Inefficiency of Automotive Transportation
- Thread starter Al
- Start date
saturation of the roads reduces the efficiency, more energy is used to cool/heat vehicles in traffic jams. How did that change in this period?
yes, and for an ICE the effciency limit is around 40% anyway. so between 2 and 3x more fuel is used for anything that's not moving from A to B than for the actual transport. Also, bad driving increases fuel consumption, a lot of it is braked away where it really didn't have to be.
the lights don't even register when you calculate it. 150 watts per hour or so for filament bulbs, 20 or so for full led.
For those that worry about it, you guys are free to give up all of your vehicles and start walking/biking, instead of wasting our resources.
The invention of the combustion engine is probably the greatest in history. It lifted billions out of poverty and provided opportunities and personal freedoms not recorded previously in history.
Efficiency has little to do with it. Walking is also inefficient. Calorie consumption vs distance traveled is very high.
The invention of the combustion engine is probably the greatest in history. It lifted billions out of poverty and provided opportunities and personal freedoms not recorded previously in history.
Efficiency has little to do with it. Walking is also inefficient. Calorie consumption vs distance traveled is very high.
The vast majority is lost as heat. This site shows where all the losses are, including city vs highway.
https://www.fueleconomy.gov/feg/atv.shtml
I thought it was our benevolent authorities that lifted us from poverty? The talking head said so?
One number in isolation doesn’t tell the story.
When you talk about “percent of the energy“, where are you starting the measurement, and where are you ending it? Do you mean fossil fuel when you say “energy”?
When you say “propelling the vehicle“ do you mean overcoming drag? Providing acceleration? Both?
The rest of the energy frankly ends up as heat. Nearly always does.
The question is - how efficient are other forms of transportation? Trains, for example, are fairly efficient. Much more so than cars. Busses a bit more efficient.
A gas turbine power plant is on the order of 40% efficient, the rest is lost as heat.
But when you lose some of the electricity generated to heat in the lines, as well as heat in the transformer, and heat in charging the battery, it turns out that perhaps an electric vehicle isn’t a whole lot better than gasoline vehicle in terms of the total energy in and number of miles traveled for that energy.
The big advantage of the true electric is regenerative braking. Instead of turning kinetic energy (created by using fuel) into heat via brakes, it is converted (not at 100% efficiency, but still) back into electric energy. Far more efficient than regular braking.
The true “tree hugger” advantage to BEV is that the electricity can be generated from a variety of “green” sources, that don’t require fossil fuel.
Today, our best gas powered vehicles achieve about 36% overall efficiency, from fuel to wheel.
Gasoline now has about 112,000 BTU per gal. Due to 10% ethanol and other refinement changes.
Most modern engines are pushing 40% thermal efficiency in the normal operating range.
Modern jets get about 120 passenger miles per gal. (note both jets and diesel trains use energy dense fuel, 130,000 BTU++ per gal)
Amtrak achieves about 55 passenger miles per gal.
The Prius highway trip with me driving achieves just under 50 MPG.
The Camry with its 40% TE engine achieves 40 MPG highway with my lead foot.
Of note, the US elec grid is now 35% efficient. So the BTU consumed at the power plant to push a Tesla down the highway (stack of losses) (no braking regen factored in) is equiv to 26MPG.
I have taken an interest in public transportation lately. We have ridden public transportation a bunch here, and in a couple other cities. Were probably going to make sure our next home has this as a realistic option at least. My wife has never liked city driving, and even less now with the morons out there - true idiots. I figured as we get older it might be nice to have an alternative. Maybe someday one of us won't be able to drive at all - so better to have a plan B.
The interesting thing about public transit is during peak - there so crowded its disgusting. Off peak - there empty. I have been on huge city buses as the only rider - for some number of stops.
So the question - how do you calculate efficiency of a bus that is 150% full 10% of the time, and almost empty 90% of the time, or more specifically - is that they number they actually use, or do they fudge for just peak?
The interesting thing about public transit is during peak - there so crowded its disgusting. Off peak - there empty. I have been on huge city buses as the only rider - for some number of stops.
So the question - how do you calculate efficiency of a bus that is 150% full 10% of the time, and almost empty 90% of the time, or more specifically - is that they number they actually use, or do they fudge for just peak?
