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yesplease
Velociraptor
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 Posted: Tue Feb 19, 2008 7:18 pm Post subject: |
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| jonk wrote: | | Also, fission generates electricity (well, it generates heat, but I don't know of any case where someone uses that heat directly to warm their homes.) As I indicated earlier, 3 watts are generated to get 1 watt delivered. On the global scale, we are consuming some 400 quads of energy. Most of that, though, is NOT electricity. It's vehicles, heat, etc. But if we decided to switch over to all-electric methods of heating, vehicle motion, etc, then we would probably require something closer to 1100 quads of electrical energy production in order to deliver the existing 400 quads (of which electricity is perhaps 15%) we currently need. (400*85%*3+400*15%) That's a serious problem. That is just a quick estimate, though, and I'd need to incorporate differences in conversion efficiencies for electric motors in cars, for example, versus current gasoline (28%, roughly) and diesel (40-45% roughly?), etc, to get better numbers for all this. But that gets us somewhere in the vicinity. It means we need to not just replace, but we need to nearly triple our expectations on top of that, to handle all the conversion and distribution losses. Maybe a little more, or less, but somewhere in that ballpark. |
Not quite... What you cited may be average peak efficiencies, but actual efficiency is much lower. Well to wheels efficiency is, on average, around 15% for the passenger vehicle fleet in the united states IIRC, and due to constraints WRT battery costs, electric passenger vehicles must be much more efficient than their fossil fuel counterparts in order to be produced at a reasonable cost with similar performance. We could have an electric SUV that could seat six to eight and tow however much while going 0-60 in N seconds with 300 miles between refilling the energy storage unit, but it would cost a half a million bucks give or take, so, a practical EV must be small and efficient. 
Fortunately, most passenger vehicle use, I'd guess at least 90+%, involves one or two people and minimal luggage, so small efficient electric vehicles can provide the same functionality that the majority of fossil fueled vehicles provide. Heavy duty applications will still need the energy density of fossil fuels, but honestly, most pick-ups and SUVs I see these days are hauling their owners to work or the store with little to nothing in them. In any event, if we had used what we've spent on the Iraq war on a mix of wind/Nuclear power we would've had enough additional capacity to completely power a fleet of small EVs. Granted, they aren't for everybody, just 95% of the population 95% of the time.  |
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jonk
Deinonychus
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| Posted: Tue Feb 19, 2008 8:19 pm Post subject: |
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| yesplease wrote: | | jonk wrote: | | Also, fission generates electricity (well, it generates heat, but I don't know of any case where someone uses that heat directly to warm their homes.) As I indicated earlier, 3 watts are generated to get 1 watt delivered. On the global scale, we are consuming some 400 quads of energy. Most of that, though, is NOT electricity. It's vehicles, heat, etc. But if we decided to switch over to all-electric methods of heating, vehicle motion, etc, then we would probably require something closer to 1100 quads of electrical energy production in order to deliver the existing 400 quads (of which electricity is perhaps 15%) we currently need. (400*85%*3+400*15%) That's a serious problem. That is just a quick estimate, though, and I'd need to incorporate differences in conversion efficiencies for electric motors in cars, for example, versus current gasoline (28%, roughly) and diesel (40-45% roughly?), etc, to get better numbers for all this. But that gets us somewhere in the vicinity. It means we need to not just replace, but we need to nearly triple our expectations on top of that, to handle all the conversion and distribution losses. Maybe a little more, or less, but somewhere in that ballpark. |
Not quite... What you cited may be average peak efficiencies, but actual efficiency is much lower. Well to wheels efficiency is, on average, around 15% for the passenger vehicle fleet in the united states IIRC, and due to constraints WRT battery costs, electric passenger vehicles must be much more efficient than their fossil fuel counterparts in order to be produced at a reasonable cost with similar performance. We could have an electric SUV that could seat six to eight and tow however much while going 0-60 in N seconds with 300 miles between refilling the energy storage unit, but it would cost a half a million bucks give or take, so, a practical EV must be small and efficient.
