Recently I have been preoccupied with pretty much only one thing, and I think it is genuinely the challenge of our times: energy and the environment. In engaging with this issue, you have to think about how we harness energy (energy isn’t created, but is instead converted to different forms), how we use power, and how we affect the environment. I’ve done a lot of calculations of humanity’s energy use, and how we might make renewable energy technologies that can meet that challenge, but it’s a fairly impersonal analysis.
To make it more immediate, I set about understanding my own power consumption. All of it. It turns out that this is a tremendously difficult project, even if you have a rather large resource of tools and information available to you.
The easy pieces are those that are de facto measured for you (my values in brackets):
Plane travel miles [6,375 watts, 110,000 miles]
I can check all my plane tickets for a given year, use an assumption of plane fuel consumption (like 1.4MJ/km), and average that energy over the year to get a measure of the amount of power I’m using all the time.
Car travel miles [1,491 watts, 10,000 miles]
I can keep track of my odometers in the various cars that I drive and get an accurate number of miles, and by tracking fuel consumption over a number of tankfuls, I have an accurate estimate.
Home electricity use [135 watts]
My home electricity use is conveniently reported to me by Pacific Gas & Electric in the form of my bill, so I have accurate year-round data for this.
Home gas use [597 watts]
PG&E also gives me my gas consumption in a bill. I can convert from therms to watts.
I fly a lot. I don’t drive much — when I do, it’s mostly in a hybrid. I have a small house. Your values will probably be different, but not grossly so. These simple numbers are not, in fact, perfectly simple.
Do I count the air miles against me personally or my company? Do I count half of the car miles because I generally travel with someone else? Are the house utilities equally shared by me and my partner, or does she get more because of her penchant for turning up the heat?
Where it gets really difficult, however, is in the objects that I consume. My computer took energy to make, as did my clothes and my bicycles and my DVD cases and furniture. But no simple calculations for those yield a satisfying answer. So I looked in detail at the energy consumption of a simple drink.
For irony’s sake, I chose an energy drink, but the calculation is reasonably applicable to any plastic bottled beverage. As I looked at the numbers, it was interesting to me that the drink already had an energy label, shown here, described as “nutrition facts.” This energy label is for the chemical energy contained in the bottle that my body can convert to mechanical energy to do work, like riding my bike to the office. So I took the liberty of calculating the energy footprint of that bottle, in reasonable detail, and I summarized the results in an alternative bottle label called “consumption facts.”
Let’s think about how one would go about estimating the energy consumption of one bottle.
1. There’s the energy embodied in the materials.
Embodied energy is a measure of the energy required to extract, purify, mix, and make the raw material. It is well calculated for many products. I’d have high confidence in this number.
2. There’s the energy consumed in the transportation of the object to us.
The energy consumed in transportation is a little more difficult. How many miles did it travel? How efficient was the truck/train/airplane used to transport it? For this example, I assumed a 200-mile travel distance and an average 8mpg truck fully loaded with full energy drink bottles.
3. There’s the energy used in manufacturing it.
The energy used in manufacturing is a little tricky for me to calculate. I’d like to divide the number of empty bottles emerging from the bottle factory by the energy bill of the bottle factory, but not surprisingly no one really advertises that fact. The value I used here is a bit of a wild guess, but not off by more than a factor of 10, I’d say. It is a small value compared to the other values.
4. In the case of food, there’s the energy used in its refrigeration and storage.
Finally, for the refrigeration of this product I took a shot in the dark. In the real world, this value should be a measure of the number of times it’s cooled, warmed, and recooled, as well as the efficiency of the refrigerators, and the number of days spent on the refrigerator shelf. Again, I used a guess-like value, for illustration.
Those are the easy things to calculate. Harder things to add to the calculation would include the energy to run the computers of the workers in the company that produced the bottle, or the energy for the fluorescent lights in the retailer’s shop.
