5 ms·

>Per capita per year, the US consumes 13.0 MWh of electricity and 436.6 gallons of gasoline. With ~132k BTU of energy per gallon, that's 16.9 MWh. >Let's say el

by D_Alex 7y ago

>Per capita per year, the US consumes 13.0 MWh of electricity and 436.6 gallons of gasoline. With ~132k BTU of energy per gallon, that's 16.9 MWh. >Let's say electric cars are 50% more efficient in terms of energy consumption Let's look up the numbers, instead of guessing. The average fuel economy of an american car is apparently 24.7 mpg, whereas a Tesla Model S gets 3.0 miles per kWhr. So if you replace one with the other, you will need about 3.5 MWhr of extra electricity. 27% extra. The good thing is that we should be able to charge the EVs at the time of our choosing, and maybe even discharge them into the grid when the power demand outweighs the generation. The utilisation of wind, solar and off-peak baseload power should increase.

benj111 7y ago
Your last paragraph is key. Even if EVs do double electricity demand, its mainly going to be off peak, and you've got 8+ hours you can spread the charging over. Maybe not a great match to solar, but a good match for wind.
reitzensteinm 7y ago
Yes, I completely fucked up the math. Muphry's Law. But my point still stands; you aren't powering that EV with renewables until the grid goes over 100% of today's production. The fact that you "can" doesn't mean you are.
- SECProto 7y ago
  No, you're powering it with whatever the grid is using. Which is what invalidates your point. Even coal is cleaner [1] than gas. The grid is continuously getting cleaner, and your diesel only gets dirtier as it gets older. [1] https://www.bloomberg.com/news/articles/2019-01-15/electric-cars-seen-getting-cleaner-even-where-grids-rely-on-coal https://www.bloomberg.com/news/articles/2019-01-15/electric-...
  - reitzensteinm 7y ago
    Wowee, it's not "my" diesel. I am in fact an EV advocate, and they're worth transitioning to even if you're powering them with coal. This is a fact that we agree on. My point is that the grid is not getting continuously cleaner if you're dumping a bunch more load on it. The marginal increase in load will be powered by fossil fuels for a significant amount of time, which is longer than the lifetime of a Tesla built today. You take your dirtiest power offline first (with a sane energy policy). Any extra load you add is by definition delaying that event. EVs are an important next step, and an absolute necessity for stabilizing the grid when transitioning to intermittent renewables. I was replying to a very specific claim made by the parent comment.
    - SECProto 7y ago
      Sorry, I didn't mean to imply ownership, and should have used the indefinite article "a" diesel, not "your" diesel. If you take the existing grid, and add a bunch of load to it, and also add a bunch of renewables, the grid is still cleaner. For the set pollution outputs, the amount of power generated is higher. Pollution per unit power is less. And the point I was making is that it doesn't matter, even if coal was where the additional power came from (and it absolutely will not be), it's still cleaner than current ICE cars (that's the link I cited in the previous post)
      - reitzensteinm 7y ago
        Right, I am 100% on the same page that EVs even when powered by coal power plants are better. No brainer, let's get it done. But you aren't thinking clearly about where the power for EVs is coming from. I'm going to attempt to illustrate with some made up numbers for simplicity. This year, we have: * 100 TWh electricity consumption * 100 TWh gasoline consumption The electricity is generated via: * 20 TWh from renewables, growing by 10 TWh a year * 80 TWh from fossil fuels, shrinking by 10 TWh a year This system will reach 100% renewable consumption after 8 years, having consumed 80 + 70 + 60 ... = 360 TWh of electricity generated via fossil fuels, and gasoline containing 800 TWh. Now if we could switch the system over to 100% EVs this year (to make the math easier), let's assume we can replace gasoline containing 100 TWh with 20 TWh of electricity. The capacity for this generation comes from our existing fossil fuel plants, which were in the process of shutting down. Our consumption is now: * 120 TWh electricity Generated via: * 20 TWh from renewables, growing by 10 TWh a year * 100 TWh from fossil fuels, shrinking by 10 TWh a year This alternate system will reach 100% renewable consumption after 10 years, having consumed 100 + 90 + 80 ... = 550 TWh of electricity generated via fossil fuels. Even on an aggressive renewable ramp (which should be more favorable than reality), the addition of load from EVs has caused 52% more consumption of electricity from fossil fuels over the course of the ramp. This is still a significant reduction in carbon emissions, as the power plants burning fossil fuels are more efficient, and it's worth doing. But it is not correct to say that the EVs are powered in part by renewables until near the end of the ramp. Any amount of renewable energy you feed the EVs is simply being taken from elsewhere in the grid. Now, you could ramp up renewables more quickly to make up the shortfall, but you could have done that anyway. The only real connection they have is that EVs can dispatch demand and even send power back in to the grid from their batteries, in order to allow the grid to remain stable as more intermittent sources of power are added to the grid. In places where wind and solar have caused an excess of energy, like Germany on occasion as discussed by a sibling commenter, or at times in my own Australia, you can start to attribute that otherwise wasted energy to fueling EVs.

