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The main thing hydrogen has going for it is the stored energy by weight which is around 142 MJ/kg. Lithium batteries are less than 1 MJ/kg. So around a factory

The main thing hydrogen has going for it is the stored energy by weight which is around 142 MJ/kg. Lithium batteries are less than 1 MJ/kg. So around a factory 200x difference. Ir you want to find something better than hydrogen energy/kg wise you have to go nuclear.

whalesalad 5y ago
Yes! Electric energy transmission and storage is a really hard problem when you look at it compared to liquid fuels. This is the nut to crack.
- cellularmitosis 5y ago
  Should we instead focus on sustainable liquid fuels? Diesel from algae for example?
ragebol 5y ago
But what is the volume of a kilo of hydrogen at practical pressures?
- bildung 5y ago
  42 kg/m³ or 0.024 m³ per kg at the usual 700 bar.
- gilbetron 5y ago
  Looks like a ballpark, current practical volume is around 25 liters per kg: https://energies.airliquide.com/resources-planet-hydrogen/how-hydrogen-stored https://energies.airliquide.com/resources-planet-hydrogen/ho... I think the greater issue with Hydrogen is how it likes to go boom, and the greater the energy density you store it at, the bigger the boom!
  - toxik 5y ago
    This is also one of the benefits of diesel, it doesn't ignite so easily.
  - cycomanic 5y ago
    Actually Hydrogen without Oxygen doesn't make boom. Also Lithium batteries also have a tendency to go boom, so I guess that's equal.
SigmundA 5y ago
Look at volume instead of weight. Hydrogen is only 8 MJ/L in liquid form vs 38MJ/L for Diesel. Think of the space needed in the vehicle. Next creating liquid hydrogen is a very energy intensive process compared to refining diesel. Next energy in lithium batteries is converted to mechanical energy with +90% efficiency in a modern electrical motor. Fuel cells just like combustion engines are only 40-60%.
- throwaway0a5e 5y ago
  Most commercial trucks are lacking for weight, not for volume. They wouldn't use all those axles and tires if they didn't need to. Weight and charging time are the current major roadblocks to adopting batteries. Hydrogen theoretically solves those but introduces a lot of technical complexity along the way and needs a supply chain that currently doesn't exist.
  - SigmundA 5y ago
    I don't see a lot of extra room on a truck for safe liquid hydrogen tanks 5 times the size of diesel tanks.
    - darksaints 5y ago
      That would be true for cars, not so much for trucks. Most trucks hit their mass limits long before they hit their volume limits. Most box trucks, for example, are transporting more air by volume than cargo.
      - SigmundA 5y ago
        Trucks have length limits and more constrained in Europe which is why you still see many cab overs there. The US loosened length limits in the 70's allowing for long nose trucks which help with aero dynamics and safety.
        darksaints 5y ago
y04nn 5y ago
You have to factor in the losses inherent to hydrogen energy storage. You have to produce the hydrogen, compress it and then use a fuel cell to convert it back to electricity. If you account for all the losses, I bet that in practice, storing electricity with hydrogen is not so much different than using lithium batteries. Does anyone have some figures?
- skystarman 5y ago
  Hydrogen is far more efficient. At least for long-haul class 7 & 8 trucks. The problem is the massive infrastructure investment needed to support it. All the substantial investments I've seen in commercial long-haul trucking are in hydrogen. You have Tesla, Nikola and others claiming they have a long-haul battery solution but they are full of shit. Tesla has already delayed their Semi for 3 years now. Nikola is a joke but even they were pushing hydrogen along with their BEV stuff. And the legacy CV companies are, again, only investing in BEV for short-haul stuff.
- intrasight 5y ago
  https://www.volkswagenag.com/en/news/stories/2019/08/hydrogen-or-battery--that-is-the-question.html https://www.volkswagenag.com/en/news/stories/2019/08/hydroge... has a good infographic showing overall efficiency. And this text: With battery-powered e-cars, only eight percent of the energy is lost during transport before the electricity is stored in the batteries of the vehicles. When the electrical energy used to drive the electric motor is converted, another 18 percent is lost. This gives the battery-operated electric car an efficiency level of between 70 to 80 percent, depending on the model. With the hydrogen-powered electric car, the losses are significantly greater: 45 percent of the energy is already lost during the production of hydrogen through electrolysis. Of this remaining 55 percent of the original energy, another 55 percent is lost when hydrogen is converted into electricity in the vehicle. This means that the hydrogen-powered electric car only achieves an efficiency of between 25 to 35 percent, depending on the model.
  - intrasight 5y ago
    But there's other ways to produce hydrogen that are both more efficient and "greener" - using algae https://en.wikipedia.org/wiki/Biohydrogen https://en.wikipedia.org/wiki/Biohydrogen Also I just found out that over 90% of our hydrogen comes from "natural gas reforming" https://www.energy.gov/eere/fuelcells/hydrogen-production-natural-gas-reforming https://www.energy.gov/eere/fuelcells/hydrogen-production-na...
davidrm 5y ago
Yes, but that's not the e2e efficiency of the hydrogen powertrain, a 120kW hydrogen stack found in Hyundai Nexo is as big as an average petrol engine and its energy efficiency is somewhere around 45%, so it's not only the hydrogen tanks and the hydrogen inside it. If we're going to analyze the volumetric and mass efficiency and compare it to a BEV, then we need to take everything into the account. Majority of hydrogen produced is made from processing oil, the energy efficiency of "green" hydrogen (electrolysis) is very poor and thus expensive. I believe there's a strong chance of using hydrogen for long haul type of transportation, however, there are a lot of misconceptions about the technology and its general practicality.

