5 ms·

Something that annoys me with these articles is that such processes are usually praised as carbon capture at the same time as it is energy storage. Well yes, bu

Something that annoys me with these articles is that such processes are usually praised as carbon capture at the same time as it is energy storage. Well yes, but not both at the same time. And I really doubt its effectiveness as energy storage in the first place - why would you burn fossil fuels (with a loss), then gather energy with renewables to capture back the CO2 (with a loss) and then use the energy of the ethanol again (again with a loss)? Just store the energy from the renewables in batteries.

oddevan 10y ago
I wonder if it would be useful to harvest excess CO2 from the atmosphere. That way, you're using the existing CO2 as a fuel source.
- m_mueller 10y ago
  Am I missing the sarcasm tag?
adrianN 10y ago
Batteries might be more expensive than storing energy in liquid fuels. They have a limited number of charge cycles after all, whereas a vat of Ethanol can be refilled forever. There is also a large number of motors available that can burn Ethanol, but a significantly smaller number of electric vehicles.
- m_mueller 10y ago
  1.) electric vehicles are also vastly simpler mechanically, so what you gain with energy storage efficiency in gasoline tanks you loose with their complex motors. 2.) if cheap energy density is the problem they want to solve, then this process at least needs to be compared to using the land to grow plants in order to turn them into ethanol fuel. So a comparison like "wind farm under average conditions + ethanol farming" vs. "wind farm under average conditions + solar under average conditions + CO2 to ethanol process" --> how many Joules of kinetic energy can you produce per square kilometer of land, given the fuel/electricity is used in the currently most efficient motors/batteries?
  - adrianN 10y ago
    Many people dislike growing plants for Ethanol production because they compete for arable land that can be used to produce food. Solar and wind farms can be built in places where agriculture is not viable.
    - eveningcoffee 10y ago
      Growing plants for fuel by itself is not a problem. Core issue is that the collective intelligence of us as species does not appear to be higher than yeast.
    - m_mueller 10y ago
      well, at the end it's just sunlight, carbon, nitrogen, water, a few minerals and a bunch of chemical reactions. I'm pretty sure you could find a biological process to put anywhere that's also viable for solar farms, including open water. In fact, haven't there been a bunch of papers using algae?
deleted 10y ago
[deleted]
ci5er 10y ago
One idea goes like this: We use nuclear or renewables to power a process to capture extant CO2 to be used as fuel, which turns it back to CO2, which will be recaptures, so run-away processes are reigned in. (I can tell by your comment that you get this.) Here's the kicker: the energy density of liquid fuels is super-hard to beat. Batteries (and super-capacitors) are getting better, but relatively speaking, on a whole bunch of dimensions, it doesn't get much easier economically, technically or infrastructurally than burning some hydrocarbon. Hopefully sulfur and mercury free. Tieing "the energy of the future" with "the infrastructure of today" is a very attractive concept that draws a lot of funding from a lot of folks. And researchers, in labs, are working on things that have various limitations of their own, such as "well, gosh, how do you make a copper-iridim-mesh-alloy-hydromister in volume?"
- m_mueller 10y ago
  Energy density is great, but for most current usecases I'd argue it's not really necessary. It's neither needed in your home (lots of space to put batteries, is connected to a power line), nor for your daily commute, nor for agriculture, nor for heavy industry (even better power lines), nor for long distance land based transport (trains are just as good and can be electrified easily) which covers the largest energy consumers right there. It is very useful for long distance individual travel by car (so, get a Chevy Volt instead of a Tesla) as well as airplanes, rockets and ocean shipping. If we'd just use the remaining fossil fuel for those purposes it would be pretty easy to be carbon negative.
  - ci5er 10y ago
    80/20 rule and all that, I agree. I'm originally from a ranch in Wyoming 65m+ from the nearest grocery store, and those use-cases (ag, distance) are burned into my gut. It makes for some bad intuitive generalized conclusions on this topic from time-to-time.
    - m_mueller 10y ago
      no sweat, it's a pleasure to communicate with people who are able to think systematically and who can do an actual discussion rather than just shouting from rooftops.

oddevan 10y ago

I wonder if it would be useful to harvest excess CO2 from the atmosphere. That way, you're using the existing CO2 as a fuel source.

m_mueller 10y ago
Am I missing the sarcasm tag?

adrianN 10y ago

Batteries might be more expensive than storing energy in liquid fuels. They have a limited number of charge cycles after all, whereas a vat of Ethanol can be refilled forever. There is also a large number of motors available that can burn Ethanol, but a significantly smaller number of electric vehicles.

m_mueller 10y ago
1.) electric vehicles are also vastly simpler mechanically, so what you gain with energy storage efficiency in gasoline tanks you loose with their complex motors. 2.) if cheap energy density is the problem they want to solve, then this process at least needs to be compared to using the land to grow plants in order to turn them into ethanol fuel. So a comparison like "wind farm under average conditions + ethanol farming" vs. "wind farm under average conditions + solar under average conditions + CO2 to ethanol process" --> how many Joules of kinetic energy can you produce per square kilometer of land, given the fuel/electricity is used in the currently most efficient motors/batteries?
- adrianN 10y ago
  Many people dislike growing plants for Ethanol production because they compete for arable land that can be used to produce food. Solar and wind farms can be built in places where agriculture is not viable.
  - eveningcoffee 10y ago
    Growing plants for fuel by itself is not a problem. Core issue is that the collective intelligence of us as species does not appear to be higher than yeast.
  - m_mueller 10y ago
    well, at the end it's just sunlight, carbon, nitrogen, water, a few minerals and a bunch of chemical reactions. I'm pretty sure you could find a biological process to put anywhere that's also viable for solar farms, including open water. In fact, haven't there been a bunch of papers using algae?

deleted 10y ago

[deleted]

ci5er 10y ago

One idea goes like this: We use nuclear or renewables to power a process to capture extant CO2 to be used as fuel, which turns it back to CO2, which will be recaptures, so run-away processes are reigned in. (I can tell by your comment that you get this.) Here's the kicker: the energy density of liquid fuels is super-hard to beat. Batteries (and super-capacitors) are getting better, but relatively speaking, on a whole bunch of dimensions, it doesn't get much easier economically, technically or infrastructurally than burning some hydrocarbon. Hopefully sulfur and mercury free. Tieing "the energy of the future" with "the infrastructure of today" is a very attractive concept that draws a lot of funding from a lot of folks. And researchers, in labs, are working on things that have various limitations of their own, such as "well, gosh, how do you make a copper-iridim-mesh-alloy-hydromister in volume?"

m_mueller 10y ago
Energy density is great, but for most current usecases I'd argue it's not really necessary. It's neither needed in your home (lots of space to put batteries, is connected to a power line), nor for your daily commute, nor for agriculture, nor for heavy industry (even better power lines), nor for long distance land based transport (trains are just as good and can be electrified easily) which covers the largest energy consumers right there. It is very useful for long distance individual travel by car (so, get a Chevy Volt instead of a Tesla) as well as airplanes, rockets and ocean shipping. If we'd just use the remaining fossil fuel for those purposes it would be pretty easy to be carbon negative.
- ci5er 10y ago
  80/20 rule and all that, I agree. I'm originally from a ranch in Wyoming 65m+ from the nearest grocery store, and those use-cases (ag, distance) are burned into my gut. It makes for some bad intuitive generalized conclusions on this topic from time-to-time.
  - m_mueller 10y ago
    no sweat, it's a pleasure to communicate with people who are able to think systematically and who can do an actual discussion rather than just shouting from rooftops.