New Study Suggests Flying Is Greener Than Driving 280
New submitter Desert Leap writes: The Washington Post reports a new study that suggests it is more environmentally friendly to fly rather than to drive. Analysis from the University of Michigan Transport Research Institute found that driving uses 57% more energy than flying per passenger mile. This is largely due to the number of occupied plane seats increasing while passengers per car decreased. Of course, "results may vary" for individual trips depending on many factors, such as distance flown (long flights are more fuel efficient) and the kind of car, and how many riders. One factoid is interesting: it takes 4,211 BTUs per person mile to drive. This number will fall as we switch over to electric vehicles. For example, a Tesla Model S takes about 1,100 BTUs per vehicle mile. Will future aircraft be able to also make the switch to electric?
What about a bus? (Score:5, Interesting)
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Using the same logic, using a bus or going by train is also more efficient since the many seats versus a couple is also true.
That should read using a BUS. Damn autocorrect.
Re:What about a bus? (Score:5, Funny)
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You only really need one.
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Your assumption is true for a loaded bus, but municipal busses, in all but a few cities, spend much more time travelling nearly empty than they do full.
Show me a plane that makes stops every few city blocks then we can accept your data as a fair comparison. Otherwise, stick to data about long-haul bus and train routes.
Re:What about a bus? (Score:4, Informative)
Fair enough. I was working from memory, couldn't remember where intercity busses fit in the mix and was too lazy to try to find it. I stand corrected. The TRBs TCRP 79 [trb.org] reports the average energy consumption for intercity buses as 713 BTU/(passenger mile). As such, the revised hierarchy ought to be:
Re:What about a bus? (Score:4, Informative)
I don't know if you're being funny or serious, but that's a common misconception so I'll assume you're being serious. The CO2 and methane that we animals spew all came directly from the atomsphere through the food chain or through breathing. It's a closed cycle - plants and animals take CO2 from the atmosphere, store it a short while, then release it back into the atmosphere. That closed cycle is the gold standard of sustainability, pretty much the opposite of "non-green".
Re:What about a bus? (Score:4, Informative)
This depends where you are. In many cities buses run full regardless of the time of day. Even when ridership does decrease the reason that bus companies do not switch to minivans is that the most expensive part of operating a bus is the driver. Switching to smaller vehicles does not save a transit authority enough money to justify the logistical nightmare involved in changing vehicles while a route is in operation.
Re:What about a bus? (Score:4, Insightful)
Maintain an extra fleet of vehicles which need to be maintained and insured, at some % utilization. I'm not really sure this saves money.
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Maintenance is based on distance traveled and as a result will cancel. Also buses use an incredible amount of fuel. They are stop start vehicles with incredible weight and huge engines.
But don't take my word for it, look to cities where they already do this (last trip to Vienna I saw after a certain time many buses changed to minivans, many double buses changed to singles, and then after a later time the entire city's route system changed so only major arterials were serviced by buses and if you wanted to t
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Re:What about a bus? (Score:5, Informative)
Re:What about a bus? (Score:5, Insightful)
On average, buses are far worse than cars for energy efficiency because of the low average load factor.
On what data is this assertion based? I spent a few minutes seeing if such data exist. I could not find data to support your claim that buses are far worse.
I found the following. A bus fuel efficiency is about 5 mpg [1]. That is with fifty-five passengers, which is the maximum capacity and therefore our lower bound. In my county, the average load-factor over all of 2012 was 479 million passenger miles divided by 44 million vehicle miles, or 10 passengers per mile.
Our average fuel consumption over number of passengers then is 50 mpg, which is not far worse than cars for energy efficiency. In 2006, the average mpg of a private vehicle on the road was about 20 mpg. Even with two people in such a vehicle, the average-loaded bus is better.
I did not dig very deeply; I was more trying to find your data and stumbled into data that seems to paint a different picture. It's quite possible that my data paints the wrong picture and you were using much more sound data, but because you did not provide it, I must ask for a citation now.
Which data had you used?
