FOSSIL fuels such as coal, oil and gas served as the basis on which the modern world has been built. Until James Watt came along with his steam engine, there was no way to think about sustained economic progress. Where would the energy for industry come from? Every time industry would start developing in the pre-steam engine age, so many trees would be chopped down to feed the boilers that the limits of industrialisation were very quickly reached.
It was fossil fuels that allowed the breakthrough into the era of modern economic growth. But right now, fossil fuels are no more a friend. The reason is when coal, oil or gas is burnt, the carbon, the basis of fossil fuels, combines with oxygen and produces carbon dioxide (CO2), which is emitted into the air and constitutes the main greenhouse gas. It warms the planet, changes the climate, endangers the ecology, humanity and every other species. So what was key to the core of the world economic growth is now at the core of a major problem.
One might say use less energy, but it is not so simple. Any useful work in an economy depends on energy. A lot of energy is wasted around the world in the form of the release of heat or friction on a much larger scale than what is needed to be. So energy efficiency is a big part of any solution for sustainable development. But the world needs energy resources for use. The use of energy with a substantial gain of efficiency is likely to increase in aggregate as the world economy expands. Here is a problem — more energy is needed.
Traditional forms of energy the fossil fuels of coal, oil, and gas cannot do it because it would create a massive intensification of the climate change problem. How big can the intensification be? The total energy used by a country would include the fossil fuels, wood burning, hydroelectric power, geothermal energy, wind and solar power, nuclear power or some other forms. Let us look quantitatively at how much energy we use and what it implies and how much carbon dioxide we, therefore, emit into the atmosphere and what it implies; and how much we change the climate. As for amount of energy used by country, for every $1,000 of total production in the economy, the total energy use expressed in tonnes of oil equivalent tends to rise, on an average, by about 190 kilograms of oil. This way, $1,000 of production, on average (expressed in 2015 dollars) is associated with about 190 kilograms of oil use or an equivalent amount of energy contained in coal, or natural gas, or one of the other non-fossil fuel forms of energy. That gives the scale of how much energy is used for each $1,000 of production. Now, in view of the mix of energy sources in the world — mostly fossil fuels but also some nuclear power, wind, solar, charcoal from trees, bio-fuels from sugar cane, corn converted to ethanol for automobile use as in Brazil and the United States, on an average, every tonne of oil equivalent energy is equivalent to about 2.4 tonnes of carbon dioxide emissions. In other words, burning a tonne equivalent of energy will add up more than two tonnes of CO2 into the atmosphere.
How much CO2 it exactly is? It depends on which energy source is used. If it is nuclear power, the emission is zero. Because nuclear power is not a fossil fuel and it, therefore, does not create carbon dioxide emissions. If it is coal, the emission is higher than the average because coal, being almost all carbon with some impurities, when it burns, creates CO2 with little other energy created by the coal. So coal creates the most carbon dioxide emissions per unit of energy among any fuels; natural gas and oil a bit less. For a tonne of coal burnt, four tonnes of carbon dioxide is emitted into the air. For the amount of natural gas equivalent to a tonne of oil in its energy content, it is about 2.4 tonnes of CO2. But for hydroelectric power, solar power and wind the volume is zero. In 2016, the world economy was at about $80 trillion, which means almost 40 billion tonnes of CO2 emissions, taking per tonne oil equivalent energy’s CO2 emission as standard.
We also emit CO2 into the atmosphere as humans in other ways. We chop down trees and in so doing, the carbon that was stored in those trees is released into the atmosphere if the trees are burnt or they decay. Hence, carbon that was sequestered biologically is released into the atmosphere as well. That adds a few billion tonnes of carbon dioxide emissions in addition to what is from fossil fuel use. For every tonne of CO2 emitted into the air, a bit less than a half of that stays in the air, because some CO2 dissolves in the ocean, some of it gets sequestered in plants and trees back on earth. Approximately, 46 per cent of the emitted CO2 stays in the air. The other 54 per cent typically is stored in natural sinks — the oceans or the land. It means, if we put 40 billion tonnes of CO2 into the air, a little over 18 billion of those tonnes stays in the air.
For every 7.8 billion tonnes of carbon dioxide put into the atmosphere, the concentration of carbon dioxide in the atmosphere rises by one part per million. So that is the translation factor to raise the CO2 concentration in the atmosphere which is filled with nitrogen and oxygen and many other types of molecules. This gives us now a quantitative sense of what we do. If we have put 16 billion tonnes of CO2 staying in the air, then the amount that we emitted into the atmosphere in 2016 from fossil fuel use raised the carbon dioxide concentration by about 2.35 parts per million or nearly three molecules for every million in the atmosphere. It is frightening. The current CO2 concentration in the air is 409.65 ppm (April 23, 2017). It was 391.15ppm in 2011.
The concentration of CO2 fluctuates for normal processes, even putting mankind out of the story over geologic time these levels of CO2 rose and fell as part of the long run carbon dioxide cycle. The cycle drove in important part by systematic changes of the earth’s orbit. A look at this reconstruction of the carbon dioxide concentration in the atmosphere over the past 8,00,000 years, starting all the way to the left hand side of the graph, will show that the first peak is a little bit over 250 parts per million. Then it fell to under 200 parts per million. Then around 7,00,000 years ago, it rose again to nearly 250 parts per million. Then it fell again; then it had another peak at 6,00,000 years ago, and so forth. Ups and downs are driven by natural changes of the earth’s orbital cycle. But then to the right on this graph, coming closer and closer to the present, it shows suddenly something weird happens. Instead of going ups and downs, it suddenly goes up and up more, fired straight up just in the past 100 years of this 8,00,000 year graph. That is mankind, burning fossil fuel. James Watt’s great invention made possible to grow the world economy, but CO2 started soaring. In 2013, it reached 400 parts per million, a concentration which has not been seen on the planet earth for millions and millions of years. What the climate scientists say is that this kind of change is consistent with a significant increase in temperatures on the planet. Indeed, if we reach 450 parts per million of CO2, we are very likely to be living on a planet that on an average is 2° Celsius warmer than before the industrial revolution.
Now, 2° Celsius might not sound much, but it implies even larger increases in temperature in the higher latitudes and it implies massive changes in the earth’s climate, including rainfall, droughts, floods, as well as an increase in sea level. So the impact of CO2 concentration on climate change, already in effect, are extremely large and dangerous. How fast this is happening? If it is at 400+ ppm today and it is rising by about more than two parts per million each year, it might reach 450ppm in 20 years from now. We cannot even transform the world energy system to renewable-based at that rate. So, we are on a trajectory that is very fast and troubling.
If the world economy triples and so does the energy use, with the same energy mix that is now, CO2 concentration will increase by five or six parts per million per year. Within a few decades, if we do not change course, we will be on a path of extraordinary peril. Because of our fossil fuel reliance, we would see mega droughts, mega floods, more extreme storms, extinction of more species, more crop failures, a massive sea level rise over time, and a massive acidification of the ocean as that CO2 dissolves into the ocean, produces carbonic acid and reduces the pH of the ocean. A change in course is therefore in order, and quickly, more quickly than politicians have so far been telling us about.
Mahbub Sumon is an engineer and works on renewable energy.
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