Industrial gas manufacturer-exporter SS Gas Lab (Gas Lab) is advancing the environmental and profit potential of biogas and the utilisation of ‘waste’ carbon dioxide (CO2) through its CO2 recycling solutions.
As global energy sectors focus on meeting ‘net zero’ targets, the reduction and elimination of CO2 – a gas that Gas Lab see as being mistakenly treated as waste - has seen entire industries spawn around carbon capture, utilisation, and storage (CCUS).
Sustainable energy alternatives such as biogas – used to decarbonise hard-to-abate sectors such as heavy transport – produce CO2 as a by-product. According to Gas Lab, this CO2 is not considered by many companies as something capable of being captured and either utilised or sold.
To help implement the recycling of the gas, Gas Lab uses various techniques such as water scrubbing, pressure-swing adsorption (PSA), and amine upgrading.
Water scrubbing is the most widely used technology for removing CO2 from biogas and landfill gas. During the process, the polluted gas stream contacts the scrubbing liquid – water, in this case – forcing it through a pool of liquid to remove the pollutants.
Usually delivering available biomethane to 90-95% purity, the technique can deliver up to 97% with a small ‘slip’ rate of just 1%. The technique is considered most cost effective in small and medium size projects.
By using organic solvents instead of water, it’s possible to dissolve CO2 around 10x more than water does, allowing the customer to reduce equipment size.
Disadvantages of organic scrubbing include corrosion and complications around CO2 recuperation.
Gas Lab also uses its PSA technology to separate CO2 through a non-continuous process: biogas is compressed and then expanded, producing a yield of around 99% with low energy consumption. The correct technology must be utilised due to the potential for methane slip ro rise to 4-5%.
“If correctly designed and operated, it should stand under 1%,” said a Gas Lab spokesperson.
Membranes used in PSA are ideal for separating nitrogen – a contaminant in biomethane. Rejected nitrogen is mixed with the CO2 and is easily extracted when the CO2 is liquified due to its different physical properties.
Ideally used in conjunction with mid-sized plants, PSA can be used to obtain food grade product or in sectors such as landfill emissions treatment.
Gas Lab’s focus for CO2 mitigation is amine upgrading – a chemical-based technology that adsorbs CO2, recycling the amines before discharging later for compression. Due to the requirement of heat, energy costs per cubic metre are higher but cost operations are lower when used in large biogas systems.
“The net zero goal through carbon capture is worrying and we have to adapt to paradigm changes,” said Gas Lab.
“If you want to review your biogas project or your actual biogas plant, it will be our pleasure to guide you towards the best fit solution.”