4 ms·

Sure, however basic physic won't change, and H2 will remain the less dense form of fuel (compared to any hydrocarbon). A group of aeronautical engineers calcula

by wazoox 6y ago

Sure, however basic physic won't change, and H2 will remain the less dense form of fuel (compared to any hydrocarbon). A group of aeronautical engineers calculated that long-haul flight planes running on H2 are impossible for energy density reasons, for instance. So H2 can only work for relatively short flights. Would you set up a whole new parallel infrastructure to cater for short flights only? Probably not.

agumonkey 6y ago
Yeah probably not, I'm just saying the world is complex, sometimes the model and the derived limits are not adequate anymore. Surely lots of people calculated that lithium batteries wouldn't be enough for cars 40 years ago. You see what I mean ?
PaulHoule 6y ago
As it is for rockets, methane is the optimal fuel for aviation https://energynews.us/2013/08/26/midwest/could-natural-gas-fuel-commercial-flights-of-the-future/ https://energynews.us/2013/08/26/midwest/could-natural-gas-f... small airports can get liquid methane the same way they get liquid hydrocarbons https://www.onlocationinc.com/energy-policy-case-studies-liquefied-natural-gas-trucks https://www.onlocationinc.com/energy-policy-case-studies-liq... large airports could have a big pipeline compressor and liquification station. At least liquid methane doesn't take weeks to get into thermodynamic equilibrium as does hydrogen: https://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen https://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen Methane is a better synthesis target than liquid fuels from biological materials, coal, asteroid tar, etc. It would be sweet if you could get the carbon out of the atmosphere somehow.
- bryanlarsen 6y ago
  > It would be sweet if you could get the carbon out of the atmosphere somehow. Some parts of the atmosphere have much higher concentrations of CO2 than others, for example at the smokestack of a cement plant. This is a convenient solution, but only one of the two gets to claim to be green. Either the cement plant gets credit for the carbon reduction or the airplane the credit for using a green fuel, but not both.
  - pfdietz 6y ago
    > for example at the smokestack of a cement plant. Which means when you burn the methane you made with that CO2, it is being released into the atmosphere. Or, you need CCS on the methane burner. In which case, you might as well just save that CO2 and reuse it.
  - PaulHoule 6y ago
    There is "BECCS" which is bio-energy with carbon capture and storage. An Ethanol factory in Decatur, IL captures waste CO2 from the fermentation process, purifies it, compresses it to about 1500 psi and pumps it into a saline aquifer. If you burned the bio fuel and captured the CO2 by https://en.wikipedia.org/wiki/Chemical_looping_combustion https://en.wikipedia.org/wiki/Chemical_looping_combustion or another method you could get CO2 and make methane by https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction then it is no longer storage, but it is keeping the carbon in short-term circulation between the atmosphere and the biosphere.
  - agumonkey 6y ago
    Do you know if politicians are thinking about raising the bar for these polluting industries ? like requiring a lot more filtering, enforcing solutions to divert pollutants from getting out at all ?
- elcritch 6y ago
  Doesn’t methane have a potent greenhouse effect? If it’s accurate then all the small leakages would possibly offset the benefit of a carbon neutrality energy system.
  - funcDropShadow 6y ago
