Stories tagged Flow of Matter and Energy

Sep
22
2010

NREL's membraine: There's so much science in his head it's projecting colorfully out into the air as a graph.
NREL's membraine: There's so much science in his head it's projecting colorfully out into the air as a graph.Courtesy NREL
You’re worried about the future again, aren’t you? You’re afraid that everything will taste like cardboard, and that most people will be robots, and that the robots will be too cool to hang with you, and that our trips to the bathroom with be confusing and abrasive, and something about bats, and that you will be hot all the time, even in your own homes.

And I wish I could tell you otherwise. But I can’t. I just don’t know enough about the future. Except on that last point—it looks like air conditioning may yet be an option in a necessarily energy efficient future.

Air conditioning can use up a lot of energy. An air conditioning unit typically cools air by blowing it over a coiled metal tube full of a cold refrigerant chemical. The refrigerant absorbs heat from the air in your house, and then it passes through a compressor, which squishes the refrigerant down, making it hot so that it releases heat outside your house. And then the refrigerant expands, and cycles back into the cool tube. (Here’s the explanation with some illustrations.)

Other cooling systems rely on evaporation. So called “swamp coolers” pull hot, dry air from outside, and blow it over water (or through wet fabric pads). The water evaporates to pull heat out of the air, so what is blown into your house is cool, humid air. Swamp coolers are more efficient, but they only work in very dry environments.

And then there’s another way to control your indoor climate: desiccant cooling. A lot of what makes warm air uncomfortable is the amount of moisture it can contain. Normal AC units remove moisture from the air, but they use a lot of energy in doing it. Another way is to use chemicals called desiccants. Desiccants suck up water. The little packs of “silica gel” crystals you might find in a new pair of shoes are full of desiccants. Blowing humid air over desiccants will result in the chemicals sucking the moisture out of the air, making it more comfortable.

Figuring out how to use the desiccants has been a challenge, however; desiccant chemicals can be corrosive to building materials, so they, and any dripping water, need to be contained. With this in mind, US government researchers at the National Renewable Energy Laboratory have developed a membrane for desiccant cooling systems that allows the water vapor in humid air to pass through it one way, but does not allow the liquid water removed from the air to pass back.

The researchers claim that this air conditioning process is up to 90% more energy efficient than standard AC. Every so often, the desiccant chemicals need to be “recharged” by heating them up so they release the trapped water (outside), a job that can be done by electric heating elements, or with a solar thermal collector. The University of Minnesota used a desiccant cooling system for their entry into the Solar Decathlon competition. Their system didn’t rely on a membrane—rather, humid air was pumped up through a drum of liquid desiccant—but they did recharge the desiccant using heat from solar thermal panels (which are basically big, flat, black boxes that collect heat from sunlight).

It’s reassuring to know that in the future, even as we’re covered in flesh eating bacteria, and spam advertisements for Spam are being beamed directly into our brains, we’ll at least be able to relax in pleasantly dry, cool air, without worrying too much about the energy we’re using to do it.

Aug
31
2010

This kid is sitting on a fortune!: That balloon will put him through college, assuming he doesn't blow it all first on candy and blackjack.
This kid is sitting on a fortune!: That balloon will put him through college, assuming he doesn't blow it all first on candy and blackjack.Courtesy Lars Plougmann
Y’all ever see Mad Max? Or Mad Max 2: The Road Warrior? Or even Mad Max 3: Beyond Thunderdome?

Some of you surely have, and I salute you. For the rest of you, the short description is this: a handsome young Australian actor, who we should just assume is now dead, played a lone wanderer, drifting across a post-apocalyptic wasteland. During the course of his adventures, he meets Tina turner, a really weird looking pilot (twice?!), a grunting, boomerang-throwing feral child, a man named Toe-cutter, and an awesome giant/little person team (sort of like Jordan and Pippen, but more inclined towards stranglings). It’s all very exciting! But the most important part of the Mad Max trilogy is this: he lives in a world without gas. Everybody was so busy blowing each other up that they forgot to be careful with their oil, so by the time Max rolls around, people are freaking out trying to get a few more drops of “the precious juice” for their dune buggies and flame throwers.

