An Inexpensive Way To Break Down Plastic

March 27, 2025 by Bryan Cockfield 11 Comments

Plastic has been a revolutionary material over the past century, with an uncountable number of uses and an incredibly low price to boot. Unfortunately, this low cost has led to its use in many places where other materials might be better suited, and when this huge amount of material breaks down in the environment it can be incredibly persistent and harmful. This has led to many attempts to recycle it, and one of the more promising efforts recently came out of a lab at Northwestern University.

Plastics exist as polymers, long chains of monomers that have been joined together chemically. The holy grail of plastic recycling would be to convert the polymers back to monomers and then use them to re-make the plastics from scratch. This method uses a catalyst to break down polyethylene terephthalate (PET), one of the more common plastics. Once broken down, the PET is exposed to moist air which converts it into its constituent monomers which can then be used to make more PET for other uses.

Of course, the other thing that any “holy grail” of plastic recycling needs is to actually be cheaper and easier than making new plastic from crude oil, and since this method is still confined to the lab it remains to be seen if it will one day achieve this milestone as well. In the meantime, PET can also be recycled fairly easily by anyone who happens to have a 3D printer around.

Producing Syngas From CO2 And Sunlight With Direct Air Capture

March 21, 2025 by Maya Posch 17 Comments

The prototype DACCU device for producing syngas from air. (Credit: Sayan Kar, University of Cambridge)

There is more carbon dioxide (CO₂) in the atmosphere these days than ever before in human history, and while it would be marvelous to use these carbon atoms for something more useful, capturing CO₂ directly from the air isn’t that easy. After capturing it would also be great if you could do something more with it than stuff it into a big hole. Something like producing syngas (CO + H₂) for example, as demonstrated by researchers at the University of Cambridge.

Among the improvements claimed in the paper as published in Nature Energy for this direct air capture and utilization (DACCU) approach are that it does not require pure CO₂ feedstock, but will adsorb it directly from the air passing over a bed of solid silica-amine. After adsorption, the CO₂ can be released again by exposure to concentrated light. Following this the conversion to syngas is accomplished by passing it over a second bed consisting of silica/alumina-titania-cobalt bis(terpyridine), that acts as a photocatalyst.

The envisioned usage scenario would be CO2 adsorption during the night, with concentrated solar power releasing it the day with subsequent production of syngas. Inlet air would be passed only over the adsorption section before switching the inlet off during the syngas generating phase. As a lab proof-of-concept it seems to work well, with outlet air stripped from virtually all CO₂ and very high conversion ratio from CO₂ to syngas.

Syngas has historically been used as a replacement for gasoline, but is also used as a source of hydrogen (e.g. steam reformation (SMR) of natural gas) where it’s used for reduction of iron ore, as well as the production of methanol as a precursor to many industrial processes. Whether this DACCU approach provides a viable alternative to SMR and other existing technologies will become clear once this technology moves from the lab into the real world.

Thanks to [Dan] for the tip.

Ultra-Low Power Soil Moisture Sensor

March 18, 2025 by Bryan Cockfield 13 Comments

Electricity can be a pretty handy tool when it stays within the bounds of its wiring. It’s largely responsible for our modern world and its applications are endless. When it’s not running in wires or electronics though, things can get much more complicated even for things that seem simple on the surface. For example, measuring moisture in soil seems straightforward, but corrosion presents immediate problems. To combat the problems with measuring things in the natural world with electricity, [David] built this capacitive soil moisture sensor which also has the benefit of using an extremely small amount of energy to operate.

The sensor is based on an STM32 microcontroller, in this case one specifically optimized for low-power applications. The other low-power key to this build is the small seven-segment e-ink display. The segments are oriented as horizontal lines, making this a great indicator for measuring a varying gradient of any type. The microcontroller only wakes up every 15 minutes, takes a measurement, and then updates the display before going back to sleep.

To solve the problem resistive moisture sensors have where they’re directly in contact with damp conditions and rapidly corrode, [David] is using a capacitive sensor instead which measures a changing capacitance as moisture changes. This allows the contacts to be much more isolated from the environment. The sensor has been up and running for a few months now with the coin cell driving the system still going strong and the house plants still alive and properly watered. Of course if you’re looking to take your houseplant game to the next level you could always build a hydroponics system which automates not only the watering of plants but everything else as well.

ice forming on surface with plus and minus pole

The Coolest Batteries You’ve Never Heard Of

March 9, 2025 by Heidi Ulrich 55 Comments

Imagine cooling your building with the same principle that kept Victorian-era icehouses stocked with lake-frozen blocks, but in modern form. That’s the idea behind ice batteries, a clever energy storage hack that’s been quietly slashing cooling costs across commercial buildings. The invention works by freezing water when energy is cheap, and using that stored cold later, they turn major power hogs (air conditioning, we’re looking at you) into more efficient, cost-effective systems.

Pioneers like Nostromo Energy and Ice Energy are refining the tech. Nostromo’s IceBrick modules pack 25 kWh of cooling capacity each, install on rooftops, and cost around $250 per kWh—about half the price of lithium-ion storage. Ice Energy’s Ice Bear 40 integrates with HVAC systems, shifting up to 95% of peak cooling demand to off-peak hours. And for homes, the Ice Bear 20 replaces traditional AC units while doubling as a thermal battery.

