No, no, the cart goes before the horse.
One day during an otherwise-normal day at school a group of alien ships appeared in the sky overhead. They proceeded to teleport all the students in your academic year aboard with only the items in your laps and the clothes on your back. They then carried you all to a distant Earth-like but uninhabited planet and deposited you on its surface, only with those items mentioned earlier. They then explained that they were representatives of a galactic federation and this was a test of mankind's fitness to join. You have been given ten years to construct a society and, at the end of those ten years, the aliens will return and judge the results. If the results are judged favorably, Earth will be welcomed into the galatic community and you will return home in triumph. If the results are judged unfavorably, you will return in disgrace and humans will be prevented from leaving their own solar system for at least the next 1,000 years.
This was, to put it mildly, an unexpected task for an English class. It was also right up my alley, seeing as how I was, even then, a long-time science fiction fan. It was thus with great pleasure that I joined with my group to produce a brave new world. Therefore, when the first argument was made for our new society, my despair was all the more acute. One of my well-meaning but (let's be honest) foolish group members asserted with unshakable conviction, "The first thing we need to do is make laws to protect the environment!"
"What? We need to do what first? Make laws to protect the environment?" I responded, "There are only a few hundred of us. If we made it our main goal for the next ten years, there aren't enough of us to do appreciable harm to a planetary environment! Don't you think we should concentrate our attention on something more immediate? Like obtaining food, water, shelter, and arranging an equitable distribution of same?"**
The answer, as you might guess, was "no." Apparently protecting the environment was more important than ensuring that we survived at something above starvation level. In retrospect I suppose this might have been a cunning plan to protect the environment by ensuring the extinction of homo sapiens sapiens on this world before we could cause harm, but I think that's being too generous. In truth, I think this person was just so immensely foolish, despite her good intentions, that she overlooked the practical dilemma inherent in her lofty objectives. This is, to be honest, a problem I've noticed since then in academia, but I digress.
This incident was very disappointing to me at the time, and has always stood out in my mind as an example of missing the obvious problems in your haste to do "the right thing." As such, it's been on my mind rather a lot lately. Recently my Sainted Girlfriend recounted a story of a trip taken with some members of her church youth group. On this trip one of her friends commented that it would be great if auto manufacturers were to add devices to cars that could harvest the energy from the outside airflow and use it to charge a battery. This "innovation" would make the care more environmentally friendly by converting it into a hybrid electric vehicle.
Now, some of you already know where I'm going with this because... well... you know me. In short, my first thought was that someone had independently replicated the work of inventor extraordinaire, and obvious lunatic, Greg Buell.*** Specifcally, this was an independent replication of his revolutionary electric windmill car. Below is an artist's concept that I have blatantly stolen from the Greg Buell Fan Club:
Having thusly recognized Greg's priority in this venture, I then proceeded to the next logical step which is, put simply, to point out that actually building such a vehicle would be a really bad idea. I've explained why this is before but, as there are apparently a large number of people who still don't get it, we're going to do this again. Here's why putting a windmill, or wind turbine, or whatever you want to call it on a car is not a sure route to environmentally-friendly land.
Okay, let's start with something simple: like a regular windmill used for the generation of electrical power. Now, in this case, the motion of the blades drives a generator which produces electricity. This is simple, so let's make it a little more complex: where does the energy come from to drive the blades? I mean, the blades don't turn themselves, right? Well, it's called a windmill, so I'm hoping the answer is pretty obvious here. The motion of the wind drives the blades around, which drives the turbine and generates electricity. Perhaps more important for our purposes, a certain amount of energy is transferred from the moving air we know as "wind" to the stationary windmill and thus the wind slows down slightly**** as the blades are accelerated. This process is fairly well covered by a little something known as thermodynamics. Taken a step further, let me ask where does the wind get its energy from? The answer, of course, is our old friend, that gigantic fusion reactor in the sky: the sun. The heat of the sun adds energy to the Earth which, due to differential rates of heating and cooling in different materials, and the rotation of the Earth, produces currents of air that we know as wind. So, ultimately, a windmill is just an oblique way of harvesting solar energy. Everyone with me?
Okay, now let's consider our "electric windmill car." Now, when a car is moving is there airflow over it? The answer, of course, is yes: because the car is moving through an atmosphere, that atmosphere is flowing over it. To the car's occupants, who are stationary with reference to the car, it may seem like there is a strong wind blowing outside. However, from an external frame of reference (say a pedestrian) it is not the air that is moving rapidly, but rather the car moving quickly through a stationary mass of air. Now, given this, we need to ask the same questions about our car-mounted windmill that we asked about our stationary windmill. What drives the blades? Well, the same thing: moving air. In this case, however, it isn't the air that is moving, but rather the windmill itself. The situations are, at this level, equivalent. But let's back it up a smidge. Where does the windmill get its energy from? Well, since the air isn't moving, it effectively means that the windmill on our car cannot be harvesting energy from the air. So, if the energy isn't coming from the air, where is it coming from?
Right- it's coming from the moving car. The windmill, rather than converting the kinetic energy of the wind into electrical energy is converting the kinetic energy of the car into electrical energy. And, just as the stationary windmill slows the wind, the windmill on the car must slow the car down. Let me emphasize that again: if there is a mechanism extracting energy from the airflow, it must result in a slowing of the vehicle. Everyone still with me? Okay, now here's the kicker: where does the car's kinetic energy come from? Well, in the case of our stationary windmill it came from a clean, renewable source: the sun. In this case, however, cars do not move at high speeds because of the sun, but rather because they burn fossil fuels. What this all means is that, put simply, the energy that the windmill recovers from the airstream was, originally, generated by burning irreplaceable and polluting fuels. More importantly since we aren't just accelerating the windmill, but also the car it's mounted on, we must spend more energy in the form of gas than we recover from the windmill in the form of electricity even if every part of the system is 100% efficient. Since no mechanical system is 100% efficient (due to a little thing called "friction") what this boils down to is that any car with such a windmill will burn more fuel than an identical car without one, and the energy we recover from said windmill will not offset the extra fuel consumed. Putting such a device on a car would make it less environmentally friendly, rather than more.*****
What this all means is simple: something that sounds like a really good idea- using a wind turbine to harvest energy from the wind outside a car- ultimately may result in exactly the opposite of what is intended. In a very real way we would make things worse by persuing such a course of action.
And this takes us back to the beginning of this post: we all have lofty goals that we would like to achieve. I, like many others, would like to see our natural environment preserved, and our resources used responsibly. What that requires, however, is not a mass of good intentions and activism, but a thorough understanding of the world- a comprehension of our options as well as our constraints- and cool consideration of how best to get what we want. This may be a little less satisfying on a visceral level, but it has the compensatoy benefit of actually allowing us to achieve our goals. For me, that more than offsets the drawbacks of careful thought. Preserve those good intentions, husband those lofty goals, but temper them with reason and pragmatism.
Because otherwise, you may end up with exactly the opposite of what you want.
For those who are curious, and as we've discussed previously, pure electric cars are also worse for the environment than their gas-drinking cousins.
* As a side note: google images produces a rather hilarious set of returns when you use "Days of Yore" as the search term. In one or another case they entirely defy explanation.
** Yes, I really did talk like this from time to time. As you might guess, I didn't have a lot of sex in high school.
*** Please note that this is an entirely different Greg Buell.
**** As another side note: before you advocate mass production of windmills to meet our energy needs, maybe consider the potential effects on weather that a large-scale reduction in global airflow might have.
***** This is not the case with regenerative braking which harvests energy as electricity that would otherwise be lost to us as heat.