Sorbents Derived From Incineration and Gasification Ashes for High Temperature Carbon Capture by Calcium Looping
1 October 2026
Affiliation
NTU
Focus topic
CO2 Capture
Waste ash becomes sorbent for calcium looping capture
Summary
Amine scrubbing, the commercial default for capturing CO₂ from flue gas, consumes energy equivalent to roughly 48% of a power plant's operating expenditure, and the cheaper calcium looping alternative burns through mined limestone because the sorbent sinters and loses capacity. This technology turns incineration and gasification ash, currently landfilled, into the sorbent instead.
Achievements:
A screening and pre-processing protocol grades ash by active calcium content, crushes or agglomerates it to a fluidisable size, and strengthens it by calcination at 750oC.
Using ash from commercial municipal waste incinerators and NTU's own waste-to-energy research facility, air pollution control ash captured 442 mg CO₂/g and gasification fly ash 327 mg/g, both exceeding the 313 mg/g of commercial pure CaO.
Treated gasification fly ash held 67 mg/g after 100 carbonation-calcination cycles at 750oC and retained 97% of initial uptake after 20 cycles, and washing bottom ash cut attrition losses from about 7% to under 2.6%.
Performance was verified in dry, wet and acid (HCl) flue gas.
Carbon abatement potential is driven by the sorbent's CO₂ uptake per cycle and the number of cycles achieved. It abates emissions from cement, waste-to-energy and hydrogen plants while displacing mined limestone and diverting ash from landfill; spent sorbent can be upcycled as construction material.
What makes this novel compared to best-in-class technology?
High-temperature capture normally consumes purpose-made material derived from mined limestone. This process makes the same material from incinerator and gasifier ash instead. The input therefore costs nothing, and the plant supplying the ash saves on disposal at the same time.
TRL Level
1-3
Relevant for
Waste-to-energy plants, cement and lime kilns, high-temperature industrial furnaces using calcium looping
About
Inventors: Preston Tan Choon Kiat, Chan Wei Ping, Liu Wen, Grzegorz Lisak, Andrei Veksha
Affiliation: Nanyang Technological University, Singapore (NTU), Nanyang Environment & Water Research Institute (NEWRI)
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