Declining renewable energy costs have sparked a renewed interest in green hydrogen, which has the potential to decarbonize sectors in which electricity cannot.
Because hydrogen doesn’t occur by itself on Earth, it must be separated from other elements, such as oxygen in water. Electrolysis is the process of using electricity from renewable energy to extract hydrogen from water.
Dr. Ben Wiley, Duke University Professor of Chemistry, joins Climate Now to explain hydrogen electrolysis, where it makes sense to integrate into the energy economy, and the technology he is helping develop to improve its productivity.
Duke University Professor of Chemistry
Duke University Professor of Chemistry
Ben Wiley is a Professor of Chemistry at Duke University where he studies materials and methods for improving the efficiency of water electrolysis to create hydrogen for energy use.
Climate Now Host
Climate Now Host
Climate Now Host
Climate Now Host
Katherine Gorman is a podcast host for Climate Now. She has worked for terrestrial public radio stations across the US, and is also co-host of the podcast “The Talking Machines”. She is excited to democratize the climate conversation and to learn and share knowledge from experts in the field.
Katherine Gorman (00:02):
You are listening to Climate Now. I’m Katherine Gorman.
James Lawler (00:05):
And I’m James Lawler.
Katherine Gorman (00:07):
So, hydrogen fuel. I don’t know about you, James, but when I think about hydrogen as a fuel, I’m kind of stumped by how in the world it’s possible to power vehicles or generate electricity with just this one gas element and only get water as a by-product. It kind of feels like, like alchemy, like turning things into gold a little bit impossible.
James Lawler (00:29):
Yeah. The picture in my head is sort of fourth grade physics filling balloons. That’s where I’m at at the beginning of this conversation.
Katherine Gorman (00:39):
But despite our knowledge of fourth grade chemistry, though enthusiasm for the subject, a lot of advancements in technology have been made in this subject and investors around the world are putting in a lot of effort to change that. And with us today to give us the ins and outs of this technology is Dr. Benjamin Wiley from Duke University. And you may, during our interview hear the occasional rooster crowing in the background, Dr. Wiley is joining us from his home where he owns a coop. So Ben, thank you so much for taking the time to join us today. We really appreciate it.
Ben Wiley (01:10):
It’s my pleasure.
Katherine Gorman (01:11):
The first question that we ask all of our guests is how did you get where you are? What’s your story?
Ben Wiley (01:16):
Growing up I was definitely interested in new technologies, although not necessarily like science and engineering, in junior high and high school, I was kind of better at history and memorizing stuff. And so actually I had planned to go to Georgetown our Columbia and join like a diplomatic corps cause I was imagining this glamorous life being at parties overseas or something like that? You know, something ridiculous, which totally has no basis in reality, except in movies, I guess. You know, I didn’t get into Georgetown or Columbia, so I ended up going to the University of Minnesota, my backup school. You know, looking around and realizing I didn’t understand what the world was made of is like part of it. I ended up choosing chemical engineering, which was a great major at the University of Minnesota. I didn’t really enjoy science and engineering in the classroom, but once I was able to actually try and do a bit of it on my own, that really lit the fire for me because doing something that no one had ever done before just seemed really cool. I went to graduate school in Seattle in kind of the heyday of nanotechnology. And so I ended up joining a group Younan Xia, where he was making all these crazy shapes on the nanoscale. And I thought that was so magical.
Katherine Gorman (02:38):
So when we’re talking about nanomaterials, are we talking about structures larger or smaller than proteins and sort of the complicated level of the folding of proteins? I’m just trying to like put this into my theory of mind for basic science.
Ben Wiley (02:55):
Yeah. So proteins are kind of one or two nanometers or so, so you can make nanostructures that small. So anything in kind of the one to a hundred nanometer range would be a nanostructure and the nano wires I worked on had diameters about 10,000 times smaller than the human hair. So just to give you an idea of the length scale, one of the research projects I’ve worked on as an undergraduate was looking at these spheres assembling in this evaporating liquid and making a photonic crystal, and I was like watching that in a camera image, and I was like telling my friends, oh no one’s seen this before. I thought that was so so cool to watch that. And it, and it revealed like, yeah, there’s this hidden world, you know, at that, at that really small length scales. And then yeah, you could see that more using electron microscopes. You can even, so my job as an undergrad was like, basically cook some nanostructures up. And then in the evening go to the scanning electron microscope and see what, what shape I made.
