The Ways Of The Force

By now those of my readers who have joined me on the current 

 project – the creation of a “green wizardry” using the heritage of the appropriate technology movement of the Seventies – should have downloaded at least one of their textbooks and either have, or be waiting for the imminent arrival of, the rest. Now it’s time to get into the core principles of green wizardry, and the best way to do it involves shifting archetypes a bit. Give me a moment to slip on a brown robe, tuck something less clumsy or random than a blaster into my belt, and practice my best Alec Guinness imitation: yes, Padawans, you’re about to start learning the ways of the Force.

Well, almost. The concept that George Lucas borrowed from Asian mysticism for his Star Wars movies is an extraordinarily widespread and ancient one; very nearly the only languages on earth that don’t have a commonly used word for an intangible life force connected to the breath are those spoken nowadays in the industrial nations of the modern West. I’ll leave it to my readers to make up their own minds about what the remarkable durability of this idea might imply, and to historians of ideas to debate whether it was one of the sources that helped shape the modern scientific concept of energy; the point that needs making is that it’s this latter concept that will be central to this week’s post.

That’s understating things by more than a little. Everything we’ll be exploring over the weeks and months to come has to do with energy: where it comes from, what it can and can’t do, how it moves through whole systems, and where it goes. In the most pragmatic of senses, understand energy and you understand the whole art of green wizardry; in the broadest of senses, understand energy and you understand the predicament that is looming up like a wave in front of the world’s industrial societies, and what we can and can’t expect to get done in the relatively short time we have left before that predicament crests, breaks, and washes most of the modern world’s certainties away.

Let’s start with some basic definitions. Energy is the capacity to do work. It cannot be created or destroyed, but the amount and kind of work it can do can change. The more concentrated it is, the more work it can do; the more diffuse it is, the less work it can do. Left to itself, it moves from more concentrated to more diffuse forms over time, and everything you do with energy has a price tag measured in a loss of concentration. These are the groundrules of thermodynamics, and everything a green wizard does comes back to them in one way or another.

Let’s look at some examples. A garden bed, to begin with, is a device for collecting energy from the sun by way of the elegant biochemical dance of photosynthesis. Follow a ray of sunlight from the thermonuclear cauldron of the sun, across 93 million miles of hard vacuum and a few dozen miles of atmosphere, until it falls on the garden bed. Around half the sunlight reflects off the plants, which is why the leaves look bright green to you instead of flat black; most of the rest is used by the plants to draw water up from the ground into their stems and leaves, and expel it into the air; a few per cent is caught by chloroplasts – tiny green disks inside the cells of every green plant, descended from blue-green algae that were engulfed but not destroyed by some ancestral single-celled plant maybe two billion years ago – and used to turn water and carbon dioxide into sugars, which are rich in chemical energy and power the complex cascade of processes we call life.

Most of those sugars are used up keeping the plant alive. The rest are stored up until some animal eats the plant. Most of the energy in the plants the animal eats gets used up keeping the animal alive; the rest get stored up, until another animal eats the first animal, and the process repeats. Sooner or later an animal manages to die without ending up in somebody else’s stomach, and its body becomes a lunch counter for all the creatures – and there are a lot of them – that make their livings by cleaning up dead things. By the time they’re finished with their work, the last of the energy from the original beam of sunlight that fell on the garden bed is gone.

Where does it go? Diffuse background heat. That’s the elephant’s graveyard of thermodynamics, the place energy goes to die. Most often, when you do anything with energy – concentrate it, move it, change its form – the price for that gets paid in low-grade heat. All along the chain from the sunlight first hitting the leaf to the last bacterium munching on the last scrap of dead coyote, what isn’t passed onward in the form of stored chemical energy is turned directly or indirectly into heat so diffuse that it can’t be made to do any work other than jiggling molecules a little. The metabolism of the plant generates a trickle of heat; the friction of the beetle’s legs on the leaf generates a tiny pulse of heat; the mouse, the snake, and the coyote all turn most of the energy they take in into heat, and all that heat radiates out into the great outdoors, warming the atmosphere by a tiny fraction of a degree, and slowly spreading up and out into the ultimate heat sink of deep space.