Fortunately, most passenger vehicle use, I'd guess at least 90+%, involves one or two people and minimal luggage, so small efficient electric vehicles can provide the same functionality that the majority of fossil fueled vehicles provide. Heavy duty applications will still need the energy density of fossil fuels, but honestly, most pick-ups and SUVs I see these days are hauling their owners to work or the store with little to nothing in them. In any event, if we had used what we've spent on the Iraq war on a mix of wind/Nuclear power we would've had enough additional capacity to completely power a fleet of small EVs. Granted, they aren't for everybody, just 95% of the population 95% of the time. |
I was granting the best I could for them, given that we now have CVT technology and can operate them only at their peak efficiency if we want to. In terms of electric cars, keep in mind that we get 1 watt out of 3 generated at the nuclear plant. (I'm taking those numbers from the DOE.) Then we need to transfer that energy into storage (battery, flywheel, whatever.) More inefficiency. Then, if I recall, the best electric motors are near 60% efficiency in converting to mechanical power. I could be wrong about that and it is 80%, but I know it isn't more than that. (I'll have to go back and check my references on that.) And there is the terrible volume to energy density of current technologies of storage (batteries) and in the case of superconductors, the terrible possibility of rupture and immediate release of all energy at once, should we find an economic and practical means of fielding those in cars.
Anyway, what I'm asking from you here is that you give me numbers, sources, etc., on electric cars, etc. Make a good case for them. I'd like to read it, in detail. I have my narrow view, at this time, based on what I've learned so far. And I would enjoy broadening that out, if you can contribute and make a good case for me.
Start with the power generation means. Nuclear, for example. I can provide some sources at the DOE for you, but actually it would be better if you researched this yourself and made your case starting at that point. I can then check to see if I follow your argument. Then follow up with the conversion and distribution losses to the vehicle location. Then the same with the energy storage means -- I want storage volume required, energy storage, expected storage means lifetime (too short and it is not usable), risks if involved in accidents (they happen), cost estimates, disposal/risks to environment, serviceability, and so on. Doesn't have to be too detailed, but enough so that you have realistic ballpark figures I can go check on, myself, once I see them. (I expect that the obvious, such as that it can deliver the necessary currents when required are met.) Then the efficiencies involved in the electric engine and the inefficiencies in removing realistic amounts of energy per unit time (power) from the storage means (usually, there is a cost associated with high draw, for example, in terms of self heating through internal resistances.) I think from this, we can start to make some comparisons that are more meaningful than my prior handwaving about it. (I didn't want to get too bogged down, but now that you bring it all up again, lets have you make a solid case and see where this takes us. I'm interested.)
Thanks.
Jon
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Say what you will about the sweet mystery of unquestioning faith. I consider a capacity for it terrifying. [Kurt Vonnegut, Jr.]
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yesplease
Velociraptor
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| Posted: Tue Feb 19, 2008 9:53 pm Post subject: |
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| jonk wrote: | | I was granting the best I could for them, given that we now have CVT technology and can operate them only at their peak efficiency if we want to. |
CVT or not, the amount of power the average car needs compared to what's required on average results in huge throttling losses. Combine this with extra capacity for most use as well as poor aerodynamics/excessive weight, and the average vehicle in the states gets roughly 17mpg[1] and as such requires roughly 2200Wh/mile.
| jonk wrote: | | In terms of electric cars, keep in mind that we get 1 watt out of 3 generated at the nuclear plant. (I'm taking those numbers from the DOE.) |
That's roughly true for most power generation, and goes from 30-50+% IIRC. However, if we're looking at the additional capacity, all we need to go off of is the yearly electricity production, which is roughly four trillion kWh/year[2].
