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Ethanol has no long-term future because the vehicle fleet is already shifting to using no fuel at all. John Deere already manufactures electric tractors and fa

Ethanol has no long-term future because the vehicle fleet is already shifting to using no fuel at all. John Deere already manufactures electric tractors and farmers can simply utilise replaceable battery packs, charged on-site using solar power.

cogman10 6y ago
Counterpoint, For land travel all electric vehicles make a TON of sense. However, for airline and oceanic travel, the energy density of a battery simply isn't high enough. Biofuels may be the only carbon neutral way to accommodate such forms of transport.
- adrianN 6y ago
  Counter-counterpoint: Photosynthesis is only 2-4% efficient (measuring solar input to biomatter). Solar panels are ~20% efficient. Making fuel directly from electricity and CO2 is probably (I didn't do the math) more efficient per acre than making fuel from plants. You can of course supplement this with Ethanol made from waste that you get as a byproduct of food production.
  - cogman10 6y ago
    It's not an energy efficiency problem, it's an energy density problem. Burning hydrocarbons peeks out at something like 40% efficiency. Yet we are only now getting to the point where EVs have the same range as ICE vehicles, even though the battery->motor conversion is something like 90% efficient. Why is that? Because the amount of energy that can be stored in batteries is MUCH lower than the amount of energy released from burning fuel. Transport needs to carry all of it's energy with it (or, have something like a 3rd rail to provide energy). That's the argument for biofuels in the future. Not that you can't replace 99% of transport with electricity, but rather some forms of transport require a lot of energy. We are JUST getting to the point where batteries have enough density to power a prop plane for ~ 1hour worth of flight. We are no where near the energy density where a cargo ship could sail from china to the US or for international flights. One alternative to biofuels is hydrogen from something like electrolysis. One thing I think we'll both agree on. Ethanol for cars/trucks is a terrible idea. EVs are the future there.
    - philipkglass 6y ago
      The parent post meant making hydrocarbon fuels from electricity, water, and carbon dioxide. You make electrolytic hydrogen from electricity and water and then use it to hydrogenate CO2 to methane. Liquid methane has excellent energy density and would be suitable for fueling rockets, aircraft, and large ocean going ships. Or you could create synthetic kerosene by a different choice of chemical processes, if it's acceptable to trade lower efficiency for a fuel that is conveniently liquid at room temperature and compatible with legacy systems. https://www.power-eng.com/2020/07/08/power-to-gas-examining-storage-as-route-to-optimizing-renewable-energy-assets/ https://www.power-eng.com/2020/07/08/power-to-gas-examining-... https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces... The advantage of synthetic fuels over biofuels is that you can get a lot more fuel out of 100 hectares of solar panels than 100 hectares of crops, because plants are very inefficient at capturing solar energy as useful chemical energy. The advantage of biofuels over synthetic fuels would be lower capital costs. Biofuels have an advantage while non-fossil fuel demand is low, but they can't scale as well. Since artificially capturing CO2 from the air is expensive and inefficient so far, an attractive hybrid path combines biomass and electrolytic hydrogen to make methane or heavier hydrocarbons. The main role of the plants is to concentrate carbon from the air. A kilogram of dry cellulose has an enthalpy of combustion of 17.5 MJ [1]. It contains enough carbon to make 0.76 kg (47.6 moles) of methane, once fully hydrogenated. That methane has an enthalpy of combustion of 41.9 MJ [2]. The biomass would supply all of the carbon and a minority of the chemical energy while electrolysis would supply the majority of the hydrogen and the final energy content of the methane. [1] https://en.wikipedia.org/wiki/Cellulose https://en.wikipedia.org/wiki/Cellulose [2] https://en.wikipedia.org/wiki/Methane_(data_page) https://en.wikipedia.org/wiki/Methane_(data_page)
- xorcist 6y ago
  Batteries may not be energy dense enoguh, but hydrogen should be.
bluGill 6y ago
John Deere has made prototype electric tractors. The battery operated one was a ~100 (150?) horse power tractor packed full of batteries that was able to do everything the equivalent diesel tractor could do - for about 1 hour then the battery was dead. Note that the above tractor is considered mid size, the big tractors that sell the best have far more horse power. The other is a tractor with a 1km (or longer?) cable to it can plug into the grid at all times. Neither is practical for real farmers, though they do work. I'm a Deere Employee. I cannot talk about projects other than the above, but I wouldn't hope for practical electric tractors in the near future.
bigbubba 6y ago
As far as I'm aware, nearly all tractors much larger than a lawn mower now use diesel, not gasoline/ethanol. This wasn't always the case, but I understand it to be true particularly since the later half of the 20th century. So for the most part biodiesel, not ethanol, is the relevant biofuel for powering large farm equipment. Their larger trucks burn diesel too, though their pickup trucks and other small road vehicles are often gas/ethanol burners.

