efficiency_now:the_big_picture
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| efficiency_now:the_big_picture [2022/07/28 16:50] – [Literature] wfeist | efficiency_now:the_big_picture [2023/01/24 18:24] (current) – [Energy service: Transport] wfeist | ||
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| |<WRAP box 10cm>How relevant actually is space heating? The adjacent pie chart shows that the two energy services " | |<WRAP box 10cm>How relevant actually is space heating? The adjacent pie chart shows that the two energy services " | ||
| =====Energy service: Transport===== | =====Energy service: Transport===== | ||
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| - | \\ \\** $ e_{spez} = \frac {E_{sprit}}{s_{EDL}} = 80 \frac {kWh}{100 km} $ **\\ \\ | + | \\ ** $ e_{spez} = \frac {E_{sprit}}{s_{EDL}} = 80 \frac {kWh}{100 km} $ ** \\ \\ |
| (Incidentally this equates to almost exactly 8 litres per 100 km; this value has hardly changed over the decades((Although the technical efficiency of the motors has increased considerably in these periods. In this area the industry has applied improved efficiency almost exclusively for further increasing the engine power, vehicle weight and the final speed. This is often called the " | (Incidentally this equates to almost exactly 8 litres per 100 km; this value has hardly changed over the decades((Although the technical efficiency of the motors has increased considerably in these periods. In this area the industry has applied improved efficiency almost exclusively for further increasing the engine power, vehicle weight and the final speed. This is often called the " | ||
| </ | </ | ||
| - | |<WRAP box 10cm>The fact that this energy service (transporting a person from A to B) can certainly be provided with considerably higher efficiency also with a conventional car is shown in this slide. A mass of 1400 kg contains everything that is necessary for a good car - the car is also fast enough and with 45 kWh per 100 km, the specific consumption is only 56% of the total fleet average. Thus considerable increases in efficiency are also possible in car transportation and are even available with conventional vehicles on the market.</ | + | |<WRAP box 10cm>The fact that this energy service (transporting a person from A to B) can certainly be provided with considerably higher efficiency also with a conventional car is shown in this slide. A mass of 1400 kg contains everything that is necessary for a good car - the car is also fast enough and with 45 kWh per 100 km, the specific consumption is only 56% of the total fleet average. Thus considerable increases in efficiency are also possible in car transportation and are even available with conventional vehicles on the market.</ |
| |<WRAP box 10cm>The breakthrough in efficiency came with the use of electrical propulsion systems - because modern electric motors in this class have efficiencies of more than 95%, which is much higher than any combustion engine((Of course, some attention must be paid to how the electricity for this is produced ultimately - but even fossil fuel based modern gas-fired power plants have efficiencies higher than 50%, and even with such electricity the overall system is still always far better than using an internal combustion engine.)) . Added to this is the fact that electric motors can work reversibly: I can " | |<WRAP box 10cm>The breakthrough in efficiency came with the use of electrical propulsion systems - because modern electric motors in this class have efficiencies of more than 95%, which is much higher than any combustion engine((Of course, some attention must be paid to how the electricity for this is produced ultimately - but even fossil fuel based modern gas-fired power plants have efficiencies higher than 50%, and even with such electricity the overall system is still always far better than using an internal combustion engine.)) . Added to this is the fact that electric motors can work reversibly: I can " | ||
| - | |<WRAP box 10cm>The The limits of improved efficiency aren't yet reached with this, even for vehicles with combustion engines. A large car manufacturer had already created a prototype for a " | + | |<WRAP box 10cm>The The limits of improved efficiency aren't yet reached with this, even for vehicles with combustion engines. A large car manufacturer had already created a prototype for a " |
| |<WRAP box 10cm>As practice just shown, the efficiency of vehicles can obviously be improved to a great extent. Is there a limit to this in physical or technical terms? An initial clue for answering this question can be found in bicycle technology: if we calculate the (complete!) food intake of the person riding the bike as the energy expenditure (input) of the system, then this will result as 2.4 kWh per 100 km. This is just barely about 3% of the reference consumption. A bicycle is a vehicle with an extremely high technical efficiency. This will apply even if we additionally equip the bike with an electric hub motor - and we will then become a little faster on average. | |<WRAP box 10cm>As practice just shown, the efficiency of vehicles can obviously be improved to a great extent. Is there a limit to this in physical or technical terms? An initial clue for answering this question can be found in bicycle technology: if we calculate the (complete!) food intake of the person riding the bike as the energy expenditure (input) of the system, then this will result as 2.4 kWh per 100 km. This is just barely about 3% of the reference consumption. A bicycle is a vehicle with an extremely high technical efficiency. This will apply even if we additionally equip the bike with an electric hub motor - and we will then become a little faster on average. | ||
| Naturally the energy service here is not comparable to one with that of a car: I am slower, I don't have a roof over my head and I can't transport as many things. But, this technology can be expanded in this direction without problem. See Slide 32. | Naturally the energy service here is not comparable to one with that of a car: I am slower, I don't have a roof over my head and I can't transport as many things. But, this technology can be expanded in this direction without problem. See Slide 32. | ||
| - | </ | + | </ |
