0

I would like to start with a new project to convert a conventional school bus (approx 50 seater) to electric. The idea being that most School buses in my region are diesel which is ofcourse going to die in a few years. I would like to use the same bus body but convert it into a electric bus with a range of around 80-100 kms. Considering that a typical school bus runs for a maximum of 2 hours in the morning and then again 2 hours in the evening, giving it ample time for a good enough re-charge during the school hours. It would be a cheaper option (in the long run) for the schools as well as good for the environment. I need the community's opinion about the idea and I would be really grateful if you could point out the things I need to be careful about and what it would cost me(approximately) for this conversion assuming that the school bus to be converted would be made available free of charge.

closed as too broad by Rory Alsop, JPhi1618, Chenmunka, tlhIngan, MooseLucifer Jan 17 '18 at 20:22

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Have you checked out the Heavy trucks that are now electric? – Solar Mike Jan 17 '18 at 14:59
  • @SolarMike yes I have, but what are you getting at? – Ricky Jan 17 '18 at 15:26
  • I have no idea why my question was down voted, it is not really an invalid question in my opinion. – Ricky Jan 17 '18 at 15:27
  • @Ricky - I suspect it's because you're asking for costs, which is generally considered to be off-topic as it is very localised and changes rapidly. The question is also very broad – Nick C Jan 17 '18 at 15:41
  • @Ricky, your question was downvoted because it's very broad and not a great fit for our site. We try to not have opinion based questions (you specifically ask for opinions) and instead like focused questions that have factual answers. Also in the help pages you will see that shopping/pricing questions are also not considered on topic. That said, I did not downvote, but I did vote to close because it's not a good fit. – JPhi1618 Jan 17 '18 at 15:42
2

Diesel is not going to die in heavy vehicles. There is no other option. Large diesel engines are very energy efficient, and diesel has a much larger energy density than batteries. Also, cleaning the exhaust gases is more feasible in large vehicles when compared to small vehicles.

If you'd like to do the conversion, consider how much diesel the bus uses (30 L/100 km)? Consider then how long you want it to go (100 km)? So, 30 L of diesel is required. This is about 40 MJ/liter, or 1200 MJ or 333 kWh. Have you seen a 333 kWh battery pack? I certainly haven't but have seen much smaller battery packs, and even they are HUGE.

About 7 kg gives you 1 kWh, so you need more than 2 tonnes of batteries for your idea. Cost is $400 / kWh, so you need more than $100 000 for your idea. In contrast to this, 30 liters of diesel is 25 kg, about one hundredth of the weight of your batteries. A 30 liter diesel tank costs much less than $100 000. And I'm pretty sure your bus has more diesel than 30 liters.

My opinion: not worth it! (And before somebody complains, I picked up the 30 L / 100 km figure out of thin air. If somebody has more accurate figure, feel free to edit my answer.)

Edit: forgot that efficiency of large diesel engines is 33%, so you could divide the battery size by 3. But it's still quite a lot. So I remain unconvinced.

  • Thank you for your very valid points, however then it makes the whole electric trucks/buses theme irrelevant which is not the case. Ofcourse they are not talking about conversions per se, but the same logic would hold true to manufacture an electric-truck in the first place wouldn't it? – Ricky Jan 17 '18 at 15:23
  • @juhist - Have you seen what Elon Musk has in store for semi trucks? With a range of 300 or 500 miles (depending on the battery pack), it can move a normal amount of truck carried cargo. Figure a bus is not nearly as weighty as a semi truck filled with cargo. Should be easy to convert this tech over to a bus without issue and have it run all day long. – Pᴀᴜʟsᴛᴇʀ2 Jan 17 '18 at 17:45
  • @Pᴀᴜʟsᴛᴇʀ2 I partially agree that yes, you can do it, but seriously, at the prices of Tesla who are going to purchase those unless you get free parking, free bus lane usage rights, government tax incentives, etc.? And besides, a bus has parking and bus lane usage rights already. The answer might change in 10 years from now, however, due to improved battery technology. You can't improve diesels 3x but you can definitely improve batteries 3x. – juhist Jan 17 '18 at 18:26
  • The efficiency of electric vehicles is neither 100%(or close to that), so I think the actual figure will more likely be 2 times as less as your first guess, not 3 times as less. – Bart Jan 17 '18 at 19:49
  • @juhist - I guess you really didn't look at the Tesla model for how the trucks are going to work out. They suggest, due to the lower "cost of ownership" (ie: cost to run them & lower cost of maintenance), the owner would recoup the cost of the tractor within two years. Don't think busses or semi-tractors are cheap, by any means. I'm not a Tesla fanboy, by any means, but the future is here whether you're ready for it or not. Elan Musk is building better batteries right now. – Pᴀᴜʟsᴛᴇʀ2 Jan 17 '18 at 20:45
1

It's certainly feasible, but whether it's cost effective is another matter. Electric buses are readily available, and becoming more common in European cities, while trolleybuses (buses powered by overhead wires) have been in use since the 1880s.

The challenge, as @juhist says, is getting enough batteries. You need to consider the range you need. 2 hours in urban traffic is, I'm guessing, around 60 miles/100km? A bit of googling suggest 6mpg for a London double-decker, or 39L/100km, so juhist's figures aren't far off...

Wikipedia (https://en.wikipedia.org/wiki/Electric-vehicle_battery) suggests that the cost of batteries in 2016 was $145/kWh, so you're still looking at around $50k just for the batteries (I suspect the rest, motors, electronics, etc is cheap in comparison)

Of course, this cost will drop dramatically over the next few years as they become more common...

  • After more googleing - Volvo advertise a bus with a 76kWh battery, so that would be around $11k. However nothing in their brochure suggests what the range might be – Nick C Jan 17 '18 at 15:37
  • Thanks a bunch for the answer Nick, it does help bring things into perspective, I am guessing when Volvo is advertising something like that, it comes at a cost of extreme engineering too, considering the truck design overall with drag optimised aerodynamic body and similar optimisations taking into account, which are out of scope for the project idea that I am dealing with at the moment. – Ricky Jan 17 '18 at 15:58
  • You may also need to consider local vehicle laws - it may be that changing the power type means the vehicle has to be re-registered, and that in turn may mean it needs to meet the latest standards for safety, accessibility etc, which an older bug might not be able to do - e.g. the stereotypical US school bus doesn't have a low floor & ramp for wheelchair access – Nick C Jan 17 '18 at 16:09

Not the answer you're looking for? Browse other questions tagged or ask your own question.