When is it worth remanufacturing?

MIT study shows sometimes it saves energy, sometimes it doesn’t — and sometimes it makes things worse.


It seems like a no-brainer: Remanufacturing products rather than making new ones from scratch — widely done with everything from retread tires to refilled inkjet cartridges to remanufactured engines — should save a lot of energy, right?

Not so fast, says a new study by researchers at MIT.

In some cases, the conventional wisdom is indeed correct. But out of 25 case studies on products in eight categories done by a team led by Professor of Mechanical Engineering Timothy Gutowski, there were just as many cases where remanufacturing actually cost more energy as cases where it saved energy. And for the majority of the items, the savings were negligible or the energy balance was too close to call.

Why are the new results so different from what might have been assumed? The MIT team looked at the total energy used over the lifetime of a product — a life-cycle analysis — rather than just the energy used in the manufacturing process itself. In virtually all cases, it costs less money and less energy to make a product from the recycled “core” — the reusable part of the product — than to start from scratch. But the catch is that many of these remanufactured products are less energy efficient, or newer versions are more energy efficient, so the extra energy used over their lifetime cancels out the savings from the manufacturing stage.

A simple and familiar example is retread tires. They do indeed require less energy to make than new tires, but their rolling resistance might turn out to be just a bit higher, which would mean their energy advantage is eaten up by the extra gas used while driving on them.

The study, published in the journal Environmental Science & Technology, is the latest from Gutowski and his students that, as he puts it, “takes what appears to be a simple, straightforward problem and shows that the world is a far more complicated place than people thought.” The paper was co-authored by MIT materials science and engineering graduate student Sahil Sahni; Avid Boustani SM ’10, a recent graduate from the Department of Mechanical Engineering; and Stephen Graves, the Abraham J. Siegel Professor of Management in the MIT Sloan School of Management. The work was supported by the MIT Energy Initiative and the Singapore-MIT Alliance.

What often turns out to be the case, Gutowski says, is that “new technology shows up that is so much more efficient, from an energy point of view, that you should get rid of the old device” rather than having it fixed or buying a remanufactured version. For example, the efficiency of many new appliances — such as refrigerators and washing machines — are  so much improved over older models that, in terms of energy use, a new model is almost always the better choice.

Unfortunately, that is typically not the way people and businesses make their choices. “The decision is always on cost, not energy,” Gutowski says. For example, a remanufactured electric motor, in which the metal core is reused but wound with new wires, is typically 0.5 to 1 percent less efficient than a newer motor. “There is still a cost advantage” to the remanufactured motors, he says, “but from an energy point of view, it’s the opposite.”

Other effects stem from remanufactured products going to different markets than their original destinations. For example, old cell phones can be remanufactured, but the remanufactured phones tend to be sold in developing countries. “If it goes to a different market, it leads to an expansion of the market,” Gutowski explains, so the overall level of cell phone usage globally — and the energy needed to power them — ends up increasing.

For some kinds of products, the benefits of remanufacturing are unequivocal. It clearly makes sense to remanufacture anything that consumes an insignificant amount of energy when it is being used, he says — for example, furniture.

Julian Allwood, a senior lecturer and leader of the Low Carbon Materials Processing Group at the University of Cambridge in England, says this is a very original analysis and the findings are of high quality because they are “carefully informed with real numbers.” He adds that while the results seem to be valid for the product categories the team studied, “My only concern is that their product catalogue was mainly consumer products — i.e., not buildings, infrastructure, industrial equipment — which are probably all more significant categories as drivers of global environmental impacts.”

Gutowski emphasizes that this research does not necessarily suggest a specific course of action. For any given product, there may be other reasons for preferring the remanufactured version even if it produces a net energy penalty. For example, remanufacturing may reduce the burden on landfills, reduce use and disposal of some toxic materials, or produce needed jobs in a particular area. And the expanded use of cell phones may have important social benefits, such as contributing to the recent wave of revolutions in North Africa and the Middle East. “We’re not saying you shouldn’t do it,” he says — just suggesting that it’s worth understanding the decision’s effects in their entirety.

“You think you’re doing the right thing, it sounds so simple,” Gutowski says. But when it comes to understanding the true impact of purchasing decisions on energy use, “things are far more complicated than we expect.”