| jonk wrote: | | Then we need to transfer that energy into storage (battery, flywheel, whatever.) More inefficiency. Then, if I recall, the best electric motors are near 60% efficiency in converting to mechanical power. I could be wrong about that and it is 80%, but I know it isn't more than that. |
No need to worry about all that (although you probably could go through everything if you wanted to) just look for a specific example of an EV that can provide for what most people do and go from there. Aptera for instance. Their EV has a 10kWh pack and is reported to do around 120 miles per charge, which is around 85Wh/mile.
| jonk wrote: | | And there is the terrible volume to energy density of current technologies of storage (batteries) and in the case of superconductors, the terrible possibility of rupture and immediate release of all energy at once, should we find an economic and practical means of fielding those in cars. |
The poor energy density is precisely why an EV with decent range also doesn't require much in the way of energy to run. We either have to make it efficient for it to have decent range, or really expensive. Aside from a few bad Lithium based batteries in laptops I haven't heard anything about problems with battery packs. Sufficed to say, both in theory and practice, 300+kWh of liquid fuel that can be ignited by a spark is far more dangerous than 10kWh of energy stored in batteries that have seen isolated/minimal problems at best.
| jonk wrote: | | Start with the power generation means. Nuclear, for example. I can provide some sources at the DOE for you, but actually it would be better if you researched this yourself and made your case starting at that point. I can then check to see if I follow your argument. Then follow up with the conversion and distribution losses to the vehicle location. Then the same with the energy storage means -- I want storage volume required, energy storage, expected storage means lifetime (too short and it is not usable), risks if involved in accidents (they happen), cost estimates, disposal/risks to environment, serviceability, and so on. |
Well, given a fleet or fairly efficient two seaters, such as the Aptera, that use around 100Wh/mile on average, and that Americans drive roughly three trillion miles per year[4], we would need an additional 300 billion kWh worth of electricity generation per year, or a roughly 7.5% increase in generation. Since we probably could get away with a mix of one and two seat EVs, I'm guessing that 5% of current electricity generation could cover most of our transportation needs. Besides, it's not like we can't keep gasoline powered vehicles around for trips when more than one or two people are in a vehicle, it's just that since most of our vehicle miles are one or two people with minimal cargo, something like this could allow for some measure of energy independence and lower the cost swe pay, both directly as in fuel and maintenance, and indirectly via health care costs/lost productivity from pollution and trouble due to Carbon emissions.
[1]http://www.bts.gov/publications/national_transportation_statistics/html/table_04_09.html
[2]https://www.cia.gov/library/publications/the-world-factbook/print/us.html
[3]http://www.aptera.com/details.php
[4]http://www.fhwa.dot.gov/policy/ohpi/hss/faqs.htm |
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jonk
Deinonychus
Joined: Nov 18, 2007
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| Posted: Wed Feb 20, 2008 4:12 am Post subject: |
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| yesplease wrote: | | jonk wrote: | | I was granting the best I could for them, given that we now have CVT technology and can operate them only at their peak efficiency if we want to. |
CVT or not, the amount of power the average car needs compared to what's required on average results in huge throttling losses. Combine this with extra capacity for most use as well as poor aerodynamics/excessive weight, and the average vehicle in the states gets roughly 17mpg[1] and as such requires roughly 2200Wh/mile.
| jonk wrote: | | In terms of electric cars, keep in mind that we get 1 watt out of 3 generated at the nuclear plant. (I'm taking those numbers from the DOE.) |
That's roughly true for most power generation, and goes from 30-50+% IIRC. However, if we're looking at the additional capacity, all we need to go off of is the yearly electricity production, which is roughly four trillion kWh/year[2].
| jonk wrote: | | Then we need to transfer that energy into storage (battery, flywheel, whatever.) More inefficiency. Then, if I recall, the best electric motors are near 60% efficiency in converting to mechanical power. I could be wrong about that and it is 80%, but I know it isn't more than that. |
No need to worry about all that (although you probably could go through everything if you wanted to) just look for a specific example of an EV that can provide for what most people do and go from there. Aptera for instance. Their EV has a 10kWh pack and is reported to do around 120 miles per charge, which is around 85Wh/mile.
