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Hydrogen is sexy but alcohol matches our existing context better. Small-scale alcohol fuel production integrated into regenerative agriculture farms is differe

Hydrogen is sexy but alcohol matches our existing context better. Small-scale alcohol fuel production integrated into regenerative agriculture farms is different from mass ethanol production. You can ferment anything that has starch or sugar, the leftovers from the distillation can be composted or fed to livestock. Most existing internal combustion engines can be modified to use alcohol fuel. And it's carbon-neutral.

dredmorbius 6y ago
Feedstock is the problem here: there's simply not enough net primary productivity on the planet, and humans already appropriate ~20%. There are some marginal gains possible, but on the order of single-digit percentages of present fossil fuel consumption. Maybe low double-digits. The US had a largely biofuel based transport system in 1900. Horses consumed 20% of all US grain production, the population was under 100m, and transport generally was a small fraction of today's values (or at least last year's) per capita: closer to 300 mi/yr, much of that walking, than 15,000.
- elago 6y ago
  According to the U.S. Department of Agriculture, the U.S. has 434,164,946 acres of “cropland”—land that is able to be worked in an industrial fashion (monoculture). This is the prime, level, and generally deep agricultural soil. In addition to cropland, the U.S. has 939,279,056 acres of “farmland.” This land is also good for agriculture, but it’s not as level and the soil not as deep. Additionally, there is a vast amount of acreage—swamps, arid or sloped land, even rivers, oceans, and ponds—that the USDA doesn’t count as cropland or farmland, but which is still suitable for growing specialized energy crops. Of its nearly half a billion acres of prime cropland, the U.S. uses only 72.1 million acres for corn in an average year. The land used for corn takes up only 16.6% of our prime cropland, and only 7.45% of our total agricultural land. Even if, for alcohol production, we used only what the USDA considers prime flat cropland, we would still have to produce only 368.5 gallons of alcohol per acre to meet 100% of the demand for transportation fuel at today’s levels. Corn could easily produce this level—and a wide variety of standard crops yield up to triple this.
  - philipkglass 6y ago
    US oil consumption for transportation was 14.16 million barrels per day (595 million gallons per day) in 2018: https://www.eia.gov/energyexplained/oil-and-petroleum-products/use-of-oil.php https://www.eia.gov/energyexplained/oil-and-petroleum-produc... That's 595,000,000 * 365 = 217,175,000,000 gallons per year of oil. Using 100% of cropland producing at 369 gallons of ethanol/acre gives 434,164,946 * 369 = 160,206,865,074 gallons per year of ethanol. That's only 74% as many gallons as oil consumption. It's actually much worse than that, because the energy content of a gallon of ethanol is only about 65% the energy content of a gallon of oil: https://en.wikipedia.org/wiki/Energy_density#Tables_of_energy_content https://en.wikipedia.org/wiki/Energy_density#Tables_of_energ... This much ethanol would only provide 48% of the energy currently consumed by oil based transportation. It's actually much worse than that because most crop land is already used to grow crops eaten by animals and people. If we feed all the crops to transportation machinery, others will go hungry.
    - deleted 6y ago
      [deleted]
  - dredmorbius 6y ago
