Context:
- A strain of bacteria could potentially remove methane from major emission sites such as landfills, paddy fields, and oil and gas wells, according to a new study.
Why it is important?
- The bacterial strain Methylotuvimicrobium buryatense 5GB1C consumes methane, which is over 85 times more potent than carbon dioxide (CO2) on a 20-year timescale. It is responsible for nearly 30 per cent of the total global warming.
- Researchers from the University of Washington explained that the global average temperature rise can be reduced 0.21-0.22 degree Celsius by removing 0.3-1 petagrams of methane by 2050.
Benefit:
- Harnessing these bacteria on a large scale can keep 240 million tonnes of methane from reaching the atmosphere by 2050.
- Methane-eating bacteria (methanotrophs) can be an attractive option. But they grow best when the methane concentration is around 5,000-10,000 parts per million (ppm).
- However, methane levels in key emission sites are around 500 ppm. So the researchers screened a range of existing methanotrophs to identify those that consume such low methane (500 ppm) at significantly higher rates.
- They found that Methylotuvimicrobium buryatense 5GB1C performed the best at 500 ppm. Further tests also showed that this strain grew well even at 200 ppm.
- It can grow at low methane concentrations ranging from 200-1,000 ppm. These features make this strain a promising candidate for methane removal technology.
- By incorporating these changes, nations across the globe can prevent 240 million tonnes of methane from major emission sites from entering the atmosphere by deploying 50,000-300,000 treatment units for 20 years.
How it happen?
- Bacteria produce biomass after consuming methane. This biomass can be used as feed in aquaculture. For every tonne of methane consumed, the bacteria can generate 0.78 tonne biomass dry-weight methane. It has a value of roughly $1,600 per tonne.
- The researchers proposed designing biofilters — vessels that contain nutrients necessary for the growth of microorganisms.
- They also recommend making genetic changes to the bacterial strain. This can be done by inducing gene mutations and choosing strains with desired characteristics.
- If the methane in the atmosphere was decreased by 300-1000 million tonnes by 2050, it would result in a global temperature decrease of about 0.21-0.22°C, So 240 million tonnes is predicted to have a significant effect on global warming.
Challenges:
- Researchers expect a few challenges if the technology is scaled up. For instance, controlling temperature is tricky. As the optimal temperature range is 25-30oC, both too-low and too-high temperatures become problematic for bacterial growth.
- Controlling temperature will be expensive and impact both economic feasibility and energy balance. So, the issue is about cost and energy usage when considering temperate versus tropical versus arctic climates, for instance.
- The researchers called for more field studies to test the feasibility of deploying the technology. Analysing the environmental life cycle and techno-economics of the technology is needed to ensure it is economically feasible and provides environmental benefit.