We think of the power we generate as coming from all these different kinds of sources. Oil, gas, coal, nuclear, wind… so varied! And yet they all fundamentally come down to moving a gas through a turbine to actually spin up a generator and make some juice. Even some solar plants worked this way, using the sun’s energy to heat water into steam to spin some blades and keep the lights on.
A solar updraft tower works along these basic principles, too, but in a rather unique configuration. It’s not since the dawn of the Industrial Age that humanity went around building lots of big chimneys, and if this technology makes good sense, we could be due again. Let’s find out how it works and if it’s worth all the bluster, or if it’s just a bunch of hot air.
A triboelectric nanogenerator (TENG)Â certainly sounds like the sort of thing you’d need to graduate from Starfleet Engineering to put together, but it actually operates on the same principle that’s at work when you rub a balloon your head. Put simply, when friction is applied to the proper materials, charges can build up enough to produce a short burst of electrical energy. Do it enough, and you’re on the way to producing useful power.
In a recent paper, [Leo N.Y. Cao], [Erming Su], [Zijie Xu], and [Zhong Lin Wang] describe how a functional TENG can be produced on a standard desktop 3D printer. What’s even more impressive is that the method doesn’t appear to require anything terribly exotic — just some commercially available filaments and a bunch of PTFE beads.
TENGs can be printed in any size or shape.
So how do your print your own TENG? First, you load up an electrically conductive PLA filament and lay down a base into which a series of channels has been designed. At around the half-way point, you pause the print to insert your PTFE beads, and then swap over to standard filament for a few layers to produce an insulator. Finally, you pause again and switch back over to the conductive filament for the rest of the print, encasing the beads inside the structure.
As [Leo N.Y. Cao] demonstrates in the video below, you then clip leads to the top and bottom of the print, and give it a good shake. If everything went right, LEDs wired up to your new high-tech maracas should flash as the PTFE beads move back and forth inside. But there’s a catch. Going back to the balloon-on-the-head example, the effect at play here produces high voltages but low current — the paper says a TENG containing 60 beads should be capable of producing pulses of up to 150 volts.
Naturally, you won’t get very far with just one of these. Like other energy harvesting concepts we’ve covered in the past, such as vibratory wind generators, it would take a bunch of these working together to generate a useful amount of power. But given how cheap and quickly these printable TENGs can be produced, that doesn’t seem like it would be too much of a challenge.
We live in an exciting time with respect to electrical power, one in which it has never been easier to break free from mains electricity, and low-frequency AC power in general. A confluence of lower-power appliances and devices using low-voltage external switch-mode supplies, readily available solar panels and electronic modules, and inexpensive high-capacity batteries, means that being your own power provider can be as simple as making an online order.
But which parts should you choose? Low Tech Magazine has the answer, in the form of a guide to building a small solar power system. The result is an extremely comprehensive guide, and though it’s written for a general audience there’s still plenty of information for the Hackaday reader.
Perhaps the most important part is that it’s demystifying the subject, there in front of us are a set of pretty straightforward recipes for personal power. The computer this is being written on spends a significant proportion of its time on the road with the ever-present company of a very hefty USB-C power pack for example, and the realization that a not-too-expensive solar panel and USB PD source could lessen the range anxiety and constant search for a train seat with a socket for a writer on the move is quite a powerful one.
Inside shot of the Modvion wooden wind turbine tower.
Modern-day wind turbines are constructed using mostly concrete and steel, topped by the fiberglass composite blades mounted to the nacelle that houses the gearbox and generator, along with much of the control systems. With the ever increasing sizes of these turbines transporting the components to the installation location is a harrowing task, something which Swedish company Modvion claims to improve upon with its wooden tower elements that come mostly packaged flat, for on-site assembly. The BBC recently took a look at the first of these partially wooden wind turbine towers. At 105 meters tall, it features a standard V90-2.0MW turbine and blades.
Rather than using concrete slabs at the base with steel tower segments on top, or a fully steel tower like with most wind turbines, Modvion uses segments of layered wood which it calls ‘the module‘. These are assembled out of 144 layers of 3 mm thick spruce, with ring segments assembled on-site. This means that multiple of these modules can be stacked onto a standard truck with no concerns that come with oversized transports. According to Modvion these wooden towers should last about the same number of years as their steel counterparts. Continue reading “Making The Case For Wooden Wind Turbines With Swedish Modvion”→
How many plastic spoons, knives, and forks do you think we throw away daily? [Stefan] noted that the compostable type is made from PLA, so why shouldn’t you be able to recycle it into 3D printing stock? How did it work? Check it out in the video below.
[Stefan] already has a nice setup for extruding filament. However, unsurprisingly, it won’t accept spoons and forks directly. A blender didn’t help, so he used an industrial plastic shredder. It reduced the utensils to what looked like coarse dust, which he then dried out. After running it through the extruder, the resulting filament was thin and brittle. [Stefan] speculates the plastic was set up for injection molding, but it at least showed the concept had merit.
In a second attempt, he cut the ground-up utensils with fresh PLA in equal measures. That is, 50% of the mix was recycled, and half was not. That made much more usable filament. So did a different brand of compostable plasticware.
The real test was to take dirty plasticware. This time, he soaked utensils in tomato sauce overnight. He cleaned, dried, and shredded the plastic. This time, he used 20% new PLA and some pigment, as well. We aren’t sure this is worth the effort simply on economics, but if you are committed to recycling, this might be worth your while.
You may not think much of origami or its cousin-with-cutouts kirigami, but the latter could (and already is) helping to save the planet. But let’s back up a bit.
Most readers will be familiar with origami, the Japanese art of folding paper. But there is also kirigami, which uses a series of cuts to produce 3D shapes from 2D stock. Turns out that if you cut paper just right, you can turn it into highly-recyclable packaging that even interlocks with itself, negating the need for folding or even tape.
The video after the break takes a look at 3M’s Scotch Cushion Lock⢠protective wrap through the eyes of its inventor, Tom Corrigan. It all started when 3M wanted to create a self-assembling box from a flat piece of cardboard.
So far, that particular invention hasn’t come to fruition, but after many long nights with paper and X-Acto knives, Tom came up with a honeycomb design with strong vertical walls that absorb energy much like bubble wrap or packing peanuts. The toothiness of each honeycomb wall adds height which adds strength, and allows the packaging to interlock with itself.
Not only is this packaging easier to recycle, it takes up way less space than other packaging alternatives. Once expanded, a 1,000 square foot roll of this stuff is equal to 2,500 square feet of bubble wrap, which constitutes about a dozen rolls.
Getting fresh water from salt water can be difficult to do at any kind of scale. Researchers have developed a new method of desalinating water that significantly reduces its cost. [via Electrek]
By mimicking the thermohaline circulation of the ocean, the researchers from MIT and Shanghai Jiao Tong University were able to solve one of the primary issues with desalination systems, salt fouling. Using a series of evaporator/condenser stages, the seawater is separated into freshwater and salt using heat from the sun.
Evaporating water to separate it from salt isn’t new, but the researchers took it a step further by tilting the whole contraption and introducing a series of tubes to help move the water along and create eddy currents. These currents help the denser, saltier water move off of the apparatus and down deeper into the fluid where the salt doesn’t cause an issue with the device’s operation. The device should have a relatively long lifetime since it has no moving parts and doesn’t require any electricity to operate.
The researchers believe a small, suitcase-sized device could produce water for a family for less than the cost of tap water in the US. The (paywalled) paper is available from Joule.
