John Michael Greer:
"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."
Four Laws of Energy Usage
The concept of infinite energy is dangerous lunacy, explains John Michael Greer:
"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 book Filters 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." (http://thearchdruidreport.blogspot.com/2010/07/ways-of-force.html)