| jonk wrote: | | And there is the terrible volume to energy density of current technologies of storage (batteries) and in the case of superconductors, the terrible possibility of rupture and immediate release of all energy at once, should we find an economic and practical means of fielding those in cars. |
The poor energy density is precisely why an EV with decent range also doesn't require much in the way of energy to run. We either have to make it efficient for it to have decent range, or really expensive. Aside from a few bad Lithium based batteries in laptops I haven't heard anything about problems with battery packs. Sufficed to say, both in theory and practice, 300+kWh of liquid fuel that can be ignited by a spark is far more dangerous than 10kWh of energy stored in batteries that have seen isolated/minimal problems at best.
| jonk wrote: | | Start with the power generation means. Nuclear, for example. I can provide some sources at the DOE for you, but actually it would be better if you researched this yourself and made your case starting at that point. I can then check to see if I follow your argument. Then follow up with the conversion and distribution losses to the vehicle location. Then the same with the energy storage means -- I want storage volume required, energy storage, expected storage means lifetime (too short and it is not usable), risks if involved in accidents (they happen), cost estimates, disposal/risks to environment, serviceability, and so on. |
Well, given a fleet or fairly efficient two seaters, such as the Aptera, that use around 100Wh/mile on average, and that Americans drive roughly three trillion miles per year[4], we would need an additional 300 billion kWh worth of electricity generation per year, or a roughly 7.5% increase in generation. Since we probably could get away with a mix of one and two seat EVs, I'm guessing that 5% of current electricity generation could cover most of our transportation needs. Besides, it's not like we can't keep gasoline powered vehicles around for trips when more than one or two people are in a vehicle, it's just that since most of our vehicle miles are one or two people with minimal cargo, something like this could allow for some measure of energy independence and lower the cost swe pay, both directly as in fuel and maintenance, and indirectly via health care costs/lost productivity from pollution and trouble due to Carbon emissions.
[1]http://www.bts.gov/publications/national_transportation_statistics/html/table_04_09.html
[2]https://www.cia.gov/library/publications/the-world-factbook/print/us.html
[3]http://www.aptera.com/details.php
[4]http://www.fhwa.dot.gov/policy/ohpi/hss/faqs.htm |
Too late, tonight, and I have a full schedule tomorrow and Thursday, plus a car to repair on Friday (one of the few times I'm solid up for three consecutive days.) But I'll take your thoughts when I get a moment (maybe in between things, I can only hope) and see what I can agree with and what I'll need more from you about. Off hand, I definitely remember the DOE expecting to switch over the US passenger fleet to hydrogen in their 2040 plan and that requires, they project, some 150 million tons of H2 a year. That's 120MJ/kg of energy from H2, from memory. So that's more than 15 quads by itself. Your 300 billion kW-hr figure is 1 quad. Way, way below what the DOE is suggesting to meet their hydrogen plan. So without going any further at all, I'd like to ask you to help me save a little time and see if you can put this into context. I know you are making a case for miles driven, watt-hours per mile, and producing a number. But it is WAY off of what the DOE is suggesting and I'd like to have your opinion about why before I do some looking. Why is it that the DOE arrives at an energy requirement in the fuel itself that is 15 times higher? (Even taking into account a 60% fuel cell efficiency for hydrogen systems and even taking into account some differences in opinion about the amount of hydrogen estimated [National Academy of Sciences suggests 110 million tons instead of 150 million], I just can't get from here to there.)
Jon
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Say what you will about the sweet mystery of unquestioning faith. I consider a capacity for it terrifying. [Kurt Vonnegut, Jr.]