Katherine Gorman (03:59):
I love that though. But it must’ve been discovering a new planet every day at 6:30, right? Like what did we get this time?
James Lawler (04:06):
You’re making me want to ditch everything and go back to school.
Ben Wiley (04:09):
That’s great. Yeah. I would make these new shapes like, uh, right pyramids and nano bars and nano rice. And so it was a lot of fun. Yeah.
James Lawler (04:20):
So to get us started, can you talk to us about the basic chemistry of producing this pure hydrogen and the process of using that to generate electricity? So what are the chemical reactions that we’re talking about?
Ben Wiley (04:32):
So this is great, because I’m currently teaching these in my general chemistry class. So it’s all very fresh in my mind. When you apply a voltage to water, say you apply just, you know, 1.5 volts off of a battery, or maybe you want to apply a little bit higher like two volts. So that driving force is enough for you to transfer electrons to the hydrogen atoms in water. So hydrogen, as part of water, each hydrogen atom actually has what’s called a plus one oxidation state, meaning it’s just a proton without its electron. Whereas the oxygens are in a minus two oxidation state, meaning they have two extra electrons per atom. And so what you’re doing when you’re splitting water is you’re putting electricity in that the electrons are going to the hydrogen atoms and then the hydrogen atoms as they gain electrons are combining to make hydrogen bubbles on the what’s called the cathode is where you’re putting electrons in and then they kind of just float off.
Ben Wiley (05:36):
And then at the same time simultaneously, you’re taking electrons out of the oxygen atoms in the water at what’s referred to as the anode, oxidation of the anode, the vowels go together there. So you’re taking electrons out of the oxygen and bringing them back to a zero oxidation state from -2 to 0 and they’re recombining to make oxygen. So you have to take, you know, 4 electrons out of the oxygen atoms in water, and then recombine them into oxygen to make this reaction happen. And it’s that step, which people refer to as oxygen evolution, that tends to be the least efficient step in the process. So that’s how you split water. And then you can use this same, you can just use the reverse reaction to get energy out.
Katherine Gorman (06:27):
Awesome. So in terms of renewable energy, the question I’d like to start off with is in this energy over supply/storage problem. Can you describe what it is exactly? And then how does that relate to hydrogen production via electrolysis?
Ben Wiley (06:43):
Yeah, sure. As you increase the proportion of renewables on the grid, right, I mean, any renewable, it just generates power whenever. You can’t, like, throw in more coal or take out less coal or, you know, it’s just gonna, wind is going to blow, sun’s going to shine. And so you’re just generally going to have some mismatch between that power that’s generated and how much power you can use. And for example, in California, I was just looking up this past month, about 4% of the electricity was curtailed or wasted from the solar power. And they have about 25% renewables on their grid right now. So you can imagine, if we’re trying to get to a world where it’s 100% or at least 80% of renewables – maybe the rest would be something like hydro and nuclear, that’s a little more stable – but even at 80, even at 50%, it’s going to be more, it’s going to be like 10% of the generation. And it’s kind of an open question, whether that’s a real problem. I mean, maybe that’s just the cheapest thing to do is to make a bunch of solar panels and just dump the electricity.
Katherine Gorman (07:52):
So renewables, aren’t always running, and sometimes when they are running, we don’t use all the electricity they produce. So we need some way to store the extra energy to use when they’re not running.
Ben Wiley (08:03):
Hydrogen generation is one of those [ways to store the extra energy]. I mean, probably people are more familiar with lithium-ion batteries, right, as kind of a temporary storage solution and shifting some of that load over. But that’s really, it’s quite expensive. Those batteries are quite expensive, especially if you wanted to store a lot of electricity.
