Category Archives: Environment

A Hairy Proposition

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Teenager invents £23 solar panel that could be solution to developing world’s energy needs … made from human hair

Color me skeptical. The story, of course, is very skimpy on the science, but let’s look at this. The claim of “9 V (18 W)” is really hard to believe, because P=IV means 2 A of current flowing through the hair, though that will be divided up. Still, the diameter of a hair is thinner than AWG 32 wire (at about 200 microns), which has a current limit of less than 0.1 A for power transmission, and that’s for a good conductor. Hair? Not so much. The pictures show a grid of interconnected hair, which doesn’t have all that much area, so capturing any more than a small fraction of the few hundred W/m^2 of insolation is not in the cards. A 20 x 20 grid at less than 0.2mm per hair is just a few square mm of hair — it can only get you a fraction of a Watt.

Question: why don’t we have our hair generating electricity like this while it’s attached to our heads?

At best, somebody dropped a prefix representing several orders of magnitude somewhere. At worst it’s a scam.

Not 'Ha Ha' Funny

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Ozone threat is no laughing matter

Nitrous oxide (N2O) has become the greatest threat to the ozone layer, a new analysis suggests. The ozone-destroying abilities of the gas have been largely ignored by policy-makers and atmospheric scientists alike, who have focused on the more potent chlorofluorocarbons (CFCs) — historically the dominant ozone-depleting substances in the atmosphere.

I Object

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U.S. Chamber of Commerce seeks trial on global warming

The U.S. Chamber of Commerce, trying to ward off potentially sweeping federal emissions regulations, is pushing the Environmental Protection Agency to hold a rare public hearing on the scientific evidence for man-made climate change.

Chamber officials say it would be “the Scopes monkey trial of the 21st century” — complete with witnesses, cross-examinations and a judge who would rule, essentially, on whether humans are warming the planet to dangerous effect.

What a bad idea for science.

This doesn’t bring the Scopes trial to my mind, as mentioned in the article — that wasn’t primarily about whether evolution was valid science. This is more like the story of how the Indiana House once unanimously passed a bill to make pi a rational number (3.2; the bill died in the senate). Our legal system doesn’t get to decide what is sound science or not; if it attempts to make such a decision, mother nature won’t care at all and won’t serve any contempt-of-court sentence for disobeying the judge.

The legal system doesn’t argue the same way that science does, which is why this is a common tactic for anti-scientists. Creationists putting Darwinism “on trial” in literature is not uncommon. The absurdity of calling evolution “Darwinism” aside for the moment, these “trials” include appeals to ridicule that might sound convincing to some, because there is much about science that isn’t intuitive. In physics, one could probably convince a lay person that quantum mechanics and relativity are wrong using a legal style of argument, just by pointing out some of the counterintuitive, nonclassical (or non-Galilean) aspects (A single particle goes through both slits? Absurd! Twins can age at different rates? Preposterous!) But QM and relativity are true, regardless of how much they contradict classical experience.

It can’t merely be lining up experts, either, because there is no science so well-established that you can’t find a somebody, somewhere, who has a degree and disagrees with the mainstream. There are physicists who disagree with QM and relativity, just as there are biologists who are creationists (or cdesign proponentsists). The bench isn’t very deep of course (there are more biologists named Steve who agree that evolution is true than all who are touted to disagree), but they are out there. What matters is the empirical evidence, and the people best qualified to tell us this are the scientists who do the kind of work in question, not a judge. True, the judge might/should rule in favor of the scientists in this kind of case, but if he didn’t, that wouldn’t change the fact that smoking causes cancer, evolution is true, photons interfere with themselves, pi is irrational and humans are causing global warming. That’s what the evidence tells us.

Energy: It's Nothing to Snicker At

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Of Car Crashes and Snickers Bars

Pop quiz, hotshot. Using the caloric energy content of a candy bar (e.g. Snickers, at 250 food calories), what is the kinetic energy of a two-ton behemoth SUV traveling at about 70 mph? A first-order approximation is fine — no need to worry about more than one significant digit.

Got it? Think of your number and then proceed to the analysis.
Continue reading →

Cash for Thermodynamic Clunkers

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Refrigerator Recycling Programs Take Off

The recent flurry of new programs in New England stems in part from the recent introducton of the Regional Greenhouse Gas Initiative, a Northeastern program that caps greenhouse gas emissions in an effort to combat climate change, as well as from energy efficiency initiatives in individual states, according to Mr. Sirkin.

Utilities commonly estimate that homeowners can save up to $150 a year on their electricity bill by dumping their old refrigerator or freezer. Old refrigerators, made prior to 1990, also use three times as much electricity as new ones, the utilities say. In addition, refrigerators made before the mid-1990s may also emit ozone-depleting chlorofluorocarbons.

Is it Really Green?

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Sainsbury’s brings green power to the checkout with ‘kinetic plates’

Energy will be captured every time a vehicle drives over “kinetic road plates” in the car park and then channelled back into the store.

The kinetic road plates are expected to produce 30 kWh of green energy every hour — more than enough energy to power the store’s checkouts. The system, pioneered for Sainsbury’s by Peter Hughes of Highway Energy Systems, does not affect the car or fuel efficiency, and drivers feel no disturbance as they drive over the plates.

My first reaction is that somebody apparently thinks they can violate the first law of thermodynamics. If the energy comes from the car, then it will necessarily affect the car — it will slow it down. Now, this makes sense if you install it where the car was going to slow down anyway, like an approach to a stop sign. But not if the car is going to want to maintain speed, or if the slowdown/stopping is unnecessary.

