Monthly Archives: July 2013

My new sci-fi book: Space Anchor

I haven’t blogged for a while. That’s because I have been busy writing my first sci-fi book, which is now out.

ISBN-13: 978-1491220023 in paperback

FrontCover

and as ASIN: B00E9X02IE in ebook form, with a lighter cover:

kindle cover

It is a not-too-serious book, set towards the end of this century, and is first one I have written on the adventures of Carbon Girl and her partner Carbon Man, who manage to make an entire superhero lifestyle using carbon and not much else. Although it is meant to be a bit light-hearted, most of the tech in it is supposed to be reasonably plausible. I have had to make a couple of concession to artistic license for the space bits – a sad fact of life in sci-fi is that if you want ships to go any distance in a short period, you have to invent some pseudo-scientific way of side-stepping what we currently think of as basic physics. It has AI romance and zombies in it too.

With recent complaints in the media that most sci-fi has a severe shortage of female characters, my book tries to improve the balance a bit, and uses Carbon Girl as its main character. A couple of examples of its general flavour so far:

“When a sexy woman puts on a figure enhancing cat-suit and lethal stilettos, usually people fall in line. Just in case they didn’t, she also took her whip. Now she felt right. She was Carbon Girl again. She was dressed to kill. No, today, they would probably form a queue to be killed by her.”

“It isn’t every day that your arch-nemesis becomes your lover, but then again, as Carbon Man frequently observed “Sometimes, things come right back and bite you on the bum.””

“Corel surrendered totally and unconditionally to temptation, invited it in and told it to make itself feel at home.”

It is available in paper and e-book form. Both available from 2/8/13 via Amazon.

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3D printing the highest skyscraper? 600km tall structures may be feasible.

What would you do with a 600km high structure? That would be hundreds of times higher than the highest ever built so far. I think it is feasible. Here I will suggest super-light, super-strong building materials that can substitute for steel and concrete that can be grown up from the base using feasibly high pressures.

I recently proposed a biomimetic technique for printing graphene filaments to make carbon fur (- in this case, for my fictional carbon-obsessed super-heroine Carbon Girl. I am using the Carbon Trio as a nice fun way to illustrate a lot of genuine carbon-related concepts for both civil and military uses, since they could make a good story at some point. Don’t be put off by the fictional setting, the actual concepts are intended to be entirely feasible. Real science makes a better foundation for good science fiction. Anyway, this is the article on how to make carbon filaments, self-organised into fur, and hence her fur coat:)

http://carbondevices.com/2013/07/01/carbon-fur-biokleptic-warmth-and-protection/

Here is the only pic I’ve drawn so far of part of the filament print head face:

printing graphene filaments

Many print heads would be spread out biomimetically over a scalable area as sparsely or densely as needed, just like fur follicles. A strong foundation with this print head on top could feasibly form the base of a very tall vertical column. If the concept as described in the fur link is adapted slightly to print the filaments into a graphene foam medium, (obviously pushed through the space between the follicles that produce the filaments) a very lightweight foam structure with long binding filaments of graphene graphene foam would result, that would essentially grow from the ground up. This could be very strong both in compression and tension, like a very fine-grained reinforced concrete, but with a tiny fraction of the weight. Given the amazing strength of graphene, it could be strong enough for our target 600km. Graphene foam is described here:

https://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

Extruding the supporting columns of a skyscraper from the ground up by hydraulically growing reinforced graphene foam would certainly be a challenging project. The highest hydraulic pressures today are around 1400 bar, 1.427 tonnes per sq cm. However, the density of graphene foam with graphene filament reinforcement could be set at any required density from below that of helium (for graphene spheres of 0.014mm with vacuum inside), to that of solid carbon if the spheres are just solid particles with no vacuum core. I haven’t yet calculated the maximum size of hollow graphene spheres that would be able to resist production pressures of 1400 bar. That would determine the overall density of the material and hence the maximum height achievable. However, even solid carbon columns only weigh 227g per metre height per sq cm of cross-section, so even that pressure would allow 6.3km tall solid columns to be hydraulically extruded. Lower densities of foam would give potentially large multiples of that.

This concrete substitute would be nowhere near as strong as basic graphene, but has the advantage that it could be grown.

(The overall listed strength of solid graphene theoretically allows up to 600km tall, which would take you well into space, perfect for launching satellites or space missions such as asteroid mining. But that is almost irrelevant, since graphene will also permit construction of the space elevator, and that solves that problem far better still. Still, space elevators would be very costly so maybe there is a place for super-tall ground-supported structures.)

