With battery energy storage gaining momentum and capturing not just the electric vehicle market, but also starting to capture more of the home and grid energy storage market as well, I’ve been left wondering why so many companies are still supporting fuel cells. What are the pros and cons? And is there a future for fuel cells versus batteries beyond cars?
Last year I put out a video that focused in on just fuel cell cars, but since then I keep hearing from some of you about fuel cells as a potential solution for electric flight, large scale transportation like buses, trains, and boats. There are some interesting innovations and fuel cell products on the market worth taking a look at, but before we get to that it’s important to understand some of the basics. How do fuel cells work? And how do they compare to batteries … which is where you’ll start to see why a lot of people think fuel cells missed their window of opportunity.
Fuel cells aren’t a new concept at all. In fact they go all the way back to 1838 when Sir William Grove invented them. But it wasn’t until almost a century later that Francis Thomas Bacon invented the hydrogen oxygen fuel cell, which eventually became the cornerstone for commercialized fuel cells. In fact, it’s often referred to as the Bacon fuel cell … I’m getting hungry just thinking about it. This alkaline fuel cell has been used by NASA to power satellites and capsules since the 1960s. It’s during this timeframe that they really start to gain some commercialized success.1
The way fuel cells work should look kind of familiar if you know how batteries and supercapacitors work. They’re made up of an anode, cathode, and electrolyte just like a battery. On the anode side you supply a source of fuel, like hydrogen, which uses something like platinum to act as a catalyst causing the fuel to undergo oxidation … generating ions. The ions, which are positively charged travel to the cathode through the electrolyte and the electrical circuit. This is where the direct current is captured and put to use. The cathode catalyst, which is usually something like nickel and flooded with oxygen, turns the ions into waste. In the case of hydrogen, because we’re using oxygen on the cathode, we’re talking about creating water as a by-product. Most fuel cells produce water, heat, and depending on the fuel source, nitrogen dioxide.
Fuel cells are similar to combustion engines and generators in that they require a constant supply of fuel in order to keep operating. Where they differ is that instead of burning a fuel to release that power as captured heat, fuel cells use chemical reactions to release and capture ions to generate electricity. That’s where they’re more similar to batteries. Fuel cells kind of sit in the middle between the two technologies.
And that’s also true when it comes to efficiency. How effective are they at capturing and using the energy they generate? Most fuel cells fall somewhere between 40-60% efficient. If they’re designed to capture the heat they generate as well, they might be able to get up to the 80% range. Car engines on the other hand are somewhere around 25% efficient. But the winner is batteries which are around 80-90% efficient.
If you look at the cost, things don’t get much better for fuel cells. The leveled cost of energy (LCOE) is a good way to evaluate how different forms of energy generation compare to each other. In an analysis by Lazard they showed that the unsubsidized $/MWh for fuel cells is between $103 – $152, which makes it more expensive than gas peaker plants and on par with nuclear and coal. Meanwhile solar and wind are dramatically cheaper starting around $40 and $29 respectively.2
I won’t go into too much detail about the different types of fuel cells, but the usual suspects are Proton Exchange Membrane, Alkaline, Molten Carbonate, Phosphoric Acid, Solid Oxide, and Direct Methanol.3 You know … those old chestnuts. Each one has its own set of pros and cons, like how much they cost to manufacture, how much heat they output, how much power generation they’re good for, you get the idea. The last one of those, Direct Methanol, is the least efficient at around 20%. Some are better for smaller, portable power options like Proton Exchange Membrane; others for large-scale power generation like Molten Carbonate.
But it’s the power efficiency that’s the Achilles heel of all fuel cells when you compare it to battery energy storage. Even if you focus on hydrogen as a fuel source, which is the most abundant element on the planet and offers extremely clean operation, it’s not a flattering comparison. You can generate hydrogen from water using electrolysis, which takes energy. Even if you use renewable sources like solar and wind to generate the hydrogen, that process is about 70% efficient. Then the hydrogen is compressed into tanks, which has an efficiency of about 90%. Then running the actual fuel cell is between 40-60% efficient. So when you start adding up all of these efficiency losses across the use cycle of a fuel cell, you end up with something around a 35% overall efficiency. Compare that to battery storage from solar or wind, which can be over 90%.4 Even the electricity loss over power lines is more cost effective than transporting hydrogen tanks. Doesn’t look so rosy, does it?