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yesplease
Velociraptor
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| Posted: Wed Feb 20, 2008 5:18 am Post subject: |
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| jonk wrote: | | Why is it that the DOE arrives at an energy requirement in the fuel itself that is 15 times higher? (Even taking into account a 60% fuel cell efficiency for hydrogen systems and even taking into account some differences in opinion about the amount of hydrogen estimated [National Academy of Sciences suggests 110 million tons instead of 150 million], I just can't get from here to there.) |
Offhand, I'm guessing the DOE is referring to retrofitting the current fleet, which is something that just can't be done with batteries due to cost constraints. The EV I referenced uses around 25 times less energy per mile than the average vehicle on the road today because it's roughly twenty five times more efficient due to relatively low weight and an aerodynamic shape, as necessitated by relatively high battery costs. If you shove a bunch of batteries, or a stack of fuel cells, in a two ton SUV with the aerodynamics of a brick, it's still a two ton SUV with the aerodynamics of a brick.
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jonk
Deinonychus
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| Posted: Wed Feb 20, 2008 3:22 pm Post subject: |
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| yesplease wrote: | | jonk wrote: | | Why is it that the DOE arrives at an energy requirement in the fuel itself that is 15 times higher? (Even taking into account a 60% fuel cell efficiency for hydrogen systems and even taking into account some differences in opinion about the amount of hydrogen estimated [National Academy of Sciences suggests 110 million tons instead of 150 million], I just can't get from here to there.) |
Offhand, I'm guessing the DOE is referring to retrofitting the current fleet, which is something that just can't be done with batteries due to cost constraints. The EV I referenced uses around 25 times less energy per mile than the average vehicle on the road today because it's roughly twenty five times more efficient due to relatively low weight and an aerodynamic shape, as necessitated by relatively high battery costs. If you shove a bunch of batteries, or a stack of fuel cells, in a two ton SUV with the aerodynamics of a brick, it's still a two ton SUV with the aerodynamics of a brick. |
That helps a lot. And it leads to other questions, since it probably isn't feasible to replace all light duty vehicles with that one particular vehicle type. I placed a table showing energy densities for various forms, including batteries through to cryogenic hydrogen, that sure puts the difficult questions to using batteries. Still, your point about 25X less energy per mile makes the battery question much more interesting. I need to look at that particular vehicle's details, even though yet again I don't think (being ignorant right now about it) that it is likely to be a panacea for the US or the world. It sounds very interesting to me just for technical reasons. Thanks for making me aware of it. By the way, I did find a comment from Romm, a man who oversaw the Energy Department's program for clean energy and alternative fuels at one time, suggesting that it is feasible that we could achieve up to 4X better overall Joules/mile efficiency with electric cars. Which, if I take it as an informed guess about things, might put a rational number we could accept tentatively for calculations.
I need to put all that into a larger context, of course. And keep in mind that we generate 3 watts and lose 2 watts just in conversion, distribution, and other losses to the home or business. Before it gets used. Electricity is the most high-valued, expensive (energy-wise) form we have. I'm tentatively holding the position that it should be used in hospitals and manufacturing, not wasted horribly for heating a home or passenger driving cars around.
Jon
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Say what you will about the sweet mystery of unquestioning faith. I consider a capacity for it terrifying. [Kurt Vonnegut, Jr.]
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yesplease
Velociraptor
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| Posted: Wed Feb 20, 2008 4:40 pm Post subject: |
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| jonk wrote: | | By the way, I did find a comment from Romm, a man who oversaw the Energy Department's program for clean energy and alternative fuels at one time, suggesting that it is feasible that we could achieve up to 4X better overall Joules/mile efficiency with electric cars. Which, if I take it as an informed guess about things, might put a rational number we could accept tentatively for calculations. |
The seems reasonable, assuming we retrofit/mimic the current fleet. But assuming we can retrofit the current fleet is unreasonable in terms of economics, both from the POV of electric or fuel cell powered vehicles. If... Fuel cells drop in price to where ICEs are today, maybe we can have a fuel cell powered fleet of similar size, but so far, given energy prices and the cost of alternatives, it looks like we will need to downscale.
