Results of study into Enzymatic Technology for CO2 capture in industry

Jul 02 2019

The technology appears to have significant environmental and operational advantages over alternative post-combustion capture technologies, such as advanced amine technology.

CO2 Solutions and COAL21, funded by the Australian black coal industry for the demonstration of low emission coal technologies, such as carbon capture and storage (CCS), have announced the results of a study examining the performance of the Corporation's enzymatic technology when applied to coal-fired power plants for post-combustion carbon capture. The study was conducted over the past 18 months by PROCOM Consultants (Brisbane, Australia) and funded by the COAL21 Fund.

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. The simulation software used was Aspen Plus.

Two reference cases were modelled: i) US DoE SC reference case (B12B) and ii) 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 unoptimized process books of its enzymatic technology at different scales based on its ProTreat® models to the PROCOM study.

Following are the main study conclusions reached by PROCOM Consultants:

  • The enzymatic technology appears well suited to coal-based industrial plants (e.g. iron and steel, cement) in particular for its tolerance to the oxides in flue gas and appears to have significant environmental and operational advantages over alternative post-combustion capture technologies, such as advanced amine technology.
  • By using low-grade, residual thermal energy in the form of hot water, the modelled unoptimized enzymatic solvent performance yields marginally more electricity in the context of an existing coal-fired power plant in Australia compared to the advanced 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 Desulfurization (FGD) and Selective Catalytic Reduction (SCR).
  • 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 optimization of the enzymatic technology would extend this advantage.
  • In addition to being able to use residual, low-grade heat in the form of hot water as its thermal energy, the enzymatic technology could also tap into renewable energy sources such as geothermal and solar thermal sources for its energy requirements, options which are more challenging to the advanced amine technology which requires steam. Tapping into these sources of external renewable heat would potentially significantly reduce the thermal parasitic load of carbon capture.
  • The PROCOM study confirmed the enzymatic process minimizes the environmental footprint through the use of an ionic (non-volatile) and environmentally benign solvent.
  • The enzymatic technology converts a portion of the oxide contaminants in the flue gas (SOx and NOx) into high-value sulphates, sulphites, nitrates and nitrites, which accumulate over 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 fertilizer, which reduces the overall operating cost of the enzymatic technology. This approach is not available to the advanced amine technology.
  • Through expected optimization, 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, CO2 Solutions' Chief Technology Officer, commented, "The detailed report prepared by Procom Consultants highlights the low-cost and environmentally friendly qualities of our process. It further confirms the major paradigm shift that the enzymatic technology represents for the carbon capture industry. We strongly believe that the future of carbon capture rests on modern, innovative, low environmental footprint, and low-cost technologies. It's time to face today's carbon challenge with 21st-century technology."

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