You may have heard of it: Hydrogen. It’s the most abundant element in the known universe and is found nearly everywhere including water, table sugar, and the sun. Hydrogen can also be used to produce energy with little to no harmful byproducts—if done properly.
If it’s so abundant and has the ability to create energy, why haven’t we used hydrogen on a larger scale? Let’s look at the basics.
Hydrogen, as you may recall from middle school science class, is an element. When transformed through biological and chemical processes, it can be turned into a fuel source known as hydrogen energy.
Hydrogen energy is currently used to power some fuel-efficient vehicles, refine petroleum, produce fertilizer as well as generate electricity, power, and heat, and it’s beginning to take the forefront in discussions about renewable energy.
Since hydrogen—the “H” in H2O—makes up a large chunk of the Earth, namely the ocean, it provides a large energy source that’s practically untapped. When generated using clean energy, hydrogen is considered to be a zero-emission fuel where the only significant output is water.
Hydrogen energy isn’t a new concept; it dates back to the 1800s with minds like Jules Verne in 1874 who recognized that coal was not a forever fuel, and continued with Rudolf Erren in the 1930s, who patented the use of hydrogen energy through electrolysis. There was a large gap in the timeline until around the 1960s when General Electric introduced modern hydrogen fuel cells for generating electricity to use on the Apollo and Gemini space missions.
In 1974, many studies were conducted to research hydrogen’s uses in the energy sector for electricity production. Hydrogen was officially considered an alternative fuel source under the Energy Policy Act of 1992, and today, hydrogen is used to power cars, provide energy for larger transportation, and even produce electricity.
Let’s break down what a fuel cell is. At its most basic definition, a fuel cell is a device that combines electricity and chemistry to produce an electrical current directly from a chemical reaction.
So how does this work using hydrogen? The fuel cell generates energy by combining hydrogen and oxygen and performing what’s called a redox reaction. A hydrogen fuel cell is similar to a battery, except that they don’t run out of charge as long as a fuel (hydrogen) is being supplied.
In a fuel cell, pure hydrogen is used as the fuel source and is put in one side of the cell, and air is fed into the other. The hydrogen fuel is separated into its basic units called protons and electrons. The electrons flow through an external circuit which creates a flow of electricity turning the hydrogen fuel into usable hydrogen energy.
Hydrogen in its common form isn’t available for electrical use. So hydrogen is converted into electricity using a fuel cell. But first hydrogen needs to be broken down and extracted from other sources so it can be used as fuel. The fuel is then used to power the reactions inside the fuel cell which creates energy and water as the byproduct.
Hydrogen isn’t widely available in its elemental form, it’s usually found in combination with other elements in substances like water, or hydrocarbons like methane, gasoline, coal, or natural gas.
Hydrogen molecules need to be extracted from these compound sources before they can be used. There are many methods for extraction, including biological methods using bacteria and solar photolytic methods, but the most common ways are steam reformation and electrolysis.
Electrolysis is a process that extracts pure hydrogen from water. This allows the hydrogen to be used as fuel to create electricity.
Electrolysis occurs within a machine called an electrolyser (pretty easy to remember, right?). The electrolyser uses an electrical current to split water (H2O) into separate hydrogen and oxygen molecules creating a ready supply of hydrogen fuel that can be put into a fuel cell.
Right now, coal or natural gas provides the majority of the energy an electrolyser uses to split water, which is why hydrogen fuel isn’t typically considered a clean energy source.
Luckily, researchers are conducting studies focusing on using more renewable sources such as wind energy or nuclear power to replace the energy source in the electrolyser, to assist in making hydrogen energy as clean as possible.
The Texas-based start-up Green Hydrogen International (GHI) announced a 60 gigawatt renewable hydrogen energy project in South Texas, using wind and solar power as primary inputs, along with a salt cavern for hydrogen storage. They plan on using the project to produce a clean source of rocket fuel for SpaceX.