Harder still are the negative effects of the nonenergy, noneconomic factors of the product, like the aesthetic pollution they cause if washed up on beaches, or the health effects of toxic components like the plasticizers. This ethical calculus is very poorly developed, and in my mind one of the most important, difficult, and interesting areas of study in our times. If you’re a student of economics, ethics, or philosophy, this is the frontier.
What comes out of the analysis? Given my confidence in the embodied energy value, I can definitely say that a lower bound for the individual bottle of 5 million joules (MJ) and an upper bound estimate of 8MJ are reasonable.
That’s the energy value; so how did I use this in the calculation of my daily allowance? Humanity currently uses around 15 terawatts (TW) of power. Watts are a rate, that is, an amount of power being consumed all the time: 100 joules consumed each second equals 100 watts.
Undoubtably, 15TW is a lot of power. It’s hard to get an accurate figure, but to level off our CO2 emissions to prevent global warming, we probably can only afford to make 2TW of that power with carbon-based fuels. The other 13TW would need to come from nuclear power and renewable sources that collectively produce barely 1.5TW right now.
There are 6.65 billion people on the planet. If you take the bold assumption that they all deserve an equal measure of the Earth’s power resources, that would be 15×1012 / 6.65×109 = 2,255 watts each. The average American already uses more than 10,000 watts. I’m going to use 2,000 watts as your average daily allowance for two reasons: 1) It sounds fair. 2) It sounds familiar; we should consume a roughly 2,000-calorie diet to be healthy.
There are 60×60×24 = 86,400 seconds in a day.
That means on the day you drink this bottle of energy drink, you are using about 90W. That’s right, drinking that single bottle and disposing of it is like keeping an old incandescent light bulb on all day.
If you drink a bottle every day, it’s like you have your own personal light bulb following you around — always. Illuminating, eh? And I didn’t even count the energy required to make the drink inside!
So why didn’t I use carbon footprint as a measure?
Well, CO2 is sort of the enemy here, but it’s the secondary effect caused by our lifestyles. If you calculate in terms of CO2, it’s tempting to believe you can “offset” that carbon by planting a tree. That might be true in the far future when carbon programs are well-managed and stable, but there’s no guarantee that the tree you plant today will last forever and not simply return that CO2 to the atmosphere when it dies. I prefer to measure our impact in SI units (International System of Units), because there can be nothing ambiguous about the results.
Every act of consumption we engage in has consequences — consequences that are not very visible to us. We aren’t presented with the ramifications when we purchase the product, we don’t see the direct repercussions of the single act, and our only way of seeing the end result is by abstract association with headlines like “Polar Bears Dying for Lack of Ice,” or “Dolphins Choking on Plastic in the Pacific.” I suspect we’d act a little better if we knew the consequences of our actions at the point of purchase. Here’s an attempt to kick us off in that direction. Perhaps one day all products will sport both labels: nutrition facts and consumption facts.
Why would I want to bring this up in MAKE magazine? Partly because the solutions we seek are, in essence, engineering problems, and we need you to go out and start solving those problems. But also because when I think about the future, it doesn’t look so good unless we change the way we generate and consume power. This will require everyone to change the way they do pretty much everything — and that’s the good option. The bad scenario is that we don’t change much, we kill all the supporting ecosystems, and descend into a future that makes Tank Girl look like a fairyland paradise.
And finally, because it seems to me that buried in the maker ethos is a fundamental part of the solution. Makers reuse things. Makers repurpose things. Makers repair things. I will bet that a handmade table built to last 200 years has an energy label not much different from an IKEA table built to last 7 years — except for the fact that you can amortize that energy over a time period almost 30 times as long. That means it effectively uses 1/ 30th of the energy.
High-quality things that are appreciated, repaired, and handmade become an important part of your life. My hope for a more beautiful future is that we will have fewer things pass through our lives, of higher quality, and love them more.
So go energize yourself by making an heirloom-quality, reusable water jug.
If you’re interested in learning more, I recently gave an extended talk on this subject at O’Reilly’s ETech conference, and the slides and accompanying text are available at wattzon.com.
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