Upgrading biogas with CCS in brine

About Solution

  • To reduce the emissions of greenhouse gas, electricity generation from biogas containing methane had been initiated by Southeast Asian countries in the recent years.
  • Nearly 30 biogas plants with the total electricity capacity more than 240 MW had been commissioned in Malaysia since 2009.

Bad news, we cannot do much with BIOGAS.

  • Biogas contains 20 – 60 % carbon dioxide (CO2) which reduces its heating value for various industrial users.
  • Hence, carbon capture technology is required to expand the potential of biogas in Malaysia and other countries.

Can we solve this problem?

  • Water scrubbing using an absorber is still one of the most widely used technologies in the industries to removal CO2.
  • The absorber size and cost can be greatly reduced by incorporating a hydrophobic, microporous membrane which provides a large surface area to transfer CO2 from a gas mixture into water circulated at the other side of membrane.
  • In our past studies, microporous PVDF membranes with great hydrophobicity have been developed for the separation of CO2 from methane.

Any other challenge?

  • Upgrading the greenhouse gas, namely biogas into biomethane by removing CO2 efficiently is not the only quest.
  • The final fate of CO2 captured from biogas has been long questioned. Scottish Carbon Capture and Storage (SCCS) reported on 78 carbon capture and storage (CCS) projects initiated in Europe at the commercial scale.
  • Some of these projects involves the utilization of CO2 for mineral carbonization, Enhanced Oil Recovery (EOR) and industrial uses, while some other projects involve the storage of CO2 in saline formation as well as depleted oil and gas formations.
  • The Petra Nova plant in U.S. and the Boundary Dam plant in Canada are fossil-fuelled power plants currently generating electricity with CCS. These plants capture more than 2 million tons CO2 per year for EOR.
  • However, these options are not suitable for biogas plants or landfill gas plants located far away from the storage site.

How can we do better for our future?

  • This project is designed to create an option to store the CO2 in brine which is the waste of reverse osmosis (RO) processes.
  • RO-desalinated water is not only used as potable water in many countries with limited freshwater sources, it is also highly demanded in the manufacture of electronic parts, speciality food and pharmaceuticals.
  • RO has been even commercially integrated into the household water filter units to produce drinking water. However, about 1.5 L of highly concentrated brine is produced for every 1 L of pure water produced by RO.
  • Brine disposal to the sea affects marine life and environment.
  • Several research teams proposed to react CO2 in water with the brine containing precipitating cations like Ca2+ to form insoluble carbonate salts at high pH.
  • CO2 gas was bubbling into water to form bicarbonate or carbonate in the water.
  • Unlike others, our project focuses on the development of membrane gas absorber-reactor (MGAR) that allows simultaneous CO2 absorption and brine carbonation at high mass transfer rate and less scaling.
  • The developed MGAR will be useful to propagate the knowledge in biogas purification and carbon storage in Southeast Asian countries.

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