Steam reforming is a different process of extraction where steam is kept at a high temperature and pressure which reacts with fuels. Most commonly the fuel used for steam reformation is methane but other sources such as gasoline, propane, diesel, and ethanol are also common.
These fuels get broken down from high temperature and pressure and release hydrogen which can then be used as fuel. Hydrogen produced specifically through steam reforming using methane is considered “gray” and is not generally regarded as an effective solution to climate change due to having other byproducts such as carbon dioxide, nitrous oxide, and sulfur dioxide that are harmful to the environment.
Approximately 95% of hydrogen energy produced is through steam reformation using natural gas.
Hydrogen is so widely abundant in the universe that it can be locally sourced and produced almost anywhere by extracting the fuel from a range of sources including water, oil, gas, natural gas, and even sewage.
This high availability reduces countries' dependence on external energy suppliers which could reduce common conflicts surrounding coal and oil, like the oil-price war that emerged between Saudi Arabia, Russia, and the US earlier in 2020, as well as the conflicts surrounding current gas prices due to international conflict.
Hydrogen fuel is more environmentally friendly, efficient, and can be renewable (if clean energy is used to create it).
When broken down, hydrogen energy seems like a simple solution, but is it an environmentally friendly option? The short answer is: it can be.
Elemental hydrogen on its own is carbon-free, producing only water as a byproduct. However, having water as the only byproduct relies solely on using renewable energy sources while extracting and splitting hydrogen from element-filled compounds.
But if the compounds are fossil fuels, that is not a clean way to extract hydrogen. We know that fossil fuel combustion has detrimental effects on the environment and on human health, such as eye, nose, and throat irritation, difficulty breathing, and in severe cases cancer and long-term damage to the immune system as well as the neurological, reproductive, and respiratory system. Because of hydrogen’s potential to be used as clean energy, it could be one solution to the health problems the world (both people and our planet) currently faces from modern energy production.
Hydrogen has a high energy density, meaning it can provide almost three times the energy that gasoline combustion can produce per unit mass. Roughly, hydrogen contains 16.5 kilowatt hours of energy per pound whereas petrol or diesel contains close to only 6 kilowatt hours per pound.
Imagine you’re backpacking across the country, would you rather carry a phone battery as heavy as a brick or as light as a feather? Hydrogen is the lightest element which makes it ideal for transportation—it takes less energy to haul around a lighter energy source. This makes hydrogen fuel an efficient and powerful source of energy when produced correctly.
One astounding benefit of hydrogen energy is that it can be recycled. When hydrogen energy is produced, the only byproduct of the reaction is water. The water can then be fed back into the system to be broken back down into hydrogen fuel to create more energy.
This loop can continue and create an incredible source of energy since the hydrogen still exists, just in a different compound. This means that all the hydrogen that is currently on the Earth will always be available to use as energy, as opposed to fossil fuels which can be completely used up, making them nonrenewable sources.
Hydrogen can be used as a fuel in a multitude of processes including the industrial process of refining fuels. Specifically, hydrogen has already been used to refine metal ores and to upgrade heavy oils and tars to be more efficient. Similarly, hydrogen is used in refineries to reduce the sulfur content in diesel fuel. Sulfur regulations on fuels have become more intense so the use of hydrogen in refineries has risen dramatically both domestically and internationally.
Hydrogen is associated with “Hindenburg Syndrome” where anything utilizing hydrogen becomes a feared practice. This syndrome is based on the Hindenburg accident in 1937 where a blimp carrying approximately 7 million cubic feet of hydrogen gas caught fire and was destroyed.
Despite its dark history, hydrogen companies such as GenH2 are constantly researching, discovering, and developing new methods and technologies to store and use hydrogen safely so that it can transition into a clean energy solution. While being dangerous to work with, hydrogen energy can also be expensive, hard to store, and still utilize fossil fuels in its production.
