What can be done (climate change debate)?

[Try2B_Comprehensive]

I’d much rather stick with using the Model S as the yardstick and leave the Leaf out of it. Nothing against the Leaf, but the Model S is more advanced.

Your estimates don’t jibe with the actual gas mileage of a rig, though 1000 miles does seem like a long trip for an ev semi. Surely there are shorter routes- the rigs running those get the same lousy milage as the rest. I’m proposing a hybrid semi that hauls batteries in the trailer. Since these things run all week long, the fuel savings actually have a chance to be cost-effective.

[Sam_Stone]

Where are you getting your numbers from? I believe the model S has two batteries available - a 60 kw/h and an 85 kw/h battery. The larger battery weighs about 550 kg.

Also, I don’t know where you are getting 8 kwh of energy in a gallon of gas. A U.S gallon of gas has the energy equivalent of 33.41 kWh. Diesel is 37.95 kWh.

So, 550 kg of battery equals a little over 2 gallons of diesel. To replace 200 gallons would require roughly 50,000 kg, which is the ballpark of my original estimate.

Now the Tesla Model S has an epa rating of 89 mpg gasoline equivalent, so I guess they are factoring in the efficiency of a gas engine in converting fuel energy to motion. So let’s be generous and double the energy equivalent. That still requires around 27,000 kg of batteries to replace 200 gallons of diesel. Not feasible.

The numbers I used for solar power were the actual numbers from the most efficient panels available today.

[Sam_Stone]

As for charging… You are off by a factor of about 4 in your estimate of the energy in a gallon of gas. Even if we used your 10 kw estimate for the solar cell production, that’s at peak efficiency. And it doesn’t account for charging losses, dirt and snow (the top of a trailer is a dirty place), the fact that the panels are poorly aligned towards the sun, etc. I suspect that in the real world you’d be lucky to get half the rated power, and more realistically perhaps 30%. Let’s be generous and say 5 kwh when it’s sunny. An 8 hour day in the sun might get you the equivalent of a little over 1 gallon of diesel in usable energy at the battery. Depending on how many sunny days there are, that might net you 300 gallons of diesel per year, saving you maybe $1200 per year. Which will never pay back your investment. And be prepared to spend a lot of time high up on your trailer cleaning solar cells.

[Try2B_Comprehensive]

@Sam_Stone

Where are you getting your numbers from? I believe the model S has two batteries available - a 60 kw/h and an 85 kw/h battery. The larger battery weighs about 550 kg.

Ah, I thought they were much bigger. My hybrid semi is only carrying 340 kwh then, not 1040.

Also, I don’t know where you are getting 8 kwh of energy in a gallon of gas. A U.S gallon of gas has the energy equivalent of 33.41 kWh. Diesel is 37.95 kWh.

I get it from the Volt- it has about 40 miles of ev range and uses 8kwh (the battery capacity is 16kwh, but it doesn’t full-cycle). I treat that as about a gallon of gas.

Does ‘energy equivalent’ take into account the low efficiency of ICE engines? A good one isn’t better than 25%, while electric motors are in the high 90’s. 33.41 kwh * .25 is pretty close to my 8 khw per gallon.

So, 550 kg of battery equals a little over 2 gallons of diesel. To replace 200 gallons would require roughly 50,000 kg, which is the ballpark of my original estimate.

This can’t be right. The Model S has a range of 260 miles. A car as heavy as it is would get about 25mpg, which averages out, again, to around 8 kwh per gallon.

Now the Tesla Model S has an epa rating of 89 mpg gasoline equivalent, so I guess they are factoring in the efficiency of a gas engine in converting fuel energy to motion. So let’s be generous and double the energy equivalent. That still requires around 27,000 kg of batteries to replace 200 gallons of diesel. Not feasible.

Well, you’d have to divide it by 4 and not 2. And the battery does not need to amount to the full 200 gallons. If it is 100 gallons equivalent and you charge it once en route as described above, you run up to 75% ev miles. And I think there are gains using fuel to run a generator vs. a 12-cylinder motor, but I’m not sure how big those are. Still, even if 8 kwh is correct, that would require 10 Model S batteries, maybe 12,000 lbs. Semis can haul 45,000 lbs, so while ‘not feasible’ is going to far, we still lose a quarter of our weight limit.

The numbers I used for solar power were the actual numbers from the most efficient panels available today.

Our numbers on this aren’t so different. We would need to settle the question of how many kwh equals a gallon of fuel before we can judge if this can be cost-effective. 40 square meters is kind of a lot- it is several houses’ worth at least.

[Farin]

@Try2B_Comprehensive

I’d much rather stick with using the Model S as the yardstick and leave the Leaf out of it. Nothing against the Leaf, but the Model S is more advanced.

Your estimates don’t jibe with the actual gas mileage of a rig, though 1000 miles does seem like a long trip for an ev semi. Surely there are shorter routes- the rigs running those get the same lousy milage as the rest. I’m proposing a hybrid semi that hauls batteries in the trailer. Since these things run all week long, the fuel savings actually have a chance to be cost-effective.

I think the Leaf is actually the better target. it uses a 98% efficient motor versus a 90% efficient motor on the Model S.

