Author Archives: tmurphy

Futuristic Physicists?

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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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Rocking the AC

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When it comes up in casual conversation that I do not generally heat or cool my house, people either move to another seat or look at me with some mixture of admiration and disbelief. When non-Californians then find out that I live in San Diego, they might huff or spew, which often involves some embarrassing projectile escaping their mouth. But the locals are more consistently impressed—more so by my forsaking heat than AC (San Diego has very mild summers by U.S. standards). This summer, I turned on the AC for the first time since we bought the house three years ago. All in the name of science! I was blown away. Here is what I learned.

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Battery Performance Deficit Disorder

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Batteries fail—as certainly as death and taxes. Rechargeable batteries at least offer the possibility of repeating the cycle, so are in this sense more like recurrent taxes than death. But alas, the story cannot repeat indefinitely. One cheerful thought after the other, yes?  But wait, there’s more… Add to their inevitable demise an overall lackluster performance in battery storage technology, and we have ourselves the makings of a blog post on the failure of batteries to live up to their promises.

To set the stage, the specific energy of gasoline—measured in kWh per kg, for instance—is about 400 times higher than that of a lead-acid battery, and about 200 times better than the Lithium-ion battery in the Chevrolet Volt. We should not expect batteries to rival the energy density delivered by our beloved fossil fuels—ever.

A recent article in APS News reported on an emerging view that batteries are failing to live up to our dreams in the electric car realm:

Despite their many potential advantages, all-electric vehicles will not replace the standard American family car in the foreseeable future. This was the perhaps reluctant consensus at a recent symposium focused on battery research.

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Solar Data Treasure Trove

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I have not kept it secret that I’m a fan of solar power. Leaving storage hangups aside for now, the fact that the scale of available power is comfortably gigantic, that perfectly efficient technology exists, that it’s hard-over on the reality axis (vs. fantasy: it’s producing electricity on my roof right now), and that it works well almost everywhere—what’s not to like? Did you trip over that last part? Many do. In this post, we’ll look at just how much solar yield one may expect as a function of location within the U.S.

The ancient Mayans laboriously accumulated a substantial set of observational data on solar illumination across America well ahead of the present need. Okay, it wasn’t actually the ancient Mayans. It was the National Renewable Energy Lab (NREL), who embarked on a 30-year campaign beginning in 1961, covering 239 locations across the U.S. and associated territories. Imagine this. How many people were even cognizant of solar power in 1961? Yet the forward-thinking scientists at NREL appreciated the value of a solid baseline dataset way back then. This level of foresight seems akin to the Mayans constructing a calendar going all the way to 2012. That’s all I’m saying. It’s a gift from the past.

I have often consulted and enjoyed the product of this work over the years—called the NREL Redbook, or more formally, the Solar Radiation Data Manual for Flat Plate and Concentrating Collectors. But with a snazzy blog post as motivation, I have taken it up a notch and produced a variety of graphical representations of the dataset to explore what it can tell us. Let’s begin the guided tour.

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My Modest Solar Setup

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I have made repeated references in past posts to the modest off-grid photovoltaic (PV) system I built to cover a large share of our—again modest—electricity usage.  By popular demand, I’ll take you on a tour of the system: it’s history, its composition, and adaptation to my house.

In 2007, I acquired a single, second-hand solar panel—intent on doing something useful with it. Confronted with a variety of options, and eager to explore multiple paths, I purchased a second panel and proceeded to set up a dual system: two stand-alone off-grid PV systems mounted side by side. It was really cool. I was able to power my television console and living room lights off of the two systems, while experimenting with different components and learning to live (part of) my life on natural power. I wrote a comprehensive article about how to size and design such a system, which may be worth reading first. Since that initial success, I have incrementally expanded my system so that I now get more than half of my electrical power from eight panels sitting in the sun. This is their story.

I have enough to say about my solar setup (and PV systems in general) that I must break this topic into multiple posts. In this, the first, I will describe the components, functions, and evolution of the system. In a future post, I will present system performance data and an assessment of efficiency of the various components. Perhaps even later I can explore the impacts of panel orientation, tracking, horizon obstructions, and geographic location.

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Do the Math Turns One: Place Your Orders

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One year ago today, Do the Math was born with a post on the absurdity of continued growth—in this case illustrating a Galaxy-consuming civilization in a mere 2500 years. Within a month, the site was getting thousands of pageviews per day, as I cranked out a backlog of thoughts and analysis surrounding the energy challenges we face.

In the process, adhering to a weekly schedule forced me to perform many new calculations on topics I had not previously explored very deeply. So besides being a cathartic experience, I gained new understanding, finding the exercise of constructing the alternative energy matrix to be particularly clarifying. One of the major lessons for me has been that while the physical scale of any alternative energy resource is important—and sometimes a showstopper—more often it’s the practical limitations that form the biggest barriers.

Finding the time and (mental) energy to keep the blog rolling has been challenging, but it’s you folks who inspired me to keep trucking. Knowing that each post would be read by thousands, and knowing that I could look forward to some excellent and thought-provoking (although sometimes just provoking) comments made the enterprise worthwhile.

At this point, I have dropped the cadence to bi-weekly, and my list of future topic ideas is slowly being whittled down. Many comments in the past have requested that I write a post about issue or another. I invite you to submit requests (even if repeated) in the comment forum below. Note that I might not have the background, interest, or time to invest if serious analysis is required. But there is some chance I’ll take the bait—and the idea may already even be on my list! Please refer to the Guide to Posts for a refresher of what’s been covered already.

Also, I think it fitting on this first anniversary to extend a note of gratitude to Asher Miller of the Post Carbon Institute for inspiring me to start writing, and for putting me in touch with the fine folks at the Energy Bulletin. The EB editors: Bart Anderson, Kristin Sponsler, and Simone Osborn offered early guidance and good advice (plus instant readership) that was vital to getting Do the Math off the ground. So a hearty thanks to these folks! 1.5 million pageviews later, their contributions have clearly had an impact.

And thanks to you, the readers, for your role in making this a successful and rewarding endeavor.

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TED-Stravaganza

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My wife calls it spying. I call it data. To-may-to, To-mah-to. It’s true that I know what she’s been up to (electrically) while I’m away. And it’s true that I can access this information anywhere in the world that has an internet connection. But domestic surveillance is not my aim (cameras and microphones would be far more informative in that regard). I just care about the energy angle.

In this post, I will present example results from monitoring and recording my home electricity use, demonstrating the marvelous secret world it reveals. My interest lies in putting numbers on my own behaviors, and in characterizing the appliances in my house. Some of this rubs off on my wife, and some of it rubs her the wrong way. But as I explained in an earlier post, I kept a note she once wrote that said: “Okay, TED’s pretty cool.”

Who is TED? TED is The Energy Detective. That same earlier post told the story of TED’s tortured journey to our home—a tale of excitement, rejection, and ultimate acceptance.

This post is not meant to convey anything deep and meaningful about the energy challenges we face, except for the fact that those challenges provided a background motivation for me to explore and monitor energy data in my home (it should be obvious by now that I’m a data-holic). Rather, I will simply showcase a number of data captures from TED so you can see for yourself the interesting hidden behaviors of appliances, and develop some intuition about how much of a toll various devices take.

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