That’s the first example. For the second, let’s take a solar water heater, the simple kind that’s basically a tank in a glassed-in enclosure set on top of somebody’s roof. Once again we start with a ray of sunlight crossing deep space and Earth’s murky atmosphere to get to its unintended target. The sun passes through the glass and slams into the black metal of the water tank, giving up much of its energy to the metal in the form of heat. Inside the metal is water, maybe fifty gallons of it; it takes a fair amount of heat to bring fifty gallons of water to the temperature of a good hot bath, but the steady pounding of photons from the sun against the black metal tank will do the trick in a few hours.

Most of what makes building a solar water heater complex is a matter of keeping that heat in the water where it belongs, instead of letting it leak out as – you guessed it – diffuse background heat. The glass in front of the tank is there to keep moving air from carrying heat away, and it also helps hold heat in by way of a clever bit of physics: most of the energy that matter absorbs from visible light downshifts to infrared light as it tries to escape, and glass lets visible light pass through it but reflects infrared back the way it came. (This is known as the greenhouse effect, by the way, and we’ll be using it over and over again, not least in greenhouses.) All surfaces of the tank that aren’t facing the sun are surrounded by insulation, which also helps keep heat from sneaking away. If the system’s a good one, the pipes that carry hot water down from the heater to the bathtub and other uses are wrapped with insulation. Even so, some of the energy slips out from the tank, some of it makes a break for it through the insulation around the pipes, and the rest of it starts becoming background heat the moment it leaves the faucet for the bathtub or any other use.

Here’s a third example: a house on a cold winter day. The furnace keeping it warm, let’s say, is fueled by natural gas; that means the ray of sunlight that ultimately powers the process came to Earth millions of years ago and was absorbed by a prehistoric plant. The plant died without being munched by a passing dinosaur, and got buried under sediment with some of its stored energy intact. Millions of years of heat and pressure underground turned that stored energy into very simple hydrocarbons such as methane and ethane. Fast forward to 2010, when the hydrocarbons found their way through pores in the rock to a natural gas well and got shipped by pipeline, possibly over thousands of miles, to the house where it gets burnt.

The furnace turns the energy of that ancient sunlight to relatively concentrated heat, which flows out through the house, keeping it warm. Now the fun begins, because that concentrated energy – to put things in anthropomorphic terms – wants nothing in the world half as much as to fling itself ecstatically into dissolution as diffuse background heat. The more quickly it can do that, though, the more natural gas has to be burnt to keep the house at a comfortable temperature. If you’re the green wizard in charge, your goal is to slow down the dionysiac rush of seeking its bliss, and make it hang around long enough to warm the house.

How do you do that? First, you have to know the ways that heat moves from a warm body to a cold one. There are three of them: conduction, which is the movement of heat through solid matter; convection, which is the movement of heat carried on currents of air (or any other fluid); and radiation, which is the movement of heat in the form of infrared light (mostly) through any medium transparent to those wavelengths. You slow down conduction to a crawl by putting insulation in the way; you slow down convection by sealing up cracks through which air can move, and doing a variety of things to stop convective currents from forming; you slow down radiation by putting reflective barriers in the way of its escape. If you don’t do any of these things, your house leaks heat, and your checking account leaks money ; if you do all of these things – and they can be done fairly easily and cheaply – the prehistoric sunlight in the natural gas you burn has to take its time wandering out of your house, keeps you comfortable on the way, and you don’t have to spend anything like so much on more natural gas to replace it.

There are four points I’d like you to take home from these examples. The first is that they’re all talking about the same process – the movement of energy from the sun to the background radiation of outer space that passes through systems here on earth en route, and accomplishes certain kinds of work on the way. At this point, in fact, the most useful thing you can take away from this entire discussion is the habit of looking everything that goes on around you as an energy flow that starts from a concentrated source – almost always the sun – and ends in diffuse heat radiating out into space. If you pick up the habit of doing this, you’ll find that a great deal of the material that will be covered in posts to come will suddenly seem like common sense, and a great many of the habits that have are treated as normal behavior in our society will suddenly reveal themselves as stark staring lunacy.