[1] http://www.nrel.gov/docs/fy00o... [nrel.gov]
[2] http://metro.kingcounty.gov/am... [kingcounty.gov]
[3] http://www.project.org/info.ph... [project.org]
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If you are up for it, search for information related to the Google self-driving car project. The data I saw was part of a presentation by one of their engineers at an IEEE RAS (Robotics and Automation Society) meeting that showed that in most cities, self-driving taxis would be a big efficiency win over buses, entirely because of low off-peak load factor.
I didn't make it up, but I don't have a link.
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I don't require a link, but perhaps a name of an engineer or a name of a study or which RAS meeting? I am not finding any of what you mention online. Perhaps my search terms are lacking, so anything else to go on?
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On average, buses are far worse than cars for energy efficiency because of the low average load factor.
The data I saw was part of a presentation by one of their engineers at an IEEE RAS (Robotics and Automation Society) meeting that showed that in most cities, self-driving taxis would be a big efficiency win over buses, entirely because of low off-peak load factor.
Your two quotes above are very different assertions. You never said anything about comparing buses to self-driving taxis. Once we get self driving taxis I think anyone would agree they would be more efficient than buses. For one, nothing is stopping these self-driving taxis from being buses when loads are high enough or mini-smart cars when driving one person. When you don't have to worry about a human driver needing to make a living, who cares if a particular vehicle is only in service 2 hours per day? The
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I found the following. A bus fuel efficiency...
This is one of those arguments where the units can really change perception. I'm NOT trying to ignite one of those frequent Slashdot wars between those who say liters/100km is the best measure or mpg is stupid or whatever. I think various measures are better for various comparisons or circumstances.
In this case, buses are traveling a fixed route, so the mileage is fixed. Buses are also frequently used for commuting fixed distances. Therefore, what we mostly care about is how much gas is used per unit
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I found the following. A bus fuel efficiency...
This is one of those arguments where the units can really change perception.
I don't see why we should even be comparing efficiency. If emissions is the thing we care about then compare emissions, not efficiency.
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If efficiency is emissions per passenger mile, then it is the right thing to compare
But they are not measuring emissions per passenger mile, they are measuring passenger miles per gallon. Two different things, particularly when they are using different fuels. If you don't care about emissions, then what it the point of the comparison to start with?
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Not to mention that an airplane is useless for traveling a handful of miles.
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Actually, buses are terrible. They only run fully occupied during peak times, and transit companies don't pull the big buses and replace them with minivans during off-peak hours. So most bus miles are run with very light loads. On average, buses are far worse than cars for energy efficiency because of the low average load factor.
You're talking about city buses. You can't compare city buses with city to city buses. Chartered city to city buses run at or near 100% at
all times just like alot of airlines. Chartered airlines are the same way. That's the reason certain getaway packages are so cheap. They sell
every seat and know that every seat is sold and only leave when it's full unlike city buses and some airlines where they are running 12
rounds a day whether someone is riding or not.
Re:What about a bus? (Score:4, Informative)
I remember some years back that the Ford Excursion Diesel was rated one of the top most fuel efficient vehicles. The caveat was that you had to fill all 9 seats with people. If you did that, your economy per passenger was better than just about every car out there, even a Prius with a full passenger load. Of course, I would usually only see one or two people in them on the road so the real world figures weren't as good as that. But the point being made was that bulk transportation of people was more efficient than individuals driving cars.
But that also underlines another point..
We really didn't need another very expensive study to tell us the very obvious. Of course flying is more efficient than driving, so long as everyone is going from the same origin to the same destination on a direct flight.
One of the things I'm pretty sure they didn't factor in was how far people had to travel to get to the airport before the flight and how far they had to travel to get to their destination afterwords, not to mention what type of transportation they used. Certainly, if you're driving from one airport to another the model holds true. But the farther away from the airport you are before and/or after your flight, the more the numbers can skew. And I'm pretty sure they don't factor in when you have to fly through a hub airport that takes you hundreds of miles out of your way. So if you got a deal on a United ticket and you have to fly from Iowa through Denver's hub on your way to Orlando, I'm pretty sure any fuel efficiency you would have gained on the airplane is negated by the fact that you're going something like 1,500 miles farther than you would have on the drive.