But my math was off. I divided by the kWh of the battery twice and I multiplied 80,000 by the 0.085 pounds instead of divided. My apologies. I shouldn’t try to math late at night.

The Leaf actually hauls 2.06 pounds per kWh hour per mile. Scaled up to a hauler, that’s 38,835 kWh of battery needed per mile.

For comparison, the specs of the Model S: 85kWh battery, 4,700lbs weight, 265mile EPA estimated range, same 400lbs passenger load: 60 pounds carried 265 miles per kWh; which is 0.226 pounds per kWh per mile. That would be 353,982 kWh of capacity needed per mile at 80,000 pounds.

This disparity isn’t all that surprising. The Leaf was built for economy. The Model S was built for performance. It’s like comparing the mpg rating of a Toyota Avalon versus a Toyota Yaris. One was built for economy first and one was built for performance first and it’s easily reflected in the MPG ratings: 20/31 Avalon; 30/37 Yaris.

Even around town, hauling a full load is expensive in an EV, not just in battery capacity but in time for charging. As I said, before, hybrids are getting out there and that may be bee’s knees. But the pioneers are putting them through the ringers so that the rest of the heavy truck industry can plan accordingly.

It’s simply too early in the process to say that these are where the hauling fleets should go without causing some pretty rough economic hardships. And I’m not talking to the companies that haul - the consumer that pay for the hauled goods would be worst affected.

[Try2B_Comprehensive]

@Farin

I think the Leaf is actually the better target. it uses a 98% efficient motor versus a 90% efficient motor on the Model S.

But my math was off. I divided by the kWh of the battery twice and I multiplied 80,000 by the 0.085 pounds instead of divided. My apologies. I shouldn’t try to math late at night.

I’m doing all napkin-math and getting it wrong too; no apologies necessary.

The Leaf actually hauls 2.06 pounds per kWh hour per mile. Scaled up to a hauler, that’s 38,835 kWh of battery needed per mile.

For comparison, the specs of the Model S: 85kWh battery, 4,700lbs weight, 265mile EPA estimated range, same 400lbs passenger load: 60 pounds carried 265 miles per kWh; which is 0.226 pounds per kWh per mile. That would be 353,982 kWh of capacity needed per mile at 80,000 pounds.

This cannot be the way to calculate the battery power needed to haul a semi. For instance, the USS Ronald Reagan, the largest vehicle of any kind in human history, is an ev. It uses two A4W nuclear reactors which each supply 104 MW for propulsion. You are claiming that a semi would require 353 MWh per mile. No way a semi requires more power than a nuclear-powered aircraft carrier. I bet you could haul the thing into orbit with that much power.

Better, I think, to calculate the gas equivalence of a kwh and then map that to the gas mileage of existing semis. If the energy potential in a gallon of gas is ~33kwh, and an ICE engine converts 25% of that into momentum, then it looks 8kwh is roughly equivalent to a gallon of gas.

If these rigs really are allowed to weigh 80,000 lbs though and not 45,000 like I thought, then a 12,000 lb battery actually looks do-able, if still oversized.

This disparity isn’t all that surprising. The Leaf was built for economy. The Model S was built for performance. It’s like comparing the mpg rating of a Toyota Avalon versus a Toyota Yaris. One was built for economy first and one was built for performance first and it’s easily reflected in the MPG ratings: 20/31 Avalon; 30/37 Yaris.

Well, semis aren’t exactly built for efficiency. They’re designed for torque. I don’t think the strength of the motors will be an issue though- an electric semi could easily be designed with 4 motors, one each in 4 separate wheels in the tractor, and generate more torque than any semis ever have, all without requiring any advancement whatsoever in current electric motor technology. Pound for pound, electric motors are simply superior.

Even around town, hauling a full load is expensive in an EV, not just in battery capacity but in time for charging. As I said, before, hybrids are getting out there and that may be bee’s knees. But the pioneers are putting them through the ringers so that the rest of the heavy truck industry can plan accordingly.

To be clear, I look at a 30 year time horizon for phasing in electric semis (same time-frame for globe-scale solar). The first generation will be the beta-test; the next generation will utilize updated technology in batteries and generally what the beta-test taught us, and each successive generation will be better than the last, phasing in basically as old diesels are retired. They may not work for every situation, but then again we don’t have to eliminate diesel consumption, just reduce it.

As for charging, I like the Tesla example. Their superchargers deliver 480v, and charge a Model S halfway in 20 minutes (the rate slows down as the batteries fill, so after an hour it still isn’t 100%). Adapted for semis, you’d charge battery segments with 4 separate circuits simultaneously, allowing for a better than 50% recharge en route in less than an hour. But obviously I’m talking about infrastructure that doesn’t exist.

It’s simply too early in the process to say that these are where the hauling fleets should go without causing some pretty rough economic hardships. And I’m not talking to the companies that haul - the consumer that pay for the hauled goods would be worst affected.

The time is now! Fueling a semi costs a fortune- hybrid semis will save money and not just carbon emissions. But yeah, it is hard to predict in my spare time what form they will take. I like the idea of putting solar panels on semis since there is no added footprint and the power goes directly to the source of your worst carbon pollution. But if they don’t work in practice, we have to forget it.