Unlike lithium-ion, ice batteries don’t degrade chemically – their water is endlessly reusable. Combining the technology with this hack, it’s even possible in environments where water is scarce. But the trade-off? They only store cooling energy. No frozen kilowatts for your lightbulbs, just an efficient way to handle the biggest energy drain in most buildings.

Could ice batteries help decentralize energy storage? They’re already proving their worth in high-demand areas like California and Texas. Read the full report here and let us know your thoughts in the comments.

Continue reading “The Coolest Batteries You’ve Never Heard Of” →

A balding man in a blue suit and tie sits behind rows of plants on tables. A bright yellow watering can is close to the camera and out of focus.

Phytoremediation To Clean The Environment And Mine Critical Materials

February 28, 2025 by Navarre Bartz 10 Comments

Nickel contamination can render soils infertile at levels that are currently impractical to treat. Researchers at UMass Amherst are looking at how plants can help these soils and source nickel for the growing EV market.

Phytoremediation is the use of plants that preferentially hyperaccumulate certain contaminants to clean the soil. When those contaminants are also critical materials, you get phytomining. Starting with Camelina sativa, the researchers are looking to enhance its preference for nickel accumulation with genes from the even more adept hyperaccumulator Odontarrhena to have a quick-growing plant that can be a nickel feedstock as well as produce seeds containing oil for biofuels.

Despite being able to be up to 3% Ni by weight, Odontarrhena was ruled out as a candidate itself due to its slow-growing nature and that it is invasive to the United States. The researchers are also looking into what soil amendments can best help this super Camelina sativa best achieve its goals. It’s no panacea for expected nickel demand, but they do project that phytomining could provide 20-30% of our nickel needs for 50 years, at which point the land could be turned back over to other uses.

Recycling things already in technical cycles will be important to a circular economy, but being able to remove contaminants from the environment’s biological cycles and place them into a safer technical cycle instead of just burying them will be a big benefit as well. If you want learn about a more notorious heavy metal, checkout our piece on the blessings and destruction wrought by lead.

Continue reading “Phytoremediation To Clean The Environment And Mine Critical Materials” →

An overhead shot of a parking lot. A road with cars parked along it is on the right hand side of the image. The top center shows a drilling rig on tracks drilling at a slight angle into the ground. Many different semi trailers dot the parking along with several different pallets of construction supplies. An excavator and skylift/forklift are also at work in the lot.

District Heat Pump Systems Save Money And Gas Utilities

February 26, 2025 by Navarre Bartz 50 Comments

Ground-source heat pump systems are one of the most efficient ways to do climate control, but digging the wells can be prohibitively expensive for the individual citizen. What if you could do it at a larger scale?

Starting with a pilot to serve 37 commercial and residential buildings in Framingham, MA, Eversource is using its experience with natural gas drilling and pipe to serve up a lower carbon way to heat and cool this neighborhood. While district heating via geothermal has precedents elsewhere in the country, Boise is a notable example, it has remained a somewhat niche technology. Once networked, excess heat from one location can be used elsewhere in the system, like data centers or industrial facilities being used to heat homes in the winter.

As gas utilities look to transition away from fossil fuels, their existing knowledge base is a perfect fit for geothermal, but there are some regulatory hurdles. Six states have passed laws allowing natural gas utilities to expand beyond just gas, and bills have been filed in six more. This will likely accelerate with the formation of the Utility Networked Geothermal Collaborative which includes many utilities including giants like Dominion Energy who are looking to expand their energy portfolios.

If you want to dig more into district heating systems or geothermal energy, we’ve covered cogeneration from power plants to serve up the heat instead, doing it with wind, or even using old coal mines for geothermal heat.

NEMA Releases Standard For Vehicle-to-Grid Applications

February 22, 2025 by Navarre Bartz 70 Comments

Vehicle-to-grid (V2G) has been hailed as one of the greatest advantages of electrifying transportation, but has so far remained mostly in the lab. Hoping to move things forward, the National Electrical Manufacturers Association (NEMA) has released the Electric Vehicle Supply Equipment (EVSE) Power Export Permitting Standard.

The new standards will allow vehicle manufacturers and charger (EVSE) suppliers to have a unified blueprint for sending power back and forth to the grid or the home, which has been a bit of a stumbling block so far toward adoption of a seemingly simple, but not easy, technology. As renewables make up a larger percentage of the grid, using the increasing number of EVs on the road as battery backup is a convenient solution.

While the standard will simplify the technology side of bidirectional charging, getting vehicle owners to opt into backing up the grid will depend on utilities and regulators developing attractive remuneration plans. Unfortunately, the standard itself is paywalled, but NEMA says the standard “could put money back in electric vehicle owners’ pockets by making it easier for cars to store energy at night or when turned off and then sell power back to grids at a profit during peak hours.”

We’ve covered some of the challenges and opportunities of V2G systems in the past and if you want something a little smaller scale, how about using a battery that was once in a vehicle to backup your own home?