With REALLY Huge Fans... (Score:2, Insightful)
Will future aircraft be able to also make the switch to electric? Yes, of course. Electric driven propellers should do the trick.
Of course, the size of the batteries needed will preclude carrying any passengers or cargo.
Re:With REALLY Huge Fans... (Score:4, Insightful)
That's not very forward looking....
People said the same thing about cars & range.
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Oh sure it is... The issue is ENERGY density.
Aircraft are more efficient when the energy storage is lighter and smaller. Batteries are not lighter and smaller than liquid hydrocarbons that contains the same amount of energy. Not to mention that as you burn off liquid fuel, the aircraft weighs less and gets more efficient as a result.
So, until batteries get small enough and light enough to have the same range with the same payload, liquid hydrocarbons will be the fuel of choice. I don't think we will b
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Actually the issue isn't just battery density. It may not be as long as you think before we get lithium air batteries with similar battery density to fossil fuels, but the problem with refueling time remains. You would need an impractically sized cable to carry the voltage required to "fast charge" a plane battery, and that would still be much slower than using a liquid fuel.
I think hydrogen will eventually supplant fossil fuels in aerospace.
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Let's assume that you had some sort of battery that could store the same amount of energy as a full airplane fuel tank and was light enough to not cause issues. Couldn't you standardize the batteries across aircraft, make the battery removable, and charge them in the airport between flights. So airplane lands, everyone disembarks, the flight crew (among other things) removes the depleted battery, puts in a fully charged battery, and then puts the depleted battery in the airport's charging system until it
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Yeah it's true. Battery technology has a long way to go for flight. Non-production electric airplanes *could* be a curiosity in about 15 years, but we're probably closer to 30 years for truly viable electric aircraft... and that's assuming we ever get to the point where energy density of batteries are able to close in on the energy density of petroleum distillates.
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I would think it also depends on when the plane is flying. If it's entire trip is during daylight hours, and it's above the clouds as most larger aircraft flights are, then you may be able to use solar panels in place of the majority of the batteries. Plus you won't have to carry the weight (as much) in fuel.
It's probably not a practical solution currently. But as efficiencies increase, it's at least feasible it may be at some point in the future.
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And that's why I finished my post with the following: "It's probably not a practical solution currently. But as efficiencies increase, it's at least feasible it may be at some point in the future."
Battery tech has also been improving recently. There's no reason that it may become much lighter in the future and a combination of PV and batteries may become practical. It's also entirely possible that PV will never reach the necessary efficiencies and batteries don't reach the energy density necessary. That's
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There are already electric small airplanes that take a couple people.
Airplanes are obviously the highest-hanging fruit for switching over to electric drive, but they're not impossible. On the pure electric front you're first going to see the current growth trend in small personal electric airplanes continuing and short-range business uses like crop dusting and the like grow. From there you'll move to the little short
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That's stupid. Just taxi with an electric tug-car. Why carry the weight of the electric motor system in the air where it isn't doing any good?
Do we really want the O'Hare runways to look like the LA freeway system at peak times?
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The system is actually not that big [safranmbd.com]. The batteries are small because, despite the weight of the plane, the distances traveled are very short; and electric motors pack a lot of power into a small package. Having it all built into the plane reduces ground delays, ground staff, and additional ground hardware. It's a "pushback and go" system, the pilot can move the instant he gets clearance to, he doesn't have to wait for anyone else. It's estimated to save about 2 minutes over using tugs, which may not sound
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The answer to both of those issues ("green" fuels for aviation and trucking) is biofuel or synthetic (hydrocarbon) fuel. (FYI, we had an article here about the latter just a few days ago.)
Nobody said we need to be "carbon-less;" it's sufficient to be "carbon-neutral."