| jonk wrote: | | I'm tentatively holding the position that it should be used in hospitals and manufacturing, not wasted horribly for heating a home or passenger driving cars around. |
I suppose, but we have so much of it. We waste a few percent each year on AC because it's not profitable to encourage insulation, incandescents because CFLs are dangerous, etc... We waste more than enough to power our hospitals. ; |
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jonk
Deinonychus
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| Posted: Wed Feb 20, 2008 5:46 pm Post subject: |
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| yesplease wrote: | | jonk wrote: | | I'm tentatively holding the position that it should be used in hospitals and manufacturing, not wasted horribly for heating a home or passenger driving cars around. |
I suppose, but we have so much of it. We waste a few percent each year on AC because it's not profitable to encourage insulation, incandescents because CFLs are dangerous, etc... We waste more than enough to power our hospitals. ; |
I must not have expressed myself well enough. The point here is that producing highly convenient electricity is an "uphill" move. It costs us very, very dearly to produce that kind of convenience. In pushing things uphill like that, with the then attendant costs of delivery (50% lost in transmission alone, if I remember), it's not something we can play stupid games with. We can't be idiots that way. There are other, better ways to heat and cool -- though not as convenient. But the point is that we MUST lose our desire for convenience. Using electricity, hard won and hard delivered to the siite, should be reserved for real needs in society. Not frivolously wasted. We pay too dear a price getting it in the first place.
Jon
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Say what you will about the sweet mystery of unquestioning faith. I consider a capacity for it terrifying. [Kurt Vonnegut, Jr.]
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yesplease
Velociraptor
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| Posted: Wed Feb 20, 2008 7:02 pm Post subject: |
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Electricity transmission is generally quite efficient[1].
| Wikipedia wrote: | | Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. |
It's far easier to regulate emissions from a centralized plant and have high efficiency of operation than it is to do the same from mobile generation, eg ICEs. While fossil fuels are advantageous due to high energy density, generally speaking they aren't nearly as efficient as newer batteries, not to mention the most energy dense substances we have, fissile materials, can provide more energy than fossil fuels ever could.
The biggest doubt in terms of electricity generation in the coming years is how exactly it will be done due to high precious metal prices (making centralized generation more expensive) and dropping distributed generation and storage costs (eg thin film solar and battery advances). We waste all forms of energy, and honestly, the only reason we don't waste more electricity is limits on energy transmission. If it had the energy density that liquid fossil fuels have, we'd likely be using, and wasting, far more, because it's financially remunerative to encourage conspicuous consumption. If the owners of these resources don't take this approach, and instead encourage moderate and sensible use, they would make a small fraction of the profit that they currently do.
[1]http://en.wikipedia.org/wiki/Electric_power_transmission |
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jonk
Deinonychus
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| Posted: Thu Feb 21, 2008 2:06 am Post subject: |
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| yesplease wrote: | Electricity transmission is generally quite efficient[1].
| Wikipedia wrote: | | Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. |
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I'm culling through the various charts and data at the DOE to get my figures, plus it's as much as stated that way. For example, current US nuclear production is 8 quads while the usable, delivered portion is less than 2.7 quads. There is a nice chart there that lays this out in picture form. I'll pull the sites together for you, later. Busy now.
Added: Take a look at http://www.eia.doe.gov/emeu/aer/pdf/pages/sec9_5.pdf . On that PDF page, look at the first column labeled "Nuclear Electricity Net Generation" and note the care in using "NET" in the title. Then look down at 2006 and see the preliminary number of 787.2 billion kW-hr there. Now, go to google and enter: "(787.2*10^12 watt*hour) in btu" Note that the answer is "2.68603789 × 10^15 btu" That is 2.686 quads. Now go to: http://www.eia.doe.gov/emeu/aer/diagram5.html and look at the picture titled "Electricity Flow, 2006" and take a look on the left side, which is the __generation__ side. There, you will see the figure for nuclear as 8.21 quads. You will also see most of the total electrical generation is not delivered. There is, on a different chart in a 10.3meg file, once you get to the net figure after the other losses, what are called "T&D" losses which are what I think you are talking about. That part of it is 251 billion kW-hrs out of something like 3900, which is 6.4% or so. But that's after the net, so what it left is kind of a net-net or something, I think. Take a look and see what you think. The reasons these make sense to me is that what I'm saying also conforms well to figures I've seen at the National Academies of Science on electrical __generation__; and elsewhere, as well. I can go contact a scientist in this area, if needed, to clarify. Perhaps that would be best.
