DALL·E generated image of an airplane flying over a container ship on a sunny day, digital art

What Do Battery Energy Density Improvements Really Mean For Trucks, Ships, & Planes?

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At the moment I’m writing this, I’m about 30 hours out from sitting on a stage with people whose day job is energy for ships, in front of a big audience of global technical leaders for a major European privately owned shipping concern. They are having their annual technical summit and have invited me to debate with the other panelists and their experts about how shipping will actually decarbonize.

Of course, as I’ll tell them, there are completely good reasons for them to wonder what the heck I’m doing there. Unlike pretty much everyone else in the room, I don’t make, sell, or buy fuel for ships. I don’t buy, sell, or operate ships. I don’t design ships as many of the people in the audience do. I don’t specify the power requirements for ships, once again something the attendees do.

MT Fossil Fuels Shipping by decade through 2100, chart by author
MT Fossil Fuels Shipping by decade through 2100, chart by author

But I’m there because I’ve done for marine shipping what I’ve done for aviation, hydrogen, steel, V2G, and grid storage. I’ve spent a bunch of my time looking at the problem space, comparing all the purported solutions, projecting demand and supply curves forward in a reasonable scenario for decades, and then sharing what I think with supporting evidence. Since a lot of this is about energy, it means that stuff that I learn in one domain is applicable in another. I can cross-pollinate insights a bit more easily than people who spend all of their time working in one domain.

Of course, that means that I have to be really careful of not being a leading example of Dunning-Kruger syndrome, and sometimes I make mistakes that people call me on, but those are mostly manageable concerns with only a small side order of occasional humiliation.

What does this have to do with battery energy density? Well, one of the people on stage tomorrow is a representative of Echandia Marine AB. Their day job is putting batteries in ships, something I consider a major maritime decarbonization wedge. In my 2100 projection, all inland shipping and two-thirds of short sea shipping will be running on batteries, and those batteries will increasingly be charged with low-to-zero carbon electricity. The longer hauls will still need liquid fuels for this century, as replacing 16,000 tons of bunker fuel with batteries to get across the Pacific is just not likely to happen by 2100.

The Echandia material makes a very specific marine range point. Its battery system is good for 40 nautical miles (NM), about 74 kilometers. That doesn’t sound like much, but it covers a lot of big boat and ship journeys.

The system uses lithium titanium oxide (LTO) batteries. That’s what the company considers useful and salable at this point in the decarbonization journey. That chemistry doesn’t have particularly high energy density, but it has good cycle rates and is good for big power draw applications. Good for marine torque and  horsepower requirements today.

Brief nerdier digression: when we talk about energy density and batteries, we’re talking about watt-hours per kilogram (Wh/kg). Diesel runs at about 9,007 Wh/kg. Jet-A aviation fuel runs about 7,778 Wh/kg. They usually aren’t represented that way, because people who sell or use fossil fuels in transportation don’t use units of electricity.

Big marine and big jet engines are absurdly efficient beasts, about as good as it’s possible to get. Decades of focused innovation, demanding customers, and brilliant engineers will tend to have that result. But the Carnot, Diesel, and Brayton cycles have hard thermodynamic limits that they run up against. Big marine engines convert about 50% of the energy in their fuels into forward motion. Modern jet engines turn 55% of the kerosene they gulp into useful energy, at least when they are at 30,000-38,000 feet running at optimal cruising speed.

That means that marine engines get about 4,500 Wh/kg of useful energy out of diesel, and jet engines get perhaps 4,300 Wh/kg. The batteries Tesla uses have about 269 Wh/kg, and while electric drivetrains are much more efficient, don’t turn all of that into forward motion, typically around 85%, or perhaps 225 Wh/kg. There’s a big difference between 4,300-4,500 Wh/kg and 40-225 Wh/kg. Diesel and Jet-A kerosene are running about 20 times as energy dense as the batteries Tesla uses, given the efficiency differences, and obviously a bigger factor for Echandia’s LTO batteries.

But there’s a story here that’s worth telling. The batteries Tesla uses have three times the energy density of LTO, which means that using the same batteries in ships, as some people are doing already, will result in a range of about 120 NM with the same battery sizes. Not much more exciting than 40 NM, but a bit more interesting.

Recently, two different firms made some battery energy density announcements. China’s CATL, the global leader in electrical vehicle batteries with 37% of the market, and Amprius, a Silicon Valley startup that’s actually shipping battery products, both made claims of 500 Wh/kg, about double Tesla’s energy density.

Double Tesla for maritime shipping, and that 120 NM becomes 240 NM. Hmm. That’s covering a lot more sea routes. But we aren’t done yet.