But let’s look again at the pressures and densities. I think we can do a lot better than 6km. My own proposal a while back suggests how 30km tall structures could be built using graphene tube composite columns structures. I did think we’d be able to grow those.

https://timeguide.wordpress.com/2013/02/22/super-tall-30km-carbon-structures-graphene-and-nanotube-mesh/

We’d need higher pressures to extrude higher than 6km if we extruding solid columns, but these tube-based columns with graphene filament reinforced graphene foam packing would have a far lower density. The print heads in the above diagram were designed to make fur filaments but I think it is possible (though I haven’t yet done it) to redesign the print heads so that they could print the tubular structures needed for our columns. Tricky, but probably possible. The internal column structures are based on what nature uses to make trees, so are also nicely biomimetic. If we can redesign the print heads, then printing low density columns using a composite of filament reinforced foam, in between graphene tubes should work fine, up to heights well above the 30km I originally suggested. An outer low pressure foam layer can be added as the column emerges. It doesn’t have to withstand any significant pressure so can be as light as helium and add the strength needed to prevent column buckling. With the right structure, perhaps the whole 600km can be achieved that way. Certainly the figures look OK superficially, and there’s no hurry. It’s certainly worth more detailed study.

Getting estuary tidal power without damaging an estuary

Once in a while, people suggest using the Severn Estuary to generate tidal power. Many other countries with coastlines also have estuaries with sufficient tidal range to make them attractive candidates too. Tidal range is the vertical difference between the water depth at high and low tide, and when the shape of the estuary is factored in, this obviously represents the potential energy available to be harvested. The placing of the barrage determines most of the cost.

A good US overview is at

http://www.oceanenergycouncil.com/index.php/Tidal-Energy/Tidal-Energy.html

Building a dam is established technology, as is hydroelectric generation. The environmental problem is that estuaries are also valuable ecosystems, and it would be nice if we could get power that way without needing the estuary. Putting the enclosures, or impoundments off shore solves that. One option is to build a tidal lagoon. A nice UK site describes the idea:

http://www.tidalelectric.com/technology-lagoons.shtml

As a diversion, you could also just float a lagoon one and tether it, but that probably isn’t a great idea. This is why: A huge man-made enclosure with high walls in a high tidal range area off shore could open its gates to let water flood in via generators as the tide comes in and/or hold it to be released via generators as the tide goes out. But if we make it from plastic, it wouldn’t be able to withstand much pressure and wouldn’t last long. If we make it from steel, it would be stronger, but would take a lot of steel to make a worthwhile enclosure. Then once we’ve made it, how would it be anchored to the sea floor to stop it just rising with the tide or to stop it falling as the tide goes out. Remember, tidal generators only become useful when there is a significant pressure difference. It would need very strong anchors and very strong cables to prevent it from floating up as the tide rises. The base for the enclosure would have to be very strong with strong supports to hold up the enormous weight as the tide goes out, or it would have to sit on a huge base of concrete (assuming it can’t just sit on the sea floor because it is at sea, which is after all the whole point).

So it’s obvious once you think about it for a few minutes why people want to use estuaries or lagoons to hold the water. Only the wall is needed, not the base. The difficult half of the problem and most of the cost goes away.

We are already building off shore wind farms. They sit in regions where the sea is shallower, but since they already present an obstacle to shipping, that obstacle wouldn’t be much worse if the whole farm were to be surrounded by a sea wall. Then tidal generators could be fitted in those walls. Wind farms therefore ought to be perfect candidates for tidal lagoons. It would produce an impoundment without further damaging shipping channels or fish migration paths, while making a less hostile environment for the wind turbines and making their maintenance easier and safer.

A steel wall would be theoretically workable, but would be expensive and resource intensive. A concrete sea wall would be less expensive, but making concrete generates relatively large amounts of CO2. Stone could be used but leaves an ugly mine behind. So, the best solution for tidal lagoons is using a conventional rubble mound breakwater. 

This isn’t a new idea. It was thought through ages ago by others. One proposal for the UK that gathered support:

http://www.publications.parliament.uk/pa/cm200506/cmselect/cmenvaud/584/584we78.htm describes almost exactly this solution, identifies promising UK sites, and even does all the appropriate surveys and calculations, showing costs compare reasonably with onshore wind turbines. It is still expensive, but not as bad as off shore wind or even a tidal barrage (because the depth of water on the path the wall follows is low, keeping construction costs down). Worth a read.

It is a sound idea already. I like it, though it is still far more expensive than developing shale gas. But instead of using just rubble, why not also use the opportunity to dispose of other waste such as plastic by using it as breakwater filler? Maybe even other kinds of landfill might work as filler. A lot of waste plastic is shipped to far-away lands for disposal. Mixed with rubble, the density would be OK to make it sink and stop it being washed away. It would get rid of waste, while providing some of the substance of the breakwater, hopefully even bringing the price down further. It is unlikely to make a huge dent in costs, but it would reduce the madness of sending plastic to China for disposal and take pressure of landfill.