Topics: Alumni/ae, Energy, Environment, Manufacturing, Materials science, Mechanical engineering, Students

Comments

Dear sirs: I fully disagree with your comments Open your mind and think about eco inovation, Heirloom design and try to make a study on how beneficial can be items done to last, under standarts etc. Can you imagine somebody recycling the car because it broke down. Have you taken into your model that we are in a limited world? Have you seen National Geografic Issue about Human impact? Of course if you compare things that are made to have a certain life thats OK. Sorry: Should we clean our clothes or just change them?
Only a genius can look at world so differently.
Professor Gutowski will be offering a short course this summer on Energy, Sustainability, and Life Cycle Assessment from June 20-22. This class addresses three aspects of sustainability from an engineering perspective: 1) energy resource analysis, 2) material resource analysis (including carbon, water, and nitrogen), and 3) life cycle assessment. Learn more at his course website: http://web.mit.edu/professional/short-programs/courses/energy_sustainability_life_cycle.html
You said it right. A machine/product goes inefficient in terms of energy consumption when its performance is not as good as that of a new one. But, all that matters is the number of times we are going to put it back to use. For example, some tested vehicles are disassembled and their parts are sold
What this shows is that markets are blind. A coal barren was once asked what costs the company more a dead worker or a dead mule. A dead mule he replied. I can always hire another worker. A mule I have to buy. The only ones who benefit from market economics is the ruling Capitalist Class. We can run the economy without the capitalists. They however can't make a profit without us.
Between 1980 and 1983 at the MIT Center for Policy Alternatives we conducted research on Energy Savings Through Remanufacturing. The CPA group also hosted two international conferences on Remanufacturing attended by some of the leading OEM's in transportations, machinery, information technology and other core industries. The long history of remanufacturing, refurbishing, upgrade, retrofit, repower or as the DoD calls it SLEP (service life extension program - which by the way accounts for almost 30% of the operational expenses). Provides ample evidence of the economic viability and benefit of these practices. The REM process does not have to stop at returning a product to "like new" specifications. In fact most successful OEM REM programs (Caterpillar being a prime example) strive for complete upgrades of all systems, controls and components to the latest specifications. If a product is designed for REM in the first place you can have for all intents and purposes an "infinite" product life. In the TURBOMACHINERY industry where I now work we routinely remanufacture 30-40-50 year old turbines and gearboxes and upgrade them to current controls, re-ratio, material upgrades, etc. A sign of a well designed and manufactured product is one that can be continually upgraded and improved while providing long reliable service (99.5% reliability is common on this industry). Clearly not everything is suitable for REM -- look back at the MIT CPA publications -- under Prof Robert Lund's leadership for some of the guidelines used to measure remanufacturability. REM will be with us for many generations, it is good to see reserch going on -- in fact the companies that don't plan for this as a part of the lifetime of their products are the ones that wont last in the capital equipment market. Way to go MIT TAG Class of 1980 and MS 83
It is a simple assumption to just take energy usage into consideration. Also, when talking about energy, one also needs to distinguish between the "type" of energy used: is it "normal" energy or "green" energy? As far as I can tell, this distinction has not been made in this research. Other research on closed loop supply chains has shown that remanufacturing can greatly reduce CO2 emissions and save costs for producers. Companies like http://www.durabilit.com have developed together with closed loop supply experts a calculator that shows that in the case of network equipment, remanufacturing not reduces CO2 emissions by 50-70% over the entire lifecycle of the product, depending on the type of energy used.
Energy consumption is only one of the attributes of Remanufacturing value proposition that was covered. · Conservation of natural resources and rare earth minerals · Domestic Job creation from foreign made products · Sustainability · Green house gas emission reduction · Life cycle extension · Lower Cost Service Parts Solution for OEM and consumer. China’s recent announcement of a major initiative in Remanufacturing, indicates their understanding and appreciation of Remanufacturing value proposition to their economy. If the Department of Commerce and schools such as MIT would research the size, scope, and benefits, and they would find that Remanufacturing is a major industry in the US. The Remanufacturing industry has created hundreds of thousands of jobs. This has been accomplished without the incentives that other sectors of industry receive. Remanufacturing's time has come, and should be recognized for its contribution to the environment, and its importance to our economy before another segment of US industry disappears to foreign shores.
In China, the goverment focuses on the remanufacturing program, and has costed a lot of money on it. But in fact, few companies do the correspongding things. This constrains the researches on remanufacturing closed supply chain.
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