What Lies in India’s Path to Net Zero

In his book, Rising Ambition: Carving New Pathways - India's Energy Transition, Ajay Shankar, a distinguished former civil servant and currently a Distinguished Fellow at The Energy Research Institute, gives the most authoritative description of the progress that India has made towards achieving “Net Zero” carbon dioxide emissions by 2070. This is the target Prime Minister Narendra Modi accepted at the Glasgow Climate Summit 2021. 

What distinguishes this book from every other that I have read on this subject is its detailed description of the learning curve that scientists and government officials, engaged in the transition from fossil fuels, have followed. 

The author has described in detail the process of learning by doing – which involves learning from initial mistakes – through which the government has been fine-tuning its shift from fossil to renewable energy. 

Ajay Shankar,
Rising Ambition: Carving New Pathways – India's Energy,
TERI (October 2024)

The book candidly admits that India has only just started on the long road to Net Zero. For future decision-makers, who will need to take the crucial decisions to ensure success, these pages provide invaluable insights on how to travel a road never travelled before. 

Shankar’s book is a product of research and experience. This is because he played a catalytic role in the electrification of rural India when he was in government service. By the time he retired from his post, there were only 135 villages in India that were yet to be electrified. 

The definition of an electrified village was admittedly unambitious, for it required only a single power line to be taken to a village and a minimum of ten connections to originate from it. But the laying of power lines to every village has removed the principal roadblock to their future. 

What remains to be done is to provide the power that needs to flow through those lines. So it is not surprising that about half of Shankar’s book is devoted to describing ways in which 24-hour power can be supplied to both rural and urban India from renewable sources at an affordable rate. 

Solar and wind power

The two sources of renewable energy whose potential Shankar has explored in detail are solar and wind power. His book contains the most up-to-date information on where India has reached in tapping both sources of energy. A valuable contribution of these sections is his detailed description of the process through which the Union and state governments have removed various obstacles on this front. 

Shankar concedes that while both solar and wind power generation costs are now much lower than coal-based power, neither, by themselves nor in tandem, can provide the assured 24-hour supply of electricity that the modern world needs. So the capacity to store renewable power for release when one or both sources of power are not available is imperative. He, therefore, devotes an entire chapter to “The Imperative of Storage”. 

The methods he recommends are storage in batteries at power stations; pump storage at hydro-power projects; storage in molten salt (or an alternative medium) in a concentrated solar thermal plant, and using surplus (often referred to as ‘curtailed’) solar or wind power, at times when both are available, to produce ‘green’ hydrogen via electrolysis and use it to run the generators. 

This is the one chapter that has raised more questions in my mind than it has answered. A battery power backup, of up to four hours, is already being used by most power stations to meet sudden peaks in demand and to prevent damage to sensitive equipment by giving its users time to shut these down. To the best of my knowledge, there are no major power plants with a larger permanent battery power backup, because it becomes uneconomical to have one.  However, battery storage costs have been falling rapidly in recent years, so longer economical storage times may soon become the norm.

Pump storage is a commonly used backup system in European countries because of the abundance of rain and snow fall around the year. However, the laws of physics ensure that the power that the lifted water can generate when released is at best 60-70% of the power needed to lift it to the upper reservoir. Pump storage will therefore be economically viable only when the water in the lower reservoir is lifted in the dead of night, when the demand for it from industries and homes is minimal. 

However, small pump storage projects can still play a useful role if the state governments adopt a strategy of building small reservoirs constructed at different heights to capture the increasingly frequent and destructive rain storms that have begun to hit India and many other parts of the world due to global warming. This strategy will not only conserve water for electrification but also sustain agriculture in the droughts that have followed the cloudbursts.

Shankar’s most important recommendation, however, is also the most urgently needed. This is to supplement solar photovoltaic power with solar thermal power obtained from storing the sun’s heat during the daytime to run steam boilers when the sun is not shining. 

