Tesla just changed everything

Its just the fear factor of running out of fuel during a drive isn't it?

Tesla’s biggest competitor in my eyes is Hydrogen.

Hydrogen is lot more complex of a system and really really unsafe. Not discounting it entirely but it has a lot of flaws and 0 runs on the board. Tesla has very few and several, respectively.

Although seemingly harsh I think you are too generous towards hydrogen. There is currently no way of storing it at high enough mass and energy densities for practical use, and it doesn’t show much promise for the vast improvement needed any time soon. You need to be able to squash it into a small enough volume without wasting too much energy in doing so, a problem which has eluded scientists for decades.

To add to this, from what I’ve read, even if the technology got to the point of generating Hydrogen on board a vehicle. The incentives for a large company to do this would be next to nil. The worry is corporations would stifle on board manufacturing and turn Hydrogen into the new petroleum industry, building Hydrogen stations where people would fill up at a price fixed by the companies. Just like the oil and gas industry is now. The dream of filling your car up with water to be converted into clean energy unfortunately won’t happen. Unless there is another Elon Musk out there that could solve the Hydrogen problem.

I’ve seen the old footage of the “water powered car” from the 70’s, hoping it was a giant conspiracy to withhold the technology. It’s more likely that is was a fraud.

It’s the whole ‘why can’t we have both’ issue.

You don’t need to have one dominant option, just like now there is unleaded, diesel and LPG.

Its just the fear factor of running out of fuel during a drive isn't it?

Tesla’s biggest competitor in my eyes is Hydrogen.

Hydrogen is lot more complex of a system and really really unsafe. Not discounting it entirely but it has a lot of flaws and 0 runs on the board. Tesla has very few and several, respectively.

Although seemingly harsh I think you are too generous towards hydrogen. There is currently no way of storing it at high enough mass and energy densities for practical use, and it doesn’t show much promise for the vast improvement needed any time soon. You need to be able to squash it into a small enough volume without wasting too much energy in doing so, a problem which has eluded scientists for decades.

To add to this, from what I’ve read, even if the technology got to the point of generating Hydrogen on board a vehicle. The incentives for a large company to do this would be next to nil. The worry is corporations would stifle on board manufacturing and turn Hydrogen into the new petroleum industry, building Hydrogen stations where people would fill up at a price fixed by the companies. Just like the oil and gas industry is now. The dream of filling your car up with water to be converted into clean energy unfortunately won’t happen. Unless there is another Elon Musk out there that could solve the Hydrogen problem.

I’ve seen the old footage of the “water powered car” from the 70’s, hoping it was a giant conspiracy to withhold the technology. It’s more likely that is was a fraud.

Both Honda (FCX Clarity)and Toyota (Mirai) currently produce Hydrogen powered cars but they haven’t had the coverage that Tesla gets. The issue is availability of Hydrogen refilling stations but the tech is there.

Also this guy isn’t yet a believer, not sure of his credentials or how accurate his data is (and I’m too lazy to look him up) but its probably an opinion held by a few.

afr.com/news/policy/climate/tesla-3-yet-to-exist-and-wont-save-the-world-20160407-go0ozj

Tesla 3 yet to exist and won't save the world

by Bjorn Lomborg
As Elon Musk presented the Tesla 3, a fawning press announced the “world-changing car” could “dominate” the market.

Within days, 276,000 people had put down $US1000 ($1300) to pre-order the car.

However, the Model 3 doesn’t exist yet. There is no final production version, much less any production.

Musk is “fairly confident” deliveries may start by the end of 2017.

The Tesla 3 is still far from production.
The Tesla 3 is still far from production. Supplied
However, running on schedule isn’t Tesla’s strong suit.

Meanwhile, Tesla’s current best-seller has been plagued by quality problems.

All of this may just be another iPhone v Galaxy conversation; except that these vehicles are hailed as green saviours and so are subsidised to the tune of billions of dollars.

Before unveiling the car, Musk sanctimoniously declared Tesla existed to give the planet a sustainable future.

He pointed to rising CO₂ levels. He lamented that 53,000 people died from air pollution from transportation.

Tesla, the story goes, is a lifesaver. Like other electric cars, it has “zero emissions” of air pollution and CO₂.

However, this is only true of the car itself; the electricity powering it is often produced with coal, which means the clean car is responsible for heavy air pollution.

