4 ms·

The most effective way to store hydrogen as a fuel is in hydrocarbons. Hydrogen gas, as itself, seems at first blush, to be great because it combusts into wate

The most effective way to store hydrogen as a fuel is in hydrocarbons. Hydrogen gas, as itself, seems at first blush, to be great because it combusts into water, but it doesn't store as efficiently or safely as hydrocarbons. The wax candles on your table don't spontaneously combust when you touch them with a static charged finger. The fact that plants already will produce hydrocarbons for us without much over sight only makes things easier. Now that being said, our current natural gas infrastructure can accommodate something like 10% hydrogen gas, so it would be great if we could store extra solar electricity within our own pipelines by generating hydrogen gas, back feeding it into the lines, and then deplete it later, with a molecular sieve to pull out hydrogen gas alone, or burn it with the methane.

542354234235 2y ago
I understand what you are saying but I disagree. Yes, hydrogen is not as energy dense and has different safety issues, but I think it is overall still the better long term option. Biofuel is not scalable in the same way as green hydrogen. The more biofuel we produce, the more agricultural land it competes for that could be used for food, timber or even carbon capture vegetation. The more solar and wind we add to the gird, the more load shedding issues we will have and the more opportunity we have to convert that to hydrogen. ICE engines running on biofuel are about as efficient as they are going to get, whereas hydrogen power is a fairly immature technology and has a lot of potential efficiency gains as the technology matures. I think biofuel from waste products will still be useful for certain applications, for instance in medium and long haul aviation, where the energy density of hydrogen would pose a significant challenge. But biofuels are just not scalable to the levels required for global demand vs land requirements. Using biofuels just for aviation would require cultivating land the size of Texas, California, and Florida. [0][1][2] It is just not feasible to scale as a primary fuel in a fossil fueless future. Hydrogen can scale with electrical capacity, which can come from nuclear, solar, wind, geothermal, hydro, etc. [0] back of the napkin math/conversions based on 2 and 3 [1] https://its.ucdavis.edu/blog-post/making-policy-in-the-absence-of-certainty-biofuels-and-land-use-change/ https://its.ucdavis.edu/blog-post/making-policy-in-the-absen... [2] https://www.theglobaleconomy.com/USA/jet_fuel_consumption/ https://www.theglobaleconomy.com/USA/jet_fuel_consumption/
- nanomonkey 2y ago
  I'm not talking about growing plants directly for the production of biofuels, that is a silly proposition when there are mountains of unused organic waste being produced annually by nature and by agriculture. Utilizing the organic "waste streams" that already exist to produce fuel is quite sufficient for our storage needs. Agricultural waste, poop, dead trees and branches, dry grass or other "wildfire fuels" to produce methane, hydrogen and oil through gasification , fermentation and anaerobic digestion is simply low hanging fruit that is available to us right now. I've worked in this field, doing gasification, so I'm quite aware of what is possible. Would you rather we burn grass and dead standing wood in natural environments to curtail wildfires, or would you rather it was used to make clean energy that is carbon negative? Yes carbon negative. You put carbon back into the ground through the use of biochar, where it is stable for thousands of years, and actually improves the soil. Anaerobic digestion of all of your household waste (including feces) is also possible for production of all of your stove and heating gas. Internal combustion engines aren't at their end of technology cycle. You should probably look into supercritical CO2 closed loop turbines if you think that we aren't still innovating. Regardless, by using an internal combustion engines, or an external combustion engine (Stirling engine, or modern steam engine) instead of a furnace, one can produce heat and power all in one unit from within your house or district (depending on how you want to scale things). I love solar, I really do, as well as batteries. But you need to use everything at your disposal if you want to get away from petroleum.
usrusr 2y ago
And the best way to get from hydrogen to hydrocarbons might very well be processes that merge H2 (from electrolysis) with low value biofuels (usually hydrocarbons with a low amount of hydrogen I think?) into higher density synthetic fuels. That way you can use the waste parts of food plants, not so much for their (low) energy content but for their convenient access to carbon for "repackaging" H2.
- nanomonkey 2y ago
  Yes, like hydrolyzing vegetable oil, you can pack more hydrogen onto a carbon chain. You can also use the Fischer–Tropsch process to make longer chains out of smaller molecules like carbon monoxide and hydrogen.

542354234235 2y ago

I understand what you are saying but I disagree. Yes, hydrogen is not as energy dense and has different safety issues, but I think it is overall still the better long term option. Biofuel is not scalable in the same way as green hydrogen. The more biofuel we produce, the more agricultural land it competes for that could be used for food, timber or even carbon capture vegetation. The more solar and wind we add to the gird, the more load shedding issues we will have and the more opportunity we have to convert that to hydrogen. ICE engines running on biofuel are about as efficient as they are going to get, whereas hydrogen power is a fairly immature technology and has a lot of potential efficiency gains as the technology matures. I think biofuel from waste products will still be useful for certain applications, for instance in medium and long haul aviation, where the energy density of hydrogen would pose a significant challenge. But biofuels are just not scalable to the levels required for global demand vs land requirements. Using biofuels just for aviation would require cultivating land the size of Texas, California, and Florida. [0][1][2] It is just not feasible to scale as a primary fuel in a fossil fueless future. Hydrogen can scale with electrical capacity, which can come from nuclear, solar, wind, geothermal, hydro, etc. [0] back of the napkin math/conversions based on 2 and 3 [1] https://its.ucdavis.edu/blog-post/making-policy-in-the-absence-of-certainty-biofuels-and-land-use-change/ https://its.ucdavis.edu/blog-post/making-policy-in-the-absen... [2] https://www.theglobaleconomy.com/USA/jet_fuel_consumption/ https://www.theglobaleconomy.com/USA/jet_fuel_consumption/

nanomonkey 2y ago
I'm not talking about growing plants directly for the production of biofuels, that is a silly proposition when there are mountains of unused organic waste being produced annually by nature and by agriculture. Utilizing the organic "waste streams" that already exist to produce fuel is quite sufficient for our storage needs. Agricultural waste, poop, dead trees and branches, dry grass or other "wildfire fuels" to produce methane, hydrogen and oil through gasification , fermentation and anaerobic digestion is simply low hanging fruit that is available to us right now. I've worked in this field, doing gasification, so I'm quite aware of what is possible. Would you rather we burn grass and dead standing wood in natural environments to curtail wildfires, or would you rather it was used to make clean energy that is carbon negative? Yes carbon negative. You put carbon back into the ground through the use of biochar, where it is stable for thousands of years, and actually improves the soil. Anaerobic digestion of all of your household waste (including feces) is also possible for production of all of your stove and heating gas. Internal combustion engines aren't at their end of technology cycle. You should probably look into supercritical CO2 closed loop turbines if you think that we aren't still innovating. Regardless, by using an internal combustion engines, or an external combustion engine (Stirling engine, or modern steam engine) instead of a furnace, one can produce heat and power all in one unit from within your house or district (depending on how you want to scale things). I love solar, I really do, as well as batteries. But you need to use everything at your disposal if you want to get away from petroleum.

usrusr 2y ago

And the best way to get from hydrogen to hydrocarbons might very well be processes that merge H2 (from electrolysis) with low value biofuels (usually hydrocarbons with a low amount of hydrogen I think?) into higher density synthetic fuels. That way you can use the waste parts of food plants, not so much for their (low) energy content but for their convenient access to carbon for "repackaging" H2.

nanomonkey 2y ago
Yes, like hydrolyzing vegetable oil, you can pack more hydrogen onto a carbon chain. You can also use the Fischer–Tropsch process to make longer chains out of smaller molecules like carbon monoxide and hydrogen.