We are saddened to report that Professor Dornfeld passed away in March, 2016. If you enjoyed his blog, please consider making a contribution to either of two funds at UC-Berkeley that have been established in his memory.

David A. Dornfeld Graduate Fellowship
David A. Dornfeld Scholarship

Royalties from David’s book "Green Manufacturing - Fundamentals and Applications" go to these Funds, too.

Tuesday, January 3, 2012

Green Pot? Not!

Choice Items for the New Year

I've hit the pause button on the "Tools of the Trade" postings for the moment and, on the occasion of New Year, have included here a few items that seem a propos to green manufacturing - broadly interpreted- under the headlines 'green or not'? I know it sounds a bit like a Dr. Seuss book title - but read on!

The first one is thanks to Ralph Resnick and Corey Kovalcik of NCDMM.  It is a reference to a posting in the New York Times on the carbon footprint and environmental footprint of pot growing! I think they assumed that since I am at Berkeley with all those free thinkers that I had something to do with this.

I was a "child of the 60's" but was not a pot person (not even smoked but "didn't inhale" like our esteemed former President Bill Clinton!) As I explained to my dad many years ago when I joined the Berkeley faculty, every thing at Berkeley does not smell of burning hemp or involve overthrowing "the man."

You can find the full story on this at the NYT link. I don't know Dr. Evan Mills from Lawrence Berkeley Lab, the author of the study quoted in the article, but he seems like a serious researcher to me. The report is enlightening and will pose a dilemma for many folks (theoretical as well as practical - maybe even Ron Paul supporters!). His full report can be accessed on-line.

The last such dilemma I faced was not paper or plastic bags but natural versus artificial trees! This was first reported (or my first observation) in a Science 2.0 posting in December 2007 titled "The great debate: Real vs artificial Christmas trees." The article states "While chopping down a living tree may see like the most un-environment friendly thing you can do, in this situation it actually appears to be the “greener” choice. Because it’s not so much about how many uses you can get from your tree … as it is about what the tree is made of, and what it does to the environment when it is created and when you dispose of it."

"Artificial trees are manufactured using a polyvinyl chloride (or PVC), which is a petroleum-derived plastic. The raw material for fake Christmas trees is both non-renewable and polluting. Furthermore, PVC production results in the unhealthy emission of a number of carcinogens, such as dioxin, ethylene dichloride and vinyl chloride."

"Additionally, in order to make the PVC needles on artificial trees more malleable, the manufacturers use lead and other additives that have been linked to liver, kidney, neurological, and reproductive system damage in lab studies on animals. The Children’s Health Environmental Coalition warns fake trees "may shed lead-laced dust, which may cover branches or shower gifts and the floor below the tree.""

Wow. Check out that article … the comments are rich and numerous too.

USA Today weighed in on this last December, 2011 in an article that focuses on the dispute between manufacturers of artificial trees and the National Christmas Tree Association. Not surprisingly each side sees the other as spreading misleading info. Up to you to decide if you have a need for a tree next year!

But, back to the pot.

The article starts out with the statement "indoor marijuana cultivation consumes enough electricity to power 2 million average-sized U.S. homes, which corresponds to about 1 percent of national power consumption." A lot of production is indoors these days using high intensity lights - resulting in an approximate $5 billion dollar annual electricity bill. According to Mills that contributes the equivalent in green house gas emissions to about 3 million cars on the road.

It gets worse. The smoke from consuming all that marijuana further complicates the issue. Report author Mills said a single marijuana cigarette represents 2 pounds of CO2 emissions, an amount equal to running a 100-watt light bulb for 17 hours.

Don't try going "off grid" to raise your pot and expect to save the planet either. Mills stated "for off-grid production, it requires 70 gallons of diesel fuel to produce one indoor cannabis plant, or 140 gallons with smaller, less-efficient gasoline generators."

And then there is all the water! Each marijuana plant needs between 3 and 5 gallons of water per day to grow to "harvest".

Dr. Mills' report is comprehensive and contains detailed graphics and tables of impact.  Table 4 is specially intriguing. Did you know that "one Cannabis cigarette is like driving 15 miles in a 44mpg car emitting about 2 pounds of CO2?" Which is where the equivalent to operating a 100- watt light bulb for 17 hours comes from.

It also includes suggestions as to how you can improve the energy efficiency of cannabis cultivation. I will not be using this as a case study in my graduate Sustainable Engineering course this semester but it is an exceptionally well done, and complete, study.

Finally, Neil Duffie (a friend and professor in Mechanical Engineering at UW-Madison) reminded me of this poem on the "one hoss shay" following a presentation I gave in Madison late last year on sustainable manufacturing and design for sustainability.

This is a poem by Oliver Wendell Holmes about a deacon who, apparently concerned about designing things with some components that wear out or fail faster than others (hence "wasting the over designed components and the material and effort that went into them), designed a one horse shay of components and materials that lasted exactly 100 days and then totally disintegrated all at once.  For your information, a shay is a light, covered, two-wheeled carriage for two persons, drawn by a single horse - thanks Wikipedia!

I believe the horse was fine however!

The poem starts with the following lines:

"Have you heard of the wonderful one-hoss shay,

That was built in such a logical way
It ran a hundred years to a day,
And then, of a sudden, it - ah, but stay,

And ends many lines later with:

"How it went to pieces all at once, 

All at once, and nothing first,
Just as bubbles do when they burst.

End of the wonderful one-hoss shay, 

Logic is logic. That's all I say."

You can find the whole story (or poem) on-line (and I know that other links can be found by searching.)

No mention of the carbon footprint of the shay unfortunately.

Oh, one more item! Karen Tworsey brought to my attention a recent posting on her site on the
"10 Wackiest Ideas Ever for Improving the Environment."Everyone has their own definition of "wacky" but, for me, the human powered floating gym is enough. And there is one with kangeroos but modesty prevents me from any more details on that one!

Best wishes for a prosperous and happy New Year!