whalesalad 5y ago

Yes! Electric energy transmission and storage is a really hard problem when you look at it compared to liquid fuels. This is the nut to crack.

cellularmitosis 5y ago
Should we instead focus on sustainable liquid fuels? Diesel from algae for example?

ragebol 5y ago

But what is the volume of a kilo of hydrogen at practical pressures?

bildung 5y ago
42 kg/m³ or 0.024 m³ per kg at the usual 700 bar.
gilbetron 5y ago
Looks like a ballpark, current practical volume is around 25 liters per kg: https://energies.airliquide.com/resources-planet-hydrogen/how-hydrogen-stored https://energies.airliquide.com/resources-planet-hydrogen/ho... I think the greater issue with Hydrogen is how it likes to go boom, and the greater the energy density you store it at, the bigger the boom!
- toxik 5y ago
  This is also one of the benefits of diesel, it doesn't ignite so easily.
- cycomanic 5y ago
  Actually Hydrogen without Oxygen doesn't make boom. Also Lithium batteries also have a tendency to go boom, so I guess that's equal.

SigmundA 5y ago

Look at volume instead of weight. Hydrogen is only 8 MJ/L in liquid form vs 38MJ/L for Diesel. Think of the space needed in the vehicle. Next creating liquid hydrogen is a very energy intensive process compared to refining diesel. Next energy in lithium batteries is converted to mechanical energy with +90% efficiency in a modern electrical motor. Fuel cells just like combustion engines are only 40-60%.

throwaway0a5e 5y ago
Most commercial trucks are lacking for weight, not for volume. They wouldn't use all those axles and tires if they didn't need to. Weight and charging time are the current major roadblocks to adopting batteries. Hydrogen theoretically solves those but introduces a lot of technical complexity along the way and needs a supply chain that currently doesn't exist.
- SigmundA 5y ago
  I don't see a lot of extra room on a truck for safe liquid hydrogen tanks 5 times the size of diesel tanks.
  - darksaints 5y ago
    That would be true for cars, not so much for trucks. Most trucks hit their mass limits long before they hit their volume limits. Most box trucks, for example, are transporting more air by volume than cargo.
    - SigmundA 5y ago
      Trucks have length limits and more constrained in Europe which is why you still see many cab overs there. The US loosened length limits in the 70's allowing for long nose trucks which help with aero dynamics and safety.
      - darksaints 5y ago

y04nn 5y ago

You have to factor in the losses inherent to hydrogen energy storage. You have to produce the hydrogen, compress it and then use a fuel cell to convert it back to electricity. If you account for all the losses, I bet that in practice, storing electricity with hydrogen is not so much different than using lithium batteries. Does anyone have some figures?

skystarman 5y ago
Hydrogen is far more efficient. At least for long-haul class 7 & 8 trucks. The problem is the massive infrastructure investment needed to support it. All the substantial investments I've seen in commercial long-haul trucking are in hydrogen. You have Tesla, Nikola and others claiming they have a long-haul battery solution but they are full of shit. Tesla has already delayed their Semi for 3 years now. Nikola is a joke but even they were pushing hydrogen along with their BEV stuff. And the legacy CV companies are, again, only investing in BEV for short-haul stuff.
intrasight 5y ago
https://www.volkswagenag.com/en/news/stories/2019/08/hydrogen-or-battery--that-is-the-question.html https://www.volkswagenag.com/en/news/stories/2019/08/hydroge... has a good infographic showing overall efficiency. And this text: With battery-powered e-cars, only eight percent of the energy is lost during transport before the electricity is stored in the batteries of the vehicles. When the electrical energy used to drive the electric motor is converted, another 18 percent is lost. This gives the battery-operated electric car an efficiency level of between 70 to 80 percent, depending on the model. With the hydrogen-powered electric car, the losses are significantly greater: 45 percent of the energy is already lost during the production of hydrogen through electrolysis. Of this remaining 55 percent of the original energy, another 55 percent is lost when hydrogen is converted into electricity in the vehicle. This means that the hydrogen-powered electric car only achieves an efficiency of between 25 to 35 percent, depending on the model.
- intrasight 5y ago
  But there's other ways to produce hydrogen that are both more efficient and "greener" - using algae https://en.wikipedia.org/wiki/Biohydrogen https://en.wikipedia.org/wiki/Biohydrogen Also I just found out that over 90% of our hydrogen comes from "natural gas reforming" https://www.energy.gov/eere/fuelcells/hydrogen-production-natural-gas-reforming https://www.energy.gov/eere/fuelcells/hydrogen-production-na...

davidrm 5y ago

Yes, but that's not the e2e efficiency of the hydrogen powertrain, a 120kW hydrogen stack found in Hyundai Nexo is as big as an average petrol engine and its energy efficiency is somewhere around 45%, so it's not only the hydrogen tanks and the hydrogen inside it. If we're going to analyze the volumetric and mass efficiency and compare it to a BEV, then we need to take everything into the account. Majority of hydrogen produced is made from processing oil, the energy efficiency of "green" hydrogen (electrolysis) is very poor and thus expensive. I believe there's a strong chance of using hydrogen for long haul type of transportation, however, there are a lot of misconceptions about the technology and its general practicality.