Jon
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Say what you will about the sweet mystery of unquestioning faith. I consider a capacity for it terrifying. [Kurt Vonnegut, Jr.]
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yesplease
Velociraptor
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| Posted: Thu Feb 21, 2008 5:27 pm Post subject: |
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That's true of any fuel we use because we're converting heat energy into whatever else. But, in your post, the one I responded to, you stated transmission was 50% efficient, and I showed that by the accounts I linked it wasn't. I've never contended that generation isn't relatively inefficient, so I fail to see why you're bring it up since it has little bearing on what I was posting about.
In any event, out of all the conversion processes, electricity via it's different generation methods is by far more efficient than petroleum to the point where we get almost twice as much useful energy out of distributed electricity than get get out of distributed petroleum, even though we use more petroleum. If we convert heat energy to other forms of energy, mechanical, electrical, etc... we tend to have high conversion losses, regardless of source. But, like I stated in my previous post, we don't need to look at those conversion losses if the energy needed to run a fleet of efficient EVs is a fraction of what we use now. In other words, if we can run 95% of our vehicle miles per year in efficient EVs by switching to CFLs and improving building insulation/climate control management, we don't have a whole lot to worry about practically speaking.
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ouinon
chemical reaction
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| Posted: Fri Feb 22, 2008 8:42 am Post subject: |
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| yesplease wrote: | | Out of all the conversion processes, electricity via it's different generation methods is by far more efficient than petroleum to the point where we get almost twice as much useful energy out of distributed electricity than get get out of distributed petroleum, even though we use more petroleum. |
Thank you very much for that flow chart, yesplease. It is very interesting. I started off getting one conclusion from it which agreed with your conclusion above, but ended up with a different one after a second look. So now i am wondering which is the correct "judgement" on the situation.
ie: i agree with you that the efficiency of distributed electricity ( energy loss 8.7% maximum; don't know how much of each principal loss, industrial or residential, is related to the electricity use) is far higher than that of distributed petroleum ( energy loss 21.2% minimum).
But when i look at the overall efficiency of a particular energy with respect to its source materials electricity is slightly worse than petroleum ( at 31% net to petrol's 36% net).
ie; of 38% "raw" materials electricity provides 11.9% of total energy ( after losses) at end, whereas petroleum starts off with 39.2% raw materials and ends up providing ( after almost all losses taken off) around 19%, of which 5.2 is non-fuel, therefore about 14% energy.
Is that right? Being complete novice at all things theoretical about the environment dion't know if my interpretation is wildly and naively off the mark. 
I loved looking at the chart; was great fun, VISUAL; it connected. Was totally stunned  to discover how much energy is lost, in generating electricity, and in using petroleum. Why is petroleum use so wasteful?
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lau
Quinquaginta Novem! Male Gee-knee-us + silly bits.
Joined: Jun 18, 2006
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Location: Somerset UK
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| Posted: Fri Feb 22, 2008 10:52 am Post subject: |
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| OED wrote: | quad, n.12
[Shortened < QUADRILLION n.]
A unit of energy equal to 10^15 British thermal units (about 1.054 × 10^18 joules). |
To be consistently British, it would be a billiard BTUs, or just over a trillion joules. However, it's "multiply a millon by a thousand one less than four (=quad) times".
Anyway, the numbers on the chart are in quads, not percentages.
Getting from resources to distributed electricity is (11.9/38.2) 31% efficient. I.e. the loss involved in going from raw inputs to distributed (I assume "to consumer", so it is including the losses in distribution itself) electricity is huge (just over two thirds loss), but at that point, in a sense, it is all useful energy. Hardly any distributed energy is used for transportation.