Solar Thermal (CSP) power was the first renewable source of energy to be harnessed. This happened in California in the 1980s, where it was used to meet morning and evening peaks in the demand for power. It became a 24-hour source of power only in the 1990s, when scientists found that heat could be stored for long periods in a combination of molten salts – sodium and potassium nitrate – to run generators at night.

Despite this, CSP power failed to take off because it cost twice as much as photovoltaic (SPV) power and companies had the easy option of claiming that they had gone “green” by installing PV panels on their roofs, while continuing to draw the bulk of their power from coal and gas. 

However, CSP is making a comeback because research projects funded by the US’s National Renewable Energy Laboratory (NREL) have found that silica is both cheaper and superior to sodium and potassium nitrate as a storage medium because it can be heated to 1000oC, against 595oC for molten salt. It therefore requires less space and, not being in molten liquid form, far less maintenance. 

The NREL has estimated that using silica as the heat storage medium will bring the cost of SPV generation down to 5 cents, i.e less than Rs 5 a kwh. That makes it a serious contender to coal and gas in India and almost everywhere else in the world. 

Beyond electricity

Most of the progress towards decarbonisation, both in India and the rest of the world, has taken place in the electricity sector, where sun and wind energy have supplemented hydro and nuclear power. Today, the four sources together provide 30% of the total electricity consumed by the world. Sun and wind now provide half of this. To the government’s credit, India has kept up with these global trends and, as of last year, was meeting 14.5% of its total electricity needs from sun and wind power. 

But electricity accounts for only a third of the energy that the world consumes, and India is no exception. The author is aware that in meeting the two other demands for energy – transport and industry – problems remain to be resolved. But in his view, the road to decarbonisation in both these sectors also lies through ‘green’ electricity. 

India has virtually completed the electrification of India’s rail transport system, but today nearly all the electricity the railways consume is coming from coal or natural gas. That will not change till a non-fossil-based source of electricity is found. 

For shipping, he suggests ‘green’ ammonia as an alternative to coal and heavy fuel oils. But the production of ammonia is a highly energy-intensive process, for it needs to be done at around 300 times atmospheric pressure at temperatures of 400-500° C. So the conversion of green hydrogen into ammonia will itself require a very large additional amount of green hydrogen. 

Green hydrogen is also the author’s recommendation for heavy duty road transport and for the provision of the intense industrial heat needed by the steel industry in the Direct Reduction process. But the same problem arises here: From what will the world generate the ‘green’ hydrogen that will generate the heat? The same is true of the production of cement, which requires temperatures of 1400o C. . 

If green hydrogen is the key to decarbonisation of commercial energy, then 100% of the energy humanity needs will have to be met by sun and wind energy. The electricity that will need to be generated from these two sources will therefore be stupendous. 

Today, the combined share of sun and wind in global energy production is just about 5%. Even if global GDP grows only at 2% a year, it will have doubled by 2065. Our exploitation of sun and wind energy will therefore have to grow by more than 40 times.

For the author, therefore, the road to Net Zero lies largely through green hydrogen. But since green hydrogen has, till now, been produced entirely by electrolysis, that road too circles back to the need for still more electricity. It is not possible for this writer to estimate how much electricity India, or for that matter the world, will need. But there is a strong possibility that both will run out of available land before that goal is reached. 

There is, however, another way of producing green hydrogen that the author has mentioned briefly in the closing pages of his book. Green hydrogen can also be produced from waste biomass. He has not specified what constitutes ‘waste’, but if it includes crop residues, then that might well be the road to salvation as India produces between 1.2-1.4 billion tonnes of crop and forestry residues, and over 200 million tonnes of municipal solid waste (MSW) every year. There are well established technologies for converting all of this organic matter into not only fuel for generating electricity, but also for conversion into transport fuels. 

Thus, taken together with SPV and wind power, the gasification of biomass residues can become the road to replacing fossil fuels altogether, and thereby achieving Net Zero CO2 emissions by 2070, if not earlier. This is the route that India and the entire world needs to take in the few decades we have left before our children and grandchildren are deprived of their future. 

Prem Shankar Jha is a veteran journalist and commentator.

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