3 ms·

> Or you could envision large carbon sequestration plants powered by on-site nuclear. I'm not sure I understand, you're suuggesting that we 1. Burn oil to pro

> Or you could envision large carbon sequestration plants powered by on-site nuclear. I'm not sure I understand, you're suuggesting that we 1. Burn oil to produce energy (and CO2 as a byproduct) 2. Use the energy to do X 3. Use non-fossil energy to get rid of the CO2 we created during step 1. When we could just do: 1. Use non-fossil energy to do X Am I missing something?

bhickey 10y ago
0. There's a lot of carbon in the air and we might want to get rid of it.
- ams6110 10y ago
  Yes, I was unclear. We've presumably got 100+ years of industrial carbon emissions to clean up if we want to get back to "pre industrial" atmospheric carbon. Plus ongoing emissions from transportation even if all electrical power is converted to renewable or nuclear.
david-given 10y ago
Transport. Fossil fuels are incredibly energy-dense and convenient to transport and work with, while renewables aren't. There's plenty of transport systems that are utterly reliant on fossil fuels and couldn't be converted to renewable energy. Carbon sequestering would allow continued use of these while staying carbon-neutral.
- schiffern 10y ago
  That seems like a very circuitous and inefficient way to avoid electrifying transport. Batteries are hard, but they're not that hard (as Tesla's rapid progress is demonstrating).
  - philipkglass 10y ago
    Land transportation accounts for the majority of liquid fuel use, and much of that can be replaced by battery power assuming that battery costs continue to drop. I'd guess that battery powered airliners and long distance cargo ships will not become practical. Those and other transport applications particularly demanding of energy density account for a large enough residual of liquid fuel use that it's worth thinking about how to avoid fossil emissions from them. Synthetic liquid fuels made from non-fossil energy sources is one way to do it. (Biofuels are an option too, but plants are a lot less energetically efficient than solar farms, so you need a lot more production area for biofuel than synthetic fuel.)
    - schiffern 10y ago
      >I'd guess that battery powered airliners and long distance cargo ships will not become practical. We shall see. For whatever it's worth, Tesla's CEO disagrees. https://www.youtube.com/watch?v=0871VJfvD1c&t=57s https://www.youtube.com/watch?v=0871VJfvD1c&t=57s >I think all transport, with the exception of rockets, will go fully electric. This is the most recent example, but he's been saying this since at least 2013. Surprisingly, he's also made it clear that he thinks this applies to ships and planes too. http://www.digitaltrends.com/cool-tech/elon-musk-electric-aircraft/ http://www.digitaltrends.com/cool-tech/elon-musk-electric-ai...
      - bluGill 10y ago
        I do not think batteries will ever get a useful enough energy/weight ratio for airplanes. https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density Not only does jet fuel have a much better energy to weight ratio, but you don't have to carry the weight of your spent fuel. A battery powered airplane needs to get all its fuel to altitude while a fuel powered one has much less mass to get up (and stop when you get to the ground). Ships probably will see batteries as an asset: they can place them in ideal locations for weight distribution/stability.
        schiffern 10y ago
        I think it's hard, yes. But I also think forever is a long time. ;) You certainly can't get there by taking an existing aircraft, removing the fuel and replacing it with batteries. It's the same fallacy as the gasoline automakers make with electric cars, and it results in a worse vehicle design. The whole system has to be re-imagined from the ground up to exploit the advantages of electric propulsion. Several of the design concepts for his proposed supersonic VTOL electric transcontinental commercial jet airplane have already been revealed: * The plane would fly at high altitude, somewhere around 80,000 ft. Combustion airplanes have a 30-40,000 ft ceiling limited by the need to ingest oxygen. Due to the exponential decay of density with height this dramatically reduces drag, thereby reducing engine power and structural stress. Coincidentally this is also higher than almost all bad weather. * VTOL is easier since electric motors have a better power:weight ratio than turbine engines. This eliminates constraints due to runway length and width, and means the wing can be more closely optimized for cruising. It also means smaller airports are possible, reducing gate fees. * The wings also don't need to double as liquid fuel tanks, and don't need to handle different stresses when empty vs full. * A high mass fraction of batteries compared to combustion aircraft (mid to high 70% range). Energy density at least 400 Wh/kg (which as you point out, is still much lower than kerosene). * Eliminating the tail section in favor of gimbaling the electric fan, again reducing drag and weight. * You also get about a 1% drop in weight compared to existing jets due to reduced gravity and centrifugal force. A good video compilation of quotes is https://www.youtube.com/watch?v=erjdYiwoYAo https://www.youtube.com/watch?v=erjdYiwoYAo
  - ams6110 10y ago
    Batteries are still a long way from being useful for ships, long-haul trains and trucks, and large aircraft.