And so we come to our news item, and this afternoon’s future-dread focus: helium. If you look at the Mad Max summary and pretend “gas” refers to helium gas instead of gasoline, and if you replace “dune buggies” with “scanning equipment,” and “flame throwers” with “party balloons,” it’s a pretty decent analogy.

See, we’re running out of helium. And when it’s gone, it’s gone forever.

The above statement brings to mind two points (at least for me):
1) No we aren’t. Shut up.; and
2) Even if we are running out of helium, who cares? I can fill up my party balloons with air, or Cheesewhiz, or something.

If you read the article linked to above (or one of the many articles on the subject that came out last week), you’ll find that the answer to point 1 is, yeah, we kinda are, and the answer to point 2 is, it’ll be sad to see floating party balloons go, but they’re the least of our problems. It’s all dune buggies and flame throwers from here on out.

The problem is that helium is non-renewable. We talk about oil being non-renewable, but helium is even more non-renewable. See, helium only comes from fusion reactions (hydrogen atoms slamming together to form heavier helium), or from radioactive decay (heavier elements breaking apart at the atomic level to form lighter helium). Hydrogen fusion only happens in stars (scientists are trying to replicate it as an awesome source of nuclear energy, but don’t hold your breath), so all of the helium on our planet comes from underground, where gases from radioactive decay have become trapped.

We’ve got a nice big planet here, and we’ve got lots of helium, but we’ve just been farting it away, and once helium is released into the atmosphere, it’s gone to us for good. And we’re currently farting away helium at such a tremendous rate that the gas could be all but unavailable within a couple generations. The reason for this is that it’s actually official policy to fart away helium. (More or less.)

A huge portion of the world’s helium has been mined from the American Southwest, and for a long time we were actually pretty good at storing it—we pumped it back underground into a huge system of old mines, pipes and vats near Amarillo, Texas, in a facility called the US National Helium Reserve. We stored the helium because it was strategically useful to the country—it was vital for rocket operation during the Cold War. But in 1996, a law was passed requiring the helium to be sold off, all of it, and by 2015. I’m not totally clear on the reason for the law. I suppose the idea was that the Cold War was over, and by selling the helium, the US National Helium Reserve could be paid for (sort of a Gift of the Magi kinda thing, but whatever.) Congress, however, decided that the price of the sold helium would remain the same until it was all gone, so even as available helium became scarce, it would never be more expensive.

This broke the law of supply and demand, and having this vast, vast supply of helium go on sale for cheap meant that all the helium in the world had to be cheap too. Helium has become so cheap, in fact, that there’s no economic incentive for recycling it—recapturing it after use is so much more expensive than just buying new helium, people have just been letting the used helium drift away, where we’ll never be able to reclaim it. Normally, when a resource becomes more scarce, its price will go up, and people will be better about using it. (For an example, see gas prices and fuel efficiency in cars.) Not so with helium, thanks to that 1996 law. And pretty soon, say some scientists, we’ll be running out of the precious gas.

The “precious” part is there because helium is useful for a lot more than party balloons. (Although they’re ok too.) The properties of helium make it an excellent coolant for medical scanning equipment, and the sort of detectors used in super colliders. It’s also used in telescopes, diving equipment, rockets (NASA is a huge user—and waster—of helium), fusion research, and airships. (And don’t laugh about that last one—as the price of fuel goes up, the prospect of eventually moving cargo with lighter-than-air aircraft, like blimps and zeppelins, is becoming more likely. And hydrogen is a little bit too explodey to be a great alternative lifting gas.)

Helium is so desired, and is being wasted at such a rapid rate, claims Robert Richardson (a Nobel Prize-winning physicist, whose research was on helium), that a single helium-filled party balloon ought to cost about $100.

That’s right: $100. It’s that, or we keep going until there’s no helium left. And then... it’s Thunderdome. You know the rules—there are none.

Aug
16
2010

Another tidal generator: But this one is hiding underwater. This is why I didn't know what they look like.
Another tidal generator: But this one is hiding underwater. This is why I didn't know what they look like.Courtesy Fundy
Along with wind and solar, harvesting power from tidal forces comes up a lot in discussions of alternative energy sources.

