn't necessarily change with newer products. Gutowski and his colleagues have been studying potential manufacturing routes for bringing carbon nanotubes into everyday products such as baseball bats. Data on the energy needed in manufacturing processes for carbon nanotubes was hard to come by, but some work at Rice University in Texas described some of the processes and gave data on which to base calculations.

"So we did the analysis of carbon nanotubes and we found that the energy requirements made this one of the most energy intensive materials on earth," he says. "And even though the energy requirements have been coining down, we're still in the order of gigajoules of energy requirement per kilogram, whereas most materials measure in megajoules, or 1000 times less."

But even when you have the figures, they may have little impact. "If carbon nanotubes are selling at around $100/g then the energy to make those tubes is only 1% of the selling price. So the signal's not getting through. You go and talk to people about energy costs and they just don't get that signal."

Environmentally benign manufacturing is about getting this kind of information into the mix as products are being developed. It demands a rather wider range of thinking than engineers have traditionally been taught in the past, Gutowski says.

"What should be in the engineer's toolkit when they start to develop something new? Well, the usual way with engineers and these things is that you set goals and you try to meet them and you use tools like FEA to test things like energy consumption.

"But I think you have to make a leap and say that engineers need the tools that will help them to make products that meet the needs of society, so part of their toolkits needs to be to think about how we live our lives and whether things are feasible. So step No 1 has to be lifecycle analysis and if you attempt to look at a product over its lifecycle then you'll start to include a lot more things than you originally thought of. And that's a good first step."

It sounds complex, but Gutowski isn't going to apologise for that. "There are lots and lots of variables," he says. "All of these things are complicated."

RELATED ARTICLE: Challenging norms

Some of Tim Gutowski's work in manufacturing has been controversial in terms of challenging industry's accepted norms. He has pointed out, for example, that many modern industrial processes are less energy-efficient in terms of energy per unit of material processed than older techniques and that some newer technologies require energy-intensive operations that don't actually contribute to the manufacturing, but significantly increase energy use.

An often-overlooked energy cost in modern manufacturing comes from globalisation and the location of suppliers across the other side of the world. On the MIT campus in Boston, Massachusetts, Gutowski noted that manhole covers seemed to come either from a foundry in Wisconsin or from China--the imported ones, he was told, were cheaper, so he set his students an exercise to discover what the "cost" was in energy terms. It produced a rather different answer.
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Title Annotation:Manufacturing
Author:Pullin, John
Publication:Environmental Engineering
Geographic Code:1USA
Date:Apr 1, 2012
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