Sincerely sustainable contains a quote which implies that these are being used as speed bumps. But harvesting energy from speed bumps is only green in a very abstract way, since the car is going to speed up again once past it — you’d be greener by not having the speed bumps there at all, which is one reason why you get better mileage on the highway — you eliminate those stops and starts. A car that is already going the desired speed is going to surrender energy to the device and slow down even though it didn’t need to. Green-wise, you’d be better served with an improved design of the traffic flow. (They also claim that they will generate 30 kW of electricity every hour, when they mean 30 kWh. Call the unit police.)

What they are doing is getting the customers to pay for some of their electricity.

Another example of this appears in Cocktail Party Physics : body heat (spoiler: it stars neither Kathleen Turner nor William Hurt)

Boesel has retrofitted much of his exercise equipment (stationary bikes, treadmills, elliptical machines) so that gym members can produce a little bit of usable energy during their workouts — not a lot, mind you, but enough to run the fans, for example, or the stereo system. Combine that with other strategies for improving energy efficiency, and Boege keeps his electricity costs to a bare minimum. In time, he thinks he can break even, and maybe even turn a small profit.

Tapping the energy from the exercise equipment is a fine goal for the owner, but calling it green is another thing. It’s being powered by the food we eat, via our physical exertion, and that means you have to look at the energy used to bring that food to the table. Dollars to donuts (or tofu) that energy is not green — the delivery trucks run on gas or diesel, the water may be bottled, etc. So once again, the circumstances matter. If you’re recovering otherwise wasted energy, fine, but don’t get on the treadmill for the purpose of generating energy. If someone needs to consume an extra few calories so they can go work out, they’ve basically become a very inefficient battery, and the energy they generate isn’t green. Much like the regenerative braking on Jennifer’s Prius: if you drive around the block, stopping and starting, in order to charge up the battery, then energy will have come from the gasoline.

I noticed the phrase “judicious use of the A/C.” If that means making the patrons sweat some more, there’s the cost of un-doing the dehydration. As I noted in my inaugural post, excess sweat is wasted, from a thermodynamic standpoint, and if you’re drinking bottled water, that’s one more consideration of how green this strategy is.

(and Jennifer also finds herself under investigation by the unit cops, for using “Watts per hour”)

This is reminiscent of the hydrogen economy that was touted a few years back, but about which we haven’t heard much lately. Why? One reason is that it’s not green, It sounds green, but that’s just because you’ve slapped a green-label veneer on something, but when you peel back that layer you find some very un-green components. When all is said and done, this is a little like money laundering — you’re just making it harder to trace the true source.

But there is a true source. The energy we use on this planet ultimately comes from one of two places: the sun, or radioactive materials leftover from the planet’s formation (which came from another sun). You have to trace your generation back to one of those, somehow. If that audit hits a “fossil fuel” source at any point, then your source isn’t green (assuming “green” here refers to sources that do not include sequestered Carbon). Anything involving food runs into issues of fertilization and transportation — even driving to the store to buy it — and packaging, all of which typically involve unsavory sources of energy from a “green” perspective.

So my objection is this: using “Green” makes it sound like you are having no or minimal impact on the environment, and it can be misleading. It can make you focus on a very small reduction in emissions, while distracting from the very large amount that’s already there, and other much more significant improvements that could be made. Be a little skeptical of the users of “Green” and its synonyms, because they may just be feeding you an advertising gimmick.

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Update (more space here than in the comments section. It’s good to be the king):

I don’t necessarily disagree with the comments from BlackGriffen and Jennifer — as I said, harnessing otherwise wasted energy is fine. But consider this scenario:

Someone (Not Jennifer, because I never meant to pick on her) is very impressed by such a gym that she decides to join up, and figures, “What the heck, it’s only a half mile out of my way on my commute. Just an extra mile round trip!” Now, Not Jennifer is a beast in the gym and works out for two hours a day and can manage 100W that whole time (along with 100% efficiency), and works out 25 days a month. That’s 200Whr x 25 = 5kWh of electricity generated (saving the gym owner perhaps 50 cents). And it’s only a mile extra on the commute, so that’s 25 miles of driving, and Not Jennifer drives a Prius, too, so that’s only a half gallon of gas a month. Unfortunately a gallon of gas contains more than 30 kWh of energy. So we’ve traded in excess of 15 kWh of fossil fuel for 5 kWh of human-generated energy in this (admittedly contrived, but certainly plausible) scenario.

That’s my worry — that things like this will happen, because the whole picture isn’t being considered. Yes, education is important. Human power is pretty feeble compared to the machines we have around us, which is why we have them around us. But I have trepidation about tagging things as “green” that may not be, and may not only foster a sense of community but a sense of “I’ve done my part” when that’s not really the case.

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Update II: Some numbers at Dot Physics and Hamiltonian Function for kinetic plates and humans, respectively.

A Lesson in the Scientific Method

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This has it all. A scientist, working on his own, discovering something new (and useful) using proper scientific methodology … and he’s in high school. WCI student isolates microbe that lunches on plastic bags

First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.

After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.

Six weeks later, he weighed the strips of plastic. The control strips were the same. But the ones that had been in the live bacterial culture weighed an average of 17 per cent less.

That wasn’t good enough for Burd. To identify the bacteria in his culture, he let them grow on agar plates and found he had four types of microbes. He tested those on more plastic strips and found only the second was capable of significant plastic degradation.

Oh, and yes, he won the top prize at the science fair.