Hydrogen Fuel: But How Does It Even Work?

Let’s explain the underlying technology of hydrogen fuel. In Plain English.

Hydrogen has long been touted as the clean energy source of the future, and while many hold strong opinions about the actual feasibility of hydrogen based future, I think we should all appreciate the innovative ways scientists are attempting to make a dream a reality. Let’s explain in plain English.

Before we jump right into the science, let’s take a step back and make a clear distinction between the the different types of headlines about hydrogen fuel that you see in the news. For one, there’s the application of hydrogen fuel in internal combustion engines. Using hydrogen fuel in this way wouldn’t be very different from our current gasoline powered car culture. We would have to refuel our cars in a hydrogen gas station that will at some point be available in cities. On the other hand, we have hydrogen fuel cells which store energy through a chemical reaction between hydrogen and oxygen, and produce a current of electricity directly that could be harnessed for any number of applications. While both methods are different in regards to the way they produce energy, they both have the same result, clean energy. The only byproduct of the reaction is water.

So let’s jump into the science. First, we have to produce and collect hydrogen. This is the case for both uses of hydrogen fuel. Then let’s talk about how hydrogen is used in industrial combustion engines and explain how this differs from it’s applications as a fuel cell.

Producing Hydrogen

We have many ways to produce hydrogen. Currently, the majority of our hydrogen production is produced by fossil fuels by steam reforming. I know, I know… But it’s not as bad as it sounds. Other, cleaner ways to produce hydrogen include electrolysis and biomass gasification.

Steam Reforming

Steam reforming, or methane reforming converts methane (CH4, the primary component of natural gas) to carbon dioxide and hydrogen. While this process does release carbon dioxide, it produces less emissions compared to the conventional burning of fossil fuels due to increased efficiency. Still, this process is not low- or zero carbon, which is why this process is term “grey hydrogen” as opposed to “green hydrogen”.

Electrolysis

Electrolysis is the process of splitting water molecules (H2O) into hydrogen and oxygen through the application of a strong electric current. This process can be powered by renewable or non-renewable energy sources.

Biomass Gasification

Biomass gasification is a clean method of converting organic matter into hydrogen and other products. Most of these processes are done in a two-step, non-catalytic process that gasifies and then reacts the solid organic matter to produce syngas which is a mixture consisting primarily of hydrogen, carbon monoxide and some carbon dioxide in many cases. The inclusion of methane in this list does not indicate that this gas is problematic in terms of emissions as it is when produced from natural gas. Biomass resources do not release methane into the atmosphere as it is stored within the organic material before it undergoes any chemical changes. Organic matter used in biomass gasification include waste materials, agricultural byproducts and forestry.

Algae?

One of the more innovative developments in hydrogen harvesting is to harvest it from algae. This idea was first proposed in the late 1980’s and is now being developed by a company called GreenFuel Technologies. They have developed an algae farm that harvests hydrogen from algae grown using sunlight and carbon dioxide from the atmosphere. The algae then grow using a process of photosynthesis which produces an energy-rich biomass that could be used for fuel production or fertilizer.

Turning Hydrogen into Power

Hydrogen Fuel ICE

Hydrogen gas is a gas that holds a lot of chemical energy. If you ignite it, it reacts with the oxygen in the air and releases its energy in the form of an explosion. Just like how gasoline powered explosion work in a conventional ICE, the expansion of high pressure gasses in
a hydrogen fuel ICE applies direct force to parts of the engine like pistons, transforming the chemical energy into work. Unlike gasoline power ICE’s, however, the reaction of hydrogen and oxygen produces a mixture of only water as a by-product.

Hydrogen Fuel Cells

This is where I get a little technical. The anatomy of a hydrogen fuel cell is very similar to that of a conventional battery. Like a conventional battery, hydrogen fuel cells have a cathode (with hydrogen) and an anode (with oxygen). The cathode and anode is separated by a catalyst and an electrolyte. The hydrogen wants to get to the cathode to react with the oxygen to produce H2O (water). However, the electrolyte only allows positive ions to pass. That’s where the catalyst comes in. It splits the electron from the hydrogen proton, turning neutrally charged hydrogen atoms into a positively charged hydrogen ions which flow right through the electrolyte to the cathode (where the oxygen is stored). But they can’t react with the oxygen yet because they’ve lost their electrons and they’re technically not hydrogen atoms anymore, just protons. To facilitate the reaction, an external wire must be passed in order for the electrons to flow to the cathode, bypassing the electrolyte. This flowing of electrons (due to the attraction of the oppositely charged protons at the cathode and repulsion of similarly charged electrons in the anode) creates an electric current which can be used to power anything from an EV to a cellphone. The coolest part about it? The cell can produce electricity continuously, without a need to recharge, as long as fuel and oxygen are provided. If you didn’t get it, this video will explain it much better.

Conclusion

Hydrogen fuel cells are clean, silent, and can power many things. It is a great alternative to gasoline in vehicles. Unfortunately, there are two obstacles to hydrogen fuel becoming widespread: the production of hydrogen itself (the cost of which is much higher than that of conventional gasoline) and the lack of infrastructure for producing and storing hydrogen. Gasoline already has an established infrastructure in place all over the world. Hydrogen does not. That being said, we’re making real strides in this space and an entire other article can be dedicated to listing innovative ways companies are managing to overcome these barriers.

What do you think? Will hydrogen be the way of the future? Whether or not you believe it, there is no denying that the science behind it is fascinating. I hope that this brings a little more light to the subject and makes you appreciate hydrogen fuel even a little bit more!