As green venture capitalist Vinod Khosla likes to point out, “electric cars are coal-powered cars”.

If the US had 10 per cent more petrol cars by 2020, air pollution would claim 870 more lives. A similar increase in electric ones would cause 1617 more deaths a year, mostly because of the coal burnt.

If this was scaled to Britain, electric cars would cause the same or more air pollution-related deaths than petrol-powered cars.

In China, because its coal power plants are so dirty, electric cars make local air much worse.

In Shanghai, pollution from more electric-powered cars would be nearly three times as deadly as more petrol-powered ones.

Moreover, while electric cars typically emit less CO₂, the savings are smaller than most imagine. Over a 150,000-kilometre lifetime, the top-line Tesla S will emit about 13 tonnes of CO₂. However, the production of its batteries alone will emit 14 tonnes, along with seven more from the rest of its production and eventual decommissioning.

Compare this with the diesel-powered, but similarly performing, Audi A7 Sportback, which uses about seven litres per 100 kilometres, so about 10,500 litres over its lifetime. This makes 26 tonnes of CO₂. The Audi will also emit slightly more than seven tonnes in production and end-of-life.

In total, the Tesla will emit 34 tonnes and the Audi 35. So over a decade, the Tesla will save the world 1.2 tonnes of CO₂.

Reducing 1.2 tonnes of CO₂ on the European Union emissions trading system costs £5 ($9.40); but, instead, the British Government subsidises each car with £4500.

All of the world’s electric cars sold so far have soaked up £9 billion in subsidies, yet will only save 3.3 million tonnes of CO₂. This will reduce world temperatures by 0.00001 degrees in 2100; the equivalent of postponing global warming by about 30 minutes at the end of the century.

Electric cars will be a good idea, once they can compete, which will probably be by 2032. However, it is daft to waste billions of dollars of public money on rich people’s playthings that kill more people through air pollution while barely affecting carbon emissions.

The Tesla 3 is indeed a “zero emissions” marvel, but that is only because it does not yet exist.

Bjorn Lomborg is a Danish author and environmentalist and director of a non-profit think tank, the Copenhagen Consensus Centre.

Telegraph, London

The Telegraph, London

Lomborg is a discredited contrarian. The whole “zero emissions” thing has already been discussed above. Charging stations are being built. The argument that everyone is going to burn coal to charge their cars is fantastic, today but the presumption that the article makes, that this will always be the case is just the same old tricks that Lomborg uses to distort things. The whole argument is redundant after the fluffy bits about Tesla running behind on releases.

or the holier than thou attitude of the tesla zealots.

I make no apologies for being a huge Tesla fan. Was there anything innately wrong with my post?

having a shot at howmanygoal?

Huh?

Set the Controls to the Heart of the Sun, baby.

Flloyd rules!!!

If we go by the example in the article it assumes we continue to burn coal forever, assumes solar panels won’t improve in efficiency, assuming all power sources don’t come clean (even coal!).

How about in places like France where it’s nuclear powered? Even the USA is 20% nuclear? How about Japan with their nuclear and gas?

Only saves one tonne. As opposed to using one more tonne.

It’s nit picking at it’s best.

I get the feeling that you could make a car that would run off CO2 and clean the air and there’d still be people complaining.

It’s not THE answer, but it’s a step in the right direction.

1 Like

Also this guy isn’t yet a believer, not sure of his credentials or how accurate his data is (and I’m too lazy to look him up) but its probably an opinion held by a few.

afr.com/news/policy/climate/tesla-3-yet-to-exist-and-wont-save-the-world-20160407-go0ozj

Tesla 3 yet to exist and won't save the world

by Bjorn Lomborg

I’d likely trust Christopher Skase with financial advice before I would listen to this bloke. A well known climate sceptic and right-wing crack pot.

You see, climate sceptics don’t come out and say “there is no such thing as climate change” anymore. What they do is soft target people. They say things like, “You know, solar technology is great…in theory, unfortunately the tech isn’t there”. Which is generally weasel words to sway people opinion without causing a stir, especially when its fact-less bullsh!t… It’s like when the liberal ministers says things like, “We needs to have a mature discussion about…fill in blank”. It’s simply weasel words to sway public opinion without telling them directly what to think. Lomberg is an expert of it.