[FXMastermind]

A big truck engine produces around 522 kW under full power, which they don’t use very often.

[Farin]

@Try2B_Comprehensive

This cannot be the way to calculate the battery power needed to haul a semi. For instance, the USS Ronald Reagan, the largest vehicle of any kind in human history, is an ev. It uses two A4W nuclear reactors which each supply 104 MW for propulsion. You are claiming that a semi would require 353 MWh per mile. No way a semi requires more power than a nuclear-powered aircraft carrier. I bet you could haul the thing into orbit with that much power.

kW is not the same as kWh. One is kinetic and one is potential. You are not APPLYING 353MW to the engine at once. You are needing that much capacity to haul around 80,000 pounds as comparatives to both a Leaf and a Model S using current full EV designs. It was a comparative, only.

At roughly 93 or 94% efficiency, an electric motor will have kW input = traditional horsepower. So for a tractor that I see sitting out my office window, which is an ISX Signature with a 650hp engine, we’d need two 325 kW motors, one for each drive axle, to match the potential of that engine for hauling. It’s so equipped because it commonly carries loads of up to 125,000 lbs. That needs a battery capable of 650kWh for one hour of use at maximum load. Now, granted, that is the worst case scenario. But if we assume these motors are getting driven at 25% on average (this will, of course, lower on flat highways, higher on hilly highways, and way higher in-towns), that’s still 165kWh of battery needed for one hour of operation. That’s two Model S 85kWh batteries per hour, which is roughly 1,200 pounds.

@Try2B_Comprehensive

Better, I think, to calculate the gas equivalence of a kwh and then map that to the gas mileage of existing semis. If the energy potential in a gallon of gas is ~33kwh, and an ICE engine converts 25% of that into momentum, then it looks 8kwh is roughly equivalent to a gallon of gas.

That’s a terrible way to look at it. All ICEs vary very much by what is currently happening in the driving, how it’s transmission is setup, and what’s the load. A gallon of diesel can go from 10% to 90% of applied power to the road.

For instance, accelerating an 80,000 lb load from 35mph to 60mph is where most of the power need is. It’s also where the electric motors can do the least. Maintaining 60+ mph is easy. Accelerating to 35mph is easy via torque.What is the kWh equivalence in a car is no where near what would be kWh equivalence in a heavy truck.

@Try2B_Comprehensive

If these rigs really are allowed to weigh 80,000 lbs though and not 45,000 like I thought, then a 12,000 lb battery actually looks do-able, if still oversized.

At 12,000 pounds, I can easily fit any size of diesel or gasoline engine, though. You lose a lot less poundage if you just slap an electrical generator in there running at 100kW or similar. That’s 7gph running 100% load. So, if you are long-haul trucking, you’ll dip into the battery to get going set out on your desolate highway trip and you’ll save a bunch of money versus a 5mpg tractor running down the freeway.

The current heavy truck hybrids I’ve seen aren’t doing this, though. They are setting the engine to operate at 1800 to 2200 rpm for best fuel economy and then using some of that power to help the 35-60 mph acceleration. Either way, they are saving a lot of fuel without needing other considerations.

@Try2B_Comprehensive

Well, semis aren’t exactly built for efficiency. They’re designed for torque. I don’t think the strength of the motors will be an issue though- an electric semi could easily be designed with 4 motors, one each in 4 separate wheels in the tractor, and generate more torque than any semis ever have, all without requiring any advancement whatsoever in current electric motor technology. Pound for pound, electric motors are simply superior.

Electric motors are, yes. I’ve never argued that. The argument is the power needed to run them is probably not yet feasible via battery pack.

@Try2B_Comprehensive

To be clear, I look at a 30 year time horizon for phasing in electric semis (same time-frame for globe-scale solar). The first generation will be the beta-test; the next generation will utilize updated technology in batteries and generally what the beta-test taught us, and each successive generation will be better than the last, phasing in basically as old diesels are retired. They may not work for every situation, but then again we don’t have to eliminate diesel consumption, just reduce it.

We can reduce consumption with hybrids and increase their fuel efficiency by half to 2/3rds and we don’t have a lot of infrastructure investments to get there.

@Try2B_Comprehensive

As for charging, I like the Tesla example. Their superchargers deliver 480v, and charge a Model S halfway in 20 minutes (the rate slows down as the batteries fill, so after an hour it still isn’t 100%). Adapted for semis, you’d charge battery segments with 4 separate circuits simultaneously, allowing for a better than 50% recharge en route in less than an hour. But obviously I’m talking about infrastructure that doesn’t exist.

I agree. But if we are going to invest in infrastructure and EVs, I’d eliminate the “Gas station” model and instead be way more radical. Put rails into all of the roads and charge them directly off of the power grid and have tiny batteries on the vehicles themselves. The only time you’d need an ICE is when you are doing something actively off-road (Jeeping in the mountains? Have fun. Building a new subdivision? Have fun…er work. Have work!)

