A fascinating oddity in the list of potential alternative power sources is the microbial fuel cell, in which the chemical reactions of micro-organisms digesting their food are harnessed to harvest electrons and thus generate electrical current. We’d like to know more, so [Williamolyolson]’s soil microbial fuel cell is a particularly interesting glimpse into this field.
In this type of cell, an anode is placed at the bottom of a container of anaerobic wet soil medium laced with biomass to provide a food source for the bacteria, and a cathode is placed on the top of the medium exposed to air. The cell in this project appears to be a plastic coffee tub, and the electrodes are copper pan scourers. Unlike a chemical battery they do not need to be different materials and they themselves are not part of the chemistry of the cell, instead, they serve to collect and return the electrons to the cell.
The project logs detail a series of time-series measurements and experiments with placement of the cathode. Yield seems to be in the region of 200mV at about 1mA, though peaks as high as 400mV have been seen. It’s clear that this is not a cell that will replace your grid hook-up any time soon, but it still retains a lot of possibilities for use in micropower applications. There has been plenty of work in the field of micropower harvesting using other sources such as small solar cells, and this has the advantage of microbe-laden dirt being ubiquitous and free.
As the global climate emergency continues to loom over human civilization, feverish work is underway around the world to find technical and political solutions to the problem. Much has been gained in recent years, but as global emissions continue to increase, there remains much left to do to stave off the most catastrophic effects of climate change.
Renewable energy has led the charge, allowing humanity to continue to enjoy the wonders of electricity with a reduced environmental impact. The future looks promising, with renewable sources becoming cheaper than traditional fossil fuel energy plants in many cases, both in the USand abroad. At the same time, the rise of renewable technologies has brought new and varied challenges to the fore, which must be dealt with in kind. Take wind energy, for instance. Continue reading “What Will We Do With The Turbine Blades?”→
As anyone who has been faced with a recently-manufactured household appliance that has broken will know, sometimes they can be surprisingly difficult to fix. In many cases it is not in the interests of manufacturers keen to sell more products to make a device that lasts significantly longer than its warranty period, to design it with dismantling or repairability in mind, or to make spare parts available to extend its life. As hardware hackers we do our best with home-made replacement components, hot glue, and cable ties, but all too often another appliance that should have plenty of life in it heads for the dump.
Throughout its history, humankind’s travels have often brought unwelcome guests along for the ride, and sometimes introduced species into a new environment for a variety of reasons. These so-called invasive species are all too often responsible for widespread devastation in ecosystems, wiping out entire species and disrupting the natural balance. Now researchers are testing the use of robots for population control of these invasive species.
The mosquitofish is the target of current research by NYU Tandon School of Engineering and the University of Western Australia. Originally from parts of the US and Mexico, it was introduced elsewhere for mosquito control, including in Australia. There it has become a massive problem, destroying native species that used to eat mosquitoes. As a result the mosquito problem has actually worsened.
As the main issue with these invasive species is that they do not have any natural predators that might control their numbers, the researchers created robots which mimic the look and motion of natural predators. In the case of the mosquitofish the largemouth bass is its primary predator. The theory was that by exposing the mosquitofish to something that looks and moves just like one of these predator fish, they would exhibit the same kind of stress response.
So far laboratory tests under controlled condition have confirmed these expectations, with the mosquitofish displaying clear signs of stress upon exposure to the robotic largemouth bass. Even better, they displayed decreasing weight and were found to avoid potentially dangerous areas, indicating that instead of focusing on foraging, they were in survival mode. This should limit their environmental impact, including their ability to procreate.
Who knows, before long the surface waters of Australia may be home to the first robotic species of fish.
For many of us our landscapes are dotted with wind turbines, the vast majority of which are horizontally aligned as if they were giant aircraft propellers. A much rarer sight is the vertical wind turbine, which remains a staple of the wind power experimenter. [Troy] and his brother have posted a video showing a small wind 3D printed vertical turbine, which unusually includes an alternator made from scratch as well as the rotor itself.
The machine adopts a Savonius rotor design with three scoops, which offers simplicity and high torque at a lower rotational speed than some of the alternatives. The scoops are assembled from a number of 3D-printed sections, and directly drive the generator which uses a large number of coils on a stator encircled by a rotor containing an array of magnets. A simple rectifier and three-terminal regulator produces a 5-volt output.
Sadly there was not enough wind to give it a decent test for the video, but they demonstrate it with a very large fan standing in. We like the alternator design but we’d be interested to see how the sectional rotors hold up in outdoor conditions, and perhaps that regulator could benefit from a switch-mode component. If you fancy a go he says he’ll release the files as open source if there’s enough interest. We’re interested [Troy], please do!
It seems like hardly a day goes by that doesn’t see some news story splashed across our feeds that has something to do with Elon Musk and one or another of his myriad companies. The news is often spectacular and the coverage deservedly laudatory, as when Space X nails another double landing of its boosters after a successful trip to space. But all too often, it’s Elon’s baby Tesla that makes headlines, and usually of the kind that gives media relations people ulcers.
The PR team on the automotive side of Tesla can take a bit of a breather now, though. This time it’s Elon’s solar power venture, Tesla Energy Operations, that’s taking the heat. Literally — they’ve been sued by Walmart for rooftop solar installations that have burst into flames atop several of the retail giant’s stores. While thankfully no lives have been lost and no major injuries were reported, Walmart is understandably miffed at the turn of events, leading to the litigation.
Walmart isn’t alone in their exposure to potential Tesla solar problems, so it’s worth a look to see what exactly happened with these installations, why they failed, and what we as hackers can learn from the situation. As we’ll see, it all boils down to taking electrical work very seriously and adhering to standards designed to keep everyone safe, even when they just seem like a nuisance.
In the process of finding new, low-carbon ways to provide our homes with heat and electricity, it is that one might consider sources that never before came to mind. In London such a source that has been examined by researchers and an electricity network operator are the 2.5 meter wide tunnels that run for many kilometers underneath the city. In each of them are many more kilometers worth of electricity distribution cables, each of which produces so much heat from electric resistance that active cooling is required.
Currently, every 1.8 kilometers there are shafts that lead to the surface, through which cold surface air is brought in and the warm tunnel air is exhausted into the air. The study by London South Bank University researchers and UK Power Networks looked at using this heat directly for heating local houses, replacing the use of gas boilers. This is in effect similar to heating with waste heat from industrial processes, but with noticeable differences.
The thermal power available from each 1.8 kilometer section of tunnel differs between 100 – 460 kW by installing equipment at the top of the shafts. With London looking at using heat from the London Underground for heating in a similar fashion, it would be fascinating to see whether the combined heat from both underground sources could provide the city with a sizeable source of low-carbon heat, while increasing creature comfort.