Its just the fear factor of running out of fuel during a drive isn't it?

Tesla’s biggest competitor in my eyes is Hydrogen.

Hydrogen is lot more complex of a system and really really unsafe. Not discounting it entirely but it has a lot of flaws and 0 runs on the board. Tesla has very few and several, respectively.

Although seemingly harsh I think you are too generous towards hydrogen. There is currently no way of storing it at high enough mass and energy densities for practical use, and it doesn’t show much promise for the vast improvement needed any time soon. You need to be able to squash it into a small enough volume without wasting too much energy in doing so, a problem which has eluded scientists for decades.

To add to this, from what I’ve read, even if the technology got to the point of generating Hydrogen on board a vehicle. The incentives for a large company to do this would be next to nil. The worry is corporations would stifle on board manufacturing and turn Hydrogen into the new petroleum industry, building Hydrogen stations where people would fill up at a price fixed by the companies. Just like the oil and gas industry is now. The dream of filling your car up with water to be converted into clean energy unfortunately won’t happen. Unless there is another Elon Musk out there that could solve the Hydrogen problem.

I’ve seen the old footage of the “water powered car” from the 70’s, hoping it was a giant conspiracy to withhold the technology. It’s more likely that is was a fraud.

Both Honda (FCX Clarity)and Toyota (Mirai) currently produce Hydrogen powered cars but they haven’t had the coverage that Tesla gets. The issue is availability of Hydrogen refilling stations but the tech is there.

Also this guy isn’t yet a believer, not sure of his credentials or how accurate his data is (and I’m too lazy to look him up) but its probably an opinion held by a few.

afr.com/news/policy/climate/tesla-3-yet-to-exist-and-wont-save-the-world-20160407-go0ozj

Tesla 3 yet to exist and won't save the world

by Bjorn Lomborg
As Elon Musk presented the Tesla 3, a fawning press announced the “world-changing car” could “dominate” the market.

Within days, 276,000 people had put down $US1000 ($1300) to pre-order the car.

However, the Model 3 doesn’t exist yet. There is no final production version, much less any production.

Musk is “fairly confident” deliveries may start by the end of 2017.

The Tesla 3 is still far from production.
The Tesla 3 is still far from production. Supplied
However, running on schedule isn’t Tesla’s strong suit.

Meanwhile, Tesla’s current best-seller has been plagued by quality problems.

All of this may just be another iPhone v Galaxy conversation; except that these vehicles are hailed as green saviours and so are subsidised to the tune of billions of dollars.

Before unveiling the car, Musk sanctimoniously declared Tesla existed to give the planet a sustainable future.

He pointed to rising CO₂ levels. He lamented that 53,000 people died from air pollution from transportation.

Tesla, the story goes, is a lifesaver. Like other electric cars, it has “zero emissions” of air pollution and CO₂.

However, this is only true of the car itself; the electricity powering it is often produced with coal, which means the clean car is responsible for heavy air pollution.

As green venture capitalist Vinod Khosla likes to point out, “electric cars are coal-powered cars”.

If the US had 10 per cent more petrol cars by 2020, air pollution would claim 870 more lives. A similar increase in electric ones would cause 1617 more deaths a year, mostly because of the coal burnt.

If this was scaled to Britain, electric cars would cause the same or more air pollution-related deaths than petrol-powered cars.

In China, because its coal power plants are so dirty, electric cars make local air much worse.

In Shanghai, pollution from more electric-powered cars would be nearly three times as deadly as more petrol-powered ones.

Moreover, while electric cars typically emit less CO₂, the savings are smaller than most imagine. Over a 150,000-kilometre lifetime, the top-line Tesla S will emit about 13 tonnes of CO₂. However, the production of its batteries alone will emit 14 tonnes, along with seven more from the rest of its production and eventual decommissioning.

Compare this with the diesel-powered, but similarly performing, Audi A7 Sportback, which uses about seven litres per 100 kilometres, so about 10,500 litres over its lifetime. This makes 26 tonnes of CO₂. The Audi will also emit slightly more than seven tonnes in production and end-of-life.

In total, the Tesla will emit 34 tonnes and the Audi 35. So over a decade, the Tesla will save the world 1.2 tonnes of CO₂.

Reducing 1.2 tonnes of CO₂ on the European Union emissions trading system costs £5 ($9.40); but, instead, the British Government subsidises each car with £4500.