    I (and many others more qualified) have run the numbers. It's not pretty. A decade ago biofuels were my first thought. The maths simply don't add up. Our options are far less energy per person, far fewer people, other sources of energy, or, most likely, some combination of these. The highest claimed yields are for algae, at a rather improbable 1,000 gal/(acre * year): [Y]ou might consider floating the algae offshore, along the Pacific and Atlantic costs. It's roughly 1,300 miles from San Diego, CA to Port Angeles, WA, and 1,800 miles from Homestead, FL to Lubec, ME. Dividing our 443,000 square miles by those two added together, we find we'd have to extend our grow region some distance off-shore. That is, 143 miles off-shore. The full length of both coasts. Or perhaps you'd prefer to re-purpose the Gulf of Mexico. Its total area is about 600,000 mi2, we'd need about 3/4 of it dedicated to algae growth. https://old.reddit.com/r/dredmorbius/comments/2cvap7/the_intractable_problem_of_biomass_for_fuels_is/ https://old.reddit.com/r/dredmorbius/comments/2cvap7/the_int... Tom "Do the Math" Murphy: https://dothemath.ucsd.edu/2011/11/the-biofuel-grind/ https://dothemath.ucsd.edu/2011/11/the-biofuel-grind/ https://dothemath.ucsd.edu/2011/08/garbage-in-garbage-out/ https://dothemath.ucsd.edu/2011/08/garbage-in-garbage-out/ The late David MacCay's Alternative Energy Without the Hot Air gives a comprehensive breakdown for the UK of alternative energy options. Again, the picture is bleak. https://withouthotair.com https://withouthotair.com The takeaways are we use a lot of energy and there are a lot of us.
- carapace 6y ago
  You're right that you couldn't replace every use of fossil fuel, but for a large portion of non-industrial use I think it's a very valid and viable strategy. The key is that you're producing the alcohol as part of an integrated system of production that mimics Nature. You have a farm that requires no inputs (of fertilizer, and in some cases no irrigation) that produces multiple crops per year. ("Syntropic" agriculture, "Permaculture", food forests) You can grow sugar beets, yams, sugar cane, or starchy plants such as potatoes, certain kinds of reeds, tubers, etc. directly for fermentation, or use scrap fruit from the orchards, etc. Literally anything that has starch or sugar can be used as a feedstock. Scrap dough from a (doughnut) bakery. The leftovers from the fermentation and distillation aren't wasted: you feed them to livestock. Because it's a yeast culture there's more protein in it now than it had before. So your farm produces fruits and veggies, meat, and alcohol fuel. (I'm getting all this from http://alcoholcanbeagas.com/sitemap http://alcoholcanbeagas.com/sitemap )
pfdietz 6y ago
You get much more fuel out of biomass if you add hydrogen. For example, from carbohydrates, it's basically (CH2O)n + nH2 --> (CH2)n + nH2O (hydrodeoxygenation). This can make drop-in replacements for gasoline, diesel, and jet fuel.
- carapace 6y ago
  That's very interesting. If you've got a ready source of hydrogen, say from molten salt oxidation of plastics, which produces "syngas" (a mixture of CO and H2), I think you could run that through water to make CO2 and more H2, feed the CO2 to a greenhouse and collect all the H2 for the reaction you described. Does that make sense?
  - pfdietz 6y ago
    You could, but I think it would be better to break the plastics into smaller not-fully-oxidized fragments, and rearrange those into desired chemicals. If the plastics have oxygen (as, for example, PET does) one could use hydrogen to pull that out, if needed.
jillesvangurp 6y ago
You can synthesize alcohol and other carbohydrates straight from air and water as well. This actually is something that, similar to producing hydrogen using excess clean energy, would be technically feasible. The problem is scale. We eat far less food than we burn fuel. So replacing our fuel with a by product of food production is not going to scale. Bio fuels at scale only make sense with heavy subsidies currently E.g. the corn industry in the US is a good example of something that would not exist without subsidies.

