## Archive for the 'Environment' Category

### Nothing New Under the Sun

Energy-Harvesting Street Tiles Generate Power from Pavement Pounder

The marathon runners generated 4.7 kilowatt-hours of energy

That’s a little more than fifty cents’ worth of electricity

I’ve already commented on this system, but I’ll sum up:

- It’s converting roughly a dollar’s worth of food into a penny’s worth of electricity. If they weren’t stealing the energy from people, this would never save anyone any money.

- The energy they steal is not green, so this energy is not, despite the effort to “launder” it.

- It’s still not clear how long it would take to save enough to pay for such a system

### A Liter of Light

An Innovative and Cheap ‘Solar Bottle Bulb’ Solution Lights Homes in Manila

This is a really neat solution to the problem of dwellings that could really use passive light; it’s not truly an alternative to something like the gravitylight , which is not passive, but for closely-spaced dwellings that don’t have much in the way of window real estate relative to the interior area, and lack (affordable) electricity, it’s just the ticket to light them up during the day.

This is a kind of light pipe (one version of which is a deck prism seen on some boats). I have to think something like this would have been useful for a playhouse when I was a kid. Some more detailed instructions exist, if you are inclined to employ on of these.

### I Am Killing the Planet with my Christmas Spirit

Dot Physics: How Much Does It Cost to Power Your Christmas Lights?

Rhett also analyzes the Griswold house’s consumption from Christmas Vacation, with its over-exaggerated decoration and also set in an era when the tree lighting was less efficient.

### As Old as Methuselah

The vanishing groves

Bristlecone pines, dendrochronology, and climate change.

The chronology tells a familiar tale about what is happening to the Earth’s climate. In 2005, a researcher from Arizona’s tree-ring lab named Matthew Salzer noticed an unusual trend in the most recent stretch of bristlecone tree rings. Over the past half century, bristlecones near the tree line have grown faster than in any 50-year period of the past 3,700 years, a shift that portends ‘an environmental change unprecedented in millennia,’ according to Salzer. As temperatures along the peaks warm, the bristlecones are fattening up, adding thick rings in every spring season. Initially there was hope that the trend was local to the White Mountains, but Salzer and his colleagues have found the same string of fat rings — the same warming — in three separate bristlecone habitats in the western US. This might sound like good news for the trees, but it most assuredly is not. Indeed, the thick new rings might be a prophecy of sorts, a foretelling of the trees’ extinction.

### That’s a Big Twinkie

I’ve been reading about some people expressing frustration that they are still in a bad way after hurricane Sandy — no power, long lines for gasoline, etc. Yes, it’s tough and you have my sympathy and empathy (90 hours without power this summer after being hit with a derecho gives me an inkling of the troubles)

But this was no small thing. The NOAA website discusses the energy released in a hurricane

It turns out that the vast majority of the heat released in the condensation process is used to cause rising motions in the thunderstorms and only a small portion drives the storm’s horizontal winds.

A typical hurricane releases an average of 6 x 10^14 Watts of power — it’ll be higher where there is more rainfall — which is 200 times the electrical energy generation in the world. The wind energy is a fraction of a percent of that, but is still half the world’s electricity generation level. And Sandy was bigger, so the numbers will be higher. All of that, focused on the mid-Atlantic/Northeast coastal areas.

The point is that there was a lot of fury unleashed last week, and it takes some time to recover from that. Gasoline in short supply indicates some of the logistical problems going on. A lot of people, requiring a lot of energy, all of it needing to be imported somehow. All of the behind-the-scenes things we take for granted, until a disruption occurs.

### That Other Steroid Problem

It’s Global Warming, Stupid

An unscientific survey of the social networking literature on Sandy reveals an illuminating tweet (you read that correctly) from Jonathan Foley, director of the Institute on the Environment at the University of Minnesota. On Oct. 29, Foley thumbed thusly: “Would this kind of storm happen without climate change? Yes. Fueled by many factors. Is storm stronger because of climate change? Yes.” Eric Pooley, senior vice president of the Environmental Defense Fund (and former deputy editor of Bloomberg Businessweek), offers a baseball analogy: “We can’t say that steroids caused any one home run by Barry Bonds, but steroids sure helped him hit more and hit them farther. Now we have weather on steroids.”