James Lawler (08:29):
How is most hydrogen produced at scale today? And to what end?
Ben Wiley (08:33):
So, like two-thirds of it is made via heating natural gas with steam. So that then just converts the carbons to CO2 and then you strip off all the hydrogens off the natural gas. And then another around a quarter is made from coal, mostly in China, kind of the same process heat up coal with steam. And then about 2% is made via electrolysis, actually splitting water with current, about half of that, or 0.7% of all hydrogen is what people now referred to as green hydrogen, where you’re taking renewable energy and using it to split water, to make hydrogen and oxygen.
James Lawler (09:16):
And why do we produce hydrogen today? What are the, what’s the end market for hydrogen?
Ben Wiley (09:20):
Yeah. So the biggest end market is making ammonia for fertilizer. And then second to that is petroleum refining, so hopefully that goes away. And then another big area is in methanol and chemicals.
James Lawler (09:34):
So we’re basically producing it through these various ways, and we’re, are we compressing it? Are we liquifying it and then shipping it? Is that generally how it’s produced and then shipped around? Or is it going through pipes or how is it?
Ben Wiley (09:48):
My understanding is almost all of it is used locally, probably as part of some big refinery or chemical complex. Yeah. Because shipping it would increase costs. And that is definitely one of the problems with hydrogen is it’s not dense, less dense than helium. They used it in the Hindenburg. So it’s very hard to compress it and ship it.
James Lawler (10:13):
Are there other reasons why hydrogen is not a more prevalent sort of end use fuel right now?
Ben Wiley (10:21):
For green hydrogen the biggest issue is the cost of electrolysis. In particular that of which mostly is the cost of electricity. So kind of the resurgence of interest in green hydrogen now is people realizing that with the declining cost of renewable energy, there’s going to be some tipping point where electrolysis becomes cheaper than hydrogen from fossil fuels.
Katherine Gorman (10:49):
And when we consider using hydrogen as a means to store excess energy from renewables, as an energy carrier, tell us about what the challenges are there?
Ben Wiley (10:56):
As far as using hydrogen as an energy carrier there’s definitely, like I said, challenges. So, transportation is one and then the inefficiency of energy conversion is another. So anytime you’re converting water to hydrogen, right, you’re taking a liquid and you’re splitting it apart, into gases, right? So at least you’re applying the energy requirement to boil the water. There’s an inefficiency there. And then when you get it back, so you put the hydrogen in a fuel cell to power a car, then you have another loss in energy as this gas condenses to become water. And so I think the efficiency of renewable generation going to powering a fuel cell car, the efficiency there is about 22%. So you’re losing about 80% of electricity. Where for electric vehicles, it’s more in the 70s in terms of the efficiency, so you’re retaining most of the energy that you originally generated.
James Lawler (11:59):
So why something that we should be focused on at all, if it’s so inefficient?
Ben Wiley (12:03):
Yeah. So there’s a couple of points. So one is the areas of the economy that you can’t decarbonize with batteries, for example, long-haul shipping and aviation. Gonna be very difficult to decarbonize with batteries. And then, some industrial processes like ammonia production for example, is responsible for 1% of greenhouse gas emissions and steel production is responsible for around, I’ve seen around 7% of greenhouse gas emissions. So those type of large-scale chemical processes that generally currently produce CO2, there’s a potential to use hydrogen to decarbonize those areas. So in the case of aviation, you know, people are thinking about potentially running planes with fuel cells. You could run them with ammonia, you can burn ammonia and it’s a liquid carrier of energy for hydrogen, or you could try and make synthetic kerosene using hydrogen and even hydrogenating the carbon dioxide in the atmosphere to make kerosene or aviation fuel in kind of the same process, right? For, shipping, I mean, there is boats that carry ammonia now internationally, so they could potentially burn it. This is definitely not something that is currently economical, right? Without some significant incentives from the government.
James Lawler (13:32):
Great. And I think some of our listeners would be very keen to know what the levelized cost of hydrogen power is versus other renewables. Can you share any insight on that?
