Photo by NASA on Wikimedia

Measurements for a Green World

Piero Martin—

Will measurements save the world? Or, better, our life as humans on this planet? Certainly, they will help. Actually, they are already doing an important job sincemuch better and stronger than many words they are telling us where we are going and how urgent it is to change route. The last of a long series of alarming measurements has been published a few days ago by the World Meteorological Organization (WMO) of the United Nations. Measurements in this case are about temperature, one of the seven base quantities of the International System of Units (SI). The SI is an alphabet used by mankind to measure the world, to know our own past, understand the present, and plan the future. To the process of measuring has accompanied mankind since the beginning of civilization.

The temperature WMO is talking about is that of the air of our atmosphere and of the seas. According to WMO,

Global sea surface temperatures hit a new high in May for the second consecutive month and in June are tracking at unprecedented levels for this time of year, in particular in the North Atlantic. Antarctic sea ice extent reached a record low monthly value in May, the third time in 2023 that the monthly value has reached a record low.

The report continues by saying that,

The Northern Hemisphere had its second-warmest May on record. In the Southern Hemisphere, surface temperature ranked fourth warmest on record for the month. It was the warmest May on record for North and South America. Amid the unusually high May temperatures in North America, several hundred wildfires broke out across Canadian forests, burning over 6 million acres and causing widespread air quality deterioration across much of Canada and the U.S in late May and early June.

Numbersafter all the result of a measurement is a numberspeak clearly and loudly, and typically they are harder to dispute than words.

We need to listen to numbers and take action. We can’t continue with business as usual, but we can’t be pessimistic. Young generations do not deserve our laziness or our pessimism. Indeed, as they warn us about the risks, measurements are also key tools to find solutions.

Global warming (a measurement of temperature) is caused by the increasing emissions of greenhouse gases (a measurement of mass, in 2020, U.S. greenhouse gas emissions totaled 5,981 million metric tons (13.2 trillion pounds) of carbon dioxide equivalents), which are due mainly to our excessive use of fossil fuels to produce the energy we need (a measurement of energy, in 2021 the world has produced 136.018.000 billions of watthours with fossil fuels). The key to unlock a greener future is just in the last measurement: we need to reduce  our measurements of energy produced by fossil fuels. To this goal, a game changer could be nuclear fusion, the process which fuels the sun and the stars and which is the subject of a growing interest in public and private research.

In fusion, lightweight nuclei of hydrogen, or its isotopes, combine, and in the reaction, part of the mass of the reactants is converted into energy according to the super-famous Einstein law E=mc2. Scientists all over the world are now trying to steal the secret of the sun to reproduce this process in the laboratory. It is a rough road, but much has been done, and the hope is that in a relatively short time we will have at our disposal a source of clean, unlimited electric power, free of CO2 waste, and ideal, therefore, for ensuring a sustainable future for our planet.

In the fusion reaction, part of the mass of the reactants is converted into energy. As in the case of nuclear fission, the process working in present nuclear power plants where a heavy nucleus like that of Uranium is split. The energy liberated by a single reaction is much greater than the energy obtainable from normal chemical combustion reactions, like those produced when we burn fossil fuels. But with fusion, as with fission, no CO2 is produced. In addition, the enormous advantage of fusion is that there is no production of long-lasting nuclear waste as in fission. Moreover, the process is intrinsically safe, and the fuel (water and lithium minerals) is broadly available.

To get fusion the fuel must be heated to millions of kelvin (again a temperature measurement, but this time for the good!). At such elevated temperatures, the nuclei move very fast, and therefore they have sufficient kinetic energy to overcome the repulsive barrier which would keep them apart and to fuse. At those temperatures, matter reaches the so-called status of plasma, an ionized gas, which is, in fact, the fuel of fusion. For plasma, you need to have a container able to bear elevated thermal charges, with walls that do not degrade. To meet this need, the physicists who work on nuclear fusion have designed special doughnut-shaped steel containers in which the plasma is confined by an intense magnetic field. Scientists aim to heat the plasma of future fusion reactors to a temperature of 150 million degrees, a temperature greater than that at the center of the sun, and to keep it in a magnetic cage. Well, if you think this is science fiction, think again. There is a sky-rocketing interest both from private investors and from public research. According to the 2022 report of the Fusion Energy Association over $4.7 billion has been privately invested in the global fusion industry. More than 30 private companies are these days working to produce fusion electricity and the proposed Biden-Harris administration 2024 budget includes an historic increase in the federal funding of fusion research.  This adds to a worldwide effort, wherefor exampleChina is on the frontline and Italy is investing about 600 million euros to build a new advanced experiment called DTT.

The final goal of all this effort is measuring electricity generation (i.e. a measurement of electrical current, another base quantity of the International System of Measurements) as a result of nuclear fusion. If we will be able to get thereand we are really working hard for thatthen a greener and more sustainable future will be a reality.

Piero Martin is professor of experimental physics at the University of Padua and a science writer. He carries out research on thermonuclear fusion and is chief physicist of the international DTT fusion experiment. He lives in Venice, Italy.

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