Author Archives: tmurphy

Elusive Entropy

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partial mixWe’ve all heard it. We think we understand it: entropy is a measure of disorder. Combined with the Second Law of Thermodynamics—that the total entropy of a closed system may never decrease—it seems we have a profound statement that the Universe is destined to become less ordered.

The consequences are unsettling. Sure, the application of energy can reverse entropy locally, but if our society enters an energy-scarce regime, how can we maintain order? It makes intuitive sense: an energy-neglected infrastructure will rust and crumble. And the Second Law stands as a sentinel, unsympathetic to deniers of this fact.

A narrative has developed around this theme that we take in low entropy energy and emit a high entropy wake of waste. That life displays marvelous order—permitted by continuous feeding of this low entropy energy—while death and decay represent higher entropy end states. That we extract low entropy concentrations of materials (ores) from the ground, then disperse the contents around the world in a higher entropy arrangement. The Second Law warns that there is no going back: at least not without substantial infusion of energy.

But wait just a minute! The preceding paragraph is mostly wrong! An unfortunate conflation of the concepts of entropy and disorder has resulted in widespread misunderstanding of what thermodynamic entropy actually means. And if you want to invoke the gravitas of the Second Law of Thermodynamics, you’d better make darned sure you’re talking about thermodynamic entropy—whose connection to order is not as strong as you might be led to believe. Entropy can be quantified, in Joules per Kelvin. Let’s build from there.

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Let’s Blow this Joint

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I have a confession to make. When we moved into our current house three years ago, we had to sell our clothes dryer due to gas/electric incompatibility (happens every time we move!). So we lived without a dryer for three years, hanging clothes out to dry, and generally being frugal about washing vs. re-wearing clothes. Well, after several weather-induced trips to the laundromat this winter, we (or can I lay this all at my wife’s feet?) finally broke down and bought a used washer/dryer set on Craigslist. We’ll still let the sun dry our clothes 95% of the time, but have other options now.

Even though this little vignette does relate to the common Do the Math theme of low-energy lifestyles, the actual point of bringing it up is that the washer/dryer came from a house that had just been on display as a model for energy efficiency—including the washer and dryer. At the house, we met Jason Beckman, of Classic Residential, Inc., who had carried out many of the efficiency upgrades to the house. I thought it would be instructive to have him perform an energy audit at our home—especially a blower door test to expose ventilation issues.

As a bonus, after the nominal audit activities were over, I was able to spend some quality time with the blower door, doing extensive tests in virtually every room in the house. What I found was certainly instructive for me, and hopefully will be useful to a broad audience as well.

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Death of a Battery

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Four 150 A-h 12-V golf-cart batteries

Four golf-cart batteries used in my off-grid home PV system. Each is 12 V, 150 A-h, thus 1.8 kWh of storage.

All the metrics looked great. The 2.7-year-old lead acid batteries in my off-grid photovoltaic system appeared to have settled into a consistent mid-life performance. Monthly maintenance (equalizing, adding distilled water) promised to keep the batteries in prime condition for some time to come. Based on cycle depth, I expected another 2.5 years out of the present set of batteries. Life was good.

Then, during my absence over the course of Thanksgiving weekend, one of the batteries expired. No forewarning. Just gave up. A previous post expressed an overall disappointment in batteries, now reinforced by this sudden nosedive.

In this post, I’ll show the metrics on my system detailing the demise of “Battery E.” The gruesome graphics are intended for mature audiences.

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This Thermal House

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[A parallel treatment of some of this material appears in Chapter 6 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

If you want to make your house more efficient at repelling the unpleasantness outdoors (whether hot or cold), what should you do first? Insulate the walls? Insulate the ceiling? The roof? Better windows? Draft elimination? What has the biggest effect? While I have regrettably little practical experience tightening up a house (it’s on my bucket list), I at least do understand heat transfer from a physics/engineering perspective, and can walk through some insightful calculations. So let’s build a fantasy house and evaluate thermal tradeoffs at 1234 Theoretical Lane.

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Crippling Intellects

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[Relevant reflections on this topic appear in Appendix section D.6 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

Star Trek brainiac

People can be individually smart and collectively dumb. Or some may argue that people can be individually dumb yet collectively smart. When it comes to plotting a future path, I think we often get the worst of both worlds. In this post, I’ll look at the role that mental horsepower plays in our societal narratives, for better or for worse. We’ll explore two aspects to the problem: people who are so smart that they have dumb ideas; and smart people who are held captive by the manufactured “dumb” of society.