First and foremost, just as with any relatively new technology, hydrogen energy can be expensive. The capital cost of a current hydrogen production system ranges from $1000 per kilowatt to $3000 per kilowatt. Similarly, the cost of steam reformation is roughly shaped by gas prices due to the use of oil and gas as energy inputs in the reformation process.
Although hydrogen energy can be widespread and used almost anywhere due to hydrogen’s abundance, finding a site for a hydrogen production facility can be costly. Comparably, hydrogen fuel is far more efficient than gasoline but nearly four times more expensive sitting at the equivalent of $16 per gallon.
Storing hydrogen takes up a great deal of space, so the development of storage facilities and techniques is crucial to turning towards a hydrogen economy.
The most common methods of storage are liquidation and compression. However, liquefying hydrogen is energy intensive and time-consuming where approximately 40% of the energy is lost during the process. Although hydrogen is energy dense, losing 40% of the energy during the storing process is costly. Similarly, compressing hydrogen into a smaller volume at high pressure is an option but it becomes dangerous.
As with any fuel, there are potential consequences to be mindful of. But many studies have looked at hydrogen's safety implications, and results indicate that the dangers of hydrogen seem no worse than those of gasoline, natural gas, or any other fuel. The concerns are simply different.
Specifically, hydrogen has a large range of flammable concentrations in the air with lower ignition energy than gasoline. This means it will ignite quicker and more easily than some other fuels. The solution to this issue lies in mitigating ventilation and leak detection systems within vehicles and production areas. Similarly, hydrogen can cause certain metals to become brittle causing cracks and breaks, so research on which metals are resistant is necessary for building safe hydrogen fuel-based vehicles.
As previously mentioned, fossil fuels aren’t completely out the door with hydrogen energy. Some steam reformation is still using fossil fuels as the primary energy source when extracting hydrogen fuel. This causes hydrogen energy to be less environmentally friendly and have detrimental effects on the environment and human health.
This is a point of interest that can be addressed by implementing renewable energy such as solar power or hydropower as the chief energy source in hydrogen refinement to move towards a greener energy sector.
Hydrogen energy can be renewable.
Hydrogen energy runs on what’s called a color scale, where colors are named to define whether or not the energy is renewable. Gray hydrogen we mentioned as being non-renewable due to the main energy input being methane, a common atmospheric pollutant. Similarly, there is blue hydrogen. Blue hydrogen refers to hydrogen fuel produced from other non-renewable sources, excluding methane, in the steam reformation process. Most hydrogen currently used as energy is considered to be blue hydrogen.
On the other hand, there is also green hydrogen.
Green hydrogen is hydrogen energy produced using renewable primary sources (like wind or solar). Green hydrogen is considered renewable since it’s processed with no CO2 emissions. Green hydrogen is produced through electrolysis rather than steam reformation where the only byproduct is water.
Hydrogen energy is considered to be a good source of energy due to its high energy content, reduced environmental concerns, and its ability to aid in the refinement of other fuels. The abundance of hydrogen lends itself to being a good source of energy. As long as the technology exists, hydrogen will always be readily available in water. Hydrogen as a source itself is manageable and full of energy.
Hydrogen energy is expected to grow rapidly in the future, particularly to build cleaner vehicles. Currently, California is leading the nation in fueling stations for hydrogen-powered cars; an estimated 47 retail hydrogen stations are open to the public as of the middle of 2021.
The idea of hydrogen-fueled powertrains is proposing a solution for long-distance travel using clean energy and in 2030, 3% of global vehicle sales are expected to be hydrogen-fueled with percentages possibly reaching 36% by 2050.
Similarly, hydrogen energy is expected to provide more electricity and even, in certain circumstances, be used as a fuel for space heating.
If we can find ways to cleanly generate hydrogen fuel (focusing on green hydrogen as opposed to gray or blue hydrogen)—and continue making safe storage innovations—hydrogen could be a powerful tool in creating a more sustainable energy future.