When thinking about decarbonizing any industry, Andy Lubershane always starts with the question “why not electrify?”
As the partner and head of research at Energy Impact Partners, he sees plenty of electrification plays. And across most sectors of the economy, it’s his first choice for decarbonization because of the relatively low cost of power and the high efficiency of electric drivetrains.
But for heavy-duty transport like cargo ships, commercial flights, and long-haul trucks, there might be good reasons to avoid batteries — or at least to avoid relying on them alone.
- The topline: Two main challenges — low energy density and expensive infrastructure — make it impractical to rely solely on lithium-ion batteries in heavy-duty vehicles. “Compared to fossil fuels — they just suck,” said Lubershane on a recent episode of the Catalyst podcast. That doesn’t mean that decarbonization is a lost cause, though. It’s still early days, but alternative technologies and fuels like battery swapping or methanol show promise.
- The current take: Lubershane is especially bullish on expensive synthetic fuels, like methanol and sustainable aviation fuels, that can serve as drop-in replacements for fossil fuels. Those costs, he said, are outweighed by the even higher costs of upgrading equipment and infrastructure to electrify or use fuels like hydrogen for heavy transport. “It does make sense to find even a very expensive fuel to avoid going through all of that challenge,” he said.
One reason not to use batteries in heavy transport is that the batteries powerful enough to move a big vehicle over long distances would be huge, eating up cargo space and adding weight.
For example, diesel contains about 37 megajoules per liter. An equivalent battery in 2020 — packing 450 watt-hours, or 1.6 megajoules, per liter — would need to take up 17 times as much space. It would also need to be about 45 times heavier.
“They’re not even in the same league, really,” said Lubershane.
He predicted that the density of high-performance lithium-ion batteries could improve at least 50% in the next five to ten years, and could even double or triple beyond that. But Lubershane added that those improvements come with tradeoffs. The more energy-dense the battery, the heavier, more expensive, or slower to charge it may become. And even with those improvements, Lubershane is skeptical that batteries will ever rival the energy density of fossil fuels.
The second major hurdle is the cost and hassle of upgrading infrastructure.
“If you have enough vehicles that all have to come together to fuel in a relatively concentrated area, we’re talking about just enormous amounts of power,” Lubershane said.
For example, take drayage trucks, which could be good candidates for electrification. They carry cargo short distances to nearby distribution facilities and return to the same location every day.
Charging, however, would prove tricky. The Port of Long Beach in Los Angeles estimated that decarbonizing its entire drayage fleet would require 14,700 electric trucks by 2035. Slow charging those trucks would add 1.5 gigawatts of new peak demand to the local grid, not to mention the cost of infrastructure upgrades.
“So we’re talking about adding multiple transmission lines worth of new power, feeding the port in one of the densest operational environments you can possibly imagine,” Lubershane said. “It’s possible we could eventually get there, but … that’s not the sort of thing you can do in 10, 15, maybe 20 years without lots of additional expense and disruption.”
That said, there are certain nascent alternatives to electrification, as Lubershane unpacked in his conversation with Catalyst host Shayle Kann.
Battery swapping
While built-in batteries may be impractical, Lubershane is a big fan of battery-swapping, which he said solves several problems at once.
It addresses the density problem, because a vehicle that can swap for a fresh battery doesn’t need to carry such a large battery, and simultaneously addresses the infrastructure problem, because Lubershane said that a truck would probably need a two megawatt-hour battery to cover long distances.
Rather than attempting to charge these big batteries quickly enough to get them back on the road, battery swapping would allow for slower charging over longer periods, significantly reducing the impact on the grid.
“Battery swapping lets you theoretically refuel by swapping a battery in and out almost as quickly as you can fuel up with diesel today,” said Lubershane, “which also improves the economics because you have more time on the road and less time spent charging.”
Lubershane added that swapping falls under the bucket of “partial electrification.” Trucking company Revoy, for example, augments internal combustion drivetrains with swappable battery trailers, reducing the demand for fuel in the same fashion as a hybrid.
Biofuels
At the moment, however, biofuels are leading the push to decarbonize heavy-duty transport.
“We already use about 40% of the total U.S. corn crop today for making ethanol for blending into gasoline,” Lubershane said. “We’re now approaching about 30% of soy that’s used to produce biodiesel.”
Many industries are competing for the limited supply of fats, food crops, and other feedstocks. Airlines, for example, are paying high prices for sustainable aviation fuel made with waste oil.
One challenge is that the carbon intensity of crop-based biofuels like corn ethanol and soy biodiesel isn’t that much better than fossil fuels.
“That just raises the question of, ‘Is it worth it to go through all this trouble of using so much corn and soybeans, which could otherwise be used as food crops, to produce fuel?’” Lubershane said.
He sees more potential in “second-generation feedstocks” made of cellulosic materials like wood waste that are more abundant and tend to have a lower carbon intensity than crop-based feedstocks.
“I think that’s actually the first thing that the transport market should be going after: second-generation biofuels that can start to make a difference for emissions of certain classes of heavy duty vehicles,” said Lubershane.
The biggest problem, however, is limited supply. Lubershane said that the world’s theoretical maximum supply of first and second generation biofuels would cover only half of the needs of aviation, not to mention all the other heavy transport industries.
Hydrogen
Switching to hydrogen involves trade-offs, Lubershane said.
“It’s actually better when it comes to gravimetric energy density than fossil fuels. Hydrogen is even lighter than hydrocarbons,” he said. It also can be made with zero-carbon electricity.
A big challenge, however, is that it takes up so much space. For example, jet fuel contains about 38 megajoules per liter. An equivalent amount of liquid hydrogen, which contains about 8 megajoules per liter, would take up nearly four times as much space.
“From a pure vehicle viability standpoint, the challenge with hydrogen is that it does still require a pretty significant redesign of a vehicle in order to make it work and, and will take up more space within a vehicle than fossil fuel does today,” Lubershane said. “Now, I don’t think that necessarily rules out pure hydrogen as the fuel for those vehicles, but I think most likely we’ll want to do better than that.”
Synthetic fuels
Instead, Lubershane suggested converting zero-carbon hydrogen into synthetic fuels that can be drop-in replacements for fossil fuels.
Zero-carbon hydrogen, made from electrolysis powered by zero-carbon electricity or from fossil fuels using carbon capture and storage, can be combined with carbon molecules from captured carbon. This results in hydrocarbons like methanol, ammonia, and jet fuel.
It’s an approach that requires no changes to a heavy-duty vehicle. However, it’s expensive because of the cost of producing zero-carbon hydrogen and then synthesizing the new fuels.
But Lubershane said that these fuels may be worth the cost, because of the avoided upgrades to infrastructure and vehicles.
“Like, stop and pay attention to everything going on around you and consider what it would really take to substantially change the infrastructure,” Lubershane said. He pointed, for example, to the years-long upgrades to a terminal at New York City’s LaGuardia Airport.
“I feel like in order to upgrade LaGuardia to electrify or to add hydrogen fueling in some capacity, the amount of disruption would be ten to 100 times what I saw LaGuardia during the past seven years as they upgraded a terminal to be just a little bit nicer,” he said.