A word of warning: “smart” and “dumb” are loaded words, and even impolite. We place so much value on intelligence in our society that being called smart can make a person’s day, while being called dumb can cut to the core. We’re very sensitive to people’s perceptions of our intellectual standing, and some of the choicest insecurities are laid upon this foundation. I use “smart” and “dumb” as blunt instruments in this post, so if you’re particularly touchy on the topic, either steel yourself or skip the post and call it the smartest thing you did all day.

Let me preface what I am about to say by the disclaimer that most of this is conjecture. I have little data, relying instead on hunches about what makes people tick based on personal observations.

One other disclaimer: this isn’t a post whose veiled message is how smart I am. I might once have thought so, but then I met bona-fide geniuses when I was in grad school at Caltech. Fortunately, I was mature enough at that point for it not to cause a crisis of confidence or identity, and rather enjoyed the window I had into the off-scale brilliance of some individuals. So let’s go ahead and put me in the dumb box so we can move on to what I want to say.

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Survey the People

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The futuristic survey (covered in last post) has attracted about 1300 respondents, 900 from DtM, 300 from the Energy Bulletin (now Resilience.org), and a smattering from other places.

I will ultimately be sharing the results, but the habitual readers of the aforementioned sites are perhaps not representative of the population at large.

Thus I would like your help in pushing this out to a broader population.  See if you can get your friends and family members to take the survey, and perhaps even pass the link on to their friends, etc.  I’ve never done this sort of thing before, so do not know what to expect.  But let’s give it a try, yeah?

Here’s the link you want to pass on in whatever form (paste into e-mail, Twitter, link on FaceBook, whatever works): https://www.surveymonkey.com/s/2ZC6RD9

Thanks for your help—should be very interesting.

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Futuristic Physicists?

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www.dvdtoponline.com

One day, sitting around with a group of undergraduate physics students, I listened as one made the bold statement: “If it can be imagined, it can be done.” The others nodded in agreement. It sounded like wisdom. It took me all of two seconds to violate this dictum as I imagined myself jumping straight up to the Moon. I may have asked if the student really thought what he said was true, but resisted the impulse to turn it into an impromptu teaching moment. Instead, I wondered how pervasive this attitude was among physics students and faculty. So I put together a survey and in this post report what I found. The overriding theme: experts say don’t count on a Star Trek future. Ever.

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When Science is a Conveyor of Bad News

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Science is a phenomenal institution. Sometimes I can’t believe we created this construct that works so incredibly well. It manages to convert human imperfections into a remarkably robust machine that has aided our growth juggernaut. Yet science seeks truth, and sometimes the truth is not what we want to hear. How will we respond? Will we kill the messenger and penalize the scientific institution for what is bound to be an increasing barrage of bad news this century as Earth fills beyond capacity?

I think for many people in our society, personal contact with science is limited to science classes in school or perhaps the dreaded science fair—or maybe as adults watching shows like Nova or tuning in to Shark Week on the Discovery Channel.

So let me take a moment to explain science as I have come to understand it. (You can skip if you already have a firm grip.)

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The Energy-Water Nexus

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The principal challenge of this century, in my view, will be adapting to a life without abundant, cheap fossil fuels. It has been the lifeblood of our society, and turns out to have some really fantastic qualities. The jury is still out as to whether we will develop suitable/affordable replacements. But additional challenges loom in parallel. Water is very likely to be one of them, which is especially pertinent in my region. For true believers in the universality of substitution, let me suggest two things. First, come to terms with the finite compactness of the periodic table. Second, try substituting delicious H2O with H2O2. It has an extra oxygen atom, and we all know that oxygen is a vital requisite for life, so our new product will be super-easy to market. Never-mind the hydrogen peroxide taste, and the death that will surely visit anyone foolish enough to adopt this substitution. Sometimes we’re just stuck without substitutes.

Substitution silliness aside, water and energy are intimately related in what has been termed the Energy-Water Nexus (see for example the article by Michael Webber from this conference compilation; sorry about the paywall). We’ll explore aspects of this connection here, touching on pumping water, use of water for the production and extraction of energy, and desalination. As glaciers and snowpack melt and drought becomes more common in the face of climate change, our water practices will need to be modified, hitting energy right in the nexus.

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Blow-by-Blow PV System Efficiency: A Case Study for Storage

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A short while back, I described my standalone (off-grid) urban photovoltaic (PV) energy system. At the time, I promised a follow-up piece evaluating the realized efficiency of the system. What was I thinking? The resulting analysis is a lot of work! But it was good for me, and hopefully it will be useful to some of you lot as well. I’ll go ahead and give you the final answer: 62%. So you could peel away now and risk using this number out of context, or you could come with me into the rabbit hole…

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