From: Hannah Pell

“The most important car for 100 years.” This is how James May, co-host of the British Motor Show Top Gear, described the Honda Clarity a few years ago during its test drive. “This is the future of driving.”

What was so revolutionary about this car? It’s the fact that it’s not powered by a motor or battery – it’s powered by a hydrogen fuel cell. Hydrogen technology has received a lot of attention lately, and I wanted to know a little more about the science behind it and its role in the future of fuel.

Hydrogen production

Hydrogen is the lightest element at number 1 on the periodic table and the most abundant in the universe. Its chemical structure contains only one proton and one electron, which makes it highly reactive (flammable!) And therefore does not occur freely in nature. To get hydrogen itself, it has to be extracted from naturally occurring compounds. There are several methods of producing hydrogen: Reforming, gasification and electrolysis of steam methane.

Steam methane reforming is the process of catalyzing a reaction between steam and methane to produce hydrogen, carbon monoxide, and a small amount of carbon dioxide (collectively known as “synthesis gas”). Most of the world’s hydrogen is produced using this method, using natural gas as the primary methane source.

gasification is the process of converting biomass (agricultural residues, some plants, organic municipal and animal waste) or carbonaceous materials (i.e. coal) into synthesis gas. This process dates back more than two centuries when coal and peat were used to make town gas, which supplied London’s first public street lighting system in 1807. A more modern use of hydrogen gasification is in the production of ammonia, which, while useful in numerous household cleaners and pharmaceutical products, is classified as an extremely hazardous substance in the United States.

There is a cleaner alternative Electrolysis, the process of producing hydrogen using an electric current. Housed in an electrolyzer, a voltage is applied to a cathode and anode immersed in water or a liquid alkaline solution, causing a reaction in which hydrogen and oxygen are released in their gaseous forms. Hydrogen is then collected and stored in high pressure tanks for later use.

Credit: US Department of Energy.

Hydrogen is often labeled with four different colors – brown, gray, blue, and green – to describe the source and process from which it was made. Brown hydrogen comes from coal gasification and is the most environmentally harmful method. Gray hydrogen comes from the reforming of natural gas and steam methane. Blue hydrogen is also made from the reforming of steam methane, but it contains CCS (Carbon Capture and Storage) technologies, which reduces the negative impact on the environment. After all, green hydrogen is produced entirely from renewable sources (such as wind and sun) that power the electrolysis process.

Hydrogen as a fuel source

Hydrogen has been considered an alternative fuel source since the Energy Policy Act of 1992, which was written with the aim of reducing the United States’ dependence on petroleum by promoting the voluntary use of alternative fuels.

How can hydrogen be converted into fuel after it has been produced? Hydrogen is an energy carrier, not an energy source itself, so it has to be converted into energy by a fuel cell stack. Inside the fuel cell, the air is fed to the cathode and hydrogen to the anode. A catalyst separates the hydrogen protons and electrons and lets the electrons flow in a different path to create electricity that powers the car. When they recombine, they form water (H2O) and heat, the only by-products.

A major problem with the availability of hydrogen is the lack of infrastructure. As of 2020, the U.S. had just over forty public hydrogen refueling stations, and all but one are in California. In addition, hydrogen must be stored in high pressure tanks, so both its storage and transportation are relatively expensive compared to other fuel sources. According to the US Energy Information Administration’s Annual Energy Outlook 2021 report, the cost of capital of fuel cells is more than six times that of battery storage and corresponds to that of nuclear power plants compared to the levelized energy cost (LCOE) estimates.

Although cars powered by hydrogen fuel cells require much less refueling time (around 5 minutes on the pump versus 45 minutes of charging), the number of battery cars far exceeds the number of hydrogen cars on the road. So far, only Toyota, Honda and Hyundai produce hydrogen fuel cell cars. However, additional efforts are being made at several automobile manufacturers and other large companies to develop and deploy hydrogen fuel cell trucks, buses and trams.

How quickly could we all pump hydrogen into our cars instead of gasoline? Unfortunately, the future that James May predicted seems a bit far away.

The harmony of “and”

The future of widespread hydrogen fuel cell cars may not look bright, but hydrogen is important for a variety of other uses. Aside from automobiles, hydrogen fuel cells are used in large data centers as potential backup in the event that power is lost and batteries run down. In addition, liquid hydrogen is used to fuel NASA spacecraft, and the electrical systems on board are powered by hydrogen fuel cells.

A complex combination of clean energy solutions is required to achieve net CO2 emissions by 2050. Dr. Arun Majumdar, professor of mechanical engineering and materials science at Stanford University and former energy secretary, recently summed this up briefly on the Columbia Energy Exchange podcast: “The scale and urgency of the problem are so great that we can neither – nor have solutions. We fall into the tyranny of ‘or’ and we need the harmony of ‘and’. We need and. ”

Despite the current constraints, hydrogen technology will remain an important option in our future greener energy landscape because when it comes to combating climate change, there is no either / or.


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