[AnthonyMouse]

That's efficiency, not range. Suppose hilly terrain reduces range by a third for electric vehicles and half for diesel. The diesel bus just fills up twice as often. The electric bus needs a 50% bigger battery in order to finish the same route without stopping to charge, and then it becomes 70% because it has to lug the bigger battery up the hills.

You can just... do that, but that doesn't mean it's not a thing you have to do, and it's not free.

[adrian_b]

It is impossible for a hilly terrain to reduce the range by a third for well-designed electric buses.

The efficiency of regenerative braking increases with the power of the vehicle. The electric efficiency should be well over 90%, perhaps even 95%. The mechanical losses will lower the total efficiency to much smaller values, but even so, the total efficiency should be over 80%.

A bus with an ICE will consume 5 times more extra energy for climbing the hill and it will also consume energy while going downhill.

Values like a 50% greater battery are unrealistic, and a heavier battery adds much less to the consumption than by how much it is heavier, even when going up the hill (because most of the extra energy consumption is also recovered).

In a certain city, it may happen that the bus routes are so long that batteries are not competitive with ICEs, at least for now. However, the presence of hills in any city can only make electric buses more advantageous, not less advantageous, due to much greater cost savings for fuel and maintenance. Buses with ICEs that are operated on hilly routes also need extra maintenance, besides increased fuel costs. Well-designed electric buses do not care whether they are operated in conditions requiring higher torque.

Like I have said, I have lived in cities with hills and with electric trolley buses and there was no doubt that the trolley buses were superior to buses with ICEs exactly on the routes that were going up and down over hills.

[AnthonyMouse]

> The efficiency of regenerative braking increases with the power of the vehicle. The electric efficiency should be well over 90%, perhaps even 95%. The mechanical losses will lower the total efficiency to much smaller values, but even so, the total efficiency should be over 80%.

It's not just about conversion efficiency. Moving a vehicle up a hill requires several times as much power as traveling on level terrain, which heats the battery. Reaching the top of the hill and starting regen when going back down again, also heats the battery. On normal terrain that isn't all hills there will be level sections in between that allow the battery to cool. If the terrain doesn't have that then the battery gets too hot and the vehicle will disable regenerative braking and use friction braking to allow the battery to cool off. The steeper the hills are, the more heat is generated per unit time.

Batteries also have charge curves. In the extreme case you start at a higher elevation, go down a hill and can't use regen at all because the battery is full and there is nowhere to put it, but then you have to spend energy later to get back to where you started. The same is true even if the battery isn't fully charged, because extreme charge levels require charging to be done gradually and the battery might not be able to take as much power right now as a heavy bus would generate descending a steep grade.

> A bus with an ICE will consume 5 times more extra energy for climbing the hill and it will also consume energy while going downhill.

Modern engines will cut fuel entirely when descending a grade.

> the presence of hills in any city can only make electric buses more advantageous, not less advantageous, due to much greater cost savings for fuel and maintenance.

That doesn't contradict the point that they'll need to have larger batteries to achieve the same range on hilly terrain.

[mike-the-mikado]

If the passengers all ride up hill and walk down hill?

[AnthonyMouse]

Or they ride up hill and then get off the bus for the night because the residential district is at a higher elevation than the business district.