Opbrid Biberated Electric Buses in Spain

[micdhi]

Good evening
I think that the same author (P Langlois) has already given his opinion on compressed air.

http://web.mac.com/pierrelanglois/PLang ... -nov09.pdf

if I understood correctly, this is no longer the energy restored, like the masses of inertia, the electrical, hydraulic, and even pneumatic restitution.
it is a temporary recharge, so that the bus continues its course .....
for me it seems difficult to eliminate immediately, the compressed air, and even the hydraulics, you can very well recharge a hydraulic battery in a few minutes.
I said difficult because it lacks an important element it seems to me, THAT of the energy consumed upstream of the distribution organ, include the losses of the transfer.
cordially

[Christophe]

Thank you for this reminder ... and let's examine what Langlois said in his summary note about this study: http://iopscience.iop.org/1748-9326/4/4/044011/fulltext

Their conclusions are unequivocal: air-cooled cars
mé is not a viable avenue, for several reasons.

To demonstrate this, the authors compare three cars of 900
kg like Smart Fortwo (including driver's weight
We know that the petrol version of this small German car
consumes 5,2 liters / 100 km, and recent electric version uses
13,7 kWh / 100 km. The simulated compressed air version consumes
electricity also since it uses an electric compressor.

(...)

According to a study published in November 2009, a compressed air car consumes much more energy than an electric car (by a factor greater than 2,4), and emits more greenhouse gases than a gasoline car in Germany or the United States where there is a significant portion of coal-fired power plants

(...)

They thus estimate the energy loss at 55% between the electrical network and the
air motor of the vote. (...)

A diagram alone summarizes the energy inefficiency of compressed air as an energy carrier compared to electricity:

Figure 3. Primary energy required. When powered by renewable energies, the compressed air needs less energy per km than the gasoline car but significantly more than the battery car. The CAC needs 75% more primary energy than the gasoline because when the CAC is powered by a conventional coal plant.

Need to translate?

The only chance to pierce compressed air would be:
a) a cost of equipment and use (maintenance) much cheaper than electric propulsion ...
b) exclusive use of renewable energy

But it is far from being the case.

In terms of gain on greenhouse gas emissions it is not better:

4.3. Greenhouse gas emissions

Environmental performance as zero local emissions is one of the primary arguments for the compressed-air car. Indeed, noxious matter is not emitted locally when driving, thereby one of the main contributors to urban air pollution is eliminated. This benefit is shared by battery carsNote7. However, compressed-air tanks can be disposed of or recycled with less toxic waste pollution than batteries, depending on the precise recycling requirements. One important environmental concern relating to car use is the impact of cars on climate change. Greenhouse gas emissions themselves critically depend on the source of electricity used for charging batteries or running the CAC compressor. Whereas a compressed-air car or the BEV do not emit greenhouse gases (GHG) when operated, emissions are shifted to power plants. Emission levels then depend on the power plant characteristics.

In general there is a great deal of uncertainty associated with modeling the effect of electro-mobility on the grid. It is agreed that even huge penetration rate of electric cars can be serviced using the present power plant capacity if cars are mostly plugged-in at off-peak hours [15]. When advanced scenario-based simulations of overall grid growth, electricity dispatch and geographic generation distribution are performed, results are region specific. Usually emission reductions are larger than when assuming the current power mix [15].

Here, we calculate the emissions produced by electricity purchase from two different German utilities, RWE and EWS Schönau. Providers can be chosen in the German electricity market. Note that RWE produces the charging stations for the Smart ed in the Berlin trial. The power plant mix of RWE is dominated by coal plants, producing 887 g CO2 kWh – 1 [16], whereas EWS Schönau relies nearly exclusively on renewables and hydro-energy, producing 17.3 g kWh – 1 [17]. The future power plant mix of RWE crucially depends on policy decision, such as permissions for new coal plants.

Results are summarized in figure 4. The choice of power plant mix has significant impact on greenhouse gas emissions. The compressed-air car indirectly emits more than twice the greenhouse gases than its conventional counterpart when powered by RWE. The poor environmental performance of the CAC is due to its thermodynamic inefficiencies, see section 4.2. Even the BEV performs only similar to the gasoline car. In contrast, the CAC and the BEV mitigate greenhouse gas emissions considerably when a renewable energy provider is chosen. PG&E, a major Californian energy provider, has medium GHG emission (238 g CO2 kWh – 1). As a result, the deployment of both CAC and BEV produces some environmental benefits in California.

[chatelot16]

the idea of ​​a very low battery bus is good! but we can do better than reload at the 2 terminals! recharge in large streets easy to equip in catenary

compromise between troley bus with catenary everywhere and broken down at the slightest derailment of trolley and bus on battery charged at the end of the line

for me with sufficient road length, conventional lead-acid batteries are enough

the problem of the troley with 2 wire in the air is to catch the good wires after an interuption ... trolley with automatic pilot?

