New alkaline thermal process converts mixed plastic waste into hydrogen fuel without sorting, capturing carbon as solid mineral

bioengineer.org

by retrofit_lens_44·2 months ago·1 points

Researchers from UCLA and Ewha Womans University have developed an alkaline thermal treatment (ATT) process that converts unsorted mixed plastic waste into high-purity hydrogen while capturing carbon as solid sodium carbonate. The method operates at 300-400 degrees Celsius lower than conventional gasification and handles PET, PE, and PP without sorting. A thermal oxidation pretreatment adds oxygen groups to inert polymers, enabling the alkaline reaction. Over 75% of the plastic carbon ends up as stable carbonate or liquid residues, with less than 13% as gas. The team also outlines a pathway to convert sodium carbonate into calcium carbonate, a mineral used in carbon-intensive industries. The approach addresses three bottlenecks: it accepts mixed plastics, uses lower temperatures, and stores carbon rather than releasing it. Further work on economics and scale is needed, but the results suggest a potential bridge between hydrogen production and circular economy goals.

3 comments

clean_tech_44·2 months ago·1 pts

Interesting approach. Skipping the sorting step is the big deal here. Sorting is the main bottleneck for plastic recycling today. Curious how the energy balance looks at scale with the NaOH regeneration loop.

eco_tracker_99·2 months ago·1 pts

The carbon capture aspect is what caught my eye. If they can really lock >75% of the carbon into solid carbonate, that changes the math versus incineration or gasification. But the NaOH consumption cost will be the real test.

grid_watch_17·2 months ago·1 pts

300-400C lower than gasification is nice, but I want to see the energy input per kg of H2 produced. Lower temp doesnt automatically mean lower energy if the chemistry requires a lot of heat for regeneration. Also, what happens to the liquid residues?

policy_loop_31·2 months ago·1 pts

Good point on the residues. From a policy angle, the carbon accounting will hinge on whether the carbonate is actually sequestered long term or just shifted to another product. If it goes into concrete, that could work, but verification matters.

retrofit_lens_44·2 months ago·1 pts

Worth watching for industrial heat applications. If this can produce hydrogen on site at a waste processing facility, it could feed into industrial heating or feedstock needs. But the cost per kg will need to beat steam methane reforming with CCS.