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You speak about aerospace where you should probably speak about aeronautics. In the aerospace sector, people rely a lot on non carbon energy, except for the launch part. Of course a launch is a big energy consumption in a short period of time, but on the other hand the S/C will usually be used for 10+ years, running on solar energy. And more and more S/C use "electric" propulsion, where you have still a "fuel" of course, but most of the delta-V comes from electricity.
There are some people who want to use r
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There's also some interesting side possibilities of airplane electrification being looked at. I read a research paper at one point which focused on the fact that electric propulsion scales down far better than other forms of aircraft propulsion; they investigated the possibility of having a number of micropropellers along the wing which are run at full power during takeoff and landing but not during level flight. The concept was that though they're not as efficient as the main propeller, they dramatically i
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I wonder about airships. If we can build some that can handle the cargo of a larger plane, it takes far less fuel to keep those going than it does an average plane (mainly because an airship won't crash if the engines stop.) I can see those being quite effecient at moving cargo. Since they only go 20-60 mph (32-100 km/hr), they won't be replacing high speed rail... but airships require relatively little energy to operate compared to a plane which needs airspeed to maintain lift.
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Re:With REALLY Huge Fans... (Score:5, Funny)
Please direct your attention towards the front of the cabin as our flight attendants demonstrate the safety features of this craft.
In the event of pressure loss, an oxygen mask will drop from the overhead compartment. Please pull the mask to extend it completely and start the flow of oxygen, then place the mask over your nose and mouth and place the strap around your head to hold it in place. Put on your mask before helping children or others in need of assistance.
In the event of power loss, bicycle pedals will extend from the floor of the cabin. Please pedal as if our lives depended on it
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Will future aircraft be able to also make the switch to electric? Yes, of course. Electric driven propellers should do the trick.
Of course, the size of the batteries needed will preclude carrying any passengers or cargo.
I don't think that is necessarily true. One option is to build hybrid electrical airplanes [technologyreview.com]. And if battery power density and durability continues to improve, I think you might be surprised what is possible if you fill the wings of an airplane with electrochemical cells. Elon Musk has speculated [linkedin.com] that electric airplanes might be possible if we go beyond the incremental improvements of the current players.
Masstransit is more energy efficient than personal (Score:5, Insightful)
Nothing really too new. If you take the bus and the bus is full you are more efficient for the work being performed.
Most of the energy goes into moving the actual machine, only a small fraction goes into moving its content.
That is why the Train shipping companies advertise 1 gallon of fuel, for 500 miles per Ton of goods.
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Not just that, there are a LOT of efficiencies that airplanes can take advantage of that are just not available to ground transportation. For distances above ~400 miles, air freight can be more efficient than even a freight train for hauling just about anything with a higher value per pound than rocks and gravel.
* gas turbine engines can reach peak thermodynamic efficiencies of ~50% around 30,000 feet, where the intake air is coldest but not too thin. Any combustion engine running at surface conditions ca
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Better than that. There are internal combustion engines which reach 50% at sea level. The Wartsila-Sulzer RTA96-C 108,920 hp marine diesel exceeds 50%. Heck, even the TDI diesel engine in my 1999 Golf tops out at very close to 40%. The LM-2500+ gas turbine, a derivative of the CF6 which powers some 747s, adapted for shaft output, is over 39%.
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Most other forms of transport have no chance against a decent modern passenger car with 4+ passengers. Most passenger cars are comparatively light, well below 500kg per passenger, which is very hard to beat. They do that because there is hardly any wasted space. A bus needs a walkway and it has to be tall enough to stand in, and trains are just horrendously heavy. While rubber-on-tarmac is a bit wasteful compared to metal-on-metal, it is not that bad, and the lower weight helps a lot.
Electric trains can som
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This is stupid (Score:5, Insightful)
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Any forms of travel from point A to point B should be valid for study. If I have to travel alone 800 miles it's good to know the options for energy efficiency. Do I rent a fuel-efficient car? Do I simply fly? Do I hop on a bus? It doesn't nothing for me to only study the difference between vehicles of the same size.
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Yeah. (Score:5, Insightful)
Flying costs a lot more, and involves a period of being completely at the mercy of the no-background-check employees of the TSA.