@Try2B_Comprehensive

The time is now! Fueling a semi costs a fortune- hybrid semis will save money and not just carbon emissions. But yeah, it is hard to predict in my spare time what form they will take. I like the idea of putting solar panels on semis since there is no added footprint and the power goes directly to the source of your worst carbon pollution. But if they don’t work in practice, we have to forget it.

As I laid out: We are too early in the process to get more than pioneers on board, yet. Perhaps if you took your 30 year approach above to hybrids instead of EVs in the heavy trucks, you’d be closer to on-target.

[Try2B_Comprehensive]

@Farin

kW is not the same as kWh. One is kinetic and one is potential. You are not APPLYING 353MW to the engine at once. You are needing that much capacity to haul around 80,000 pounds as comparatives to both a Leaf and a Model S using current full EV designs. It was a comparative, only.

At roughly 93 or 94% efficiency, an electric motor will have kW input = traditional horsepower. So for a tractor that I see sitting out my office window, which is an ISX Signature with a 650hp engine, we’d need two 325 kW motors, one for each drive axle, to match the potential of that engine for hauling. It’s so equipped because it commonly carries loads of up to 125,000 lbs. That needs a battery capable of 650kWh for one hour of use at maximum load. Now, granted, that is the worst case scenario. But if we assume these motors are getting driven at 25% on average (this will, of course, lower on flat highways, higher on hilly highways, and way higher in-towns), that’s still 165kWh of battery needed for one hour of operation. That’s two Model S 85kWh batteries per hour, which is roughly 1,200 pounds.

Well, we’d have to get some more detailed data about actual semi fuel consumption to decide. I’m not sure why you say these motors are driven at 25% on average- it could be less than that.

Let’s see, 70 miles an hour, 5 to 7 mpg, that’s 10 to 14 gallons of fuel an hour. A Tesla battery amounts to ~10 gallons of fuel, so I think it is closer to one Tesla battery per hour. Now, if we’re talking 125,000 lbs, okay, maybe that would take two.

That’s a terrible way to look at it. All ICEs vary very much by what is currently happening in the driving, how it’s transmission is setup, and what’s the load. A gallon of diesel can go from 10% to 90% of applied power to the road.

For instance, accelerating an 80,000 lb load from 35mph to 60mph is where most of the power need is. It’s also where the electric motors can do the least. Maintaining 60+ mph is easy. Accelerating to 35mph is easy via torque.What is the kWh equivalence in a car is no where near what would be kWh equivalence in a heavy truck.

Well, I disagree with you. I don’t believe a diesel engine is ever 90% efficient, or even close to half that. Of course, I am always one cite away from seeing something I don’t already know.

Trucks seem to have better acceleration after 35 mph because they have apower curve. (scroll down to Engine Power and Torque Curves) An electric motor doesn’t have much of a curve- it delivers full output all the way down to zero rpm. So it is more efficient in that phase, and the ev semi doesn’t burn fuel idling. I don’t see a good reason why we couldn’t treat 8kwh as roughly equivalent to a gallon of diesel, and treat the electric motor as getting a little higher mpg.

At 12,000 pounds, I can easily fit any size of diesel or gasoline engine, though. You lose a lot less poundage if you just slap an electrical generator in there running at 100kW or similar. That’s 7gph running 100% load. So, if you are long-haul trucking, you’ll dip into the battery to get going set out on your desolate highway trip and you’ll save a bunch of money versus a 5mpg tractor running down the freeway.

The current heavy truck hybrids I’ve seen aren’t doing this, though. They are setting the engine to operate at 1800 to 2200 rpm for best fuel economy and then using some of that power to help the 35-60 mph acceleration. Either way, they are saving a lot of fuel without needing other considerations.

I have been proposing that these things be hybrids. I just want to dramatically increase the percentage of miles driven on electric power. So, yes, let’s keep the generator.

The size of the electric motor can be much bigger than offered by current hybrids. This one has a 60 hp electric motor. There is no reason they have to be this underpowered. The BMW i3 has a 170 hp electric motor, and it is just a little coupe. The Model S has 416 hp, or 310 Kw. If it ran at 25%, it would only go for an hour a charge (it actually runs 4-5 hours). For a semi, the motors could easily exceed 600hp or more. Accelerating from 35 mph to 65 mph is not an issue if we design it properly.

Electric motors are, yes. I’ve never argued that. The argument is the power needed to run them is probably not yet feasible via battery pack.

The next generation of battery chemistry would be nice for this project, yes. But it is feasible to do it. Let’s say the batteries were in their own separate trailer, 12-15 feet long, which hooks between the tractor and a standard cargo trailer. Pack an 800 kwh battery in the battery trailer, unhook it and replace it with a fully charged one at the rest station, do it again when you get to Chicago, voila! A 1000 mile electric semi trip.

Or, in cases where there are 200 mile routes, we might design a tractor that carries enough batteries for that. Source all the electricity for the recharging from solar sources like Tesla’s charging stations do, and you’re running your cargo fleet on carbon-free energy, which also happens to be dramatically cheaper than diesel.

I agree. But if we are going to invest in infrastructure and EVs, I’d eliminate the “Gas station” model and instead be way more radical. Put rails into all of the roads and charge them directly off of the power grid and have tiny batteries on the vehicles themselves. The only time you’d need an ICE is when you are doing something actively off-road (Jeeping in the mountains? Have fun. Building a new subdivision? Have fun…er work. Have work!)

