The study took place over 18 months; funded by the Coal21 Fund, it was managed by fellow Australian group Procom Consultants.
Coal21, which supports pre-commercial technologies for low emission coal developments such as carbon capture, is now recommending carbon sponge technology adoption for coal-fired plants as well as industrial processes.
"The methodology applied by Procom in this in-depth study included the development of rate-based models for absorber/stripper, the validation of the enzymatic technology's heat/mass balance and the key performance parameters and model integration of the enzymatic technology in coal-fired power plants," CO2 Solutions officials explained.
They also noted that it used the Aspen Plus simulation software to model two reference cases: the US Department of Energy (DoE) SC reference case (B12B) and the supercritical (SC) power plant from Queensland, Australia.
"In both cases, the performance of the corporation's enzymatic technology was compared to a known advanced amine technology, Cansolv. The corporation provided two unoptimised process books of its enzymatic technology at different scales based on its ProTreat models to the PROCOM study."
Post-study, Procom reported back its conclusions, including that the enzymatic technology appears to be well suited to coal-based industrial plants - in particular, iron, steel and cement for their tolerance to flue gas oxides. They also seem to have "significant environmental and operational advantages" over other post-combustion capture methods, the firm added.
Additionally, using low-grade, residual thermal energy in the form of hot water resulted in the unoptimised enzymatic solvent performance yielding marginally more electricity versus an amine process.
"The enzymatic technology's tolerance to SOx and NOx contaminants in the flue gas of low-sulphur coal-fired plants provides it with an estimated 30% capex advantage relative to the advanced amine technology since there is no requirement to polish this flue gas down to single digit parts per million (ppm) using flue gas desulphurisation (FGD) and selective catalytic reduction (SCR)," Procom also said in the report.
"Modelling has confirmed that supercritical (SC) coal-fired power plants in Australia have sufficient residual low-grade heat to give the enzymatic technology a slight power efficiency advantage over the advanced amine technology. Moreover, the likely further optimisation of the enzymatic technology would extend this advantage."
The study noted that the enzymatic tech could tap into renewable sources, such as geothermal and solar, in addition to its use with residual, low-grade heat in the form of hot water. By tapping into the external renewable heat sources, the industry could possibly see significant reductions in the thermal parasitic load of carbon capture.
"The Procom study confirmed the enzymatic process minimises the environmental footprint through the use of an ionic (non-volatile) and environmentally benign solvent," CO2 Solutions said of the technology.
It converts oxide contaminants in flue gas (SOx and NOx) into high-value sulphates, sulphites, nitrates and nitrites accumulating over a period of time in the solvent.
"As a result, the periodic bleed of this nontoxic solvent creates an opportunity to recover valuable materials, such as potassium nitrate fertiliser, which reduces the overall operating cost of the enzymatic technology. This approach is not available to the advanced amine technology. Through expected optimisation, the enzymatic technology could be more favourable than amine-based processes regarding capex and overall energy requirements, and very favourable to amine-based processes regarding aspects related to management of oxide flue gas contaminants."
Richard Surprenant, CTO of CO2 Solutions, said that the extensive and lengthy study underscores the low cost and environmentally friendly qualities of its process.
"It further confirms the major paradigm shift that the enzymatic technology represents for the carbon capture industry," he added.