I don't care if it is green. The TSA is horrible. Get rid of it, and I might fly again. Until then, I will spring for the road trip.
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Actually small planes aren't that bad- you can get 20-25 mpg at a ground equivalent of 100 mph. Figure that you are going on a straight path and the economics look pretty good.
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Either compare flying a small plane to driving a car,
I remember seeing an advertisement in 1980s magazine comparing a small plane (Mooney I think) to a car:
"Faster than a Porsche, fuel economy as a VW, luxurious as a Cadillac. It's the perfect car for business travel and yet it isn't a car at all."
Article went on to say you don't have to worry about speeding tickets because when you fly you can go as fast as your equipment can do so. This seems such a distant world compared to these days. I also remembered browsing through Aviation Week looking at tables o
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Very true, it is worth nothing though that efficiency in the air is far more important financially than it is on the ground so while taking a bus is going to be WAY more efficient over all than flying or being the one person in the car you're driving ... Airplanes are typically more efficient than any land vehicle and we should actually try to be better at incorporating things the commercial airlines do into other mass transportation options
With that said, fi that means we start using airlines for a guide t
Now Factor in... (Score:3, Insightful)
Being Robbed by the TSA, Groped and Accosted, or Simply not allowed to fly at all because of your views on social media.
I'd rather drive or walk...
to drive (Score:3)
> One factoid is interesting: it takes 4,211 BTUs per person mile to drive.
do we all drive the same car? Is this a chevy suburban or a fiat punto?
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Apparently you haven't heard of averages.
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Averages are clearer when the correct number of significant figures is used. It's not meaningful to give four significant figures for an average that's supposed to stand in for a wide range of values. At best it's really just an order of magnitude.
And while I don't doubt the number, it does imply that they're not careful with their methodology, which makes it harder to put a lot of weight on it. It would have been better with just one or two digits of precision, or (if they wanted to spend the extra space o
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Carpool (Score:2)
When I travel far enough to fly, I don't usually travel by myself, I'm usually on vacation with family or on a business trip with coworkers, so by adding just one person to the car, that makes driving and flying almost equivalent -- probably even moreso since I can drive from my house directly to my destination instead of driving 20 miles to the airport on one end, then another 30 miles on the other end.
Well then... (Score:2)
Time for a new plane (Score:2)
That circles around towns lowering 'hooks' to grab people at designated points, pick them up, whisks them through the air aways -- without having to load them up into a cabin, and drops them off at their destination when they push their personal 'eject' button.
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I'd have trouble being whisked around town dangling from a drone under my command without also being in a superhero costume.
Seriously, in our modern age, how else would a superhero get around? A fast car? Pish.
Bus Logic (Score:3)
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You can always look at the options. Is it feasible to fly to the local supermarket? If you have a helicopter, maybe it is. Does it make sense? Except for the ego boosting factor, probably not. Is it possible to drive from New York to Paris, France? If you get your car on a freight ship, it is. Does it make sense? In most cases, not, except you want that car to be in Paris for some reason.
So yes, flying and driving by car are comparable. In many cases, the
Who uses BTUs (Score:2)
"results may vary" (Score:2)
.
Yet the study picked the best of air travel and compared it to the worst of road-based travel.
I wonder how efficient it would be for me to fly from my house to the supermarket (a mile away), or any of the other numerous trips I make via automobile?
Let me see, first I have to drive three miles to the nearest airport. Get in a plane. Take off. Land at the same airport. Then drive four miles to the supermarket.
Yeah, that's more efficient than driving.
Show me the math on the Tesla. (Score:5, Insightful)
Show me the math for both ICE cars and Tesla, from well-head to road. Because generating electricity takes energy, and there are losses in the distribution system, and the charging systems are not 100% efficient either. Of course, getting oil out of the ground, refining it into gasoline, and moving the gasoline to refueling stations takes energy, too. Show me the end-to-end math, and then let's talk. A 4:1 advantage for the Tesla seems optimistic to me.