dredmorbius 6y ago

Feedstock is the problem here: there's simply not enough net primary productivity on the planet, and humans already appropriate ~20%. There are some marginal gains possible, but on the order of single-digit percentages of present fossil fuel consumption. Maybe low double-digits. The US had a largely biofuel based transport system in 1900. Horses consumed 20% of all US grain production, the population was under 100m, and transport generally was a small fraction of today's values (or at least last year's) per capita: closer to 300 mi/yr, much of that walking, than 15,000.

elago 6y ago
According to the U.S. Department of Agriculture, the U.S. has 434,164,946 acres of “cropland”—land that is able to be worked in an industrial fashion (monoculture). This is the prime, level, and generally deep agricultural soil. In addition to cropland, the U.S. has 939,279,056 acres of “farmland.” This land is also good for agriculture, but it’s not as level and the soil not as deep. Additionally, there is a vast amount of acreage—swamps, arid or sloped land, even rivers, oceans, and ponds—that the USDA doesn’t count as cropland or farmland, but which is still suitable for growing specialized energy crops. Of its nearly half a billion acres of prime cropland, the U.S. uses only 72.1 million acres for corn in an average year. The land used for corn takes up only 16.6% of our prime cropland, and only 7.45% of our total agricultural land. Even if, for alcohol production, we used only what the USDA considers prime flat cropland, we would still have to produce only 368.5 gallons of alcohol per acre to meet 100% of the demand for transportation fuel at today’s levels. Corn could easily produce this level—and a wide variety of standard crops yield up to triple this.
- philipkglass 6y ago
  US oil consumption for transportation was 14.16 million barrels per day (595 million gallons per day) in 2018: https://www.eia.gov/energyexplained/oil-and-petroleum-products/use-of-oil.php https://www.eia.gov/energyexplained/oil-and-petroleum-produc... That's 595,000,000 * 365 = 217,175,000,000 gallons per year of oil. Using 100% of cropland producing at 369 gallons of ethanol/acre gives 434,164,946 * 369 = 160,206,865,074 gallons per year of ethanol. That's only 74% as many gallons as oil consumption. It's actually much worse than that, because the energy content of a gallon of ethanol is only about 65% the energy content of a gallon of oil: https://en.wikipedia.org/wiki/Energy_density#Tables_of_energy_content https://en.wikipedia.org/wiki/Energy_density#Tables_of_energ... This much ethanol would only provide 48% of the energy currently consumed by oil based transportation. It's actually much worse than that because most crop land is already used to grow crops eaten by animals and people. If we feed all the crops to transportation machinery, others will go hungry.
  - deleted 6y ago
    [deleted]
- dredmorbius 6y ago
  I (and many others more qualified) have run the numbers. It's not pretty. A decade ago biofuels were my first thought. The maths simply don't add up. Our options are far less energy per person, far fewer people, other sources of energy, or, most likely, some combination of these. The highest claimed yields are for algae, at a rather improbable 1,000 gal/(acre * year): [Y]ou might consider floating the algae offshore, along the Pacific and Atlantic costs. It's roughly 1,300 miles from San Diego, CA to Port Angeles, WA, and 1,800 miles from Homestead, FL to Lubec, ME. Dividing our 443,000 square miles by those two added together, we find we'd have to extend our grow region some distance off-shore. That is, 143 miles off-shore. The full length of both coasts. Or perhaps you'd prefer to re-purpose the Gulf of Mexico. Its total area is about 600,000 mi2, we'd need about 3/4 of it dedicated to algae growth. https://old.reddit.com/r/dredmorbius/comments/2cvap7/the_intractable_problem_of_biomass_for_fuels_is/ https://old.reddit.com/r/dredmorbius/comments/2cvap7/the_int... Tom "Do the Math" Murphy: https://dothemath.ucsd.edu/2011/11/the-biofuel-grind/ https://dothemath.ucsd.edu/2011/11/the-biofuel-grind/ https://dothemath.ucsd.edu/2011/08/garbage-in-garbage-out/ https://dothemath.ucsd.edu/2011/08/garbage-in-garbage-out/ The late David MacCay's Alternative Energy Without the Hot Air gives a comprehensive breakdown for the UK of alternative energy options. Again, the picture is bleak. https://withouthotair.com https://withouthotair.com The takeaways are we use a lot of energy and there are a lot of us.
carapace 6y ago
You're right that you couldn't replace every use of fossil fuel, but for a large portion of non-industrial use I think it's a very valid and viable strategy. The key is that you're producing the alcohol as part of an integrated system of production that mimics Nature. You have a farm that requires no inputs (of fertilizer, and in some cases no irrigation) that produces multiple crops per year. ("Syntropic" agriculture, "Permaculture", food forests) You can grow sugar beets, yams, sugar cane, or starchy plants such as potatoes, certain kinds of reeds, tubers, etc. directly for fermentation, or use scrap fruit from the orchards, etc. Literally anything that has starch or sugar can be used as a feedstock. Scrap dough from a (doughnut) bakery. The leftovers from the fermentation and distillation aren't wasted: you feed them to livestock. Because it's a yeast culture there's more protein in it now than it had before. So your farm produces fruits and veggies, meat, and alcohol fuel. (I'm getting all this from http://alcoholcanbeagas.com/sitemap http://alcoholcanbeagas.com/sitemap )

pfdietz 6y ago

You get much more fuel out of biomass if you add hydrogen. For example, from carbohydrates, it's basically (CH2O)n + nH2 --> (CH2)n + nH2O (hydrodeoxygenation). This can make drop-in replacements for gasoline, diesel, and jet fuel.

carapace 6y ago
That's very interesting. If you've got a ready source of hydrogen, say from molten salt oxidation of plastics, which produces "syngas" (a mixture of CO and H2), I think you could run that through water to make CO2 and more H2, feed the CO2 to a greenhouse and collect all the H2 for the reaction you described. Does that make sense?
- pfdietz 6y ago
  You could, but I think it would be better to break the plastics into smaller not-fully-oxidized fragments, and rearrange those into desired chemicals. If the plastics have oxygen (as, for example, PET does) one could use hydrogen to pull that out, if needed.

jillesvangurp 6y ago

You can synthesize alcohol and other carbohydrates straight from air and water as well. This actually is something that, similar to producing hydrogen using excess clean energy, would be technically feasible. The problem is scale. We eat far less food than we burn fuel. So replacing our fuel with a by product of food production is not going to scale. Bio fuels at scale only make sense with heavy subsidies currently E.g. the corn industry in the US is a good example of something that would not exist without subsidies.