Ben Wiley (13:41):
You shouldn’t compare necessarily the levelized cost of hydrogen with renewables since that’s kind of just your direct energy that’s coming from your solar panel or your wind turbine, but you could compare it with batteries, right? Cause those are both storage technologies for long durations of storage. It makes a lot more sense to store the energy in hydrogen because you can just store it in a big steel tank rather than in a gigantic battery. And then you can run your fuel cell off that stored hydrogen for a very long time, whereas batteries they’ll typically discharge them in a matter of hours. So that’s, that’s the advantage of hydrogen is that for, you know, what people call like seasonal storage, where there might be prolonged periods of low wind and solar generation.
James Lawler (14:29):
You mentioned that there’s some inefficiencies sort of inherent in the, not necessarily in the chemistry, but in the way, in which these reactions happen, the mechanisms of these electrodes, the physical qualities of these electrodes, and you and your colleagues did a study that found that a particular kind of material was just significantly more efficient at producing hydrogen than conventional electrolysis. Can you describe what the challenges were and then what you found in the study?
Ben Wiley (15:02):
There’s been a huge amount of work on water electrolysis, but what I was interested in was almost all that work has focused on efficiency, meaning how can we get the oxygens to combine better, you know, without wasting so much energy. That’s because electricity has been the greatest cost component to making hydrogen. But the reason why people are looking at hydrogen again is because that cost component is going away.
James Lawler (15:35):
So you mean that in terms of green hydrogen, if these electrolyzers, these water splitting machines, are being powered by renewable energy, we pretty much don’t have to worry about the cost of powering them, those machines, if electricity is super cheap, as long as they’re producing enough hydrogen to meet the market demand.
Ben Wiley (15:49):
Yeah. So there, your return on investment is more driven by how hard you can drive that electrolyzer, how much hydrogen you can generate. And so I hadn’t seen much work at all on this question, surprisingly. There were a few papers, in particular group out of South Africa that had done some really great work on looking at this limit on unique electrolyzer geometry, but most people had topped out around an amp per centimeter squared (Amp/cm2) or so. And the reason is most people will study these electrolyzers where they just have two plates kind of opposed in a beaker. So if you try to run this thing really hard, pretty soon your anode or cathode – one or the other – is going to be covered with gas and you won’t be able to pass any more electricity through it. So we thought, well, how about you run a flow of the electrode, like fluid flow to drive the gas off? And then you can imagine, okay, a metal plate is good, but what if I make the surface area of that metal plate way bigger, you know? And so by splitting it into tiny nano wires. And so you can imagine taking like a piece of steel wool, like that’s going to have a lot more surface area than a piece of steel, right? So if it has more surface area, there’s more surface area to pass electricity to the hydrogen atoms in the water.
Katherine Gorman (17:18):
And you’re looking at speeding up the electrolysis process. What different material did you use?
Ben Wiley (17:22):
We looked at three different length scales of, of these kinds of porous materials made of nickel in this case. We use a nickel foam, a nickel microwire mesh, and a nickel nanowire mesh or felt. And we thought the nanowire felt what would be the best, but it wasn’t. We thought it would be the best because it has the highest surface area, but it also was very tight and trapped the bubbles from water splitting. So it was the micro wire mesh that we could flow the bubbles out. And so that ended up being the best electrode. And then when we, after choosing the best electrode, we were like, okay, how high can we drive this? You know, and we’re pumping fluid through it and driving a lot of current. And the fluid is actually also helping to cool the electrode and the highest currents we could get, where at about 25 amps per centimeter squared.
Speaker 3 (18:10):
So it’s about 50 times greater than kind of the high-end for commercial alkaline electrolyzers, and about 25 times greater than what’s typically done. And even for these very high power electrolyzers that were developed by the South African group, that was still about like six or seven times higher than that. And it was at that point, it was limited by burning the membrane. So we would be passing so much current through this membrane it would like literally melt or burn. So it could potentially go even higher if we were using a more conductive or more thermally stable membrane.
