Franklin Chang-Díaz gets into his car, turns on the radio, and hears the news about another increase in the price of gasoline. But he sets off knowing that his trip won’t be any more expensive: His tank is filled with hydrogen. His car takes that element and combines it with oxygen in a fuel cell that works like a small power plant, creating energy—which goes into a battery to power the car—and water vapor. Not only will Chang-Díaz’s trip cost no more than it did yesterday, it will also pollute far less than a traditional gasoline-powered car would.
Chang-Díaz would like to have a public hydrogen station nearby whenever he needs to fill his tank, but that isn’t possible yet, either in his native Costa Rica or in any other Latin American country. He ends up instead at the hydrogen station he built himself, as part of a project aimed at demonstrating that hydrogen generated with renewable energy sources—green hydrogen—is the present, not the future.
A physicist, former NASA astronaut, and the CEO of Ad Astra Rocket Company, Chang-Díaz has a clear vision. Green hydrogen, he believes, is a fundamental player in lowering emissions from transportation and converting regions that import fossil fuels—such as his small Central American country—into exporters of clean energy, key to avoiding the catastrophic effects of global warming.
According to data from the Inter-American Development Bank, the most polluting sectors in Latin America to which clean hydrogen technology could be applied are transportation (which generates 40 percent of the region’s CO2 emissions) and electricity and energy (36 percent of emissions). And Chang-Díaz is not alone in his belief in the promise. Large-scale hydrogen transportation will be part of the future, says Nilay Shah, a chemical engineer at Imperial College London. “By 2050, hydrogen could deliver 18 percent of the global energy supply… 28 percent of which would be destined for the transport sector,” he and his colleagues note in an article on the application of hydrogen in mobility technologies in the 2022 Annual Review of Chemical and Biomolecular Engineering.
But for green hydrogen to become an important player in the world’s energy resources, the technologies for obtaining it will need to be developed on a large scale. Latin America wants to be part of this future and is already preparing, with projects throughout the region.
Not all hydrogen is the same
Hydrogen is the lightest chemical element: Its nucleus has only one proton, orbited by an electron. It’s also the most common: Up to 90 percent of the atoms in the universe are believed to be hydrogen atoms. In its gaseous state (H2), it is tasteless, colorless, and odorless. In the terrestrial environment, it is usually found in more complex compounds, such as two hydrogen atoms bonded to one oxygen atom to form a water molecule (H2O), or four hydrogen atoms bonded to one carbon atom to form methane (CH4). If we need the hydrogen atoms alone, we must uncouple them from these compounds.
The use of hydrogen as an energy source is not new. For decades, NASA mixed H2 gas with oxygen to generate the energy needed to lift hundreds of tons and send its shuttles into space. The US Department of Energy lists it as a safer fuel than fossil fuels because it is non-toxic and dissipates quickly in the event of a leak, since it is lighter than air.
At present, hydrogen as an energy source is mainly used in the production of petroleum derivatives, steel, ammonia, and methanol. According to data from the International Energy Agency (IEA), in 2020 the world’s population consumed about 90 million tons of hydrogen—equivalent to only 2.5 percent of global energy consumption. Latin America uses only 5 percent of this hydrogen, mainly in countries such as Trinidad and Tobago, Mexico, Brazil, Argentina, Venezuela, Colombia, and Chile. It is mostly dirty hydrogen, which pollutes the planet due to the processes used to obtain it.
Depending on how it is derived, hydrogen can be classified as gray, blue, green—or even black. Gray hydrogen is generated using fossil fuels—natural gas especially, in the case of Latin America. In a process called steam reforming, carbon monoxide (CO) and water vapor (H2O) are subjected to high temperatures, moderate pressure, and a catalyst, producing carbon dioxide (CO2) and hydrogen (H2). If coal is used instead of gas to generate the heat necessary for steam reforming, the hydrogen is then considered black—the worst of all, from an environmental point of view.
Blue hydrogen uses gas or coal in the same steam reforming process, but in this case 80 percent to 90 percent of the carbon emissions end up underground through a process called industrial carbon capture and storage (CSS). Finally, green hydrogen—also called clean hydrogen—uses electrical energy generated by renewable sources, such as solar and wind power, to separate the water molecule into its two elements, hydrogen and oxygen, by means of an anode and a cathode in a process called electrolysis.
Currently, less than 0.4 percent of the hydrogen utilized in Latin America is green; the rest is linked to fossil fuels. In fact, in 2019, hydrogen production for the region required more natural gas than all of the gas consumed in Chile, a country with 19 million inhabitants. And it generated more polluting emissions than those produced in a year by all the cars in Colombia, a nation with some 7 million vehicles.
Globally, 4 percent of hydrogen production is already the result of electrolysis, but the remaining 96 percent still requires gas, coal, or petroleum derivatives.
https://arstechnica.com/?p=1916816