An exercise, which I’d like to ask those readers studying this material to do several times over the next week, will help get this habit in place. Draw a rough flow chart for one or more versions of this process. Take a piece of paper, draw a picture of the sun at the top, and draw a trash can at the bottom; label the trash can “Background Heat.” Now draw the important components in any system you want to understand, and draw arrows connecting them to show how the energy moves from one component to another. If you’re sketching a natural system, draw in the plants, the herbivores, the carnivores, and the decomposers, and sketch in how energy passes from one to another, and from each of them to the trash can; if you’re sketching a human system, the energy source, the machine that turns the energy into a useful form, and the places where the energy goes all need to be marked in and connected. Do this with a variety of different systems. It doesn’t matter at this stage if you get all the details right; the important thing is to start thinking in terms of energy flow.

The second point to take home is that natural systems, having had much more time to work the bugs out, are much better at containing and using energy than most human systems are. The solar water heater and the house with its natural gas furnace take concentrated energy, put it to one use, and then lose it to diffuse heat. A natural ecosystem, by contrast, can play hot potato with its own input of concentrated energy for a much more extended period, tossing it from hand to hand (or, rather, leaf to paw to bacterial pseudopod) for quite a while before all of the energy finally follows its bliss. The lesson here is simple: by paying attention to the ways that natural systems do this, green wizards can get hints that can be incorporated into human systems to make them less wasteful and more resilient.

The third point is that energy does not move in circles. Next week we’ll be talking about material substances, which do follow circular paths – in fact, they do this whether we want them to do so or not, which is why the toxic waste we dump into the environment, for example, ends up circling back around into our food and water supply. Energy, though, moves along a trajectory with a beginning and an end. The beginning is always a concentrated source, which again is almost always the sun; the end is diffuse heat. Conceptually, you can think of energy as moving in straight lines, cutting across the circles of matter and the far more complex patterns of information gain and loss. Once a given amount of energy has followed its trajectory to the endpoint, for all practical purposes, it’s gone; it still exists, but the only work it’s capable of doing is making molecules vibrate at whatever the ambient temperature happens to be.

The fourth and final point, which follows from the third, is that for all practical purposes, energy is finite. It’s become tolerably common for believers in perpetual technological progress and economic growth to insist that energy is infinite, with the implication that human beings can up and walk off with as much of it as they wish. It’s an appealing fantasy, flattering to our collective ego, and it makes use of a particular kind of mental trap that Garrett Hardin anatomized quite a while ago. In his useful bookFilters Against Folly, Hardin pointed out that the word “infinite” – along with such synonyms as “limitless” and “boundless” – are thoughtstoppers rather than meaningful concepts, because the human mind can’t actually think about infinity in any meaningful sense. When somebody says “X is infinite,” in other words, what he is actually saying is “I refuse to think about X.”

Still, there’s a more specific sense in which talk about infinite energy is nonsense by definition. At any given place and time, the amount of energy that is available in a concentration and a form capable of doing any particular kind of work is finite, often distressingly so. Every ecosystem on earth has evolved to make the most of whatever energy is available to do the work of keeping living things alive, whether that energy takes the form of equatorial sunlight shining down on the Amazon rain forest, chemical energy in sulfur-laden water surging up from hot springs at the bottom of the sea, or fat stored up during the brief Arctic warm season in the bodies of the caribou that attract the attention of a hungry wolf pack.

Thus it’s crucial to recognize that available energy is always limited, and usually needs to be carefully coaxed into doing as much work as you want to get done before the energy turns into diffuse background heat. This is as true of any whole system, a garden as much as a solar hot water system, a well-insulated house, or any other project belonging to the field of appropriate tech. Learn to think in these terms and you’re well on your way to becoming a green wizard.