Was that a horrible sentence? I think it was. What I meant to say is this: we can generate electricity from tides, and lots of it. "Tidal power" is often brought up alongside solar power and wind power, but while I can easily picture windmills and solar panels, I'm not always sure what sort of device we'd use to harness the power in the tides.

This sort of device! For those of you too afraid to click on a strange link (who knows... I could be linking to an image like this!), the article depicts something that looks sort of like a thick, stubby windmill, with blades on its front and back. It's a tidal turbine, and at 74 feet tall and 130 tons it's the world's largest. It should be able to supply electricity to about 1,000 households. Pretty impressive.

Tidal turbines, apparently, are so productive because water is so much denser than water, and so it takes a lot more energy to move it. An ocean current moving at 5 knots (that's a little shy of 6 miles per hour, for the landlubbers) has more kinetic energy, for example, than wind moving at over 217 miles per hour.

At least according to that article, the United States and Great Britain each have enough tidal resources (areas where this kind of generator could be installed) to supply about 15% of their energy needs.

More info on the tidal turbine, which I am calling "the Kraken," because it's big, underwater, and will occupy your mind for only a very short time.

Aug
03
2010

Aurora borealis above Lake Harriet in Minneapolis, MN: The white streak visible in the lower right of the timed exposure is an aircraft taking off from the Minneapolis-St. Paul airport.
Aurora borealis above Lake Harriet in Minneapolis, MN: The white streak visible in the lower right of the timed exposure is an aircraft taking off from the Minneapolis-St. Paul airport.Courtesy Mark Ryan
Old Sol could be stirring up the atmosphere this evening with a display of northern lights (aurora borealis). Scientists have recorded a significant burst of plasma shooting from the Sun’s surface that could mean we earthlings are in for a light show tonight or early Wednesday morning. The solar wind particles are headed right toward us, and when they reach the Earth’s magnetic field they’ll interact with atoms of nitrogen and oxygen in the atmosphere and - hopefully - produce glowing sheets and fingers of green, red, blue, or even yellow in a wonderful display in the northern skies. The southern hemisphere experiences the same phenomenon but down there it’s known as the aurora australis (southern lights).

Lately, here in the Twin Cities, the air has been supersaturated with humidity so I don’t know how crisp a view we’ll get but it could be worth stepping outside tonight to see what’s up.

SOURCE and LINKS
CNN.com report
Univ. of Alaska’s Geophysical Institute Aurora Forecast page
Michigan Tech’s Aurora page
Solar flares

Jul
25
2010

Slow boat to China: Cargo ships are cutting their sailing speeds to reduce costs.
Slow boat to China: Cargo ships are cutting their sailing speeds to reduce costs.Courtesy mikebaird

Save 40% on fuel costs by slowing down 20%

Slower speeds also reduce pollution. Too bad that is not why the shipping companies are slowing down. The tough economic times has forced many to think of ways to cut costs.

$100 million in fuel savings

It is believed that Maersk, the world's largest shipping line, with more than 600 ships has saved more than $100 million on fuel since it began its go-slow policy. Instead of the standard 25 knots to 20 knots, some container ships are slowing down to 12 knots (about 14 mph). This is slower than the speed of sailing clippers such as the Cutty Sark more than 130 years ago.

Works for cars and trucks, too

Driving too fast or rapid acceleration wastes money.

You can lower your gas mileage by 33 percent at highway speeds and by 5 percent around town.
You can assume that each 5 mph you drive over 60 mph is like paying an additional $0.24 per gallon for gas. fueleconomy.gov

There should be a law

Saving money and reducing pollution should be a no-brainer but people with too much money often choose to speed. I think slowing down should be mandatory.

Learn more about speed vs saving

Source Modern cargo ships slow to the speed of the sailing clippers The Guardian

Jul
13
2010

…of climate control systems...

Ever notice the plumes of smoke rising from many buildings, factories, and power plants on a cold day? That smoke is actually water vapor, which still contains usable energy, muahahahaha! Our buildings use lots of energy. Electricity, for example, powers everything from lights to computers to copy machines to coffee makers. Electricity eventually degrades into heat—you can feel that heat coming off of electric appliances. Current building energy management systems expel this excess heat energy instead of using it for other purposes, such as building the ultimate tilt-a-whirl of doom. Dave Solberg, an energy miser and consulting engineer-ahem-secret advisor, wants to change all that using the concept of exergy. He envisions a future where energy is used as efficiently as possible, and he has been working with Xcel Energy and organizations in the St. Paul area to re-engineer buildings.