I think that is really an impractical degree of infrastructure development. OTOH, it would not be outlandish to roll out semi charging stations along the most popular routes, and expand the network as the things catch on.

As I laid out: We are too early in the process to get more than pioneers on board, yet. Perhaps if you took your 30 year approach above to hybrids instead of EVs in the heavy trucks, you’d be closer to on-target.

I always said it should be a hybrid

[Farin]

@Try2B_Comprehensive

Well, we’d have to get some more detailed data about actual semi fuel consumption to decide. I’m not sure why you say these motors are driven at 25% on average- it could be less than that.

I can give you volumes. (Literally. I wish they’d move to digimal documents. ) That’s what my professional career is in. The problem is that you have to define it by what trip you are taking. The use profile of a trip from Denver to Chicago is very different than the use profile of Chicago to Denver.

@Try2B_Comprehensive

Let’s see, 70 miles an hour, 5 to 7 mpg, that’s 10 to 14 gallons of fuel an hour. A Tesla battery amounts to ~10 gallons of fuel, so I think it is closer to one Tesla battery per hour. Now, if we’re talking 125,000 lbs, okay, maybe that would take two.

Yes, each 325kw ~ 325hp electric motor would be consuming roughly 1 Tesla battery per hour.

@Try2B_Comprehensive

Well, I disagree with you. I don’t believe a diesel engine is ever 90% efficient, or even close to half that. Of course, I am always one cite away from seeing something I don’t already know.

You misunderstood. 90% of the **captured **energy is going to the ground. Most of the ICE energy is lost to heat.

@Try2B_Comprehensive

Trucks seem to have better acceleration after 35 mph because they have apower curve. (scroll down to Engine Power and Torque Curves) An electric motor doesn’t have much of a curve- it delivers full output all the way down to zero rpm. So it is more efficient in that phase, and the ev semi doesn’t burn fuel idling. I don’t see a good reason why we couldn’t treat 8kwh as roughly equivalent to a gallon of diesel, and treat the electric motor as getting a little higher mpg.

I would need to see some testing to back up that that’s all of the power going to the road and what the curve on that is. Idle vs red line are very different beasts.

@Try2B_Comprehensive

I have been proposing that these things be hybrids. I just want to dramatically increase the percentage of miles driven on electric power. So, yes, let’s keep the generator.

I misunderstood your points, then, as advocating for EVs as the transition-to target.

The size of the electric motor can be much bigger than offered by current hybrids. This one has a 60 hp electric motor. There is no reason they have to be this underpowered. The BMW i3 has a 170 hp electric motor, and it is just a little coupe. The Model S has 416 hp, or 310 Kw. If it ran at 25%, it would only go for an hour a charge (it actually runs 4-5 hours). For a semi, the motors could easily exceed 600hp or more. Accelerating from 35 mph to 65 mph is not an issue if we design it properly.
[/quote]

As I said: The pioneers are going first. The 2.5 to 3.0 versions of these vehicles will likely be vastly superior.

@Try2B_Comprehensive

The next generation of battery chemistry would be nice for this project, yes. But it is feasible to do it. Let’s say the batteries were in their own separate trailer, 12-15 feet long, which hooks between the tractor and a standard cargo trailer. Pack an 800 kwh battery in the battery trailer, unhook it and replace it with a fully charged one at the rest station, do it again when you get to Chicago, voila! A 1000 mile electric semi trip.

Or, in cases where there are 200 mile routes, we might design a tractor that carries enough batteries for that. Source all the electricity for the recharging from solar sources like Tesla’s charging stations do, and you’re running your cargo fleet on carbon-free energy, which also happens to be dramatically cheaper than diesel.

I disagree. Carrying excess capacity on a trailer is the opposite of feasible. It’s like saying your Model S is feasible of going 100 miles…if it has a small 8foot car trailer with batteries in the back. It’s far too much hassle for the range and payload involved.

@Try2B_Comprehensive

I think that is really an impractical degree of infrastructure development. OTOH, it would not be outlandish to roll out semi charging stations along the most popular routes, and expand the network as the things catch on.

The problem is a chicken and egg thing. It’ll need a lot of subsidy to get going while fleets that have trucks that can last 25 years get slowly phased out over time.

@Try2B_Comprehensive

I always said it should be a hybrid

Except your last few paragraphs were about EVs.

[Sam_Stone]

Try2B Comprehensive: Your numbers are still off. First of all, a gallon of diesel has 11% more energy than a gallon of gas. Second, a diesel engine has higher thermal efficiency than a gas engine - googling around seems to indicate that big diesel truck engines are around 42% efficient, and there are initiatives to raise that over 50%, such as going to turbodiesels. The DOE is setting 50-55% brake thermal efficiency targets for 2016.

Second, that heat energy is not all lost. Some of it goes to heating the vehicle.

So a gallon of diesel has 37.95 kwh of energy. If the truck engine is 42% efficient and the truck requires 200 gallons to go 1000 miles, It’s using 3187 kwh of energy, or roughly 16 kwh per mile.

