Ask Hackaday: Where Are All The Fuel Cells?

Given all the incredible technology developed or improved during the Apollo program, it’s impossible to pick out just one piece of hardware that made humanity’s first crewed landing on another celestial body possible. But if you had to make a list of the top ten most important pieces of gear stacked on top of the Saturn V back in 1969, the fuel cell would have to place pretty high up there.

Apollo fuel cell. Credit: James Humphreys

Smaller and lighter than batteries of the era, each of the three alkaline fuel cells (AFCs) used in the Apollo Service Module could produce up to 2,300 watts of power when fed liquid hydrogen and liquid oxygen, the latter of which the spacecraft needed to bring along anyway for its life support system. The best part was, as a byproduct of the reaction, the fuel cells produced drinkable water.

The AFC was about as perfectly suited to human spaceflight as you could get, so when NASA was designing the Space Shuttle a few years later, it’s no surprise that they decided to make them the vehicle’s primary electrical power source. While each Orbiter did have backup batteries for emergency purposes, the fuel cells were responsible for powering the vehicle from a few minutes before launch all the way to landing. There was no Plan B. If an issue came up with the fuel cells, the mission would be cut short and the crew would head back home — an event that actually did happen a few times during the Shuttle’s 30 year career.

This might seem like an incredible amount of faith for NASA to put into such a new technology, but in reality, fuel cells weren’t really all that new even then. The space agency first tested their suitability for crewed spacecraft during the later Gemini missions in 1965, and Francis Thomas Bacon developed the core technology all the way back in 1932.

So one has to ask…if fuel cell technology is nearly 100 years old, and was reliable and capable enough to send astronauts to the Moon back in 1960s, why don’t we see them used more today?

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A Brief History Of Fuel Cells

If we asked you to think of a device that converts a chemical reaction into electricity, you’d probably say we were thinking of a battery. That’s true, but there is another device that does this that is both very similar and very different from a battery: the fuel cell.

In a very simple way, you can think of a fuel cell as a battery that consumes the chemicals it uses and allows you to replace those chemicals so that, as long as you have fuel, you can have electricity. However, the truth is a little more complicated than that. Batteries are energy storage devices. They run out when the energy stored in the chemicals runs out. In fact, many batteries can take electricity and reverse the chemical reaction, in effect recharging them. Fuel cells react chemicals to produce electricity. No fuel, no electricity.

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Improved Hydrogen Fuel Cells Are Groovy

According to [Charles Q. Choi], a new study indicates that grooves in the hydrogen fuel cells used to power vehicles can improve their performance by up to 50%. Fuel cells are like batteries because they use chemical reactions to create electricity. Where they are different is that a battery reacts a certain amount of material, and then it is done unless you recharge it somehow. A fuel cell will use as much fuel as you give it. That allows it to continue creating electricity until the fuel runs out.

Common hydrogen fuel cells use a proton exchange membrane — a polymer membrane that conducts protons to separate the fuel and the oxidizer. You can think of it as an electrolyte. Common fuel cells use an electrode design that hasn’t changed in decades. The new research has catalyst ridges separated by empty grooves. This enhances oxygen flow and proton transport.

Conventional electrodes use an ion-conducting polymer and a platinum catalyst. Adding more polymer improves proton transport but inhibits oxygen flow. The grooved design allows for dense polymer on the ridges but allows oxygen to flow in the grooves. In technical terms, the proton transport resistance goes down, and there is little change in the oxygen transport resistance.

The grooves are between one and two nanometers wide, so don’t pull out your CNC mill. The researchers admit they had the idea for this some time ago, but it has taken several years to figure out how to fabricate the special electrodes.

Drone Flies For Five Hours With Hydrogen Fuel Cell

Multirotor drones have become a regular part of daily life, serving as everything from camera platforms to inspection tools and weapons of war. The vast majority run on lithium rechargeable batteries, with corresponding limits on flight time. A company called Hylium hopes to change all that with a hydrogen-powered drone that can fly for up to five hours.

The drone uses a hydrogen fuel cell to provide electricity to run the drone’s motors and other electronic systems. Thanks to the energy density advantage of hydrogen versus lithium batteries, the flight time can be greatly extended compared to conventional battery-only drones. Details are scant, but the company has gone to some lengths to build out the product beyond a simple tech demonstrator, too. Hylium touts useful features like the short five-minute refueling time. The drone also reportedly features a night vision camera and the capability to transmit video over distances up to 10 kilometers, though some of the video of these features appears to be stock footage.

Hylium claims the liquid hydrogen canister used for the drone is drop-safe in the event of a problem. Notably, the video suggests the company tested this by dropping the canister concerningly close to an active motorway, but from what we see, nothing went awry.

A drone that can fly for five hours would be particularly useful for autonomous surveillance and inspection roles. The additional loiter time would be advantageous in these roles. We’ve seen other aero experimenters exploring the use of hydrogen fuel cells, too.

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Largest Ever Hydrogen Fuel Cell Plane Takes Flight

In the automotive world, batteries are quickly becoming the energy source of the future. For heavier-duty tasks, though, they simply don’t cut the mustard. Their energy density, being a small fraction of that of liquid fuels, just can’t get the job done. In areas like these, hydrogen holds some promise as a cleaner fuel of the future.

Universal Hydrogen hopes that hydrogen will do for aviation what batteries can’t. The company has been developing flight-ready fuel cells for this exact purpose, and has begun test flights towards that very goal.

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China’s New 100 MPH Train Runs On Hydrogen And Supercaps

Electric cars are very much en vogue right now, as the world tries to clean up on emissions and transition to a more sustainable future. However, these vehicles require huge batteries as it is. For heavier-duty applications like trucks and trains, batteries simply won’t cut the mustard.

Normally, the solution for electrifying railways is to simply string up some wires and call it a day. China is trying an alternative solution, though, in the form of a hydrogen-powered train full of supercapacitors.

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Battery Engineering Hack Chat Gets Charged Up

Turn the clock back a couple of decades, and the only time the average person would have given much thought to batteries was when the power would go out, and they suddenly needed to juice up their flashlight or portable radio.  But today, high-capacity batteries have become part and parcel to our increasingly digital lifestyle. In fact, there’s an excellent chance the device your reading this on is currently running on battery power, or at least, is capable of it.

So let’s get to know batteries better. What’s the chemical process that allows them to work? For that matter, what even is a battery in the first place?

It’s these questions, and more, that made up this week’s Battery Engineering Hack Chat with Dave Sopchak. Our last Hack Chat of 2022 ended up being one of the longest in recent memory, with the conversation starting over an hour before the scheduled kickoff and running another half hour beyond when emcee Dan Maloney officially made his closing remarks. Not bad for a topic that so often gets taken for granted.

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