A rectangular box with a purple section sandwiched between two red sections sits on a black tabletop. The end of the box is open. Black and red wires run out of the back of the box to a breadboard.

Improving Wind Turbine Testing With A Better Air Source

When comparing the efficiency of different wind turbine blade designs, [AdamEnt] found using a hair dryer wasn’t the best tool for the job. Enter his new 3D-printed wind tunnel.

After several prototypes, [AdamEnt] decided on a design that exploits slicer infill to create a flow straightener without having to do any tedious modeling of a lattice. Combined with a box on both ends of the straightener to constrain the flow, he has a more controllable air source with laminar instead of turbulent flow for testing his wind turbines.

The BLDC motor driving the air is attached to a toroidal blade of MIT fame. We get a little bit of the math behind calculating wind turbine efficiency and see a quick test of a blade placed next to the outlet of the air source at the end of the video.

If you’re planning on building your own wind tunnel, we’ve covered a few. We’ve even seen one that goes up to Mach 20, although that probably wouldn’t be useful for wind turbine design!

Continue reading “Improving Wind Turbine Testing With A Better Air Source”

Recycling Of Portland Cement And Steel In Electric Arc Furnaces

The use of concrete and steel have both become the bedrock of modern-day construction, which of course also means that there is a lot of both which ends up as waste once said construction gets demolished again. While steel is readily recyclable, the Portland cement that forms the basis of concrete so far is not. Although the aggregate from crushed concrete can be reclaimed, the remainder tends to end up in a landfill, requiring fresh input of limestone to create more cement. Now a team of researchers from the University of Cambridge claim to have found a way to recycle hydrated Portland cement by using it as flux during steel production in electric arc furnaces (EAFs).

Not only does this save a lot of space in landfills, it also stands to reduce a lot of the carbon dioxide produced during cement and steel production, which is primarily from the use of limestone for cement and lime-dolomite for steel. The details can be found in the open access paper in Nature by [Cyrille F. Dunant] and colleagues. Essentially reclaimed cement paste is mixed with some fresh material to form the flux that shields the molten steel in an EAF from the atmosphere. The flux creates the slag layer that floats on top of the molten steel, with this slag after cooling down being ground up and turned into cement clinker, which is then mixed to create fresh cement.

The process has been patented by Cambridge, who call the product ‘Cambridge Electric Cement‘, with the claim that if using low-carbon power sources for the EAF like hydro and nuclear, it would constitute ‘no emissions’ and ‘no landfill’ cement. We have to see how this works out on an industrial scale, of course, but it would definitely be nice to keep concrete and cement in general out of landfills, while cutting back on limestone mining, as well as questionable practices like adding heavy metal-laden fly ash as filler to concrete.

Thanks to [cscott] for the tip.

Germany’s Solar Expansion And The Negative Effects Of Electricity Overproduction

Amidst the push for more low-carbon energy, we see the demolishing of one of the pillars of electric grids: that of a careful balancing between supply and demand. This is not just a short-term affair. It also affects the construction of new power plants, investments in transmission capacity, and so on. The problem with having too much capacity is that it effectively destroys the electricity market, as suppliers need to make a profit to sustain and build generators and invest in transmission capacity. This is now the problem that Germany finds itself struggling with due to an overcapacity of variable renewable power sources (VRE) like solar and wind.

With a glut of overcapacity during windy and sunny days, this leads to prices going to zero or even negative. While this may sound positive (pun intended), it means that producers are not being paid. Worse, it means that when, for example, France buys German wind power for negative Euros via the European Electricity Exchange (EEX), it means that Germany actually pays France, instead of vice versa. The highly variable output of wind and solar also means a big increase in curtailment and redispatch measures to keep the grid stable, all of which costs money and drives up operating costs.

Continue reading “Germany’s Solar Expansion And The Negative Effects Of Electricity Overproduction”

An image of an orange, translucent glowing quartz rod. Thermocouples can be seen at intervals along the rod looking in.