Our Tesla battery weighs 550 kg and contains 90 kwh of energy. But not all that energy is usable - to keep a lithium ion battery healthy and to operate it safely, you can’t let the voltage go higher or lower than its nominal operating range. In practice I believe only about 80% of the total charge is usable. So, that’s now 72kwh. And since we’re adding engine efficiency into the mix, we have to multiple by the efficiency of the electric motor - call it 90%. So, we get 65 kwh of usable power for 550kg, or about 8.5kg/kwh. We’re back up to 27,000 kg of battery for our trip.

And this is the best we can hope for. Once you get into the real world, all these numbers get worse. For example, the battery will self-discharge at a rate of about 8% per month at 20 degrees C. That might not cost a lot in range per trip, but it adds 8% per month to your energy cost. In addition, the battery may need to be heated and cooled to maintain optimum performance. At 60C, a li-ion battery discharges at a rate of 31% per month. In cold weather its performance degrades and it can’t hold a charge as long - you can lose as much as 50% of the battery’s charge capacity in cold weather - or you can heat it. But that also takes energy.

Better take into account the cooling requirements or greatly increase the volume requirements for your battery, too. You can’t just stack tesla batteries together, because the cube-square problem gets you. Even the Tesla battery requires liquid cooling to keep it from overheating. So you’re going to need a system like that, and a big-ass radiator, which then cuts into your aerodynamics.

I hope this doesn’t sound pedantic, but this stuff always sounds so simple and logical on paper, while an engineer will tell you that the devil lurks in a thousand different details. All of the details tend to work against EV power, which is why it’s so hard to do even in a tiny, highly aerodynamic passenger vehicle.

As for cost savings - 200 gallons of diesel costs you maybe $700. If you can get your electric power for 4c per kwh (which would be at the absolute low end of the scale), that would be $127. But wait - your charger is only about 70% efficient. So that’s $182. Now add in 8-10% for self-discharge losses, And you’re at about $200. We also have to calculate the energy cost of hauling the weight of the batteries and the aerodynamic loss for the radiator needed to cool them, the number of extra trips required to haul a similar amount of cargo because of space reduction, etc. The electricity cost will probably still come in lower than the cost of diesel, but the electricity for damned sure isn’t free.

One way to look at it is if 30% of our cargo capacity is taken up by batteries, the cost per kg of freight hauled also goes up by 30%. So now our $200 energy cost is suddenly $260 - but everything else also goes up by 30% - maintenance, driver wages, road taxes, capital costs for a fleet that can haul the same capacity, etc. And we haven’t even started to talk about the additional cost of all the batteries and gear required to move to electric.

Then there’s cycle durability - I think we the best we can do for li-ion right now is about 1200 full charge cycles before they need to be replaced. And charge capacity starts to drop once the battery is in use, so a mid-life battery isn’t going to have anywhere near the range of a new one. So you need to factor that into your calculations as well. And if you’re parking your big truck outside in a cold area, be prepared to heat your battery continuously, as cold temperatures can really lower their lifespan. So can heat, so if you’re running in a hot area be prepared to keep your battery cool when not in use.

All of this increases effort and maintenance costs on top of the energy costs. Then there are entire questions about the use of these batteries in heavy-duty industrial operations instead of the comparatively light-duty use in a passenger car.

Engineering is all about the details. Things that can look reasonable or feasible in a simple back-of-the-envelope calculation which we’re all doing here can become total non-feasible once real-world constraints are applied and all the little gotchas are taken care of. Vibration will be an issue. Safety is a big issue. 27,000 kg of batteries catching file is a pretty dangerous event.

I did some searching today about new truck technologies for energy efficiency, and I can’t find anyone talking about all-electric tractor-trailer units. Hybrid, yes. Battery-assist, yes. New engine technologies? Yes. But all electric is a non-starter.

[Try2B_Comprehensive]

With this attitude, you guys would never have been hired for the F-35 development team. Sheesh! But I’ll have to get back to the details later tonight.

[BrainGlutton]

The IPCC’s new report is out.

YOKOHAMA, Japan — Climate change is already having sweeping effects on every continent and throughout the world’s oceans, scientists reported on Monday, and they warned that the problem was likely to grow substantially worse unless greenhouse emissions are brought under control.

The report by the Intergovernmental Panel on Climate Change, a United Nations group that periodically summarizes climate science, concluded that ice caps are melting, sea ice in the Arctic is collapsing, water supplies are coming under stress, heat waves and heavy rains are intensifying, coral reefs are dying, and fish and many other creatures are migrating toward the poles or in some cases going extinct.

The oceans are rising at a pace that threatens coastal communities and are becoming more acidic as they absorb some of the carbon dioxide given off by cars and power plants, which is killing some creatures or stunting their growth, the report found.

Organic matter frozen in Arctic soils since before civilization began is now melting, allowing it to decay into greenhouse gases that will cause further warming, the scientists said. And the worst is yet to come, the scientists said in the second of three reports that are expected to carry considerable weight next year as nations try to agree on a new global climate treaty

[Chief_Pedant]

@BrainGlutton

The IPCC’s new report is out.