bhickey 10y ago

0. There's a lot of carbon in the air and we might want to get rid of it.

ams6110 10y ago
Yes, I was unclear. We've presumably got 100+ years of industrial carbon emissions to clean up if we want to get back to "pre industrial" atmospheric carbon. Plus ongoing emissions from transportation even if all electrical power is converted to renewable or nuclear.

david-given 10y ago

Transport. Fossil fuels are incredibly energy-dense and convenient to transport and work with, while renewables aren't. There's plenty of transport systems that are utterly reliant on fossil fuels and couldn't be converted to renewable energy. Carbon sequestering would allow continued use of these while staying carbon-neutral.

schiffern 10y ago
That seems like a very circuitous and inefficient way to avoid electrifying transport. Batteries are hard, but they're not that hard (as Tesla's rapid progress is demonstrating).
- philipkglass 10y ago
  Land transportation accounts for the majority of liquid fuel use, and much of that can be replaced by battery power assuming that battery costs continue to drop. I'd guess that battery powered airliners and long distance cargo ships will not become practical. Those and other transport applications particularly demanding of energy density account for a large enough residual of liquid fuel use that it's worth thinking about how to avoid fossil emissions from them. Synthetic liquid fuels made from non-fossil energy sources is one way to do it. (Biofuels are an option too, but plants are a lot less energetically efficient than solar farms, so you need a lot more production area for biofuel than synthetic fuel.)
  - schiffern 10y ago
    >I'd guess that battery powered airliners and long distance cargo ships will not become practical. We shall see. For whatever it's worth, Tesla's CEO disagrees. https://www.youtube.com/watch?v=0871VJfvD1c&t=57s https://www.youtube.com/watch?v=0871VJfvD1c&t=57s >I think all transport, with the exception of rockets, will go fully electric. This is the most recent example, but he's been saying this since at least 2013. Surprisingly, he's also made it clear that he thinks this applies to ships and planes too. http://www.digitaltrends.com/cool-tech/elon-musk-electric-aircraft/ http://www.digitaltrends.com/cool-tech/elon-musk-electric-ai...
    - bluGill 10y ago
      I do not think batteries will ever get a useful enough energy/weight ratio for airplanes. https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density Not only does jet fuel have a much better energy to weight ratio, but you don't have to carry the weight of your spent fuel. A battery powered airplane needs to get all its fuel to altitude while a fuel powered one has much less mass to get up (and stop when you get to the ground). Ships probably will see batteries as an asset: they can place them in ideal locations for weight distribution/stability.
      - schiffern 10y ago
        I think it's hard, yes. But I also think forever is a long time. ;) You certainly can't get there by taking an existing aircraft, removing the fuel and replacing it with batteries. It's the same fallacy as the gasoline automakers make with electric cars, and it results in a worse vehicle design. The whole system has to be re-imagined from the ground up to exploit the advantages of electric propulsion. Several of the design concepts for his proposed supersonic VTOL electric transcontinental commercial jet airplane have already been revealed: * The plane would fly at high altitude, somewhere around 80,000 ft. Combustion airplanes have a 30-40,000 ft ceiling limited by the need to ingest oxygen. Due to the exponential decay of density with height this dramatically reduces drag, thereby reducing engine power and structural stress. Coincidentally this is also higher than almost all bad weather. * VTOL is easier since electric motors have a better power:weight ratio than turbine engines. This eliminates constraints due to runway length and width, and means the wing can be more closely optimized for cruising. It also means smaller airports are possible, reducing gate fees. * The wings also don't need to double as liquid fuel tanks, and don't need to handle different stresses when empty vs full. * A high mass fraction of batteries compared to combustion aircraft (mid to high 70% range). Energy density at least 400 Wh/kg (which as you point out, is still much lower than kerosene). * Eliminating the tail section in favor of gimbaling the electric fan, again reducing drag and weight. * You also get about a 1% drop in weight compared to existing jets due to reduced gravity and centrifugal force. A good video compilation of quotes is https://www.youtube.com/watch?v=erjdYiwoYAo https://www.youtube.com/watch?v=erjdYiwoYAo
- ams6110 10y ago
  Batteries are still a long way from being useful for ships, long-haul trains and trucks, and large aircraft.