I prefer the simple catenary with 1 single wire in the air, which also requires a ground rail on the ground

[I Citro]

I did not want to take part in this subject, in particular because it tires me to constantly contradict bernardd on compressed air ...

Well done for finally putting an order of magnitude on the energy efficiency of compressed air ...

I remember that it is 2,4 times more energy-consuming than electric traction, which puts it roughly at the level of heat engines with the only advantage that there is almost no local pollutant discharge.

In terms of disadvantages, I note the ridiculous autonomy, noise, and maintenance comparable to the heat engine ...

I think the debate is closed.

[Alain G]

We kill ourselves over and over again, but he always comes back to try again and again!

I no longer have the will to fight against a concrete wall!


Thank you Christophe!

[dreamer]

Bonjour.

Christophe>
But if you want Dirk Pitt did it. Overall assessment of the thermal car, all inclusive: it's 22% we find the same (funny eh) with the electric car 22% but we will certainly find less with the air because there are 2 thermodynamic cycles with fairly low yields. .when there are only 1

Could you tell me the sources of this please?
I'm interested

Thank you

Otherwise, for compressed air, it looks badly crossed: /
Too bad it made you want.

Dreamer

[dedeleco]

You should think about the spring motor because it is not only compressed air to store energy by mechanically compressing something !!

There are a large number of compressible or deformable materials to store energy and not just air!
Springs, rubbers, plastics, and the one that stores the maximum energy per Kg is not so obvious, I do not see why it would be the air which stores the maximum of mechanical energy per Kg, tank included.
In addition, no more problem with the tank or the sealed piston and less maintenance !!

In general, especially for metals, the force increases with a decrease in the maximum possible displacement, but some rubbers and plastics are very solid, very resistant with large displacements (like tires) with properties adjustable to needs !!

[dirk pitt]

Bonjour.

Christophe>
But if you want Dirk Pitt did it. Overall assessment of the thermal car, all inclusive: it's 22% we find the same (funny eh) with the electric car 22% but we will certainly find less with the air because there are 2 thermodynamic cycles with fairly low yields. .when there are only 1

Could you tell me the sources of this please?
I'm interested

this is a small table that I made by gleaning and cross-checking a certain number of information on the net. everyone can find these values. each figure is questionable in itself since there is not a single value for a single condition but the orders of magnitude are there.
for example the heat engine can have yields ranging from less than 15% to more than 30% depending on the technology and especially the range of use.
I think that the values ​​in this table are rather optimistic for the thermal and rather pessimistic for the electric but it made me laugh to fall on the same value and then it allows to put off the controversies between the pro VE and the pro thermal.
Personally, the big advantage that I see in EV is not on its efficiency but on the fact that it can use a primary energy source other than oil in this example because electricity is only a vector energy and not a primary energy. moreover and more generally, I am convinced that precisely, for these qualities of "versatility", electricity is an energy vector of the future. (it is also already widely used)

[Christophe]

Thank you for the reminder dirk pitt, I do not know for what subject precisely you had made this comparison. I have not found using https://www.econologie.com/forums/search.php so if you don't mind, I'll make it a subject because it's important!

It was probably in this one https://www.econologie.com/forums/voiture-el ... t6294.html ou https://www.econologie.com/forums/la-voiture ... t6803.html but good considering the number of pages to search ...

There it's done: https://www.econologie.com/forums/voiture-el ... 10080.html

Springs, rubbers, plastics, and the one that stores the maximum energy per Kg is not so obvious, I do not see why it would be the air which stores the maximum of mechanical energy per Kg, tank included.

You answer the question yourself: it's not so obvious ...

If the energy applications of the springs have not gone beyond the baby mobile, the friction car or the mechanical winding watch, it may be that the storable energy can only be low ...

If we want more energy, the masses and efforts necessary for compression undoubtedly prohibit the use of springs.

There may be (had?) Other applications on a larger scale than the toy but there cold, I do not see ...

Ah if there is the spring mattress that helps you get up in the morning faster

[chatelot16]

for the spring, a few generations of mechanics and watchmakers go around: the watch spring is the best solution: it forces the steel blade to the maximum suportable stress: the rolled blade shape gives power in the form of easy to use rotation without too much weight

any other form of spring, instead of making a large number of turns at reasonable torque, would make a big effort and a weak stroke, so would require a heavy and expensive system

the result is known: a spring toy advances much less time than the same battery!

it is not even useful to calculate if it is 100 times less or 1000 times less: it is in any case too weak to hope that a better elastic material does something good

there is also the elastic twisted, for airplane: it's not glorious as a result, it's just very simple!

compressed air is between the 2: less density than the battery, better than the spring