### Tesla, the Car, Takes a Step in the Right Direction

Tesla ‘superchargers’ up the ante for green technologies

Constructing green charging stations is a step in the right direction, but this is a hard problem. I think one of the problems is that we don’t appreciate the scale of the problem of refueling infrastructure. Part of this is because there’s been a century of build-out for support of internal combustion engines, and this is an attempt to hit a critical mass in a much shorter time.

The Tesla supercharger stations have a transfer capacity of 100 kW and shoot for a 30 minute turnaround, which is supposed to provide 3 hours of driving. That’s 180 MJ of energy (50 kWh). How does it compare to gasoline? Gas contains around 132 MJ per gallon, and the EPA allows gasoline pumps to transfer no more than 10 gallons per minute, which gives us a transfer rate of 22 MegaWatts, though actual pumping speeds, and thus rates, are likely somewhat smaller. Still, 10-15 MW is a lot of power, and that’s what you’re transferring when you fill your tank.

One thing that electric cars have going for them is that they are significantly more efficient than gasoline — there’s an inherently higher efficiency and technology like regenerative braking, plus the ability to just turn off rather than idling. Overall, electric cars are around 5x as efficient as gasoline-powered vehicles. Good thing, too, because otherwise we’d have close to a 1:1 charge:travel time, and nobody is going to put up with that.

So we can fill up a tank of gas in just a couple of minutes, and it takes more than an order of magnitude longer for electric, for a more limited range. Let’s look at this from another perspective: waiting for a space to clear at a gas station is annoying even when it’s a few minutes, so waiting for a fill-up that takes 30 is probably a nonstarter. Which means that you are going to need proportionally more fill-up bays at each station, relative to the number of cars on the road. Right now that capacity is not a problem, with so few cars, but it’s an obstacle to wider adoption.

If you have a station capable of charging up multiple cars, you need to be able to deliver the power. For every 10 cars at once that means a MegaWatt of electricity. Perhaps that remains constant — if you can cut the charging time in half you deliver twice the power but don’t need as many charging stations, and you won’t be operating at peak capacity, so that doesn’t mean you need 1 MW coming in — you can store electricity when you have lower demand. But you have to generate all that electricity from solar, though you at least have the advantage of staying DC to charge up a car — no inverter losses as you’d have for a home system running your 60Hz loads. But how many cars are you going to handle? 100 a day? That’s 5000 kWh, and solar might generate 5-10 kWh/m^2 each day, (or even less) depending on location and time of year. That’s a 1000 m^2 solar array for the smaller value, and you probably need more in case the weather is bad for more than a day lest you tell your customers “We’re out of sun” very often. If you’re out, they are stranded, so I imagine there will be emergency generators (running on biodiesel, presumably). The array size may not be a problem for stations away from cities. You have the space, and don’t need to have a grid connection, so you are freer to put these where you want. In more occupied space, you’d tap into the grid if you needed to, though that’s not “green” and defeats (much of) the purpose of having an electric car. But being stranded is not going to be an option.

### The Modern Soylent Green: The People are the Product

By now we’re pretty used to being the product, as many of us participate in online activities like Facebook or Twitter, and/or photo-sharing sites, where we provide the content. (On some of those sites, what we post actually becomes the property of the host. Read carefully!) Here’s another example of being the product:

Each tile has a capacity of 6 watts, but in order to use the tile’s full capacity, there needs to be a constant flow of about 50 steps / minute.

The reality is that the tiles are seeing about 5 steps / minute, and on a good day, the kinetic sidewalk will generate about 75 watt-hours of electricity. This is equivalent to powering an old 60-watt incandescent lightbulb for about 1 hour and 15 minutes.

Let’s start with the obvious: one could take the view that this is stealing. Someone is taking work you (the actual physics definition of work, at that) and using it without paying you. It’s also being advertised as being green and self-sustainable. It also needs to be cost-effective. Is it?

