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ICE cars are around 15% efficient. Electric cars are generally 85% to 90% efficient. "50% more" is a pretty big understatement. 1.5x * 15 is only 22.5% efficient still around 1/4th as efficient as an electric car.

Also given solar's growth and the time it will take for most cars to be electric there's plenty of room for more solar production. California now requires solar on all new homes, and it's getting ever more price effective to use renewables. Seems like I see a few stories a week about a coal, NG, or similar peaker plant being cancelled, or decomissioned in favor of battery storage, solar, or both... for purely economic reasons.

A 75kw battery in a tesla gives you a range of 310 miles or so. So that's 4 miles or so per kw. So if I install the smallest Tesla solar system (4kw for $8,000) and being in central California I get a fair bit of sun. Should easily make 15-20kwh in the winter, and a fair bit more in the summer. That's 80 ish miles a day in the winter, and more in the summer. I drive about 30 miles a day on average.

So with a 8kw solar system I'd likely handle my driving needs and put a big dent in my other power needs. Tesla's new solar pricing puts it around $2.00 a watt installed. $16,000 isn't cheap, but our power bill isn't cheap either, especially in the summer.

As a nice bonus solar panels noticeably decrease the heat load in the attic, saving airconditioning costs. Amusingly solar panels over parking lots (so they provide shade) actually save a fair amount of gas. The huge win is when everyone runs their AC flat out for 15 minutes when they get into their 130F cars, if their car is closer to ambient they spend much less gas on the AC.

While solar does contribute to the "duck" shaped power production curve, cars typically spend the vast majority of their time parked, and can be programmed to use power whenever there is a surplus/whenever the price is lowest. So while electric cars can consume large amounts of power, they generally aren't picky on when they get it. At least for home users they typically schedule charging for whatever time the cheapest rates start.

I cannot comment on the US numbers, but the German numbers are as following: - total electricity production is around 600 TWh/year - switching all cars to electricity would require about 120 TWh/year (44M cars x 14000km/year * 20kWh/100km)

That would be a 20% increase in electricity production required, but from that one can deduct quite a bit for fuel refining and distribution, better buffering of peak electricity production etc.

If you take the energy content of fuel, an electric car is roughly 4x as efficient as a combustion engine. While combustion engines may reach peak efficiencies of 40%, the average over the whole driving cycle is less than 20%, as the peak efficiency is only reached in a narrow band of power productions - usually at highway speeds. That is the reason hybrid cars save fuel, the electric component reduces the inefficiencies of certain parts of the driving cycle.

I'm not surprised the German numbers are better. But even there, with Germany's remarkable progress, a Tesla bought today will be scrapped before Germany reaches 120% of today's electrical production in renewables.

Fair enough; I should have used 25% instead of 50%. In my head I was multiplying by the energy efficiency of electrical production but that of course is not relevant to this calculation. The irony of correcting a bad argument with a bad argument while complaining about the same is not lost on me. I believe my point stands.

In Germany, far more reneweable power is added to the grid as the consumption could increase. With about 44 million cars on the road, every year 3 million new cars are sold, so it would take 15 years to add that extra 10-15% of electricity consumption to the grid.

Whether the grid reaches 100% reneweable during the lifetime of an electric car bought today or not might not be clear, but the point being was, it is guaranteed to contain way more reneweables as of today and with that the base of the calculations was wrong.

If you're adding marginal consumption to the grid that does not exist today, you can't account for it as being in part powered by renewables. You are producing no more renewable energy than previously, and fossil fuel consumption will increase by exactly the amount you're adding to the grid.

I'm not arguing that EVs aren't a good idea. I'm just in favor of being clear about the choice that's being made; a switch to 100% EVs would result in significantly increased electricity consumption powered by fossil fuels until renewables catch up, but lower overall carbon emissions since you're burning the fossil fuels more efficiently.

No. At best we could add 6% more electric cars per year - if only electric cars would be sold. That is the renewal rate for cars in Germany. This means, the energy consumption would increase by 1.5% per year. The addition of reneweable energy to the grid per year far exceeds the amount of energy that could be used by electric cars even at 100% market share. Which they are unfortunately far from. So the mix gets cleaner even after accounting all new reneweable energy for the electricity demands of electric cars.

It is simply not relevant that renewable energy is being added to the grid faster than EVs are increasing energy consumption. If you add energy consumption to the grid, you are powering it with your dirtiest power, which you'd otherwise be shutting off.

EVs are still superior when powering them entirely with fossil fuels. I'm not trying to argue against them. But it's important to be truthful about where the energy is coming from.

The argumentation with the marginal mix sounds nice, but is wrong. You cannot assign a certain power source to a certain electrical device unless they are directly connected. Your lightbulb isn't running on 100% coal, just because you switch it on.

Yes, if there is a difference between the demand and the amount of reneweable energy produced, that has to come from carbon sources. So increasing the demand might increase that. On the other side, in Germany we are already at the point where we have excess energy production. Mostly because coal and nuclear plants cannot be throttled quickly. So quite often we have to take reneweable energy off the grid to keep it stable. Equally, we have negative electricity prices on the spot market. Here you would even have to calculate a negative CO2 content in the energy mix for electric cars which could absorbe that wasted reneweable energy.

In the end, electric cars are rather accellerating than slowing down the switch to more renweables in the mix and as said, the addition of reneweable sources far exceeds the addition of electric cars - at the moment even by orders of magnitude.

An electric car powering on otherwise wasted renewable energy does not have negative CO2 emissions, just zero. Germany had 134 hours of negative power prices last year, and this would indeed mean that a marginal electric car added to the grid would be proportionally powered by renewables - 1.5% in 2018. In that sense, my argument of 0% is too extreme especially as the number grows, but it is still a negligible amount even in Germany today, which is significantly ahead of most countries on the renewable transition.

It is fair to count renewable energy that could not be produced without the assistance of BEVs, via demand dispatch or battery to grid transfers. And the full amount of this energy should be counted, not just its share of contribution to the grid.

Keep in mind that 600TWh/year is likely a capacity of at least double that. But the peak rate is only under worst case scenarios like a sustained heat waves. Unfortunately that high peak capacity is very expensive and goes unused for the majority of the year.

Electric cars consume quite a bit of power, but the longer range cars like the Audi, Jaguar, Tesla, top of the line leaf, and bolt all have a 200 mile or so range. So under normal use (somewhere around 12,000 miles a year) they don't need charged every day.

So generally cars can charge off peak, but in times of dire need I can see only allowing cars to charge when there's a surplus of power... strangely enough these surpluses are becoming common because of solar. Sometimes utilities even have to pay to get rid of the power.

>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.

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.

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.

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-...

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.

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)

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.

You are missing the point. This is a long run game, since we can easily transition from fossil fuels to alternate energy source without having to replace fundamentally how EV engines work. All they need is electrons, not exploding fossil fuel. These electrons can come from any source. If it's fossil today it doesn't matter. 20, 50. 100 years from now the source of energy can shift significantly while the transportation industry just wouldn't care anymore.