I have the same gripe with calling Teslas "zero emission vehicles". They are not. They are "displaced emission vehicles". Of course, it is easier to control pollution at a single point, and pollution controls scale up quite well, so the overall emissions are less for a Tesla versus an ICE vehicle. But don't claim the emissions are zero, they are just someplace else. (And I will grant that there are benefits to simply displacing emissions -- the Los Angeles valley, for instance, is a bowl, and so pollution tends to hang around in the air for a long time certain months of the year. Displacing the emissions outside the bowl has it's own benefits.)
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That would be pointless because practically no one uses oil to produce electricity. Electric cars tend to charge at night where the coal plants are running at very low power and low efficiency. An idling coal plant has a very high average pollution per kWh produced but a very low marginal pollution per extra kWh.
Of course if it is a windy night the coal plants might just give up and shut down overnight, and then you really get your zero emissions.
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practically no one uses oil to produce electricity
But practically everyone uses natural gas and/or coal. so the point is well taken.
Of course if it is a windy night the coal plants might just give up and shut down overnight
You can't "just shutdown" a coal fired generation plant. What you can do is dump the excess power to ground.
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Not pointless -- convert everything to BTU's. The electricity has to come from somewhere. And there are distribution system losses, which for electricity are considerable. Show me BTU's end-to-end.
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Coal plants can't idle. They're either running at or near capacity, or shut down. And they do not shut down overnight, because it takes about 3 days for them to get up to operating temperature. This is why coal power plants will sell electricity at a loss overnight.
That's also why most coal power plants in the US are getting replaced with natural gas power plants. A natural gas power plant is basically a helicopter engine connected to a generator. You can throttle it up and down somewhat, and you can s
Renewable and Nuclear Power (Score:5, Insightful)
I have the same gripe with calling Teslas "zero emission vehicles". They are not.
True, but unlike petrol driven cars they could be. Both renewable and nuclear power power are zero carbon methods of generating power and while renewable has issues with cost, limited locations and variability if it were supplemented by nuclear we could significantly reduce greenhouse gas emissions. In fact if you charge your Tesla in France then 75% of that power comes from nuclear so you might not be zero emission but you will be getting close.
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I would be skeptical as well, however the Tesla is very easy to check. From the top link on Google:
"[the range of the Model S] 85 kWh battery pack is 265 miles"
86,000Wh x 3.41 BTU/Wh / 265 miles = 1107 BTU per mile
I'm going to say that their claim is "accurate" based on a very simplistic level. As you point out, there are efficiency losses in generation, transmission, and charging.
Now, if you use the EIA rates (http://www.eia.gov/tools/faqs/faq.cfm?id=667&t=3) for power generation, it's more lik
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Compare a Tesla from a solar panel to the fossil fuel pathway of ICE starting from algae 300,000,000 years ago. They share the sun's photons as a common ancestor. I
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Well, it all depends on where you're talking about. The thing electrics have going for them is that *if* you can move toward clean/renewable sources of electricity, then you're doing more than displacing pollution by going electric. For example in California, less than 10% of electricity comes from coal (http://energyalmanac.ca.gov/electricity/total_system_power.html) and almost half is natural gas, which is somewhat "cleaner" than gasoline, all factors in.
And with solar on it's current growth trajectory (
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The math is here [climatecentral.org], showing that where you drive is as important as what you drive. But as a sibling post notes [slashdot.org], even this math doesn't count the energy required to produce gasoline from scratch.
BTUs is one thing (Score:3, Insightful)
I also value my time, which I don't want to waste on a 200 mile trip waiting in line, and security theater
per passanger mile is useless metric (Score:2)
This is absolutely useless metric. How about taking your clothes to dry cleaner or doing grocery using a plane? Cars are efficient compared to planes for the purposes where cars are used. Sometimes I go from SF to LA and I rarely see another car with a single passenger. This is the case where a plane can replace cars but even in this case planes would be inefficient once you take into account 3 passengers per car, 90% plane occupancy and take off, landing and airport infrastructure energy usage (even with t
BTUs? (Score:2)
Why is energy here measured in BTUs? I've usually seen total energy use expressed in Watts, especially in the mechanical realm.