We all know that mad scientists with plans for world domination need money and power. Well, current climate control systems are expensive to build and operate, and they're bad for the environment. But retrofitting old buildings and creating the infrastructure to support Solberg's systems has a higher up-front cost than following the status quo. If Solberg can demonstrate the effectiveness and cost savings of his plan below at SMM, your regional science museum will become a model for climate control systems all over the world--I mean it will take over the world! HAHAHAHAHAHA!

At Science Museum of Minnesota, Solberg wants to make two big changes in the way we use energy:

Solberg's Plan - Phase 1
Like all large buildings, SMM takes in outdoor air, cools it to dehumidify it, then reheats the air and sends it throughout the building to control the climate. Unlike most buildings, which use giant air conditioners and boilers, SMM uses hot and cold water piped in from Saint Paul District Energy to do that job. You can learn more about District Energy in an outdoor exhibit to the left of SMM's main entrance--and you can see the building right next to us!

District Energy burnin' the biomass
District Energy burnin' the biomassCourtesy Andrew Ciscel

The first change Solberg proposes is to re-use the waste heat that SMM generates from cooling down fresh outside air. Currently, SMM's ventilation system cools outside air down to about 50 degrees F with cold water from District Energy, dehumidifies it, and then reheats that air back up to a comfortable indoor temperature with hot water from District Energy.

Solberg would have us cool the air with cold District Energy water, then use that same water (now warmer) to reheat the air back up to 65 degrees F on its way to the ventilation ducts. This change would eliminate the need to use hot water from DE to reheat air, and it would reduce use our demand on DE’s cooling system, because we would send water back to their chilled water plant at a lower temperature than we currently do.

Solberg's Plan - Phase 2
District Energy makes electricity by burning waste wood. DE then uses the heat energy still available after making electricity to produce hot and cold water, making District Energy 50% more efficient than coal-fired power plants. But at the end of the day, DE has 95-degree F water left over. Right now this excess heat is released into the atmosphere from cooling towers on top of the building (see the plume rising from the building in the image?), but that 95-degree water could meet most of SMMs heating needs. Solberg wants us to tap into that wastewater as our primary heating source, replacing the 180-degree water we currently get from DE. This would put an oft-wasted energy source to work, and it would allow the 180-degree water now being used by SMM to be used elsewhere within DE’s hot water distribution system.

This plan is so good it must be evil. In the long run, if the kinds of changes being pursued by SMM were replicated widely, they would amount to lower emissions and lower energy bills everywhere, which is ultimately healthier for our environment (not that mad scientists care about that sort of thing). In fact, we found out that if we had implemented this system when the current building was constructed, we could have saved $1.5 million in infrastructure (which we could have really used for that giant laser in the--end of message truncated--

Jul
13
2010

Brown gold!: This is actually the solid byproduct of a manure-to-methane operation. As you can see, it holds no fear for the owner of this bare hand.
Brown gold!: This is actually the solid byproduct of a manure-to-methane operation. As you can see, it holds no fear for the owner of this bare hand.Courtesy kqedquest
We’ve talked about the delights of cow feces before on Science Buzz, but mid-July always puts me in the mind of “brown gold” (coincidentally, the last occasion it came up was exactly four years ago today), and any time there’s talk of turning an animal into a fuel source, I get excited. (Remember that fuel cell that ran on the tears of lab monkeys? Like that.) Why not take another look?

So here you are: another wonderful story of cows trying their best to please us, before they make the ultimate gift of allowing their bodies to be processed into hamburgers and gelatin and cool jackets.

Poop jokes aside (j/k—that’s impossible), it is a pretty interesting story. The smell you detect coming from cattle farms is, of course, largely from the tens of thousands of gallons of poop the cattle produce every day. The decomposing feces release lots of stinky methane. (Or, to be more precise, the methane itself isn’t smelly. The bad smell comes from other chemicals, like methanethiol, produced by poop-eating bacteria along with the methane.)

