The Waste Stack
HomeAboutWriting

Writing

Explainers, teardowns, and myth-busting on waste management systems and green engineering.

AllExplainerTeardownMyth-Busting
#recycling84#plastics46#emissions36#energy27#e-waste22#landfill22#wastewater18#food-waste17#policy17
27 postsReset filters

All posts

Plastic pyrolysis: nameplate capacity is not operating performance
TeardownOctober 3, 2026

Plastic pyrolysis: nameplate capacity is not operating performance

Closures and underutilisation expose the gap between making an oil and running a profitable plastic-to-plastic system.

Rise Reforming’s container: biogas to syngas is only the first conversion
ExplainerOctober 3, 2026

Rise Reforming’s container: biogas to syngas is only the first conversion

A modular reactor could serve stranded gas sources, but downstream chemistry, contamination and energy determine the business.

How sunlight turns plastic waste into hydrogen: inside Cambridge's 1 m² photoreforming panel
ExplainerSeptember 26, 2026

How sunlight turns plastic waste into hydrogen: inside Cambridge's 1 m² photoreforming panel

A semiconductor catches light, a cobalt–zirconium catalyst makes hydrogen, and dissolved plastic supplies the electrons. The first outdoor square-metre test works — modestly.

Bobine's 'electrified plastic recycling': striking numbers, no independent evidence
TeardownSeptember 23, 2026

Bobine's 'electrified plastic recycling': striking numbers, no independent evidence

The French startup claims +45% yield, −60% energy and −45% cost by heating a catalyst with induction to turn plastic waste into olefins. Every figure is self-reported, and none has a baseline.

Amino Acid Salts Can Scrub CO2 Out of Biogas. Just Not Quite Enough
ExplainerSeptember 20, 2026

Amino Acid Salts Can Scrub CO2 Out of Biogas. Just Not Quite Enough

A Stuttgart process separates 92.3% of the CO2 from raw biogas using a benign solvent. Gas grids want methane above 96%.

HBI's EVA3: Four Known Sludge Processes, Wired Into One. No Numbers Yet.
TeardownSeptember 16, 2026

HBI's EVA3: Four Known Sludge Processes, Wired Into One. No Numbers Yet.

Hydrothermal carbonisation, gasification, energy recovery and phosphorus capture in a single automated plant near Treviso. The integration is the novelty — and the performance data is absent.

Pirelli, Pyrum, BASF and Synthos: A Tyre Loop With an Accounting Step in the Middle
TeardownSeptember 15, 2026

Pirelli, Pyrum, BASF and Synthos: A Tyre Loop With an Accounting Step in the Middle

Four companies, six steps, and one link where the recycled content is attributed rather than physically traced. The pyrolysis is real. The loop is partly bookkeeping.

Aduro's Hydrochemolytic Route: Water-Mediated Plastic Conversion, and the Refinery Problem It Does Not Escape
TeardownSeptember 12, 2026

Aduro's Hydrochemolytic Route: Water-Mediated Plastic Conversion, and the Refinery Problem It Does Not Escape

Aduro says its water-based chemistry converts waste plastic and heavy oil at lower temperatures than pyrolysis. Even if that holds, the output is still a feedstock that a refinery has to finish.

"Waste-to-Energy Is Clean Renewable Power" — No, and the Reason Is Arithmetic
Myth-BustingSeptember 5, 2026

"Waste-to-Energy Is Clean Renewable Power" — No, and the Reason Is Arithmetic

Burning municipal waste for electricity emits more CO2 per unit of power than a coal plant. The climate case for incineration rests entirely on what the waste would have done instead, not on the electricity.

Anferra Says Grinding Sludge Becomes Ferric Chloride and Hydrogen. Here Is What Is Missing.
TeardownSeptember 3, 2026

Anferra Says Grinding Sludge Becomes Ferric Chloride and Hydrogen. Here Is What Is Missing.

A startup claims up to 90% iron recovery from steel grinding sludge, a saleable coagulant, hydrogen as a by-product and a negative carbon figure. Almost none of the process detail behind those numbers has been published.

Two waste piles, one reaction: calcite and hydrogen at the same time
ExplainerAugust 30, 2026

Two waste piles, one reaction: calcite and hydrogen at the same time

An Ohio State team pairs steel slag and coal ash with captured CO2, mineralises the carbon into calcite, and spends the heat that reaction gives off on splitting water. Here is the mechanism — and what the paper does not tell you.

The magnet that cracks itself apart: how hydrogen decrepitation closes the rare-earth loop
ExplainerAugust 28, 2026

The magnet that cracks itself apart: how hydrogen decrepitation closes the rare-earth loop

Expose a neodymium magnet to hydrogen and it fractures along its own grain boundaries into a demagnetised powder that can be pressed straight back into new magnets. The mechanism is elegant. Getting the magnets out of the devices is the hard part.

Two "direct recycling" startups just got $150M from DOE
TeardownAugust 26, 2026

Two "direct recycling" startups just got $150M from DOE

Nth Cycle took $100M and Princeton NuEnergy $50M out of the DOE's $500M battery round. Both have operating plants and third-party numbers — which is more than most. Neither has solved the part a grant cannot buy: feedstock.