Industrial Solar Heat Hits 1000˚C

While electricity generation has been the star of the energy transition show, about half of the world’s energy consumption is to make heat. Many industrial processes rely on fossil fuels to reach high temps right now, but researchers at ETH Zurich have found a new way to crank up the heat with a solar thermal trap. [via SciTechDaily]

Heating water for showers or radiant floor systems in homes is old hat now, but industrial application of solar power has been few and far between. Part of the issue has been achieving high enough temperatures. Opaque absorbers can only ever get as hot as the incident surface where the sun hits them, but some translucent materials, like quartz can form thermal traps.

In a thermal trap, “it is possible to achieve temperatures that are higher in the bulk of the material than at the surface exposed to solar radiation.” In the study, the researchers were able to get a 450˚C surface to produce 1,050˚C interior temperature in the 300 mm long quartz rod. The system does rely on concentrated solar power, 135 suns-worth for this study, but mirror and lens systems for solar concentration already exist due to the aforementioned electrical power generation.

This isn’t the only time we’ve seen someone smelting on sunlight alone, and you can always do it less directly by using a hydrogen intermediary. If you’re wanting a more domestic-level of heat, why not try the wind if the sun doesn’t shine much in your neighborhood?

DIY Bimetallic Strip Dings For Teatime

Do you like your cup of tea to be cooled down to exactly 54 C, have a love for machining, and possess more than a little bit of a mad inventor bent? If so, then you have a lot in common with [Chronova Engineering]. In this video, we see him making a fully mechanical chime-ringing tea-temperature indicator – something we’d be tempted to do in silicon, but that’s admittedly pedestrian in comparison.

The (long) video starts off with making a DIY bimetallic strip out of titanium and brass, which it pretty fun. After some math, it is tested in a cup of hot water to ballpark the deflection. Fast-forward through twenty minutes of machining, and you get to the reveal: a tippy cup that drops a bearing onto a bell when the deflection backs off enough to indicate that the set temperature has been reached. Rube Goldberg would have been proud.

OK, so this is bonkers enough. But would you believe a bimetallic strip can be used as a voltage regulator? How many other wacky uses for this niche tech do you know?

Thanks [Itay] for the tip!

A small gauge showing power generated by a house's solar panels.

Cute Solar Power Gauge Brightens The Day

What’s the first thing you want after installing solar? All the sunshine you can get, of course. Especially if you did it in the wintertime. And what would be more fun than monitoring your power generation, especially leading up to the equinox, or start of spring? Probably not much, especially if you built a cute solar power gauge like [Ben] did to keep him from obsessively checking his phone.

At the heart of this build is the affordable Seeed Xiao ESP32C3, which controls an equally cost-effective automotive stepper via an L293D H-bridge driver. Then it was just a matter of hooking it into Home Assistant. As power is generated by the solar system, the cute little sun on the gauge rises and shows the kilowattage gained.

Unfortunately there’s no real data sheet for the stepper, so [Ben] opted to use the 5 V from the USB that’s powering the ESP32. However, it seems like this might not be enough power because the gauge appears to drift a bit. To fix this, [Ben] runs the stepper_init script twice a day, which cranks the dials all the way forward then all the way backward before settling on the last known value.

Are you interested in solar? Here’s how you can build a small power system.

Bad Experiences With A Cheap Wind Turbine

If you’ve got a property with some outdoor space and plenty of wind, you might consider throwing up a windmill to generate some electricity. Indeed, [The Broject List] did just that. Only, his experience was a negative one, having purchased a cheap windmill online. He’s warning off others from suffering the same way by explaining what was so bad about the product he bought.

The windmill in question was described as a “VEVOR Windturbine”, which set him back around 100 euros, and claimed to be capable of producing 600 watts at 12 volts. He starts by showing how similar turbines pop up for sale all over the Internet, with wildly inflated specs that have no relation to reality. Some sellers even charge over 500 euros for the same basic device.

He then demonstrates the turbine operating at wind speeds of approximately 50 km/h. The output is dismal, a finding also shared by a number of other YouTube channels out there. Examining the construction of the wind turbine’s actual generator, he determines that it’s nowhere near capable of generating 600 watts. He notes the poorly-manufactured rotor and aluminium coils as particular disappointments. He concludes it could maybe generate 5 watts at most.

Sadly, it’s easy to fall into this trap when buying online. That’s where it pays to do your research before laying down your hard-earned cash. Continue reading “Bad Experiences With A Cheap Wind Turbine”