cogman10 6y ago

Counterpoint, For land travel all electric vehicles make a TON of sense. However, for airline and oceanic travel, the energy density of a battery simply isn't high enough. Biofuels may be the only carbon neutral way to accommodate such forms of transport.

adrianN 6y ago
Counter-counterpoint: Photosynthesis is only 2-4% efficient (measuring solar input to biomatter). Solar panels are ~20% efficient. Making fuel directly from electricity and CO2 is probably (I didn't do the math) more efficient per acre than making fuel from plants. You can of course supplement this with Ethanol made from waste that you get as a byproduct of food production.
- cogman10 6y ago
  It's not an energy efficiency problem, it's an energy density problem. Burning hydrocarbons peeks out at something like 40% efficiency. Yet we are only now getting to the point where EVs have the same range as ICE vehicles, even though the battery->motor conversion is something like 90% efficient. Why is that? Because the amount of energy that can be stored in batteries is MUCH lower than the amount of energy released from burning fuel. Transport needs to carry all of it's energy with it (or, have something like a 3rd rail to provide energy). That's the argument for biofuels in the future. Not that you can't replace 99% of transport with electricity, but rather some forms of transport require a lot of energy. We are JUST getting to the point where batteries have enough density to power a prop plane for ~ 1hour worth of flight. We are no where near the energy density where a cargo ship could sail from china to the US or for international flights. One alternative to biofuels is hydrogen from something like electrolysis. One thing I think we'll both agree on. Ethanol for cars/trucks is a terrible idea. EVs are the future there.
  - philipkglass 6y ago
    The parent post meant making hydrocarbon fuels from electricity, water, and carbon dioxide. You make electrolytic hydrogen from electricity and water and then use it to hydrogenate CO2 to methane. Liquid methane has excellent energy density and would be suitable for fueling rockets, aircraft, and large ocean going ships. Or you could create synthetic kerosene by a different choice of chemical processes, if it's acceptable to trade lower efficiency for a fuel that is conveniently liquid at room temperature and compatible with legacy systems. https://www.power-eng.com/2020/07/08/power-to-gas-examining-storage-as-route-to-optimizing-renewable-energy-assets/ https://www.power-eng.com/2020/07/08/power-to-gas-examining-... https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces... The advantage of synthetic fuels over biofuels is that you can get a lot more fuel out of 100 hectares of solar panels than 100 hectares of crops, because plants are very inefficient at capturing solar energy as useful chemical energy. The advantage of biofuels over synthetic fuels would be lower capital costs. Biofuels have an advantage while non-fossil fuel demand is low, but they can't scale as well. Since artificially capturing CO2 from the air is expensive and inefficient so far, an attractive hybrid path combines biomass and electrolytic hydrogen to make methane or heavier hydrocarbons. The main role of the plants is to concentrate carbon from the air. A kilogram of dry cellulose has an enthalpy of combustion of 17.5 MJ [1]. It contains enough carbon to make 0.76 kg (47.6 moles) of methane, once fully hydrogenated. That methane has an enthalpy of combustion of 41.9 MJ [2]. The biomass would supply all of the carbon and a minority of the chemical energy while electrolysis would supply the majority of the hydrogen and the final energy content of the methane. [1] https://en.wikipedia.org/wiki/Cellulose https://en.wikipedia.org/wiki/Cellulose [2] https://en.wikipedia.org/wiki/Methane_(data_page) https://en.wikipedia.org/wiki/Methane_(data_page)
xorcist 6y ago
Batteries may not be energy dense enoguh, but hydrogen should be.

bluGill 6y ago

John Deere has made prototype electric tractors. The battery operated one was a ~100 (150?) horse power tractor packed full of batteries that was able to do everything the equivalent diesel tractor could do - for about 1 hour then the battery was dead. Note that the above tractor is considered mid size, the big tractors that sell the best have far more horse power. The other is a tractor with a 1km (or longer?) cable to it can plug into the grid at all times. Neither is practical for real farmers, though they do work. I'm a Deere Employee. I cannot talk about projects other than the above, but I wouldn't hope for practical electric tractors in the near future.

bigbubba 6y ago

As far as I'm aware, nearly all tractors much larger than a lawn mower now use diesel, not gasoline/ethanol. This wasn't always the case, but I understand it to be true particularly since the later half of the 20th century. So for the most part biodiesel, not ethanol, is the relevant biofuel for powering large farm equipment. Their larger trucks burn diesel too, though their pickup trucks and other small road vehicles are often gas/ethanol burners.