There have also been some very interesting breakthroughs in, once again, the USA and China. Silicon is one of the holy grail chemistries in batteries. It has the potential for 2,600 Wh/KG. After efficiency calculations are factored in, that’s about half of what marine shipping and aviation are getting today. And it’s about five times what CATL and Amprius have announced.

For marine shipping, that means perhaps 1,200 NM of range. And that covers all inland shipping distances and two-thirds of short sea distances. You won’t push a container or bulk ship across the Atlantic or Pacific with it, but you will push a roll-on roll-off (roro) or merchant cargo vessel across pretty much every scheduled route in the world.

As I’ll be asking the Stena Sphere audience, “Are there any Stena Line scheduled routes that are longer than 1,200 nautical miles?” I’m pretty sure, having looked at their scheduled routes on a map, that the answer is no. But I’m not intimate with their business, so there might be one or five. The majority, however, are vastly under that.

The batteries will mostly be in shipping containers, by the way. That’s how major battery storage firms like Tesla, Convergent Energy + Power, and Wärtsilä serving grid and big behind-the-meter deployments ship them now, pre-packaged, configured, and wired, so that they get placed on a slab, plugged in, and just work. As bulk shipping plummets as the 40% of bulk freight that is fossil fuels drops to a fraction of its current volumes, and the 15% of raw iron ore is processed locally much more, an even bigger ratio of marine shipping will be containerized. And container ships and ports already handle containers that must be plugged in, although they currently draw power for refrigeration. Ships and trains will share containerized batteries, and they’ll be charged mostly in transshipment ports, although trains will also have regenerative braking and catenary overhead lines feeding juice to batteries part of the time.

Okay, so that’s Echandia at 40 NM, Tesla-for-marine at 120 NM, CATL/Amprius at 240 NM, and silicon at around 1,200 NM. The 240 NM could be in ships next year or the year after. Silicon could be in ships in a decade, easily, based on current technology readiness levels. Range anxiety anyone?

How does this play out in aviation? Well, Tesla energy densities are already good for 300 kilometers of take-off, flying, and landing without divert or reserve energy. A number of firms are using hybrid systems where sustainable aviation fuel (SAF) can power a generator for divert and reserve, so they’ll be able to run on batteries 95% of the time, which is a very solid leap forward into the future.

CATL and Amprius’ announcement puts that at 600 kilometers. Silicon puts that at 3,000 kilometers. Do you know how far apart Gander, Newfoundland, and Ireland are? 3,000 kilometers. Yeah, that’s mind-blowing. Technology that’s been demonstrated today could fly a hundred or so souls across the northern Atlantic. Hence my projection that by 2070, crossing oceans will be completely viable with battery-electric airplanes, and we’ll then spend the next 30 years sunsetting jets that burn fuel.

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What about road freight? Well, the Tesla Semi is being used by Pepsi today. It has a demonstrated, but not third-party proven, 800-kilometer range when loaded with a reasonable mix of stuff. Pepsi has run 800 km with chips, and 640 km with flats of fizzy carbonated bilge water. But let’s use the 800 km of range. CATL/Amprius announcements make that about 1,600 km of range, about half of a big US diesel semi today. Silicon gives the potential for 8,000 km, which is just silly. What will happen as battery energy density increases is that trucks will have smaller batteries physically, and this entire silliness about the weight of battery-electric trucks will wither away.

So to summarize:

  • Marine shipping: today 40 NM, tomorrow 120 NM, the next day 240 NM, and in a few years 1,200 NM
  • Aviation: today 300 km, tomorrow 600 km, in a few years 3,000 km
  • Trucking: today 800 km, tomorrow 1,600 km, in a few years 8,000 km if you want to be silly

This isn’t magic. It isn’t even science anymore. This is just engineering. As David Cebon, the director of the Centre for Sustainable Road Freight and professor of mechanical engineering at Cambridge, said when we were talking last week, it’s about getting electricity to the chargers, not the batteries in the vehicles. It’s about the system, not the components.

The future of all ground transportation and an awful lot of aviation and marine shipping being electric, low-carbon, quieter, and a lot less smelly is within reach. It would be rude not to reach out and grab it with both hands.

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Michael Barnard

is a climate futurist, strategist and author. He spends his time projecting scenarios for decarbonization 40-80 years into the future. He assists multi-billion dollar investment funds and firms, executives, Boards and startups to pick wisely today. He is founder and Chief Strategist of TFIE Strategy Inc and a member of the Advisory Board of electric aviation startup FLIMAX. He hosts the Redefining Energy - Tech podcast (https://shorturl.at/tuEF5) , a part of the award-winning Redefining Energy team.

Michael Barnard has 747 posts and counting. See all posts by Michael Barnard