by D_Alex 7y ago

benj111 7y ago

Your last paragraph is key. Even if EVs do double electricity demand, its mainly going to be off peak, and you've got 8+ hours you can spread the charging over. Maybe not a great match to solar, but a good match for wind.

reitzensteinm 7y ago

Yes, I completely fucked up the math. Muphry's Law. But my point still stands; you aren't powering that EV with renewables until the grid goes over 100% of today's production. The fact that you "can" doesn't mean you are.

SECProto 7y ago
No, you're powering it with whatever the grid is using. Which is what invalidates your point. Even coal is cleaner [1] than gas. The grid is continuously getting cleaner, and your diesel only gets dirtier as it gets older. [1] https://www.bloomberg.com/news/articles/2019-01-15/electric-cars-seen-getting-cleaner-even-where-grids-rely-on-coal https://www.bloomberg.com/news/articles/2019-01-15/electric-...
- reitzensteinm 7y ago
  Wowee, it's not "my" diesel. I am in fact an EV advocate, and they're worth transitioning to even if you're powering them with coal. This is a fact that we agree on. My point is that the grid is not getting continuously cleaner if you're dumping a bunch more load on it. The marginal increase in load will be powered by fossil fuels for a significant amount of time, which is longer than the lifetime of a Tesla built today. You take your dirtiest power offline first (with a sane energy policy). Any extra load you add is by definition delaying that event. EVs are an important next step, and an absolute necessity for stabilizing the grid when transitioning to intermittent renewables. I was replying to a very specific claim made by the parent comment.
  - SECProto 7y ago
    Sorry, I didn't mean to imply ownership, and should have used the indefinite article "a" diesel, not "your" diesel. If you take the existing grid, and add a bunch of load to it, and also add a bunch of renewables, the grid is still cleaner. For the set pollution outputs, the amount of power generated is higher. Pollution per unit power is less. And the point I was making is that it doesn't matter, even if coal was where the additional power came from (and it absolutely will not be), it's still cleaner than current ICE cars (that's the link I cited in the previous post)
    - reitzensteinm 7y ago
      Right, I am 100% on the same page that EVs even when powered by coal power plants are better. No brainer, let's get it done. But you aren't thinking clearly about where the power for EVs is coming from. I'm going to attempt to illustrate with some made up numbers for simplicity. This year, we have: * 100 TWh electricity consumption * 100 TWh gasoline consumption The electricity is generated via: * 20 TWh from renewables, growing by 10 TWh a year * 80 TWh from fossil fuels, shrinking by 10 TWh a year This system will reach 100% renewable consumption after 8 years, having consumed 80 + 70 + 60 ... = 360 TWh of electricity generated via fossil fuels, and gasoline containing 800 TWh. Now if we could switch the system over to 100% EVs this year (to make the math easier), let's assume we can replace gasoline containing 100 TWh with 20 TWh of electricity. The capacity for this generation comes from our existing fossil fuel plants, which were in the process of shutting down. Our consumption is now: * 120 TWh electricity Generated via: * 20 TWh from renewables, growing by 10 TWh a year * 100 TWh from fossil fuels, shrinking by 10 TWh a year This alternate system will reach 100% renewable consumption after 10 years, having consumed 100 + 90 + 80 ... = 550 TWh of electricity generated via fossil fuels. Even on an aggressive renewable ramp (which should be more favorable than reality), the addition of load from EVs has caused 52% more consumption of electricity from fossil fuels over the course of the ramp. This is still a significant reduction in carbon emissions, as the power plants burning fossil fuels are more efficient, and it's worth doing. But it is not correct to say that the EVs are powered in part by renewables until near the end of the ramp. Any amount of renewable energy you feed the EVs is simply being taken from elsewhere in the grid. Now, you could ramp up renewables more quickly to make up the shortfall, but you could have done that anyway. The only real connection they have is that EVs can dispatch demand and even send power back in to the grid from their batteries, in order to allow the grid to remain stable as more intermittent sources of power are added to the grid. In places where wind and solar have caused an excess of energy, like Germany on occasion as discussed by a sibling commenter, or at times in my own Australia, you can start to attribute that otherwise wasted energy to fueling EVs.