All of the world’s electric cars sold so far have soaked up £9 billion in subsidies, yet will only save 3.3 million tonnes of CO₂. This will reduce world temperatures by 0.00001 degrees in 2100; the equivalent of postponing global warming by about 30 minutes at the end of the century.

Electric cars will be a good idea, once they can compete, which will probably be by 2032. However, it is daft to waste billions of dollars of public money on rich people’s playthings that kill more people through air pollution while barely affecting carbon emissions.

The Tesla 3 is indeed a “zero emissions” marvel, but that is only because it does not yet exist.

Bjorn Lomborg is a Danish author and environmentalist and director of a non-profit think tank, the Copenhagen Consensus Centre.

Telegraph, London

The Telegraph, London

Lomborg is a renound fookwhit and one of the three people on my who I would whack if I was a mobster vigilante list.

Thing is, if Hydrogen is such a difficult and dangerous fuel, how come both Toyota and Honda are using it in current (albeit limited edition) models? It’s already out there. Says to me the technical difficulties had been overcome. Now it’s just a matter of infrastructure.

He’s worse than that. He’s a political scientist who’s career is macro scale investment rationalisation. When you’re making calls like “freer global trade returns a benefit of $2011 for every dollar spent, making it 45 times more worthwhile than reducing child malnutrition” then there’s no wonder the likes of Abbott, Bishop and Pyne were wetting themselves over him and trying to sneak his political think tank into an Australian university, any university, last year. Funnily enough they had 3 goes and as soon as the majority of the admin, staff and student body found out they chased them out of town.

This guy is nothing more than the darling of the new right agenda to delay, obfuscate and confuse people over climate change.

Thing is, if Hydrogen is such a difficult and dangerous fuel, how come both Toyota and Honda are using it in current (albeit limited edition) models? It's already out there. Says to me the technical difficulties had been overcome. Now it's just a matter of infrastructure.

And competition with batteries. Whatever is cheaper and more convenient will quickly win the race.

Its just the fear factor of running out of fuel during a drive isn't it?

Tesla’s biggest competitor in my eyes is Hydrogen.

Hydrogen is lot more complex of a system and really really unsafe. Not discounting it entirely but it has a lot of flaws and 0 runs on the board. Tesla has very few and several, respectively.

Although seemingly harsh I think you are too generous towards hydrogen. There is currently no way of storing it at high enough mass and energy densities for practical use, and it doesn’t show much promise for the vast improvement needed any time soon. You need to be able to squash it into a small enough volume without wasting too much energy in doing so, a problem which has eluded scientists for decades.

To add to this, from what I’ve read, even if the technology got to the point of generating Hydrogen on board a vehicle. The incentives for a large company to do this would be next to nil. The worry is corporations would stifle on board manufacturing and turn Hydrogen into the new petroleum industry, building Hydrogen stations where people would fill up at a price fixed by the companies. Just like the oil and gas industry is now. The dream of filling your car up with water to be converted into clean energy unfortunately won’t happen. Unless there is another Elon Musk out there that could solve the Hydrogen problem.

I’ve seen the old footage of the “water powered car” from the 70’s, hoping it was a giant conspiracy to withhold the technology. It’s more likely that is was a fraud.

Both Honda (FCX Clarity)and Toyota (Mirai) currently produce Hydrogen powered cars but they haven’t had the coverage that Tesla gets. The issue is availability of Hydrogen refilling stations but the tech is there.

Also this guy isn’t yet a believer, not sure of his credentials or how accurate his data is (and I’m too lazy to look him up) but its probably an opinion held by a few.

afr.com/news/policy/climate/tesla-3-yet-to-exist-and-wont-save-the-world-20160407-go0ozj

Tesla 3 yet to exist and won't save the world

by Bjorn Lomborg
As Elon Musk presented the Tesla 3, a fawning press announced the “world-changing car” could “dominate” the market.

Within days, 276,000 people had put down $US1000 ($1300) to pre-order the car.

However, the Model 3 doesn’t exist yet. There is no final production version, much less any production.

Musk is “fairly confident” deliveries may start by the end of 2017.

The Tesla 3 is still far from production.
The Tesla 3 is still far from production. Supplied
However, running on schedule isn’t Tesla’s strong suit.