Petroleum is much better used for anything but transportation.
However, that's what two thirds of it is used for, and there it is hugely wasteful - only (5.3/26.5) = 20% useful. (Although I wonder how they measure this... in one sense, almost all transportation is a complete waste of energy).
The diagram does not show relative efficiencies for the use of differing inputs in the white boxes. E.g. although you can heat a house with electricity, gas or fuel oil (petroleum product), at that point, I would hazard a guess that electricity is (approximately) 100% efficient, and the others less so (as both involve directly venting hot gasses to the outside, thus wasting some proportion of the energy). Electricity is an EXPENSIVE way to heat, because of the initial losses, but once it is delivered, there is no further loss.
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ouinon
chemical reaction
Joined: Jul 11, 2007
Posts: 3144
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| Posted: Fri Feb 22, 2008 12:55 pm Post subject: |
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| lau wrote: | | The numbers on the chart are in quads, not percentages. |
Thank you for the correction. Luckily, if only for my self esteem, it doesn't seem
to have any effect on the calculations at the level i was doing them at least!  
Thank you for the clarifications about the fuels.
| lau wrote: | | ... in one sense almost all transportation is a complete waste of energy.. |
Yes, i wondered whether petroleum might not be better used for other purposes after seeing this chart.
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yesplease
Velociraptor
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| Posted: Sun Feb 24, 2008 4:57 am Post subject: |
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| ouinon wrote: | Thank you very much for that flow chart, yesplease. It is very interesting. I started off getting one conclusion from it which agreed with your conclusion above, but ended up with a different one after a second look. So now i am wondering which is the correct "judgement" on the situation.
ie: i agree with you that the efficiency of distributed electricity ( energy loss 8.7% maximum; don't know how much of each principal loss, industrial or residential, is related to the electricity use) is far higher than that of distributed petroleum ( energy loss 21.2% minimum).
But when i look at the overall efficiency of a particular energy with respect to its source materials electricity is slightly worse than petroleum ( at 31% net to petrol's 36% net). |
Where are you getting the 31% net? I think that most of the losses for residential/commercial and industrial are via natural gas, so with electricity, the initial figures are 11.9 distributed to 26.3 lost, or on the high end, including the losses for residential/commercial and industrial, 9.9 useful units compared to 28.3 lost, at ~26% eff. Compared to 5.3 useful units compared to 21.9 lost, at ~19% eff, and we see that electricity production/use from many diverse inputs is more efficient than oil use.
| ouinon wrote: | | I loved looking at the chart; was great fun, VISUAL; it connected. Was totally stunned to discover how much energy is lost, in generating electricity, and in using petroleum. Why is petroleum use so wasteful? |
Petroleum is very wasteful due to most of it's use in personal transportation. The average car is operated at about 15% eff like I mentioned before, even though with a manual gear box, and changes to gearing as well as decent driver education, this could be closer to 30%.
That being said, as lau alluded to, it's "efficiency" of use is somewhat disingenuous.
| lau wrote: | | Although I wonder how they measure this... in one sense, almost all transportation is a complete waste of energy |
This is because when looking at efficiency, we look at the efficiency of engine operation, instead of the efficiency of transporting a single individual. According to this, if we all commuted in fully loaded semis, efficiency would be through the roof at 40+%. Otoh, if we all used small compact cars that only operated at 25% efficiency, our use would be much more inefficient. But, clearly efficiency isn't the only component, reducing use, even if efficiency takes a hit, is generally good IMO, since we consume less of a resource overall, but it would show up as reduced efficiency because when figuring well to wheels efficiency, only the engine's thermal efficiency is looked at, not the fuel used in transporting one person. A similar idea is that a Ford Expedition is more efficient, well to wheels, than a Chevy Corvette, but that's a bit silly because the Chevy clearly needs less energy to do the same thing. |
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