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I'm sorry I forgot to put the /h after Watt.
Seriously, I've never seen mechanical energy expressed in BTUs, and I'm in the US. I know a few automotive engineers and they use W/h when calculating engine efficiency.
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The thing is average Americans don't use BTU's either. MegaJoules are every bit as abstract and unfamiliar.
The only things I see in "everyday" use for the BTU: Cooking stoves and window air conditioners -- things you don't buy or compare often. . In both cases, it's not "meaningful" other than a higher number is more powerful.
It's a Complex World (Score:2)
While interesting, this study is also sort of meaningless for making any sort of policy decision. I take far away vacations because the plane makes it possible. If planes weren't an option (due to price or policy), then I would shift to taking vacations closer to home (with maybe 1 trans-Atlantic cruise to explore Europe late in life), and my business travel would shift to teleconferencing. Would the resulting environmental footprint be better or worse? Hard to say. And presumably train usage would (after
Commercial air travel is actually pretty green. (Score:2)
At least from the perspective of it being very efficient. Planes burn a lot of fuel but they also complete their task very quickly.
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The problem with your theory is that the primary cost to airlines IS fuel and they set up those routing systems to maximize the fuel economy of the whole network.
The issue is the big jumbo jets when full of passengers are pretty much as efficient as it gets. Planes get less efficient per person as they get smaller.
So the concept is that you have small planes FULL of people traveling to the nearest hub, then you have as many people as possible moved from Hub to Hub via a jumbo jet. And then finally you have
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Before ICBMs became a reality, nuclear-powered planes [wikipedia.org] were significantly researched. Probably the craziest was Project Pluto, whose concept was to have an open to the air nuclear core inside a ramjet housing, acting as the heat source instead of combusting fuel. The unmanned craft was designed to be able to fly around for months at a time holding numerous atomic bombs. When given orders to attack it would have bombed Soviet cities... then with its cargo spent, continued the rest of its lifespan flying low o
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"Fast" is not an issue. Electric motors have a much better power to weight ratio than combustion motors, and li-ion batteries have no trouble feeding it. The reason things like solar impulse fly slowly is to reduce air resistance and thus minimize their power consumption needs.
Batteries have advanced tremendously in the past several decades and show no signs of slowing down. The transition of air travel will be more difficult and longer in the making than that of ground travel, mind you.
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requires extremely favorable conditions for takeoff.
If you can flight forever, who cares ? You only need to takeoff once.
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Electric traction motors are far more efficient than ICEs. That's why diesel locomotives don't actually connect the diesel engine to the wheels. The diesel engine generates electricity, which turns electric traction motors.
Same with the really big earthmoving equipment - those gigantic dump trucks down at the strip mine are using electric traction motors powered by diesel generators.
Why don't we do this in cars? Space and complexity.
So what's the point of all electric cars? It separates the energy gener
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what about that huge battery? Tesla's weigh more than similar gasoline sized cars because of the battery
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Even the most inefficient modern coal plants are significantly more efficient than an internal combustion engine.
The added bonus of electric cars is that, as the power generation shifts to less polluting sources (we hope), the electric car will become less polluting over time. The ICE powered car, however, will likely decrease in efficiency and increase the amount of pollutants it expels over time.
As for coal power, most of the electric cars in the US are located in CA, OR, and WA. Those states are primaril
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Small prop driven aircraft, ALREADY [google.is].
The market was almost nonexistent about five years ago but it's growing quite fast. Don't underestimate what the major and ongoing advances in motors, controllers, and batteries will bring in the future. There's [mh-aerotools.de] many [nasa.gov] radically [wikipedia.org] new [aviationweek.com] technologies [ieee.org] in the works to partially or completely electrify aircraft transportation, far beyond just electrically driven propellers.
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Newton is a unit of force. BTU is a unit of energy. You should be using megajoules.
1 BTU = 0.001055055853 MJ, or 1000 BTU = 1.055055853 MJ
1000 BTU per person mile = 0.6555813132 MJ/passenger-km