GARBAGE, GRAPHENE, TOWERS, TETHERS, AND TEENSY WEENSY PROBLEMSJune 17, 2020
There's a wonderful scene in the 1980s science fiction film Back to the Future which captures the flavor of today's story that was shared by B.H. In the movie, Marty McFly, played by actor Michael J. Fox, is able to travel back in time to the 1950s using a Delorean car (for those of you who remember that little scandal), which had been modified by his friend Dr. Emmet Brown (Christopher Lloyd) with a gizmo that permitted time travel. All one had to do to power the gizmo was have enough plutonium. Beyond a nostalgic glance at 1950s America when 'gas stations' were still 'service stations' and when one could get a real malt - not just a milkshake - in a malt shop, the final scene of the movie as Doc Brown returning to the 1980s from his trip to the future. Being in something of a hurry to return to the future with Marty (and his girlfriend) to avert a temporal disaster, Brown requests a bunch of garbage from Marty, because he needs power for the car to return to the future. No more plutonium needed, just common garbage. Having received the garbage, he crams it into another gizmo now fit to the car, a white plastic "coffee maker" type of contraption - an obvious commercial product purchased in some future outlet store - which was stamped with the brand name "Mr. Fusion," an obvious send-up of the popular 1980s coffee-maker, "Mr. Coffee."
That little stroll around Harvey's Barn brings us to the subject of today's blog, an article from January of this year, that was spotted by B.H., and if one really ponders its implications, its a whopper doozie:
Now, you'll note I had some difficulty "filing" today's story, on the one hand it has to do with "space" as we shall see, and hence I thought "cosmic war" would be appropriate, but it also has some pretty hefty "geoengineering" implications as well.
Scientists at Rice university have discovered a way to make graphene quite literally from garbage, and what's more, it's a method much cheaper, and simpler, to make the expensive material, which, as the article notes, currently prices out at between 67,000 and 200,000 dollars per ton. Granted, it's not exactly the price of gold, but then again, for the uses imagined for graphene, you're not going to be dealing in mere ounces. So what's the process, and why is it a big deal?
Despite its high utility, graphene isn't a part of our everyday lives yet. Part of the reason why is because of its prohibitive cost. Graphene is difficult to produce in bulk, with "the present commercial price of graphene being $67,000 to $200,000 per ton," said Tour. Common techniques include exfoliation, in which sheets of graphene are stripped away from graphite, or chemical vapor deposition, in which methane (CH4) is vaporized in the presence of a copper substrate that grabs the methane's carbon atoms, arranging them as graphene.
The new technique, called flash Joule heating, is far simpler, cheaper, and doesn't rely on any hazardous solvents or chemical additives. Simply put, a carbon-based material is exposed to a 2,760°C (5,000°F) heat for just 10 milliseconds. This breaks every chemical bond in the input material. All atoms aside from carbon turn into gas, which escape in this proof-of-concept device but could be captured in industrial applications. The carbon, however, reassembles itself as flakes of graphene.
What's more, this technique produces so-called turbostatic graphene. Other processes produce what's known as A-B stacked graphene, in which half of the atoms in one sheet of graphene lie over the atoms of another sheet of graphene. This results in a tighter bond between the two sheets, making them harder to separate. Turbostatic graphene has no such order between sheets, so they're easier to remove from one another.
But why is that a big deal? For one thing, it would have an enormous environmental impact:
The most obvious use case for what the researchers have termed "flash graphene" is to use these graphene flakes as a component in concrete. "By strengthening concrete with graphene," said Tour, "we could use less concrete for building, and it would cost less to manufacture and less to transport. Essentially, we're trapping greenhouse gases like carbon dioxide and methane that waste food would have emitted in landfills. We are converting those carbons into graphene and adding that graphene to concrete, thereby lowering the amount of carbon dioxide generated in concrete manufacture. It's a win-win environmental scenario using graphene."
Additionally, one can imagine that landfills could actually become a kind of "graphene mine" for recycled garbage. And for those really paying attention, the idea of burning material to make graphene which could be put into concrete sounds oddly like some of the stories surrounding the Tower of Babel, where the bricks for the tower had to be "thoroughly burned" for use in the Tower. In other words, we're looking, not at Back to the Future's "Mr. Fusion," but at something very much like it, "Mr. Graphene."
But there's something else lurking in all this garbage, and that's space, believe it or not. For a little over a century, ever since Russian space pioneer Konstantin Tsiolkovsky first proposed the idea, scientists and engineers have toyed with the idea of "getting up there" not by riding a rocket, but by riding an elevator. Of course, the benefit of an elevator is that over the long run, it would be cheaper than rockets, and one could use them to carry stuff up there and assemble it into large space-born structures. The problem is, the elevator would have to be made of some pretty light, and incredibly strong, material to work.
...like diamond nanotubes, carbon nanotubes, or graphene:
Now, there's a "teensy weensy" problem here that we'll get back to, but for the moment, I want to focus your attention on this idea of a space elevator. Think of it as a kind of "tower reaching unto heaven". Indeed, if one looks at the Wikipedia entry for "space elevator" (Wikipedia space elevator) we find this:
A space elevator is a proposed type of planet-to-space transportation system. The main component would be a cable (also called a tether) anchored to the surface and extending into space. The design would permit vehicles to travel along the cable from a planetary surface, such as the Earth's, directly into space or orbit, without the use of large rockets. An Earth-based space elevator would consist of a cable with one end attached to the surface near the equator and the other end in space beyond geostationary orbit (35,786 km altitude). The competing forces of gravity, which is stronger at the lower end, and the outward/upward centrifugal force, which is stronger at the upper end, would result in the cable being held up, under tension, and stationary over a single position on Earth. With the tether deployed, climbers could repeatedly climb the tether to space by mechanical means, releasing their cargo to orbit. Climbers could also descend the tether to return cargo to the surface from orbit.