They have kind of an interesting dilemma. By accelerating the anxiety of the tone around how proximate the consequences are (the actual “catastrophes” are still very much couched in WAGgish language) without any substantive realistic way to stop the energy curve here, one wonders if the net reaction will be to just decide it’s too late, and get yours while you can.

Which it is too late, but I’ve made that point upthread.

Also–and it’s more of a marketing point–they need to swap out Pachauri. He looks like he has an axe to grind, not to mention looking a little creepy.

[wolfpup]

@Chief_Pedant

They have kind of an interesting dilemma. By accelerating the anxiety of the tone around how proximate the consequences are (the actual “catastrophes” are still very much couched in WAGgish language) without any substantive realistic way to stop the energy curve here, one wonders if the net reaction will be to just decide it’s too late, and get yours while you can.

Which it is too late, but I’ve made that point upthread.

Also–and it’s more of a marketing point–they need to swap out Pachauri. He looks like he has an axe to grind, not to mention looking a little creepy.

As I mentioned upthread (or it may have been in some other thread) the WG2 report on impacts, adaptation, and vulnerability was due out at the end of March. I’m sorry that you don’t find it persuasive, though it does lead me to speculate that there is no possible finding that you would acknowledge to be sufficiently persuasive.

But you’re in good company. Between all the Republicans in Congress and the amazing states of Virginia and North Carolina – both of which have enacted lunatic legislation on things like, in one case, the methodology of how sea level rise must be projected even if it makes no scientific sense, and in the other, prohibiting the use of the term altogether in official documents (along with “climate change” – because those are all “liberal code words”) – it appears that denial is now official law. So when Virginia legislators are someday literally underwater and breathing with scuba gear, they can still claim that it’s nothing to do with climate change: it’s not sea level rise, it’s just a case of “recurrent flooding” (the officially sanctioned term), and it’s not a powerful storm surge due to climate change (because there’s no such thing), it’s just a fluke storm, that’s all. If I were living on some other planet it might be amusing to see how long this game can continue, but since I inhabit this one, I find it pretty damned depressing.

[Sam_Stone]

@Chief_Pedant

They have kind of an interesting dilemma. By accelerating the anxiety of the tone around how proximate the consequences are (the actual “catastrophes” are still very much couched in WAGgish language) without any substantive realistic way to stop the energy curve here, one wonders if the net reaction will be to just decide it’s too late, and get yours while you can.

Which it is too late, but I’ve made that point upthread.

Also–and it’s more of a marketing point–they need to swap out Pachauri. He looks like he has an axe to grind, not to mention looking a little creepy.

The report that’s out is the report from Working Group II, which focuses on risks, costs, and mitigation. The full AR5 report has not yet been released. The ‘final draft’ that’s currently available is the ‘summary for policymakers’, which has to be read with care as in the past it has been known to deviate from what the actual science says in the full technical report.

[BrainGlutton]

@Chief_Pedant

They have kind of an interesting dilemma. By accelerating the anxiety of the tone around how proximate the consequences are (the actual “catastrophes” are still very much couched in WAGgish language) without any substantive realistic way to stop the energy curve here, one wonders if the net reaction will be to just decide it’s too late, and get yours while you can.

Which it is too late, but I’ve made that point upthread.

Maybe.

[Try2B_Comprehensive]

@Farin

I would need to see some testing to back up that that’s all of the power going to the road and what the curve on that is. Idle vs red line are very different beasts.

I only have time to address one point! But it is a good one. An electric motor delivers 100% torque all the way down to zero rpm. Cite. [Scroll down a quarter page to ‘electric motors are all torque’] I don’t vouch for everything on the page necessarily, but at least click on this graph.

The orange plot represents an electric motor torque curve and the blue plot represents an electric motor power curve. By comparison, the black plot shows a high performance internal combustion engine torque curve. From this you can see the full torque from zero of the electric motor as well as the linear power delivery. It’s also interesting to note that most decent petrol engines are spent by about 8000rpm whereas a half-decent EV motor can go up to 15000rpm or so.

Here’s a more subjective description (bolding mine):

There is a pronounced difference in the driving experience when you step into an EV for the first time. There is typically no gearbox or transmission. Electric motors differ greatly from internal combustion engines in the way they deliver power and torque, and for the most part, you have full torque from the instant you mash the accelerator pedal until the motor overheats. It’s like an instant “go” pedal - there’s no hanging about waiting for the engine to get up to speed, no changing gears, nothing. Unless you’ve driven an EV it’s very difficult to explain what it feels like, but the best way is this: imagine your car in first gear with your foot flat to the floor. Now imagine that acceleration all the way up to the top speed of the car without any interruption.

[wolfpup]

@Sam_Stone

The report that’s out is the report from Working Group II, which focuses on risks, costs, and mitigation. The full AR5 report has not yet been released. The ‘final draft’ that’s currently available is the ‘summary for policymakers’, which has to be read with care as in the past it has been known to deviate from what the actual science says in the full technical report.

A few point of clarification as there are a number of confusing errors in that statement.

1. The WG2 report deals with “Impacts, Adaptation, and Vulnerability”, not with mitigation, nor with costs thereof. Mitigation options are exclusively the focus of WG3, a different working group that should be releasing its report later this month.