    Well natural gas (mostly methane) is already available in most houses in Germany. It contains an additional component, so that you can smell it easily, because a gas leak near the open fire in the heater is obviously very dangerous. Yet I can remember two or three leaks, that were covered in the media. Nothing in 40 years in my circle of neigbhours, friends, or family. Therefore, I am convinced it possible to create natural gas distribution systems without considerable leaking. Perhaps, that depend on the organisational maturity of the country we are talking about. But it seems to be possible.
    - PaulHoule 6y ago
      Roughly you have to keep methane losses well under 1% from wellhead to burner to realize the potential of methane as a low-carbon fuel compared to liquid hydrocarbons. A methane pipeline passes within a few miles of my house and there is a compression station where I've occasionally seen a giant flame burning. In case they are not able to send the gas they are receiving onward, or the gas cannot be received at the next station, they will burn the gas to prevent a dangerous situation in terms of fire. (The old "synthesis gas" from the age of gaslight was 50% or more Carbon Monoxide as was immediately toxic to life.) The system is resilient and pretty easy to manage because at worst you have a small hole in a large volume of pipe. The loss can be contained by closing a valve upstream of the leak; the sealed pipe is a huge volume and can accommodate a lot of gas just by pressuring up, giving the upstream time to stop pumping. The spacing of the shut off valves is usually set by safety concerns in residential areas that the pipeline passes through. If you are pumping Carbon Dioxide back into the ground you have to install more shut off valves because the gas sinks and can asphyxiate people in nearby low spots. In deep rural areas the shut off valves could be far apart and the network not well maintained -- it would not destroy the economics of a natural gas network to lose 2-3% of the gas that way. === Accidents are a real thing: neighborhoods around Boston were blew up (pressure wave first then fire) by the residential methane network a few years ago; earlier Time Warner Cable blew up a block of downtown Kansas City when their fiber optic excavator hit a gas line; uninigited gas leaks from a malfunctioning methane network have been a problem in Southern California. Look for trouble at the well-head too. In many places people want liquid hydrocarbons and have no market for the methane and are tempted to burn it right there rather than face immediate or eventual calamity from venting it.
- epistasis 6y ago
  CO2 capture from air exists, with current materials: https://en.wikipedia.org/wiki/Direct_air_capture#Methods_of_capture https://en.wikipedia.org/wiki/Direct_air_capture#Methods_of_... The startup Carbon Engineering claims that direct air capture of CO2, solar power, and hydrolysis, they can will be able to make cost-competitive, carbon-neutral liquid fuels by the mid 2020s using existing technologies: https://www.youtube.com/watch?v=sYopOt9siLg https://www.youtube.com/watch?v=sYopOt9siLg To do green methane, they just need to stop before the gas to liquids step. There are also some seemingly wacky ideas for cryogenic energy storage as well: make liquid air or liquid nitrogen, store the excess heat over time, then power a turbine when converting the liquid to gas again: https://en.wikipedia.org/wiki/Cryogenic_energy_storage https://en.wikipedia.org/wiki/Cryogenic_energy_storage These cryogenic methods require extracting CO2 using the same sorts of filters and though I imagine the amounts of CO2 might be small, it seems that transfer of low level waste heat could make for an effective combination of systems? (Pure speculation there from me.)