James Lawler (18:48):
So it sounds like that’s a pretty big kind of game-changing proposition there. If you’re, if you’re able to improve the amount of hydrogen by, is it, I guess twenty-five times that yo\u’re producing?
Ben Wiley (19:01):
Yeah, yeah. Something like that, right. Depending on what you’re comparing.
James Lawler (19:06):
Yeah. You know, you can imagine sort of massive, that having a huge impact. And obviously, you know, you mentioned that you got into science to get rich, so…
Ben Wiley (19:16):
I mean, it’s not totally untrue. I mean, it’d be nice to have, so, but I’m doing okay.
James Lawler (19:27):
Yeah, I mean why not? What are the next steps there?
Ben Wiley (19:29):
Yeah. So, funny you mentioned that. So there actually was an individual who kind of leads a group of investors who reached out last summer. And so we’ve been kind of iterating on a plan to bring it to market. So that is actually in the works.
James Lawler (19:48):
So, next question, you know, are there any sort of near term scalable applications of green hydrogen fuel?
Ben Wiley (19:56):
Yeah. I think the lowest hanging fruit is those applications where it’s currently people using hydrogen from natural gas or coal. Right. So ammonia is a huge one. Methanol is another one. And then people are interested in using hydrogen to make steel. People are also looking at electrifying iron production, like just using kind of electrolysis directly, but in molten iron. That has more scalability challenges potentially. So that would be a great application, right? Probably longer term out is looking at using ammonia for shipping, powering shipping and powering aviation. Right now, that’s, there’s just like, it’s in the conceptual stage. I think there’s, I don’t even know if there’s any, you know, plane, I think there might be a plane powered off a fuel cell, but yeah. It’s nothing commercial yet. And of course there’s been like a long drive to make fuel cell vehicles, like back from Bush era right, in the early 90s. And that has gone nowhere because Mercedes closed its program, I think there was another car company, yeah, like a Swedish car, like car and truck maker that shut down its fuel cell program, just because of the efficiency issue and the cost issue. You know, they just never scaled up. There’s been an estimate that if they could make like a million fuel cell cars a year, you could start to get economies of scale there, but it just never got to that point. And then of course you need hydrogen refueling infrastructure, which also doesn’t exist. You can’t just plug it into the wall like you can with a battery car. So that ship seems to have sailed. So that’s probably not where hydrogen is going to go. So it’s more in these hard to decarbonize areas is the greatest potential. Yeah.
James Lawler (21:51):
Well Ben, thanks so much for joining us. We really enjoyed speaking with you.
Ben Wiley (21:55):
Thanks James. I appreciate you guys reaching out.
James Lawler (22:03):
Ben Wiley of Duke University, talking to us about his research and hydrogen as an energy carrier. From what I understand about hydrogen fuel cell vehicles, you know, even though they have had a bit of a rough time breaking into the market due to costs and efficiency, lack of infrastructure, there are some pros. Recharging time, for example, electric cars on average could take between 45 minutes to several hours to fully refuel. Whereas with hydrogen cars, you can refuel them, you know, within a couple of minutes. So they do have that advantage.
Katherine Gorman (22:33):
Yeah, and what’s even better is you can go longer distances because of how energy dense hydrogen fuel is.
James Lawler (22:40):
This would make hydrogen particularly attractive. Therefore for long haul shipping and aviation, like Dr. Wiley was saying. In fact, you know, the larger the vehicle, the more sense hydrogen might make from a cost and energy use perspective.
Katherine Gorman (22:54):
And the only emissions coming from vehicles powered by hydrogen is water, which is mindblowing! So that is it for this episode of the Climate Now podcast. For more details and visuals on hydrogen fuel and how it’s made check out our hydrogen fuel video on our website. You can also check out other interviews, watch all of our videos, and sign up for our newsletter at climatenow.com. And if you want to get in touch, email us at firstname.lastname@example.org or tweet at us @weareclimatenow. We hope you’ll join us for our next conversation.