Aside from being, you know, gross, all of that poop is pretty bad for the environment. The methane is released into the atmosphere, where it traps heat and contributes to global warming (methane is 20 to 50 times more potent than carbon dioxide as a greenhouse gas), and the poop itself is spread onto fields as fertilizer. Re-using the poop as fertilizer is mostly a good idea, but not all of it gets absorbed into the soil, and lots of it ends up getting washed away into rivers, lakes, and streams, where it pollutes the water.

Some farms have managed to address all of these problems, and make money while doing it.

Instead of spreading the manure onto fields right away, the farms funnel all the poop into swimming pool-sized holding tanks, where it is mixed around and just sort of stewed for a few weeks. All of the methane gas produced by bacteria as it breaks down the manure is captured in tanks. What’s left is a fluffy, more or less sterile, solid that can be used as bedding for the animals, or mixed in with soil, and a liquid fertilizer that can be spread onto fields.

The methane can then be used on-site to generate electricity, either by burning it in a generator, or using it in a fuel cell. (The methane is broken apart and combined with oxygen from the air to produce electricity, water, and carbon dioxide.) A large farm will produce enough electricity to power itself and several hundred other houses. (The extra electricity is just put back into the power grid and sold to the power company.)

Whether the methane is burned or used in a fuel cell, the process still creates carbon dioxide. However, CO2 isn’t nearly as bad as methane when it comes to trapping heat, and because the original source of the carbon was from plant-based feed, the process can be considered “carbon-neutral.” (Although one might argue that the fossil fuels involved in other steps of the cattle farming process could offset this. But let’s leave that be for now. It’s complicated.)

The downside is that setting up an operation to capture and process manure, and to generate power by burning it is expensive—it took about 2.2 million dollars to do it at the farm covered in the article, with about a third of that coming from grants. Still, the byproducts (electricity, fertilizer, soil/bedding) are profitable enough that the system could pay for itself over the course of a few years.

It’s amazing, eh? Out of a cow’s butt we get soft, clean bedding, liquid fertilizer, and electricity, all without the bad smell. What a world.

Jun
04
2010

Roooaaaarrrr!!!: I have the poison in me!
Roooaaaarrrr!!!: I have the poison in me!Courtesy http://www.flickr.com/photos/kuroha/638778686/
Like all ogres, Shrek is a greedy and covetous beast. He has millions of fine, fine goblets, but should you attempt to drink from any one of them, you risk becoming the target of one of his powerful cancer spells.

“But, Shrek,” you say. “You have so many wonderful cups, brought to us by McDonalds and Shrek 4 Eva. Why can’t I drink from just one of them?”

“Because,” Shrek would surely reply, “they’re all mine. All of them! That’s why I put cadmium in them. Ogres are immune to cadmium, but it is a carcinogen in humans.”

“A carcinogen? In your cups?” you ask.

“Yes, a carcinogen. With long term exposure, carcinogens can increase your chances of developing cancer!” says Shrek.

“Cancer?” you say.

“Yes. Cancer,” says Shrek.

And it’s not only Shrek’s goblets that are cursed; drinking from the cups of Princess Fiona will soften your bones, and sipping from the vessels of Puss in Boots will cast the hex of severe kidney damage upon you. And you should never drink out of something called “Donkey,” no matter what it’s made of.

Fortunately, all of the cups are being recalled to Ronald McDonaldland, to become a part of Ronald’s personal collection. Because clowns feed on poison.

May
11
2010

Assorted rubbish may be pumped into the leaking oil well: To make it more fun.
Assorted rubbish may be pumped into the leaking oil well: To make it more fun.Courtesy obiwanjr
You know, when that oil rig went down and started spilling hundreds of thousands of gallons of crude oil into the Gulf of Mexico, I thought, “What a downer. My reruns of ‘Yes, Dear’ are going to be interrupted with news footage of crying beavers and stuff for months now.”

But then BP came up with that idea for the containment dome, and I thought, “This is so crazy… it just might work. This could be more entertaining than ‘Yes, Dear.’ If such a thing is possible.”

But, no. The dome failed. Petrochemicals and near-freezing ocean water combined to form crystals in the dome, and it didn’t work. And it was super far underwater, so the failure couldn’t even be set to Benny Hill music or anything. Not entertaining.

