Sunday, April 18, 2010

Green Bits

We've spent the last posting discussing supply chains from a manufacturing and green aspect. Following on these discussions, I wanted to mention an upcoming webinar on "Supply Chain Carbon Mapping in Four Industries" to be presented by Climate Earth on  Tuesday, April 20th, at 11 am PDT/ 2 pm EDT (1 hour). There is no cost for the seminar and you can register at or go to There is an archived webinar on "Carbon Efficient Supply Chains" at The four industries covered are food processing, packaged goods, manufacturing, and services

A recent survey by McKinsey on "How companies manage sustainability" caught my eye. You need to register to download the full report (but it is free) at The survey was done in February 2010 covering almost 2000 executives in a wide range of industries and locations. Among the results shown is a table showing how companies keep track of the "value created by sustainability programs." Although no detail is given on the programs the results support some of our earlier musings on why green (or sustainable) matters.

The items tracked are:
- reputation building (over half agree this is a key metric)
- growth opportunities
- cost savings
- risk avoidance
- employee attraction, retention and productivity
- customer loyalty

The study also identified "proactive" executives (surprisingly only about 6% say "sustainability is a top-three priority" in their agendas with the associated actions associated with it.) These executives tend to be much more proactive in seeking ways to enhance the sustainability of their organizations. They list the following statistic - "84 percent of respondents at engaged companies are aware of whether or not their companies measure their carbon footprint" and, more importantly,  these engaged companies are more likely, with respect to their supply chain and customers,  to be keeping track of "relevant sustainability indicators such as waste, energy and water use, and labor standards."

Now to some green technology wedges!

I participated in and spoke at a conference earlier this month in Nashville sponsored by AMT and NCMS - two organizations well engaged with the manufacturing industry in the US. It was called the 2010 AMT/NCMS Manufacturing Technology Forum and the focus was on green manufacturing. You can see some details at

I presented an overview of issues and opportunities in green manufacturing (many of them discussed in these postings) and spoke again about the concepts of the technology wedges. I first introduced these in the September 15, 2009 blog (see I related this concept to specific approaches to reducing energy consumption in manufacturing with examples from machine tool design and operation.

One of the other speakers, Scott Hibbard, Vice President of Technology at Bosch Rexroth in Illinois. Besides being a very sharp engineer in the drive and controller business we both have roots in Wisconsin. He discussed drive & control technology to increase energy efficiency and spoke of many bits of enabling technology for some of the exact applications I have been thinking about in the past. Things such as energy recovery from machines during changeover or down cycles, reduction in "tare" energy for machines, reduction (or increase in efficiency) of process related energy, etc.

He showed the required "what percentage of US consumption my particular area is responsible for" slide derived from Department of Energy data but this time reflecting motors and drives. Turns out about 70% of industrial energy consumption falls in this category. He further broke that category down to specific applications of these motors and drives to include pumps (hydraulic and others) 27%, compressed air systems 18% material movement (also known as motion control - this is used in machine tools, robots, conveyors, etc.) 30%, for example.

Just to make sure we are all on the same page let's define a few terms. Drives (often adjustable speed) is usually a combination of hardware and software that powering and adjusting the operating speed of a mechanical load. This is often an electric motor and a speed controller or power controller. The "drive" often refers to just the controller. In machine tools these motors can be synchronous or induction, AC, DC (brushed or brushless), or step motors and can be rotary or linear motion providers. Try our old friend Wikipedia for a quick source of info. The combination of a motor and drive with some higher level control hardware/software makes up one axis of motion of a modern numerically controlled machine tool as we've discussed them before.

Scott identified 4 major areas for energy savings and, incidentally, increasing productivity:

- Efficient components (use products and systems with optimized efficiencies)
- Energy on demand (only use energy when needed; recall our tare vs process energy discussion a few blogs back)
- energy recovery (store and reuse or sell back excess energy; and we had referred to energy recovery from the spindle of a machine tool also)
- Energy conscious system design (include energy consumption and efficiency in the design of the machine or system from the start)

One of his examples showed 20% regenerative power from "machinery braking" and the return of that power to the electricity utility. "Energy exchange" between motor and generator drive modes is also a possibility with 15% recovery.

One neat example relied on storing of excessive energy not required during short-time operation and intermittent operation by means of hydraulic accumulators and accumulator charging circuits. Without getting into the details, accumulators in hydraulic systems are pressure storage reservoirs containing a hydraulic fluid (considered to be incompressible - meaning doesn't compress under load - most liquids are like this) that is held under pressure by an external source such as a spring, compressed gas (gases do compress under load!), weights or other mechanisms. Using an accumulator, the pump on the hydraulic system need not be as large to accommodate the load variations and, they can store energy! Combine this with a variable speed pump which can use up to 65% less energy  thanks to utilization of stand-by mode when idle-running and speed reduction with slower motions.

Scott showed this technology applied to a hydraulic press. These presses are used for forming large sheets of metal as in automotive components like fender, hoods, etc as well as a variety of formed metal products. Think of a giant hydraulic cylinder with a forming tool set (punch and die) and sheets of metal.

The figure below, from Scott's presentation, shows a typical energy use cycle for a hydraulic press. The top figure shows the press cycle with a rapid down motion, the press forming section,

decompression and return of the cylinder (and top die) to top position. The bottom portion compares the energy used over time with the conventional and variable speed pump drive with regeneration. There is a dramatic savings. In addition, since motors generate heat, etc. there will be a reduced building environmental load as well.

We've gotten a little heavy on the tech talk this time. But, it is an excellent example of the potential in operation of our manufacturing machinery to apply wedges that, in combination with a lot of other machine improvements, make big differences. A typical automotive manufacturing press shop will have dozens of these presses operating 24/7 (when production is good of course) and the savings realized on one machine multiplied by all adds up.

More tech stuff next time!

And, for youtube fans, we've posted two videos on our lab website from a recent open house called "Cal Day": one is on how we calculate the carbon footprint of our laboratory and another on a recent experiment showing side by side energy consumption and a milling experiment in the lab. Both are accessible at Enjoy!


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