So why haven’t fuel cells faded off into the land of misfit toys? Well, this is where it gets interesting because fuel cells start to make a pretty good case for themselves when you need to deliver non-stop power in a specific location. A good example of this is data centers, which are opting to use fuel cell installations as emergency backup more and more. Apple is using Bloom Energy fuel cells for some of their backup needs, and pairing it to their self-contained micro grid of solar panels and rechargeable batteries.5 6 It’s like an insurance policy in case their grid goes down, their batteries are drained, and they aren’t able to resupply themselves with enough solar energy: enter their fuel cell backups.
And Microsoft is testing fuel cells as a replacement for their diesel backup generators at their data centers as well. One of the appealing aspects is fitting the installations with an electrolyzer that could take advantage of excess wind or solar energy to generate and store their own hydrogen. Then during peak demand they could spin up their hydrogen fuel cells to generate energy for themselves or the grid.7 While not as efficient as battery storage for capturing that excess energy, it’s two birds with one stone. Normally these backup systems sit unused 99% of the time. This could give backup systems like this extra benefit, and a way to save additional money.
Fuel cells can also provide power to rural areas that are too remote to be tied into a broader grid. It’s a method to effectively create micro grids whenever and wherever they’re needed. The South African government is partnering with several companies to do just this. They’re also using fuel cells to power a field hospital in Pretoria that’s set up to handle the influx of COVID patients. Fuel cells are a simple way to bring more renewable methods of energy generation to remote areas, and they let you easily setup power when and where you need it.8 These types of solutions are replacing the need for diesel generators.
Looking back towards transportation is large scale shipping, like freight shipping by sea, which can also benefit from fuel cells. Samsung Heavy Industries, which is one of the largest ship builders in the world, is partnering with Bloom Energy to develop a new fuel cell powertrain for their commercial ships. The ultimate goal is to replace oil-based power generation, which accounts for the vast majority of ships today. They’re hoping to show off a design by 2022.9 When you think of trying to build out a new hydrogen economy to support transportation, large scale shipping makes a lot of sense as a place to start. You can focus the development efforts around the ports where ships would be refueling. In comparison, building out an infrastructure for passenger vehicles is a lot trickier and more costly, which is one of the many reasons that passenger fuel cell vehicles haven’t caught on.
And there’s been some really interesting advancements in making fuel cells cheaper to manufacture and last longer. The company Ceres has a process to create a SteelCell solid oxide fuel cell (SOFC), which is capable of using everything from natural gas to hydrogen. This adaptability means it could take advantage of existing natural gas infrastructure for use in homes and businesses … and be adapted down the road when hydrogen and other fuels become more prevalent. Since it’s made from steel and ceramics, it’s using commodity materials and processes that can keep costs down.
While the future of fuel cells for passenger vehicles is most likely over — and you can check out my video on that topic — it doesn’t mean that fuel cells as a technology is over. They’re a big improvement in efficiency and pollution compared to burning fossil fuels,10 and will continue to get cleaner as we get better about generating hydrogen from clean energy sources like solar and wind. If you think about a fuel cell as a generator, there are an incredible array of opportunities for fuel cells to carve a niche for themselves, and be a valuable part of the energy mix.
- Wikipedia – Fuel Cell ↩︎
- Lazard’s Levelized Cost of Energy Analysis – Version 12.0 ↩︎
- Battery University – How does the Fuel Cell Work? ↩︎
- EESI – Fact Sheet: Energy Storage ↩︎
- Cnet – Apple data center helps fuel Bloom Energy move to East Coast ↩︎
- Apple Insider – Apple’s Campus 2 to use updated Bloom Energy fuel cells first deployed at NC data center ↩︎
- Microsoft tests hydrogen fuel cells for backup power at datacenters ↩︎
- Hydrogen fuel cell technologies to provide electricity to rural areas and hospitals ↩︎
- GreenBiz – Could Bloom fuel cells be a solution for maritime emissions issues? ↩︎
- Union of Concerned Scientists – How Clean Are Hydrogen Fuel Cell Electric Vehicles? ↩︎