Meanwhile, Tesla’s current best-seller has been plagued by quality problems.

All of this may just be another iPhone v Galaxy conversation; except that these vehicles are hailed as green saviours and so are subsidised to the tune of billions of dollars.

Before unveiling the car, Musk sanctimoniously declared Tesla existed to give the planet a sustainable future.

He pointed to rising CO₂ levels. He lamented that 53,000 people died from air pollution from transportation.

Tesla, the story goes, is a lifesaver. Like other electric cars, it has “zero emissions” of air pollution and CO₂.

However, this is only true of the car itself; the electricity powering it is often produced with coal, which means the clean car is responsible for heavy air pollution.

As green venture capitalist Vinod Khosla likes to point out, “electric cars are coal-powered cars”.

If the US had 10 per cent more petrol cars by 2020, air pollution would claim 870 more lives. A similar increase in electric ones would cause 1617 more deaths a year, mostly because of the coal burnt.

If this was scaled to Britain, electric cars would cause the same or more air pollution-related deaths than petrol-powered cars.

In China, because its coal power plants are so dirty, electric cars make local air much worse.

In Shanghai, pollution from more electric-powered cars would be nearly three times as deadly as more petrol-powered ones.

Moreover, while electric cars typically emit less CO₂, the savings are smaller than most imagine. Over a 150,000-kilometre lifetime, the top-line Tesla S will emit about 13 tonnes of CO₂. However, the production of its batteries alone will emit 14 tonnes, along with seven more from the rest of its production and eventual decommissioning.

Compare this with the diesel-powered, but similarly performing, Audi A7 Sportback, which uses about seven litres per 100 kilometres, so about 10,500 litres over its lifetime. This makes 26 tonnes of CO₂. The Audi will also emit slightly more than seven tonnes in production and end-of-life.

In total, the Tesla will emit 34 tonnes and the Audi 35. So over a decade, the Tesla will save the world 1.2 tonnes of CO₂.

Reducing 1.2 tonnes of CO₂ on the European Union emissions trading system costs £5 ($9.40); but, instead, the British Government subsidises each car with £4500.

All of the world’s electric cars sold so far have soaked up £9 billion in subsidies, yet will only save 3.3 million tonnes of CO₂. This will reduce world temperatures by 0.00001 degrees in 2100; the equivalent of postponing global warming by about 30 minutes at the end of the century.

Electric cars will be a good idea, once they can compete, which will probably be by 2032. However, it is daft to waste billions of dollars of public money on rich people’s playthings that kill more people through air pollution while barely affecting carbon emissions.

The Tesla 3 is indeed a “zero emissions” marvel, but that is only because it does not yet exist.

Bjorn Lomborg is a Danish author and environmentalist and director of a non-profit think tank, the Copenhagen Consensus Centre.

Telegraph, London

The Telegraph, London

Lomborg is a renound fookwhit and one of the three people on my who I would whack if I was a mobster vigilante list.

Please tell me “I call my self a Lord, but no one in the political houses recognises me” Monkington is another one on your list.

If we go by the example in the article it assumes we continue to burn coal forever, assumes solar panels won't improve in efficiency, assuming all power sources don't come clean (even coal!).

How about in places like France where it’s nuclear powered? Even the USA is 20% nuclear? How about Japan with their nuclear and gas?

Only saves one tonne. As opposed to using one more tonne.

It’s nit picking at it’s best.

I get the feeling that you could make a car that would run off CO2 and clean the air and there’d still be people complaining.

It’s not THE answer, but it’s a step in the right direction.

I would not make that call so quickly. If the model 3 is as advertised as far as price and range go there is a very strong chance it ends up the In the FTI garage when the lease runs out on my wife’s current car. Now that’s probably got about 2 and bit years to run, more than enough time for the thing to actually launch. Now it’s proposed to cost around 45k Australian by the time it’s launched here.

My wife’s car she leases is a Ford Kuga 1.5lt ecoboost, great on fuel, gets around 7.5ltrs per hundred town and around 5 on the highway. It’s leased so it’s on a fuel car but when we negotiated the last lease we estimated That she spends 5k in fuel per year, so over the 3 years on the lease she has spent around 15k, take into account the car cost around 35 to buy when she got it and it’s 5k less than her Kuga.

I know what you guys are saying about charging at home and the increased cost of my power bill, she works at University of Queensland, and they have charging stations on campus put in by Nissan a few years back.

