Environment

Mitigating Climate Change Is Possible, but Only If We Are Serious About It

The world has to limit warming to 1.5 degrees by 2100. To achieve that, it must halve human carbon dioxide emissions by 2030 and bring them down to zero by 2055.

For more than a decade now, the world has been living under the cosy illusion that if the mean atmospheric temperature of the planet does not rise beyond 2oC by 2100, human beings will be able to continue living more or less as they have lived so far. When climate scientists and leaders of smaller and island nations, have warned that 2 degrees is far too high, their warnings have been brushed aside peremptorily by the larger nations.

The IPCC’s latest report has shattered the cocoon. Even a 1.5 degree rise above pre-industrial times, the report has pointed out, will put all nations under immense additional stress. An extra half degree will further double the crop loss and decline in marine life, and treble the frequency of extreme heat waves. The world, therefore, has to limit warming to 1.5 degrees. To achieve that, it must halve human CO2 emissions by 2030 and bring them down to zero by 2055.

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The time limit it has given the world is about right, but the warning is not sufficiently severe, for extreme heat, raging forest fires, monster hurricanes, ravaged crops and dying oceans are not the only threats that the world faces. What the report has left out is the very real possibility of abrupt climate change. This is the sudden, autonomous acceleration of global warming that will take place once earth exhausts its capacity to absorb the heat being generated and has no other way of adjusting to the greenhouse effect of carbon dioxide than by increasing its capacity to radiate heat by growing hotter.

The immediate threat comes from the rapid disappearance of the polar icecap in the Arctic Ocean. In A Farewell to Ice, Cambridge University professor of Ocean Physics, Peter Wadhams, who has led 40 polar expeditions to study what is happening to the ice caps, has warned that not only has the permanent ice cover of the Arctic shrunk to less than half of what it was four decades ago, but its mass has also shrunk by at least 40%. What is worse, a growing part of the ice that remains is so thin that more and more of it is being broken up by storms and ocean currents in summer and floating away into the Atlantic and the Pacific. This is greatly speeding up the decline of ice cover in summer.

Extreme heat, raging forest fires, monster hurricanes, ravaged crops and dying oceans are not the only threats that the world faces. Credit: Reuters

The temperature of water in the Arctic has changed very little so far because most of the sun’s heat has been absorbed by the melting of the ice. But this cushion will disappear the moment the last of the ice is gone. It takes 80 calories of heat to change one gramme of ice into water at the same temperature. So every year, in late summer when there is no more ice left to melt, the sea will warm 80 times as fast as it is doing today. Since the average depth of the Arctic is just over a thousand metres, the warming will soon reach the billions of tonnes methane that is currently locked in ice crystals called clathrates. When these melt – as they have already begun to at two points in the East Eurasian Basin of the ocean – they will release a burst of methane into the atmosphere. Methane generates 24 times as much warming as CO2, although for a shorter period. Wadhams has therefore estimated that this will raise the mean global air temperature by an additional 0.6oC in a single decade. This means that the world could reach 2oC of warming as early as 2030-40 and not in AD 2100. If that happens, global warming is almost certain to go out of human control.

It is therefore imperative that the world heeds the IPCC’s warning. But is replacing all fossil fuels by 2055 even remotely possible? In Donald Trump’s world, will anyone even listen to the IPCC? Not a single government has done so this far, so investment in fossil fuels has continued to grow unchecked. In 2010, the UN had estimated that the world had only 1,000 GT of ‘carbon space’ left till 2100 AD if it wanted to limit global warming to 2oC. Lowering the target to 1.5 degrees halves that ‘space’. But barely five years later, it estimated that new investment already in the pipeline would add 723 billion tonnes (Giga tonnes) of CO2 to the atmosphere by 2030. We will therefore have overshot the carbon space available for a 1.5o C rise by close to 200 billion tonnes 70 years before the end of the century. It is not surprising, therefore, that the undertone of the IPCC report, and of the spate of comments it has provoked, is despair.

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The despair springs from an unspoken but nearly universal belief that none of the alternatives to fossil fuels that have been commercialised so far can go very far in replacing fossil fuels. For instance, everyone sings the praises of wind, and solar photovoltaic (SPV), power generation, but almost no one ever mentions that, being only intermittently available, neither can supply the base load, round the clock power, or any of the process heat that industry needs. In much the same manner, ethanol has reached the limits of substitution for gasoline as a transport fuel because it is being produced from food crops. Finally, there is no substitute as yet for conventional diesel and aviation turbine fuel.

This deep pessimism is, however, not warranted because there are other renewable energy technologies that can replace fossil fuels altogether. These capture the limitless power of the sun, either directly as heat, or indirectly through biomass, and have been known for the past forty to a hundred years. They were discussed at length during the meetings of the Energy panel of the World Commission for Environment and Development between 1985 and 1987, but have been studiously neglected since then. These are concentrated solar thermal (CSP) power, and the gasification (as distinct from fermentation) of biomass to produce synthesis gas – a mixture of carbon monoxide and hydrogen that can be combined into any transport fuel or petrochemical one chooses.

