I like how ChatGPT thinks it would take at least five tower cranes to constuct that little shed/shelter.
Hydrogen vs. Battery Buses: A European Transit Reality Check
21–30 of 193 posts
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#22I think battery buses have comprehensively won this one, to be honest. The biggest hydrogen bus fleet seems to be 35 vehicles; there are many BEV bus fleets in the hundreds and some in the thousands. As a certified old person, I'm having trouble getting used to them. It is unnatural for a double-decker bus to pull up near-silently, and then move off smoothly when you get on. They are _supposed_ to vibrate violently a…
Where I live in the US my kids still take “cheese buses” to school that haven’t changed a bit. They’re diesel and you can hear them blocks away. When they pull up with their air brakes going off and their diesel shifting to idle it sounds like one of those spice miner things from Dune going to work. If they ever go electric I’m not sure how we’ll know it’s time to take the kids out. Won’t be able to hear them coming.
My school district has some that are electric and they are quite noisy also. sounds like gear noise mainly, so they must have a reduction gear or some sort of transmission. They also still have air brakes so you hear the compressor and the PSSSSHT of air when they stop.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#23Fundamentally battery buses are going to be cheaper to run. Regardless of initial outlay costs electricity that goes directly in with no conversion is achieving near 100% efficiency. Whereas with hydrogen that same electricity is being used to do electrolysis to get the hydrogen to begin with, compressing into fuel containers, travelling the fuel around the country and then pumping the fuel back in and then all the c…
> same electricity is being used to do electrolysis Nowhere in the world is electrolysis done at scale. Industrial hydrogen almost exclusively comes from steam methane reforming (SMR).
What do they do with the carbon?
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#24Earlier quoted context omitted.
> same electricity is being used to do electrolysis Nowhere in the world is electrolysis done at scale. Industrial hydrogen almost exclusively comes from steam methane reforming (SMR).
What do they do with the carbon?
either release to the atmosphere or inject into an oil well to increase well production.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#25Busses currently have big engines and fuel tanks (or motors and batteries). That intuitively makes sense - obviously a big vehicle needs more energy than a small one like a car. However, typical city bus routes spend most of their time under 30 mph, cutting aerodynamic drag by a whopping 90% compared to 70 mph highway cruising that a car does. With more work on rolling resistance (buying super-good bearings and fancy…
The low speed means they are using the power to accelerate against inertia, not to maintain speed against air resistance.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#26I'm not really sure there is any place for a discussion - you would need a whole new infrastructure for hydrogen powered buses, while keeping a lot of the downsides of fossil fueled air breathing vehicles (eq. air filters filters regardless of if you burn the hydrogen or use it in fuel cells). With battery buses - you might need to slightly beef up the local transformer and installs some new wires and that's it. Or e…
While I agree with you; just to be clear it's not "slightly" beef up the local transformer. If you imagine a medium sized depot with 50 buses stabled at any one time, and 300kW chargers (I believe you could go higher), that's 15MW peak which is not trivial to add in many cities overnight. You really need some sort of HV connection for that kind of load, the existing local LV distribution grid isn't going to handle it…
Luckily, humans are rather expert water-boilers at this point in time.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#27Earlier quoted context omitted.
Where I live in the US my kids still take “cheese buses” to school that haven’t changed a bit. They’re diesel and you can hear them blocks away. When they pull up with their air brakes going off and their diesel shifting to idle it sounds like one of those spice miner things from Dune going to work. If they ever go electric I’m not sure how we’ll know it’s time to take the kids out. Won’t be able to hear them coming.
My school district has some that are electric and they are quite noisy also. sounds like gear noise mainly, so they must have a reduction gear or some sort of transmission. They also still have air brakes so you hear the compressor and the PSSSSHT of air when they stop.
It wasn't easy, but the bus company managed to make their EV leak oil and need gear maintenance.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#28Busses currently have big engines and fuel tanks (or motors and batteries). That intuitively makes sense - obviously a big vehicle needs more energy than a small one like a car. However, typical city bus routes spend most of their time under 30 mph, cutting aerodynamic drag by a whopping 90% compared to 70 mph highway cruising that a car does. With more work on rolling resistance (buying super-good bearings and fancy…
The low speed means they are using the power to accelerate against inertia, not to maintain speed against air resistance.
Inertia that can then be recovered, which you can't with air resistance.
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#29Busses currently have big engines and fuel tanks (or motors and batteries). That intuitively makes sense - obviously a big vehicle needs more energy than a small one like a car. However, typical city bus routes spend most of their time under 30 mph, cutting aerodynamic drag by a whopping 90% compared to 70 mph highway cruising that a car does. With more work on rolling resistance (buying super-good bearings and fancy…
I'm not sure how important double glazing is when you're opening the inner air volume to ambient air every few minutes, but maybe?
Re: Hydrogen vs. Battery Buses: A European Transit Reality Check
#30Busses currently have big engines and fuel tanks (or motors and batteries). That intuitively makes sense - obviously a big vehicle needs more energy than a small one like a car. However, typical city bus routes spend most of their time under 30 mph, cutting aerodynamic drag by a whopping 90% compared to 70 mph highway cruising that a car does. With more work on rolling resistance (buying super-good bearings and fancy…
The low speed means they are using the power to accelerate against inertia, not to maintain speed against air resistance.
0.7 m/s^2 is a typical acceleration for a city bus - most people won't fall over whilst standing at that acceleration.
A city bus perhaps holds 50 70kg passengers = 3.5 tons of cargo, and a lightweight bus design is perhaps 6.5 tons (typical bus=10 tons). Total = 10 tons.
Peak Power required to accelerate 0.7 m/s^2 up to 30 mph = 93 kilowatts.
Which is car territory. The cheapest tesla model 3 has a 208 kilowatt motor, so would be plenty enough power.