2. The WG2 Summary for Policymakers as released is the fully approved text, not a “final draft”, but still requires copyediting and final formatting (for instance putting all the figures and tables into their correct places). But every word of the narrative has been vetted and cleared for publication.

3. Any differences between the “final draft” of a full report and the Summary for Policymakers (SPM) are generally very minor and technical and simply reflect the fact that the SPM is more recent, whereas the full report is a work that has been in progress for many years. So the suggestion that the SPM should be “read with care” is rather misguided for no less than two different reasons: it is typically the full report that requires small revisions to conform with the SPM and not the other way around, and secondly the revisions are of no consequence to the average reader. That said, in the case of the AR5 WG1 SPM, a couple of errata were noted and recently corrected. These were things like, for instance, one bullet point discussing certain categories of CO2 emissions and giving the amounts as 365 and 545 GtC, which were corrected in an erratum to 375 and 555 GtC (probably due to a typo in the source material). These are not the kinds of changes that make any difference to the typical reader and to suggest that such documents, which have been vetted line by line prior to publication, should be treated as some kind of casual drafts is just ridiculous.

4. In terms of what is currently released and what isn’t: the published SPM and the published full report on the Physical Science Basis (Working Group 1) of the IPCC Fifth Assessment are available now at the IPCC website. The approved SPM with pending copyedits and the final draft of WG2 on Impacts, Adaptation and Vulnerability are available here. The mitigation report from WG3 should be available later in April.

[Try2B_Comprehensive]

@Sam_Stone

Try2B Comprehensive: Your numbers are still off. First of all, a gallon of diesel has 11% more energy than a gallon of gas. Second, a diesel engine has higher thermal efficiency than a gas engine - googling around seems to indicate that big diesel truck engines are around 42% efficient, and there are initiatives to raise that over 50%, such as going to turbodiesels. The DOE is setting 50-55% brake thermal efficiency targets for 2016.

Looks like you are correct. I did not know diesel engines were this much more efficient than gasoline engines.

So a gallon of diesel has 37.95 kwh of energy. If the truck engine is 42% efficient and the truck requires 200 gallons to go 1000 miles, It’s using 3187 kwh of energy, or roughly 16 kwh per mile.

Our Tesla battery weighs 550 kg and contains 90 kwh of energy. But not all that energy is usable - to keep a lithium ion battery healthy and to operate it safely, you can’t let the voltage go higher or lower than its nominal operating range. In practice I believe only about 80% of the total charge is usable. So, that’s now 72kwh. And since we’re adding engine efficiency into the mix, we have to multiple by the efficiency of the electric motor - call it 90%. So, we get 65 kwh of usable power for 550kg, or about 8.5kg/kwh. We’re back up to 27,000 kg of battery for our trip.

And this is the best we can hope for.

It doesn’t look good in 2014 for a long-haul semi to get a 1000 mile electric range. The batteries are just too heavy. Let me ask you and Fairn: What do you consider to be the maximum weight and cargo displacement for a battery? We have to design our hybrid semi around what is practical.

From there, it looks like our best bet will be on improving battery technology. Skipping ahead, you say:

All of the details tend to work against EV power, which is why it’s so hard to do even in a tiny, highly aerodynamic passenger vehicle.

We have to also acknowledge that all the data work against sticking with the status quo as well. We can’t keep burning diesel like this because 1. carbon emissions and 2. diesel isn’t getting cheaper or more plentiful.

I can refer you to New battery management technology could boost Li-ion capacity by 40%, quadruple recharging cycles. IF it can deliver, that would be very helpful.

We can look ahead to the next generation of battery chemistry, here:

Researchers at the US Department of Energy’s Lawrence Berkeley National Laboratory have demonstrated in the laboratory a lithium-sulfur (Li/S) battery that has more than twice the specific energy of lithium-ion batteries, and that lasts for more than 1,500 cycles of charge-discharge with minimal decay of the battery’s capacity.

I follow this story- it does look like the lithium sulfur battery will be feasible as well as a big improvement over current technology. Let’s plug those numbers into our maximum-battery model and see how we’re doing.

I’m not so worried about passive discharge, dealing with vibration or the need for heating/cooling. Yes, those will eat into profits and yes, my initial projections were too optimistic, but your argument also gets unrealistic when you get to this:

The electricity cost will probably still come in lower than the cost of diesel, but the electricity for damned sure isn’t free.

Even a few % change in margin can make the competitive difference. If the hybrid electric semi turns out to be cheaper at all to run, it will be a success. I think it will be, and I think it can only improve. And again, we can’t ignore freight if we are going to get emissions under control.

As problematic as this question is, I don’t think a list of criticisms actually concludes that the whole project is unworkable. We pretty much have to chase this down- being talked out of it is a dead end. Running shorter routes is an option- if a 300 mile range can be achieved, rapid recharges would allow for mostly electric transport across a majority of routes. The question is ‘what can be done?’ Dramatically improving the efficiency of semis with electric motors can be done now, and with advances that are already visible on the horizon, the goal of a full-ev semi may be achievable. We may have to change the way we manage freight to revolve around what is possible with ev semis.