None of the alternatives to fossil fuels that have been commercialised so far can go very far in replacing fossil fuels. Credit: Dan Riedlhuber/Reuters

CSP power plants can completely replace coal- and gas-fired plants because, unlike SPV, they store the sun’s energy for use at night at very little cost, in the form of molten salt. Gemasolar, a CSP plant near Seville in Spain, has been supplying 20 MW of power round the clock to a town named Fuentes de Andalucia, with little or no need for fossil fuel backup, since 2011. Since then, much larger CSP plants have come into operation in the US and Morocco, and are being built in Saudi Arabia, Dubai, Israel, Australia and Chile. These are storing the sun’s heat in a mixture of sodium and potassium nitrate that loses less than 3% of its heat in 24 hours.

In the past four years, the cost of generation in CSP plants with heat storage has plummeted from 15.9 cents per Kwh at a 540 MW plant in Morocco, to 6.3 cents a unit in the first of three large plants being built in Chile and under 5 cents for the remaining two. This is less than half the price that consumers in the US, or for that matter anywhere else in the world, pay for their electricity today.

While solar thermal power is beginning to gain recognition, the capacity of biomass gasification to replace oil and gas for producing not only transport fuels, petrochemicals and coking coals, is still largely unrecognised. Synthesis gas from coal provided the transport fuel that sustained the German war effort in the Second World War. It continues to meet a substantial part of the demand in South Africa and China.

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What is still almost unknown is that synthesis gas can now be obtained from any type of biomass, ranging from sewage sludge to crop wastes through biomass gasification. Unlike transport fuels from coal, those from biomass will be carbon-neutral because they will use the carbon that plants extract from the air through photosynthesis.

But that too is on the verge of changing. A medium-sized plant has been producing aviation turbine fuel from crop wastes in Wuhan, China, for the past five years. A much larger plant, also intended to produce aviation turbine fuel, is under construction outside Reno, Nevada, in the US.

Solar thermal power plants require no rare metals such as the Tellurium and Cadmium needed by the latest generation of photovoltaic cells. There is also no foreseeable shortage of biomass residues – the production of cereals and coarse grains yields between 5 and 6 billion tonnes of crop residues every year; our towns and cities produce 1.3 billion tonnes of municipal solid waste; and the global sugar industry generates more than 2 billion tonnes of bagasse and sugar cane waste. Every tonne of these wastes can yield 0.3 to 0.6 tonnes of transport fuels, depending upon the fuel produced.

Solar thermal power plants require no rare metals such as the Tellurium and Cadmium needed by the latest generation of photovoltaic cells. A solar plant in Phetchaburi province, Thailand. Credit: Reuters

Replacing fossil fuels by 2055-60 by harnessing these technologies is therefore entirely possible. Beyond the subsidies normally given to pioneering enterprises to reduce their level of risk, there will be little or no need for long-term financial support. But it cannot be done in the teeth of opposition from the conventional fuels industry. On the contrary, harnessing the huge organisational and capital-mobilising capabilities of the fossil fuels industry will almost certainly spell the difference between success and failure.

The first requirement for enlisting the fuel lobby is to respect its compulsions. The most important is to give it time to recoup its current investment in fossil fuels. Fortunately, we still have the time to do this because even a brand new coal-based power plant requires much less than 40 years to recover its investment. Oil and gas do so, as a rule, much more quickly. Thus, all that the world’s governments need to do to start the shift is decide that they will not sanction any more fresh investment in fossil fuels.

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But investors in renewable energy will need a second assurance: a guaranty of price stability for transport fuels during the transition. That is what the completely unregulated, speculation-ridden global commodities market has been denying to prospective investors ever since the oil price slump that began in 1985, and the crashes of 2009 and 2014. Today, few investors are even willing to look at synthetic fuels projects because they have no idea when the next crash will occur.

Biomass-to-transport fuels projects have been announced, and price agreements signed, more than once in the past two decades. But they have been stillborn due to the unpredictable behaviour of world oil prices, which have risen to dizzy heights thrice in the past four decades, only to fall to a third of its value a few years later. Investment in biomass-to-transport fuels technologies will not truly take off until the world’s decision-makers agree to link domestic fuel prices to the long term average price of coal, gas and oil in the international market. Arriving at this consensus is the challenge that the next climate change summit faces.

Prem Shankar Jha was a member of the energy panel of the World Commission on Environment and Development, 1985-88. He is the author of Dawn of the Solar Age: an end to Global Warming and Fear (2018), and will be a visiting fellow at Harvard University’s Department of Engineering and Environmental Sciences (SEAS) in spring 2019.

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