by wazoox 6y ago

agumonkey 6y ago

Yeah probably not, I'm just saying the world is complex, sometimes the model and the derived limits are not adequate anymore. Surely lots of people calculated that lithium batteries wouldn't be enough for cars 40 years ago. You see what I mean ?

PaulHoule 6y ago

As it is for rockets, methane is the optimal fuel for aviation https://energynews.us/2013/08/26/midwest/could-natural-gas-fuel-commercial-flights-of-the-future/ https://energynews.us/2013/08/26/midwest/could-natural-gas-f... small airports can get liquid methane the same way they get liquid hydrocarbons https://www.onlocationinc.com/energy-policy-case-studies-liquefied-natural-gas-trucks https://www.onlocationinc.com/energy-policy-case-studies-liq... large airports could have a big pipeline compressor and liquification station. At least liquid methane doesn't take weeks to get into thermodynamic equilibrium as does hydrogen: https://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen https://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen Methane is a better synthesis target than liquid fuels from biological materials, coal, asteroid tar, etc. It would be sweet if you could get the carbon out of the atmosphere somehow.

bryanlarsen 6y ago
> It would be sweet if you could get the carbon out of the atmosphere somehow. Some parts of the atmosphere have much higher concentrations of CO2 than others, for example at the smokestack of a cement plant. This is a convenient solution, but only one of the two gets to claim to be green. Either the cement plant gets credit for the carbon reduction or the airplane the credit for using a green fuel, but not both.
- pfdietz 6y ago
  > for example at the smokestack of a cement plant. Which means when you burn the methane you made with that CO2, it is being released into the atmosphere. Or, you need CCS on the methane burner. In which case, you might as well just save that CO2 and reuse it.
- PaulHoule 6y ago
  There is "BECCS" which is bio-energy with carbon capture and storage. An Ethanol factory in Decatur, IL captures waste CO2 from the fermentation process, purifies it, compresses it to about 1500 psi and pumps it into a saline aquifer. If you burned the bio fuel and captured the CO2 by https://en.wikipedia.org/wiki/Chemical_looping_combustion https://en.wikipedia.org/wiki/Chemical_looping_combustion or another method you could get CO2 and make methane by https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction then it is no longer storage, but it is keeping the carbon in short-term circulation between the atmosphere and the biosphere.
- agumonkey 6y ago
  Do you know if politicians are thinking about raising the bar for these polluting industries ? like requiring a lot more filtering, enforcing solutions to divert pollutants from getting out at all ?
elcritch 6y ago
Doesn’t methane have a potent greenhouse effect? If it’s accurate then all the small leakages would possibly offset the benefit of a carbon neutrality energy system.
- funcDropShadow 6y ago
  Well natural gas (mostly methane) is already available in most houses in Germany. It contains an additional component, so that you can smell it easily, because a gas leak near the open fire in the heater is obviously very dangerous. Yet I can remember two or three leaks, that were covered in the media. Nothing in 40 years in my circle of neigbhours, friends, or family. Therefore, I am convinced it possible to create natural gas distribution systems without considerable leaking. Perhaps, that depend on the organisational maturity of the country we are talking about. But it seems to be possible.
  - PaulHoule 6y ago
    Roughly you have to keep methane losses well under 1% from wellhead to burner to realize the potential of methane as a low-carbon fuel compared to liquid hydrocarbons. A methane pipeline passes within a few miles of my house and there is a compression station where I've occasionally seen a giant flame burning. In case they are not able to send the gas they are receiving onward, or the gas cannot be received at the next station, they will burn the gas to prevent a dangerous situation in terms of fire. (The old "synthesis gas" from the age of gaslight was 50% or more Carbon Monoxide as was immediately toxic to life.) The system is resilient and pretty easy to manage because at worst you have a small hole in a large volume of pipe. The loss can be contained by closing a valve upstream of the leak; the sealed pipe is a huge volume and can accommodate a lot of gas just by pressuring up, giving the upstream time to stop pumping. The spacing of the shut off valves is usually set by safety concerns in residential areas that the pipeline passes through. If you are pumping Carbon Dioxide back into the ground you have to install more shut off valves because the gas sinks and can asphyxiate people in nearby low spots. In deep rural areas the shut off valves could be far apart and the network not well maintained -- it would not destroy the economics of a natural gas network to lose 2-3% of the gas that way. === Accidents are a real thing: neighborhoods around Boston were blew up (pressure wave first then fire) by the residential methane network a few years ago; earlier Time Warner Cable blew up a block of downtown Kansas City when their fiber optic excavator hit a gas line; uninigited gas leaks from a malfunctioning methane network have been a problem in Southern California. Look for trouble at the well-head too. In many places people want liquid hydrocarbons and have no market for the methane and are tempted to burn it right there rather than face immediate or eventual calamity from venting it.
epistasis 6y ago
CO2 capture from air exists, with current materials: https://en.wikipedia.org/wiki/Direct_air_capture#Methods_of_capture https://en.wikipedia.org/wiki/Direct_air_capture#Methods_of_... The startup Carbon Engineering claims that direct air capture of CO2, solar power, and hydrolysis, they can will be able to make cost-competitive, carbon-neutral liquid fuels by the mid 2020s using existing technologies: https://www.youtube.com/watch?v=sYopOt9siLg https://www.youtube.com/watch?v=sYopOt9siLg To do green methane, they just need to stop before the gas to liquids step. There are also some seemingly wacky ideas for cryogenic energy storage as well: make liquid air or liquid nitrogen, store the excess heat over time, then power a turbine when converting the liquid to gas again: https://en.wikipedia.org/wiki/Cryogenic_energy_storage https://en.wikipedia.org/wiki/Cryogenic_energy_storage These cryogenic methods require extracting CO2 using the same sorts of filters and though I imagine the amounts of CO2 might be small, it seems that transfer of low level waste heat could make for an effective combination of systems? (Pure speculation there from me.)