Sustainable Means Bunkty to Me

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What? Don’t know what bunkty means? Now you know how I feel about the word “sustainable.” My paper towels separate into smaller segments than they once did. It’s sustainable! These potato chips arrive in a box that says SUSTAINABLE in big letters on the side. I’m eating green!  When I’m in a hotel, I hang the towel back up rather than throw it on the floor (would I ever do this anyway?) and the placard says I’m being sustainable. Can it be that easy? I claim that not one among our host of 7 billion really knows what our world would look like if we lived in a truly sustainable fashion.  Let’s try to come to terms with what it might mean.

I think most would agree that the rapid depletion we currently witness in natural resources and services, climate stability, water availability, soil quality, and fisheries—to name a few—suggests that we do not live sustainably at present. We can not expect to keep up our current practices with 7 billion people in this world without some major changes.

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Putting the Genie Back in the Toothpaste Tube

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You may have heard about the excess carbon dioxide in the atmosphere as a result of our combustion of fossil fuels. If we wanted to sweep the excess CO2 out of the air, what would it take? How much is there? Where would we put it? In this post, we will put the numbers in perspective and briefly examine a few of the possibilities for storage.

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Don’t Be a PV Efficiency Snob

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[An updated treatment of some of this material appears in Chapter 13 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

A common question I get when discussing solar photovoltaic (PV) power is: “What is the typical efficiency for panels now?” When I answer that mass-market polycrystalline panels are typically about 15–16%, I often see the questioner’s nose wrinkle, followed by dismissive mumbling that 15% is still too low, and maybe they’ll wait for higher numbers before personally pursuing solar. By the end of this post, you will understand why this response is annoying to me. At 15%, we’re in great shape: it’s plenty good for our needs. Let’s do the math and fight the snobbery.

polycrystalline silicon PV cell

A close-up of a polycrystalline photovoltaic (PV) cell, showing blue tint and a patchwork of crystal domains.

First, let’s look at the efficiencies of other familiar uses of energy to put PV into perspective. I will act as if I’m directly addressing the PV efficiency snob, because it’s fun—and I would never be this rude in person. This may not apply to you, the reader, so please take the truculent tone in stride.

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Got Storage? How Hard Can it Be?

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The recent city-wide power outage in San Diego made me appreciate my small off-grid photovoltaic system using four golf-cart batteries to store energy for use at night. Unlike most San Diegans, I did not immediately eat the ice cream in my freezer, which trucked along under stored solar energy just like it does every night. Energy storage becomes more important as we transition away from fossil fuels—already its own energy storage medium—to more intermittent sources. But besides batteries—which offer a limited number of cycles and for some types require monthly maintenance—what other non-fossil in-home energy storage alternatives might we consider, and how much energy might we expect to store in each case? We will look at gravitational storage, flywheels, compressed air, and hydrogen fuel cells as possible options. Some might even cost less than $100,000 to implement in your home.

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Power Out, People Out

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Yesterday at about 15:40 local time, San Diego lost power—along with many other parts of Southern California, Arizona, and Mexico. Our power was out for 11 hours. The experience was fascinating for me, because it changes the rules of the game suddenly, and exposes certain fragilities in our system. This is a brief account of what I learned from the experience. Continue reading →

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Discovering Limits to Growth

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After inaugurating the Do the Math blog with two posts on the limits to physical and economic growth, I thought it was high time that I read the classic book The Limits to Growth describing the 1972 world computer model by MIT researchers Meadows, Meadows, Randers, and Behrens. I am deeply impressed by the work, and I am compelled to share the most salient features in this post.

To borrow a word from a comment on the Do the Math site, I’m gobsmacked by how prescient some of the statements and reflections in the book are. Leaving aside remarkably good agreement in the anticipated world population and CO2 levels thirty years out (can’t fake this), I am amazed that many of the thoughts and conclusions I have formed over the past several years are not at all new, but were in black-and-white shortly after I was born. Continue reading →

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Garbage In, Garbage Out

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How many times have you heard it: if we could tap into the energy embedded in our copious waste streams, we could usher in a new era of energy independence—freeing ourselves of the need to support oppressive regimes who happen to sit atop the bulk of the oil reserves in the world. In fact, these sorts of claims are abundant enough to give the impression that we have a cornucopia of fresh (and sometimes not so fresh) energy solutions to pursue if we got really serious. This is a hasty and dangerous conclusion, so in this case, waste makes haste.

I consider this perceived abundance of technological solutions to be one of our worst enemies in developing sensible solutions to the coming fossil fuel energy crunch. If ideas abound, each claiming some ability to free us of foreign oil, then surely we’ve got the situation under control and don’t need to invest substantial time and energy today to solve what looks like a non-problem of tomorrow. But what if the claims are overblown, hyped, or just plain wrong? At best, this is irresponsible behavior. At worst, the resulting sense of complacency could delay substantive action to our ruin. Continue reading →

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MPG for Electric Cars?

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A typical efficient car in the U.S. market gets about 40 MPG (miles per gallon) running on gasoline. A hybrid car like the Prius typically gets 50–55 MPG. In a previous post, we looked at the physics that determines these numbers. As we see more and more plug-in hybrid or pure electric cars on the market, how do we characterize their mileage performance in comparison to gasoline cars? Do they get 100 MPG? Can they get to 200? What does it even mean to speak of MPG, when the “G” stands for gallons and a purely electric car does not ingest gallons?

This post addresses these questions. Continue reading →

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Recipe for Climate Change in Two Easy Steps

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[A considerably expanded treatment of this material appears in Chapter 9 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

Today, we’re going to make the world less comfortable, in two easy steps that each of you can do at home. Step 1 shows how easy it is to account for the carbon dioxide excess in the atmosphere based on our cumulative use of fossil fuels. Step 2 bypasses intricacies of thermal radiation to put an approximate scale on the amount of heating we would expect the excess CO2 to produce. Serves 7 billion.

Climate Change in Context

I view climate change as a genuine challenge to the stability of our coexistence with the planet. But it is not my primary concern. A far more dangerous threat to the human endeavor is, in my mind, our reliance on finite resources and the difficulty our economic systems will have coping with a decline in the availability of cheap energy. That said, the issues are closely linked—through fossil fuels—and both benefit from a drive toward renewable resources. Continue reading →

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Personal Energy Cubes

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In this post, we’ll put a physical, comprehendible scale on the amount of energy typical Americans have used in their lifetimes. No judgment: just the numbers.

The task is to estimate our personal energy volume, so that we can mentally picture cubic tanks or bins corresponding to all the oil, coal, natural gas, etc. we have used in our lives—perhaps plunked down in our backyards to bring the idea home. Go ahead and try to guess/picture how big each cube is.
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