Let’s run the numbers. The pad flexes ~5mm when you step on it, so that’s about 5 Joules of work for a mass of 100 kg, so that’s roughly in agreement with the 50 steps/min giving 6 Watts, assuming high efficiency. 75 W-h is 270 kJ of energy. At an electricity rate of $0.12 per kWh, this represents a penny of electricity. A penny. The device has to be less than 100% efficient and your body’s conversion of food into the energy being harvested certainly isn’t (I’ll assume around 25%), so at 4.18 kJ per Calorie, the people providing this energy collectively burned about 270 Calories, which came from the food they ate. The cost of that food can vary widely, but it’s going to be on order of a dollar, making this system’s cost efficiency about 1%. (This won’t change at higher power production, either) And here’s where (and why) the claims of “green energy” fall apart. Touting human power as green is dubious, because you don’t know where the food came from, but odds are it’s not all that “green”, and to tout this as a replacement — at 1% efficiency — means that the people providing the energy need to have 1/100 of the carbon footprint of the raw electricity. Transporting the food, preparing it, etc. has to be greener than the energy it replaces by a factor of 100, and there’s no way it is. This is a misdirection, moving the carbon footprint issue out of immediate sight, asking us to pay no attention to the carbon footprint behind the curtain. Human power is not green — the only time it works is if you are harnessing energy that would otherwise be wasted, similar to regenerative braking on electric cars. Is it cost-effective? I couldn’t find a credible price anywhere, save for a promised target of$50 per tile once production ramps up. Installation is probably the largest cost, along with some infrastructure of wiring, batteries and an inverter. At the target traffic load giving an output of 6 Watts, even if the traffic were present all day long, that’s 1 kWh per week per tile. At $0.12 per kWh saved, that’s just barely$6 a year in electricity savings. The tiles were installed at a tube station at the Olympics and generated just 20 kWh from 12 tiles. The olympics ran 16 days (the story says two weeks); it’s ballpark agreement either way. 20 kWh is \$2.40 of electricity.

Unless I’m missing something, there’s no way this is cost-effective. You can pay for it out of your advertising budget, raising awareness of, well, something, since it’s not green, which means it’s just a gimmick.

### You Can Call Me Al

It takes far less energy to recycle an aluminum can than to make one from scratch – recycling 40 Aluminum cans is the equivalent of saving a gallon of gasoline. One problem is that not all of the can is Aluminum.

Toward a Greener Soda Can

[R]ecycling the cans turns out to be harder than it looks, because the basic soft drink or beer can is actually made of two kinds of aluminum. The bottom and sides are made from an aluminum sheet that is strong enough to be stamped into a round shape without tearing. For the top, which must be stiff enough to help the can retain its shape and withstand the bending force when it is opened, can makers blend aluminum with magnesium.

### NOAA’s Really Making It Happen Out There

Wow, four records! Keep your eye on this kid — he’s going places.

Four Major U.S. Heat Records Fall In Stunning NOAA Report

According to NOAA’s National Climatic Data Center, the spring of 2012 “was the culmination of the warmest March, third warmest April, and second warmest May. This marks the first time that all three months during the spring season ranked among the 10 warmest, since records began in 1895.”

### I Think That Should be Thick Air

Wind turbine creates water from thin air

All air trapped during this procedure is then directed through an electric cooling compressor situated behind the propellers. This contraption extracts humidity from the air, creating moisture which is condensed and collected.

One turbine can produce up to 1,000 liters of water every day, depending on the level of humidity, temperature and wind speeds, says Janin

Still pricey, however.

### Where in the World are Henry David Thoreau’s Plants?

Where Are Henry David Thoreau’s Plants Now?

[Thoreau's] journals offer an unparalleled phenological record — that is, a log of the timing of events, like a first flower or leaf growth. Looking back through Thoreau’s logs, as well as those of later botanists, Primack and Miller-Rushing found the first flowering date for 43 of the most common species has moved up by an average of 10 days.