To achieve its clean energy goals, the world has to find a way to ditch fossil fuels for better alternatives.
The U.S. is one of dozens of countries working to curb pollution and promote a greener environment. Although retiring fossil fuels is the goal, renewables may not be the fastest way to get us there. Luckily, renewables can help us produce fuel with zero emissions and a seemingly endless supply.
Thanks to advancements in hydrogen technology and more renewables, green hydrogen could solve our problems. But before calling it the next apex fuel, we must maximize its potential.
Hydrogen is the most abundant element in the universe and can be found naturally underground or produced through gasification – breaking down water molecules into hydrogen and oxygen.
But if hydrogen is so abundant, why isn’t it widely used as an energy source? The reason is simple: it’s too hard to access. Although the USGS (United States Geological Survey) estimated the amount of hydrogen hidden underground could potentially fuel the world for thousands of years, most isn’t accessible. Most likely, the hydrogen is buried too far underground, in hard-to-reach areas, or in small amounts, making it not worth the risk.
The USGS did have good news, though. Even harvesting lesser amounts of the estimated natural hydrogen deposit could last hundreds of years, replacing fossil fuels as a primary energy source. Even with only estimates, global companies are investing billions into finding and capturing naturally occurring hydrogen.
Just because the end product burns the same doesn’t mean it’s all created equally. Depending on how the hydrogen gas is produced, a color is assigned. As you can probably guess, the more polluting the production method, the darker the color.
Naturally occurring hydrogen is the cleanest form of hydrogen available. Sometimes called gold hydrogen, the pure gas is trapped in hard-to-reach rock layers, making it difficult to access, trap, and extract.
Scientists are still unsure how it’s forming underground but have suggested several possibilities. Meanwhile, companies are investing in innovative technologies to find and extract hydrogen for electricity production, welding, manufacturing fertilizer, and more.
When we talk about clean hydrogen production, green hydrogen is what most experts get excited about.
Although it isn’t naturally occurring like white hydrogen, green hydrogen uses electricity supplied by renewable energy from solar and wind to split water molecules. The electrical currents cause a reaction in the water that breaks the water molecules into hydrogen and oxygen, which are both captured and used.
Because the electricity and resulting gases don’t create greenhouse gases, this hydrogen production method is considered “green.”
In the battle of green vs. blue hydrogen, green is more attractive because it produces no greenhouse gases. With that said, blue is much more prevalent. According to data from the International Energy Agency (IEA), roughly 95% of the low-carbon hydrogen generated in 2020 was blue.
To make blue hydrogen, natural gas is combined with high-temperature steam to form hydrogen. The by-products end up being hydrogen, carbon monoxide, and carbon dioxide. Next, carbon monoxide is combined with more steam to create more hydrogen and carbon dioxide.
Much of the carbon dioxide, a well-known greenhouse gas, is trapped before it can enter the atmosphere.
Here is where hydrogen production starts to become less clean.
Gray or grey hydrogen (based on location) follows a similar process as blue hydrogen but with one omission. While blue hydrogen production does its best to capture carbon dioxide before it can enter the atmosphere, gray hydrogen releases it.
Some carbon dioxide is good for the environment, helping plants survive and keep Earth’s temperature high enough to sustain life. But too much CO2 can cause the Earth’s temperature to rise. If carbon dioxide ends up in the oceans, it can change the water’s acidity over time.
Brown and black hydrogen are made when coal is used as gasification fuel. The type of coal used will dictate whether it’s brown or black.
This production method is the most common way to produce hydrogen, converting carbon-based materials into hydrogen and carbon dioxide.
The resulting carbon dioxide is released into the atmosphere, but the process could be called blue if captured.
Electricity demand is growing, but so is the need for more carbon-neutral options.
Right now, hydrogen plays a major role in oil refining, and in the production of several products, including ammonia, methanol, and steel. Unfortunately, the hydrogen used is generated using fossil fuels, which contributes to climate change.
As exciting as the idea is, renewables aren’t ready to power everything. However, they can help create hydrogen, which then produces more power. The best part is that surplus renewable electricity from sunny or windy days could be used for the reaction. The resulting hydrogen could then be stored underground in salt caverns, converted abandoned mine shafts, or in tanks for later.
Hydrogen can also be used with combustion turbines, including natural gas ones, though they need retrofitting. Once the plants have been converted to hydrogen, water vapor is the only by-product emitted during combustion. That’s very different from the CO2 natural gas produces.
As much as we love discussing the impending energy transition from fossil fuels, hydrogen may not be ready for the spotlight.
Hydrogen is cleaner than natural gas but comes with several drawbacks. It’s harder to control because of its lower and higher flammability limits. These defined limits dictate the amount of oxygen disbursed throughout a flammable material for it to burn, and hydrogen’s range is larger than natural gas.
Hydrogen: 4%/74%
Natural gas: 5.3%/15%
Control is one problem, but so is the molecule’s size. Hydrogen is the smallest element, making it easy to leak out of containers and from underground holds.
It also burns quickly but doesn’t produce as much energy as natural gas. Although hydrogen is about 2.5 times denser than natural gas, you need about 3 times more to generate the same power. That means you need more fuel to produce a similar result.
Despite these drawbacks, the clean energy generated could be worth switching from oil and gas to blue, green, or white hydrogen.
As the world approaches its 2050 climate change goals, it’s time to consider maintaining and increasing momentum.
Solar and wind are powerful green energy sources but have limitations. Hydrogen is a clean-burning fuel that can be stored and used in traditional fossil fuel plants to keep the lights on. Of course, making the necessary changes to safely burn hydrogen requires billions of dollars in retrofitting.
Outside of simply generating power for our homes and businesses, green hydrogen production could someday replace gasoline in vehicles using fuel cells. Several vehicle models are on the market, but the technology has yet to fully catch on.
But whether it’s white, blue, green, or gray hydrogen, there’s a lot of interest in expanding its use. Sure, there are questions still, but the potential for long-standing, safe, and clean energy is possible.
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