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Hydrogen fuel cells — good or bad for the environment?

Scotland is planning to have its first hydrogen-powered train ready to go by November of this year. It’s a huge undertaking involving many partners, including the Hydrogen Accelerator at the University of Saint Andrews and engineering firm Arcola Energy. “With Scotland’s focus on achieving net zero emissions by 2035 and rail playing a leading role in this, hydrogen offers a safe, reliable and zero carbon alternative to other forms of rail propulsion,” Clare Lavelle, Scotland Energy business lead at project partner Arup said in a statement. “This project is not only a crucial step in helping us understand the practical challenges of using hydrogen traction power on our railways, but an example of the type of investment Scotland needs to take advantage of the opportunity to build a secure, flexible, cost effective and zero carbon energy network.”

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But not all experts are sure that hydrogen fuel cells are a clean enough power source to warrant enthusiasm. Many still question whether this mode of powering cars, planes and trains will actually help slow climate change. Some even worry hydrogen production will accelerate it.

Related: Scotland to become first country to test 100% green hydrogen

Hydrogen fuel cells 101

Even if you never took or passed chemistry class, you probably know that hydrogen is exceedingly common, putting the H in water’s H2O. Hydrogen is also present in compounds like methane and coal. This gas could be a potent source of clean energy, and, according to the U.S. Energy Information Administration, it has the highest energy content by weight of any common fuel source.

In terms of emissions, burning hydrogen for energy doesn’t hurt the environment, as the only byproducts it releases are heat and water. The problem comes when separating out the hydrogen. To make it usable as a fuel, hydrogen must be separated from water, coal, natural gas or animal or plant waste. Currently, most of the 9 million metric tons of hydrogen the U.S. produces annually comes from methane via steam reforming. This process releases greenhouse gases. Still, hydrogen can also be separated from water through a process called electrolysis, which can be powered by wind, solar or other renewable energy sources. The downside of this option is the much higher cost.

Hydrogen is also currently used in food processing, treating and refining metals, NASA’s space fuel and to power a few exclusive car models, such as the Toyota Mirai. As Popular Mechanics explains it, hydrogen cars are electric cars. “When we talk about electric cars, that includes plug-in hybrids, hybrids, battery electrics, fuel cells, and anything else that may come along later that still uses an electric motor,” said Keith Wipke, laboratory program manager for fuel cell and hydrogen technologies at the National Renewable Energy Laboratory. However, a fuel cell is much different than the giant lithium-ion battery you find in electric cars. The hydrogen fuel cell produces electricity through electrochemical reactions when the hydrogen combines with air.

Pros and cons of hydrogen fuel cells

Inventors and engineers have experimented with hydrogen as a clean energy source for decades. Back in 2003, the Bush administration dedicated $1.2 billion for hydrogen research. The fact that hydrogen is about three times as efficient as gasoline for fueling cars entices many.

But, in addition to the cost challenges of clean hydrogen fuel production, there’s a danger of the gas escaping into the atmosphere while being stored or transported. Hydrogen is tricky to transport because it needs to be stored under high pressure. According to models designed by researchers at the California Institute of Technology, without a completely efficient way to produce, store and transport hydrogen, 10% to 20% of the gas will escape into the atmosphere. “More or less dramatic scenarios are equally imaginable, but clearly the potential impact on the hydrogen cycle is great,” the researchers concluded. These researchers theorized that oxidized hydrogen would cool the stratosphere and make more clouds, adversely affecting the polar vortex and increasing the holes in the ozone layer

But let’s say the production, storage and transportation problems could be overcome and hydrogen’s efficiency safely tapped into. Before there’s a hydrogen-powered auto in every garage, the costs will have to come down and the convenience will need to go up. Right now, the three premier hydrogen-powered cars — the Toyota Mirai, the Honda Clarity and the Hyundai Nexo — cost between $50,000 and $60,000. You could buy about three Civics for that. And you’re not going to get very far in a hydrogen-powered vehicle unless you have somewhere to refuel. For now, in the U.S., that means cruising through California or tooling around Wallingford, Connecticut, according to the U.S. Department of Energy website. Whether or not major oil companies will ever willingly add hydrogen tanks to gas station offerings remains to be seen. In addition to competing with their prime commodity — gasoline — companies also face the issues of safe storage and, so far, low demand.

We obviously need to make some big energy changes, and there’s hope for hydrogen. But for now, better hold onto your Civic. Or, better yet, your bike.

Via How Stuff Works: Science, Physics World, and U.S. Department of Energy

Images via Matthew Venn

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