PSA oxygen plants — the cleaner, cheaper tech that could help ease India’s current crisis

As India battles a dramatic rise in Covid cases & subsequent oxygen shortage that has handicapped its healthcare response, ThePrint explains what PSA plants are & why they matter.

Workers refill cylinders with medical oxygen in Patna, on 27 April 2021 | Representational image | PTI

New Delhi: On 25 April, more than a year into the pandemic, the Government of India announced that 551 Pressure Swing Adsorption (PSA) Medical Oxygen Generation Plants will be set up in public health facilities across the country. This is in addition to the 162 plants that were announced earlier and for which Rs 201.58 crore was allocated.

The issue has become a controversial one as states and the Centre are locked in a blame game over whose responsibility it was to set up these plants. The debate has taken centre-stage given the alarming rise in Covid-19 cases in the country that has led to a severe shortage of medical oxygen.

Such has been the demand that hospitals have been putting out SOS calls for more oxygen, appealing to courts to intervene, while there have also been multiple incidents of supply disruption leading to hospital patients dying while under medical care.

In light of this, ThePrint takes a look at what PSA plants are, how much they cost and why it’s a game-changer in India’s Covid-19 battle.

The technology

Adsorption is defined as the affinity of a fluid for a solid surface. Using the differential affinities of various components of a gas mixture (such as air) it is possible to separate the various components. That, essentially, is the principle used by a PSA oxygen plant.

Such a plant can come in varying capacities to generate oxygen. It employs a technology that absorbs nitrogen from ambient air to concentrate oxygen for supply to hospitals or the industry, as the case may be. The oxygen thus generated can be supplied straight to the site of use either through a dedicated pipeline or compressed to fill cylinders.

Medical grade oxygen has an oxygen concentration between 90.0 per cent and 96 per cent. The remainder is principally argon and nitrogen.

They operate at near-ambient temperatures and use specific adsorbent materials like zeolites, activated carbon, molecular sieves etc., to trap oxygen at high pressure. While the oxygen produced by these plants is believed to be less pure than liquid oxygen derived from cryogenic technology, the outrage in the country currently centres around the debate about whether these plants could have helped ease the ongoing medical oxygen crisis.

The crisis that has brought Delhi to its knees, has affected all states with the exception of Kerala and Tamil Nadu, and caused countless deaths in the last one week.

The cost

PSA oxygen plants have an initial set-up cost, which depends on the capacity of the plant. But that is more than offset by the savings in monthly oxygen bills, say hospital owners who have opted for these plants.

The 150 oxygen plants for which the Central Medical Services Society (CMSS), an autonomous body under the Ministry of Health and Family Welfare, invited tenders last year, ranged in capacity from 100-3,200 litres per minute (LPM). However, only 33 have been set up so far.

The 150 plants cumulatively would have had a capacity of 80,500 litres per minute. A plant that can supply 24 cylinders worth of gas per day costs about Rs 33 lakh to set up and can be completed in a couple of weeks.

A 240-bed hospital would require about 550 LPM oxygen. A hospital of that size, say with 40 ICU beds, ordinarily uses oxygen worth about Rs 5 lakh per month.

But oxygen usage has gone up dramatically because of Covid-19. Industry sources say a PSA plant that costs about Rs 50 lakh would be adequate for such a hospital. This means the hospital would have recovered the investment in terms of monthly oxygen bill savings in 18 months.

Advantages of PSA plant

There are two obvious advantages of the technology — the first is that the hospital gets a captive plant that can generate all the oxygen it needs, doing away with the need for cylinders etc. As the home ministry said Monday, India’s problem is not oxygen generation but oxygen transportation.

Handling cylinders also has a safety aspect to it as oxygen under high pressure is highly inflammable. Several fires in Covid-19 hospitals across the country in the last few days have been grim reminders of those risks. The plant can also give it some buffer during times of augmented demand. It is not an expensive technology.

But what works very well for hospitals also is the fact that PSA is ‘clean technology’. The raw material that it uses is the ambient air. It also takes very limited space; the maximum area occupied by a PSA oxygen plant is about 7 ft/9ft/7ft. It takes just a few weeks to get a plant up and running and there are at least 25 vendors in the country who can supply between 2-20 plants per month.

(Edited by Manasa Mohan)