Engine efficiency is not overall efficiency. But mola may be righ. I see feW alternatives
I think the real issue is that fossil fuels have made energy so cheap(financially) that we've become very inefficient overall. So we've got stuff like 6000lb boxes of air transporting 200lbs of person to sit a desk 50 miles away everyday. Container ships full of single use plastic junk moving around the world, etc.
It is a great thing for personal freedom to have your own car and roads everywhere, but it would be a good idea to figure out how to preserve most of that without playing russian roulette with increasing greenhouse gases to very high levels, and seeing what happens?
I'm not advocating going back to the stone ages, but probably we could maintain or improve our quality of life with much less fossil fuels usage. Is anyone's life really much better with plastic drink bottles everywhere? Get rid of them, no one will miss them except pepsi and coke....
It is a great thing for personal freedom to have your own car and roads everywhere, but it would be a good idea to figure out how to preserve most of that without playing russian roulette with increasing greenhouse gases to very high levels, and seeing what happens?
I'm not advocating going back to the stone ages, but probably we could maintain or improve our quality of life with much less fossil fuels usage. Is anyone's life really much better with plastic drink bottles everywhere? Get rid of them, no one will miss them except pepsi and coke....
I agree with this.
However Cafe has been doing this for years. Overall mile efficiency has increased a bunch. Is it worth the effort to push the last 5% of efficiency into the system by forcing everyone into EV's or whatever, or would we be better off to declare victory - and put our money into low hanging fruit - like public transit and getting rid of plastics or improving roads so traffic can more more easily or even doing bike paths that go somwhere?
The thing is, only 14% of national energy use is Automotive/light truck/SUV.
So knock that down to 9%, closes a few refineries, takes a 1/3 of the fuel tanker trucks off the road, get rid of 1/4 of disposable stuff/junk big box stores sell, that takes some more trucks off the road, reduces the number of trips to costco,etc by a 1/3... Less fracking and drilling is needed, which all uses lots of energy too. Roads get less damaged, need repaving less....
It is kind of scary how much of the economy depends on cheap energy and fossil fuels, but there will be lots of work to do in a conversion to a durable good economy that is more energy efficient. Maybe we'll go back to the 50's where 1 persons labor sustained a family home? A farmer could make a honest living with a couple hundred acres and 200hp of equipment?
It seems with modern manufacturing efficiency and technology improvements, that one persons labor should be providing a home now?
Worry? No. I am just pointing out information in an article. Of course none of us will stop doing what we are doing. But I do reflect on the earth in general. The quality of life for 50% of the planet is so low compared to us that its laughable. And "NO)" I am not going to give up my privileged corner of the world.
There is not conceivable solution that will "end" this. The rich will get richer at the expense of the poor. It will always be that way. We the privilaged will use the earths resources. The Poor will continue to procreate and it will only get worse.
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Thus endeth my philosophical thoughts for the day.
It's partially that it's somewhat cheap. The biggest thing is that fossil fuels are very calorie dense, ie a gallon of gas is like eating a triple bacon cheeseburger. Batteries are long way from being as dense.
yes, I think some bio liquid fuels are needed too. Lots of things need the energy density and storability of liquid fuels. And even some fossil fuels will still be needed, but just burning them up for making and hauling and disposing of plastic disposable junk because its cheaper than making something durable could end very quickly, and people won't miss the pointless waste too much....
Worry? No. I am just pointing out information in an article. Of course none of us will stop doing what we are doing. But I do reflect on the earth in general. The quality of life for 50% of the planet is so low compared to us that its laughable. And "NO)" I am not going to give up my privileged corner of the world.
There is not conceivable solution that will "end" this. The rich will get richer at the expense of the poor. It will always be that way. We the privilaged will use the earths resources. The Poor will continue to procreate and it will only get worse.
'
Thus endeth my philosophical thoughts for the day.
But there are many people that do worry. Just look at the “stop oil” movement. They block major highways, cause massive traffic jams, and best of all, cause extra emissions with their antics.
Without oil, the whole world economy and civilization will collapse. Personal transportation is but a small fraction of oil consumption.
So to advocate against oil, is to advocate for human poverty and suffering.