Does BASF's tyre-derived wall paint close the loop?
TeardownAugust 19, 2026

Does BASF's tyre-derived wall paint close the loop?

End-of-life tyres go into a pyrolysis reactor; a certified share of recycled feedstock comes out attributed to a tin of interior paint. The chemistry is real, the audit is real, and the word doing the most work is "attributed".

HUI has a waste-to-SAF licence. It does not yet have a plant
TeardownAugust 18, 2026

HUI has a waste-to-SAF licence. It does not yet have a plant

On 17 August, Hydrogen Utopia International bought a $500,000 UK licence for plasma gasification aimed at sustainable aviation fuel. A licence is a real asset. It is also nine milestones short of a litre of jet fuel.

Recycling does not always use more energy than making something new
Myth-BustingAugust 14, 2026

Recycling does not always use more energy than making something new

Collection trucks and sorting lines are visibly energy-hungry, which makes the myth feel obvious. EPA's own numbers say otherwise for most materials — but the word doing the damage in the myth is "always", and it cuts both ways.

Divert's 2.5-million-pound food-to-energy claim: circular loop or scoped case study?
TeardownAugust 13, 2026

Divert's 2.5-million-pound food-to-energy claim: circular loop or scoped case study?

Divert and US Cold Storage say 2.5 million pounds of unsold food became renewable natural gas and fertiliser in 15 months. The operating facts are solid. The carbon accounting behind them is not published.

No, burning trash for electricity does not make recycling pointless
Myth-BustingAugust 10, 2026

No, burning trash for electricity does not make recycling pointless

Energy recovery has a legitimate place in a waste system. It sits below prevention, reuse, recycling and composting - and roughly a tenth of what goes in still comes out as ash bound for landfill.

A KitKat wrapper made from soft plastics: closed loop, or mass-balance proof of concept?
TeardownAugust 8, 2026

A KitKat wrapper made from soft plastics: closed loop, or mass-balance proof of concept?

Nine and a half tonnes of pyrolysis oil, five tonnes of resin, seven million wrappers. A real supply chain ran end to end - and almost none of the numbers that would prove it works were published.

A dead lithium-ion battery is not safe in the trash or the blue bin
Myth-BustingAugust 7, 2026

A dead lithium-ion battery is not safe in the trash or the blue bin

A battery that no longer powers your device still holds enough energy to start a fire when it is crushed in a collection truck or a sorting line. The recycling symbol on it does not mean curbside.

"Two Indonesian waste-to-energy projects secured" - award, milestone, or conditional headline?
TeardownAugust 6, 2026

"Two Indonesian waste-to-energy projects secured" - award, milestone, or conditional headline?

SUS ENVIRONMENT says it was selected as preferred partner for two Indonesian WtE projects. The announcement contains no capacity, financing, schedule or emissions data - and a Conditional LOA is not a project.

Casablanca's $1.5B waste-to-energy bet: circular solution or combustion lock-in?
TeardownAugust 5, 2026

Casablanca's $1.5B waste-to-energy bet: circular solution or combustion lock-in?

A 33.5-year exclusive treatment concession, three combustion lines and roughly 1 TWh a year. The contracts are signed. The financing, the emissions baseline and the recycling question are not.

Tire-to-fuels campus: breakthrough, or a press-release milestone?
TeardownAugust 5, 2026

Tire-to-fuels campus: breakthrough, or a press-release milestone?

Waste Energy says its Midland, Texas campus has entered final commissioning. That is a real construction milestone — and it is not the same thing as proven commercial scale.

Reading the BITS Pilani Wastewater Claim Line by Line
TeardownAugust 1, 2026

Reading the BITS Pilani Wastewater Claim Line by Line

Six nines of disinfection, 90% organics removal, reusable water and biogas — announced without an energy balance, a cost figure, or a recovery yield. A teardown of what the numbers do and do not say.

Electric Pulses, Bacteria, Biogas: A Three-Stage Loop for Biopharma Wastewater
ExplainerAugust 1, 2026

Electric Pulses, Bacteria, Biogas: A Three-Stage Loop for Biopharma Wastewater

A BITS Pilani system disinfects pharmaceutical wastewater with electric pulses, digests the organics biologically, and turns the leftover sludge into methane. Here is the logic of each stage.

Is Turning Plastic Into Hydrogen Actually Recycling?
Myth-BustingAugust 1, 2026

Is Turning Plastic Into Hydrogen Actually Recycling?

The chemistry is real. The label is doing a lot of work. If the outputs are hydrogen gas and mineral carbonate, no plastic has been recycled — something else has happened.

How Alkaline Thermal Treatment Pulls Hydrogen Out of Unsorted Plastic
ExplainerAugust 1, 2026

How Alkaline Thermal Treatment Pulls Hydrogen Out of Unsorted Plastic

A new PNAS study converts mixed PET, PE and PP into >90% pure hydrogen in one reactor — no polymer sorting, and most of the carbon never reaches the gas phase.

The Waste Stack

Independent writing on waste management systems and green engineering.

All writingAbout
#plastics#recycling#e-waste#landfill#wastewater#energy#food-waste#emissions#policy