So when you start to look at the 3 as a car that can do the work/school run, that is cheaper to run that a mid spec ford. It starts to look a hell of a lot more like an answer than a step.

If EVs are in the conversation is a more cost effective alternative transport than petrol cars then that’s the turning point. No other way to look at it.

Now it’s proposed to cost around 45k Australian by the time it’s launched here.

I keep reading around the traps that it’ll be $60k+ when it hits our shores. Personally I believe it’ll be closer to what you think ben. Tesla don’t operate like other car companies, more like apple computers. I think there would be a huge backlash if they sold their car 15 grand more after currency conversion and the last thing they want is negative publicity when they are trying to convert the sceptics. I’d think it’s be what the currency conversion is plus a couple of grand to be safe.

I think when car writers quote $60k, they are assuming the typical import model they’ve been used to for decades and looking into the way the company operates or even sells the car. There is no “dealership”, no traditional showroom. You order online and pick the car up from a central small showroom when its ready. No traditional salesmen, no trade-ins, no haggling for free car mats. It’s like ordering a burger.

mmmm burger

Set the Controls to the Heart of the Sun, baby.

Flloyd rules!!!

Certainlly do, man, certainlly do.

If we go by the example in the article it assumes we continue to burn coal forever, assumes solar panels won't improve in efficiency, assuming all power sources don't come clean (even coal!).

How about in places like France where it’s nuclear powered? Even the USA is 20% nuclear? How about Japan with their nuclear and gas?

Only saves one tonne. As opposed to using one more tonne.

It’s nit picking at it’s best.

I get the feeling that you could make a car that would run off CO2 and clean the air and there’d still be people complaining.

It’s not THE answer, but it’s a step in the right direction.

I would not make that call so quickly. If the model 3 is as advertised as far as price and range go there is a very strong chance it ends up the In the FTI garage when the lease runs out on my wife’s current car. Now that’s probably got about 2 and bit years to run, more than enough time for the thing to actually launch. Now it’s proposed to cost around 45k Australian by the time it’s launched here.

My wife’s car she leases is a Ford Kuga 1.5lt ecoboost, great on fuel, gets around 7.5ltrs per hundred town and around 5 on the highway. It’s leased so it’s on a fuel car but when we negotiated the last lease we estimated That she spends 5k in fuel per year, so over the 3 years on the lease she has spent around 15k, take into account the car cost around 35 to buy when she got it and it’s 5k less than her Kuga.

I know what you guys are saying about charging at home and the increased cost of my power bill, she works at University of Queensland, and they have charging stations on campus put in by Nissan a few years back.

So when you start to look at the 3 as a car that can do the work/school run, that is cheaper to run that a mid spec ford. It starts to look a hell of a lot more like an answer than a step.

If EVs are in the conversation is a more cost effective alternative transport than petrol cars then that’s the turning point. No other way to look at it.

I still think it’s a step till the car is actually delivered.

I’d rather just wait and see rather than proclaim it early.

If you’d put it in a Mini then my missus would buy it anyway.

Why do people think the car won’t be delivered?

Not saying it won’t be, but let us see the final product on the road in thousands in all situations and see if it really works. The same reason I didn’t order a Mustang till I saw one in person.

I work as a research scientist doing chemical physics. I don’t have any special knowledge of hydrogen storage but I do understand the basics and have spoken at length about it with a friend who used to work in that field.

Currently to use hydrogen in a car they compress it to awfully high pressures. This is required because the hydrogen atom is so small and means it costs far more energy to compress hydrogen than say propane (LPG). Hydrogen storage is a very well funded area of scientific research, that tries to find a way around this inefficiency, and has made very modest progress over several decades. For various reasons getting a tank full of hydrogen wastes a lot of energy.

The basic problems with hydrogen cars are summarised fairly well in the article below. In my opinion hydrogen cars don’t offer much competition to battery ones. It’s one thing to have a small number about, but to have a large portion of people driving them, their basic inefficiency would become acute. But I am a scientist, and my views on this issue are largely shaped by talking with other scientists and thinking about the basic science. Perhaps engineers have different ideas and they would be concerned with many practical issues that I tend to ignore

evobsession.com/hydrogen-cars-vs-electric-cars-detailed-comparison-efficiency/