I was just resigning myself to the fact that such a horrible accident might not actually be funny, when the jokers at BP let slip that they might have another hilarious trick or two up their sleeves. The dome didn’t work? Let’s try a giant “top hat”!

Yes, BP will be sinking a giant top hat onto the leaking oil pipe. It’s not really a top hat, of course; it’s actually a smaller version of Friday’s giant failure. I’m guessing it’s a sort of a bonus joke. But BP claims that the smaller contraption should have better chance of success, except that even if it does work, it won’t work as well as the dome was supposed to. (The dome was supposed to capture something like 85% of the leaking oil. But it captured 0%, so that’s sort of academic. Or, again, a bonus joke.)

And BP even has another plan, a Plan C, if you will, in the works, in case this one flops. Sort of how they filmed the second and third Matrix movies at the same time. According to my sources, the discussion behind plan C went sort of like this:

“So… what does everyone hate?”
“Nazis.”
“Yes, for sure Nazis. What else?”
“Um… oil spills?”
“Correct! Oil spills.”
“Ooh! We should do one of those!”
“No, people hate them. Plus we already have one. So what does everyone like?”
“Top hats.”
“Top hats, obviously. So we should throw one of them in the mix. But, if someone doesn’t like top hats, what do they probably like?”
“Everybody likes… ball pits?”
“Ball pits! Exactly! Let’s do something like that!”
“And tires! Old tires!”
“Yes, old tires too!”

So, in case the top hat doesn’t work, BP is considering injecting the leaking system with golf balls. And old tires. And then they would cap it off with some cement. Oh, right, and there’s this part too:

“What should we call it?
“A ‘junk shot.’ Duh.”
“Oh, my God. Totes perfect.”

And then, I assume, everybody else in the room had to go wash their ears out after hearing the unfortunate term “junk shot.”

Others have warned that such a “junk shot” could have repercussions beyond the phrase appearing in print: damaging the huge valve system at the base of the well could result in oil leaking out even faster—as much as 12 times the current rate.

Performing a junk shot against the flow of oil and the under the pressure at that depth will be extremely challenging, too. According to an expert from Tulane University, such an operation would have to cope with 2,200 pounds per square inch of upward pressure, which would make pumping golf balls and tires down very tricky.

However it turns out, it’s sure to be a barrel of laughs. Or oil. Thousands and thousands of barrels of spilled oil.

(I don’t have any better ideas, by the way. Except not to have a leaking pipeline a mile underwater. But you know what they say about hindsight.)

Apr
16
2010

Is this house a biogeochemical hotspot?
Is this house a biogeochemical hotspot?Courtesy monkeyc.net
To ecologists who study the environment, cities and suburbs are fascinating places. For one thing, they're full of people, and people take-up space, consume materials and energy, and create waste every single day. When people do this together in concentrated areas like cities and suburbs, they create what scientists call "biogeochemical hotspots" - places where chemical and energy reaction rates are much faster than in surrounding areas.

Individual houses are also hotspots. A group of scientists at the University of Minnesota, led by researchers Sarah Hobbie and Kristen Nelson, are trying to understand more about urban ecosystems and how chemicals and energy cycle through different people's homes.

They've begun to study a small group of people whose homes are here in Minnesota - asking them questions about their behavior and taking surveys and samples on their property.

What they've found might surprise a few people. It turns out that not everyone uses energy and chemicals the same way. Small numbers of individuals and families consume and waste much more than others - creating a bigger footprint in their ecosystem.

So who are these disproportionate polluters? There is a lot that scientists still don't know, especially about why people make the choices they do, but one thing seems to be clear - generally speaking, the more money that a family makes, the bigger their ecological footprint.

These bigger impacts come from a few behaviors that wealthier Americans tend to exhibit more than their less-wealthy counterparts. Flying in airplanes, buying a much larger home, having more pets and driving a car more often all contribute to a family's impact on their ecosystem.

While studying the role individuals play in urban ecosystems, another thing these scientists found to be true was that small individual actions - for example, turning down the thermostat in the winter just a few degrees, or using less chemicals on lawns, did have a significant impact on the environment.

You can see a recording of two of the researchers involved this study .