| The following video fits very nicely here, which shows the performance of a well-trained athlete on a bike: he manages a little more than one minute with a mechanical output of 700 watts ((' | The following video fits very nicely here, which shows the performance of a well-trained athlete on a bike: he manages a little more than one minute with a mechanical output of 700 watts ((' | ||
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| Racing professionals normally manage to reach speeds around 40 km/h on average with more like 350 W for a longer period of time. This is mechanical energy of around 0.9 kWh/(100 km) and matches the energy efficiency values of bicycles ((Note about the above-mentioned 2.4 kWh/(100 km): The value of 0.9 is solely the mechanical energy which a human can ' | Racing professionals normally manage to reach speeds around 40 km/h on average with more like 350 W for a longer period of time. This is mechanical energy of around 0.9 kWh/(100 km) and matches the energy efficiency values of bicycles ((Note about the above-mentioned 2.4 kWh/(100 km): The value of 0.9 is solely the mechanical energy which a human can ' | ||
| - | |<WRAP box 10cm> And we can be even more efficient than with bicycles. As demonstrated by this car of the University of Bochum participating in a Solar Competition: | + | |<WRAP box 10cm> And we can be even more efficient than with bicycles. As demonstrated by this car of the University of Bochum participating in a Solar Competition: |
| - | + | ===== Moving fast? ===== | |
| What does physics say about this? We have already learnt about the definition of the energy service in transportation (person-km or cargo-km). | What does physics say about this? We have already learnt about the definition of the energy service in transportation (person-km or cargo-km). | ||
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| Also for lighting, the improvement in efficiency was the most important parameter for achieving the currently customary level of comfort. It is still worthwhile to apply approaches in which light is used in a targeted way in the places where it is actually needed - and switch it off where it does not provide a benefit. However, with the level of efficiency available today, the provision of sufficient light at all times completely on the basis of renewable energy sources is possible, the couple of hours of electricity storage necessary for this is also easily available for such a small consumption.</ | Also for lighting, the improvement in efficiency was the most important parameter for achieving the currently customary level of comfort. It is still worthwhile to apply approaches in which light is used in a targeted way in the places where it is actually needed - and switch it off where it does not provide a benefit. However, with the level of efficiency available today, the provision of sufficient light at all times completely on the basis of renewable energy sources is possible, the couple of hours of electricity storage necessary for this is also easily available for such a small consumption.</ | ||
| - | =====Rebound-Effect?===== | + | ===== Rebound |
| In this example one can also discuss the question, what role the so called “rebound effect” can play. In order to “consume” the savings made possible by the improved light source, we would have to increase the luminous flux by a factor of 17. Of course, that is possible – but it’s actually not done in practice. Yes, there has been some improvement in illumination, | In this example one can also discuss the question, what role the so called “rebound effect” can play. In order to “consume” the savings made possible by the improved light source, we would have to increase the luminous flux by a factor of 17. Of course, that is possible – but it’s actually not done in practice. Yes, there has been some improvement in illumination, | ||
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| + | This article will show how this is possible in many ways: Passive House buildings require such a small amount of heating energy that the remaining demand is no longer difficult to meet, lightweight electric vehicles based on bicycle technology can be supplied with power from solar panels on the roof of the house, and LED lights only have an extremely small electricity demand. | ||
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| + | Moreover, there is no reason why we shouldn' | ||
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| + | The situation is different for efficiency potentials: these can in fact be implemented without having a debate on the virtues of abstinence; in many cases, there may even be an increase in the energy service, with the savings remaining high despite this. Everyone can benefit from exploiting these efficiency potentials, regardless of their position on these questions. || | ||
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| + | |<WRAP box 8cm> As an amateur astronomer, I would like to touch on a related subject: light pollution, which is increasing worldwide. We have become so used to the availability of cheap light all day long that in some places everything is lighted up even all throughout the night, with the consequence that often we can no longer see the stars in the sky, let alone the subtle band of the Milky Way - a real cultural deficit, robbing us of the connection to our cosmic home. Astronomic observations are increasingly becoming difficult.\\ \\ | ||
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| + | With growing material prosperity, more and more people can now afford to consume more of previously scarce goods. In my view this undoubtedly constitutes progress in overcoming hunger, disease, homelessness and shameless exploitation - that must be kept in mind by those who seek a solution exclusively in abstinence. However, if I already have 500 lux available to me on my desk then the next 500 by far will no longer be such an enormous increase in the quality of life. If I demand that such amounts of light at least should not be emitted into the night sky through the windows is a legitimate demand for the quality of life of my fellow human beings, particularly that of astronomers.\\ \\ | ||
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| + | **Conclusion: | ||
| ===== Energy service: communication, | ===== Energy service: communication, | ||
efficiency_now/the_big_picture.1659019856.txt.gz · Last modified: by wfeist