The concept of a tower reaching geosynchronous orbit was first published in 1895 by Konstantin Tsiolkovsky. His proposal was for a free-standing tower reaching from the surface of Earth to the height of geostationary orbit. Like all buildings, Tsiolkovsky's structure would be under compression, supporting its weight from below. Since 1959, most ideas for space elevators have focused on purely tensile structures, with the weight of the system held up from above by centrifugal forces. In the tensile concepts, a space tether reaches from a large mass (the counterweight) beyond geostationary orbit to the ground. This structure is held in tension between Earth and the counterweight like an upside-down plumb bob.
To construct a space elevator on Earth, the cable material would need to be both stronger and lighter (have greater specific strength) than any known material. Development of new materials that meet the demanding specific strength requirement must happen before designs can progress beyond discussion stage. Carbon nanotubes (CNTs) have been identified as possibly being able to meet the specific strength requirements for an Earth space elevator. Other materials considered have been boron nitride nanotubes, and diamond nanothreads, which were first constructed in 2014. (Italicized emphasis added)
If you're thinking "Gee, this sounds awfully familiar," it should, because as I recall the last time humanity attempted to build such a tower, it didn't turn out too well. In fact, as I recall, it ended up creating a babbling gaggle of confusion as we ended up speaking a multitude of languages instead of just one. In fact, there may even be a sort of high octane speculation why, which takes us back to that article "How does a space elevator work" which is linked above.
In that article, notice the "little" statement:
Graphene is a fantastic 2D material. It is 200 times stronger than steel, transparent, flexible and conducts electricity better than copper. However, graphene can only be made commercially in little bits with the current technology. (Italicized emphasis added)
Well, maybe it used to be made "commercially in little bits," but the Rice university discovery may end up changing all of that. But before you ride that elevator to the top of the Tower, you might want to consider the electrical conductivity of graphene for a moment, and another movie, and a failed experiment on the space shuttle. That failed experiment was the space shuttle "thether experiment," remember that one? (Qv The Space Tether Experiment) The idea was simple:
- The space tether experiment, a joint venture of the US and Italy, called for a scientific payload--a large, spherical satellite--to be deployed from the US space shuttle at the end of a conducting cable20 km (12.5 miles) long. The idea was to let the shuttle drag the tether across the Earth's magnetic field, producing one part of a dynamo circuit. The return current, from the shuttle to the payload, would flow in the Earth's ionosphere, which also conducted electricity, even though not as well as the wire.
One purpose of such a set-up might be to produce electric power, generating current to run equipment aboard the space shuttle. That electric comes at a price: it is taken away from the motion energy ("kinetic energy") of the shuttle, since the magnetic force on the tether opposes the motion and slows it down. In principle, it should also be possible to reverse this process: a future space station could use solar cells to produce an electric current, which would be pumped into the tether in the opposite direction, so that the magnetic force would boost the orbital motion and would raise the orbit to a higher altitude.
The first attempt at the tether experiment ended prematurely when problems arose with the deploying mechanism, but the one on February 25, 1996, began as planned, unrolling mile after mile of tether while the observed dynamo current grew at the predicted rate. The deployment was almost complete when the unexpected happened: the tether suddenly broke and its end whipped away into space in great wavy wiggles. The satellite payload at the far end of the tether remained linked by radio and was tracked for a while, but the tether experiment itself was over.
It took a considerable amount of detective work to figure out what had happened. Back on Earth the frayed end of the tether aboard the space shuttle was examined, and pieces of the cable were tested in a vacuum chamber. The nature of the break suggested it was not caused by excessive tension, but rather that an electric current had melted the tether.
Or to put it country simple, the vast amount of particles and radiation from the Sun generated an enormous electrical current in the tether, which melted and snapped. And anyone with a basic grade-school level of physics could have predicted the result. Now imagine an electrically conductive tether from up there, grounded on the Earth itself and...
...well, you get the idea. It might so zap the planet that the entire magneto-electric ecosphere of the planet could be effected in a variety of very unpleasant ways. Think of it as a massive lighting rod.
Or think of that wonderful John Candy-Dan Aykroyd comedy, The Great Outdoors. In that movie, Candy and Aykroyd encounter a man in a bar, whose speech is a stuttering scramble of barely understandable conversation as the man shakes and quivers, and tries to explain why he has such difficulty talking: he was struck by lightning 66 times.
But, as the above-linked article "How does a space elevator work?", scientists and technicians are following the development of materials science closely, looking for any promising material which which to construct that all important tether. I look in vain, however, for any signs of how they plan to handle that electrical conductivity problem, or perhaps that's not a concern at all, and the real intention is to "zap the Earth."
In which case, we may end up like the man at the bar in The Great Outdoors.
Just a thought, a little high octane speculation.
Have a nice day.
See you on the flip side...