Proterra Catalyst electric bus sets records at Altoona in efficiency, gradeability, weight and acceleration
10 June 2015
Proterra has completed the structural testing program at the Altoona Bus Research and Testing Center with its new Catalyst battery-electric bus (earlier post), in the process setting records for efficiency, gradeability, weight and acceleration. The full public Altoona report is available here.
While conventional diesel buses average 3.86 mpg (60.9 l/100 km), the Proterra Catalyst achieved the best overall average fuel consumption rating yet for a 40' transit bus at 22.16 MPGe (equivalent to 10.7 l/100 km) (1.70 kWh/mile). Nearly six times more efficient than a diesel or CNG bus, the Catalyst is also ~15% more energy efficient per mile than its closest competitor’s electric bus on the same test (BYD, which averaged 1.988 kWh/mile), which translates to a lower lifetime energy consumption of 15%. Proterra’s new 40' bus is more energy efficient per mile than most light-duty trucks and SUVs on the road today.
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| Partial summary of energy economy results from Altoona report. Click to enlarge. |
In addition to energy efficiency, the Proterra Catalyst broke records in gradeability, weight, and acceleration.
Gradeability has been a historic obstacle for electric buses, which until now, weighed more and had less power, making steep inclines difficult if not impossible to climb. The Catalyst conquered a 15.5% grade, unprecedented in this test by an electric bus, making it an option to serve metropolitan areas with challenging topography in West Coast cities, including San Francisco and Seattle.
Made of carbon fiber and advanced composite materials, Proterra’s unibody design is a prime driver for its high performance with regard to weight and durability. With a curb weight of 27,370 lbs (12,415 kg), the Proterra Catalyst is not only lighter than any other electric bus, leading to greater efficiency, but is also more durable than buses made of aluminum or steel and less prone to corrosion. The transit industry has traditionally struggled with vehicle weight, especially for new technologies like hybrid, CNG and EV. By designing the vehicle from the ground-up, using the most advanced technology and materials, Proterra has eliminated the vehicle weight concern for EV.
The Proterra 40' Catalyst also achieved 0-20 mph acceleration in 6.7 seconds. Rapid acceleration is particularly critical for keeping routes running on time, allowing bus operators to move in and out of traffic with greater ease.
The Proterra Catalyst drivetrain features a 220 kW peak permanent magnet drive motor delivering 678 N·m (500 lb-ft) of torque, coupled to the Proterra 2-speed auto-shift EV transmission. The bus is powered either by an advanced Lithium Titanate fast-charge energy storage pack or an NMC extended range energy storage system.
To break not one, but four records at Altoona is a major milestone not just for us, but for the industry as a whole and is a testament to how far electric bus technology has come. In an industry hungry for innovation, to receive these kinds of results from rigorous testing organizations such as Altoona helps to assure transit managers and civic leaders that electric buses can outperform fossil fuel vehicles and are a durable and reliable investment.
—Ryan Popple, CEO of Proterra
It seems that the electric bus space is primarily occupied by Proterra and BYD. Subsidies aside, is there a site that has a spec comparison between the two? I'd think that the key comparisons would be the following:
1. Cost
2. Range
3. Recharge time
4. Passenger number
5. Acceleration
It would also be nice to know expected battery life, but that might be speculative.
Posted by: jzj | 10 June 2015 at 11:35 AM
@ jzj: Here is a link to the BYD specs: http://www.byd.com/na/auto/ElectricBus.html#p2.
I also found this at Proterra's site: http://www.proterra.com/wp-content/uploads/2015/05/Tearsheets_CatalystPlatform.pdf
Posted by: Brent Jatko | 10 June 2015 at 11:52 AM
Brett, thanks for the reference pages. Still, I could not get enough info to compare apples-to-apples. The buses are about the same size and hold about the same number of passengers, but the rest of the info is too variable or not present. About the most you can say is that the BYD has wheel-motors that don't seem especially powerful and 324KWH of battery, and the Proterra has a single motor that doesn't seem especially powerful and up to 770 pounds of battery, which might be around 35KWH, so the BYD can go a lot further (which may or may not matter, depending upon route and charging speed).
Posted by: jzj | 10 June 2015 at 12:49 PM
I wish Proterra well, but it has a tough battle with BYD which already has very large volume, in the thousands per year.
Good data is hard to come by, but the price of a BYD 'bus' ( there are actually more than one variant) is around $850k:
'A BYD electric bus costs approximately $850,000, Ortiz said, compared to the $400,000 for a regular diesel bus. Though more expensive, Ortiz said he anticipates the electric bus will be more cost-efficient to run.'
http://usa.chinadaily.com.cn/epaper/2013-09/18/content_16978814.htm
Proterra's upfront cost seems to be fairly similar, but the catch is:
'Proterra doesn't scale, though. Proterra requires an expensive infrastructure of $600,000 per charging station per route, BYD only requires a slow-charger at the depot for $6,000. What's more, BYD buses drive the cost for its battery technology down dramatically, while Proterra's SCiB technology is specialist use; BYD LiMnFePO4 can potentially power cars, taxis, grid storage, and more'
http://www.torquenews.com/2250/electric-bus-manufacturers-byd-and-proterra-are-making-serious-moves
(Inst, comment)
Proterra costs:
'As is the case with electric cars, electric buses are significantly more expensive than their gas-guzzling counterparts. According to the American Public Transportation Association, in 2012, the basic city bus cost $447,000 while hybrid diesel-electric buses cost $593,000.* The base price of a Proterra has fallen to $825,000, from about $1 million a few years ago. And purchasers don’t get a tax credit or rebate for buying one. “But we don’t need grant funding to make the business case work,” said Popple. Over the 12-year lifetime of a vehicle, a diesel bus can consume between $500,000 and $600,000 of fuel, while it would consume about $80,000 worth of electricity, based on average industrial electricity rates. At its current price, in other words, the lower-emission Proterra pays for itself over time in the form of lower operating costs.'
http://www.slate.com/articles/technology/the_juice/2014/09/electric_buses_proterra_wants_to_rid_america_of_emission_spewing_buses.html
So from the article above:
'Nearly six times more efficient than a diesel or CNG bus, the Catalyst is also ~15% more energy efficient per mile than its closest competitor’s electric bus on the same test (BYD, which averaged 1.988 kWh/mile), which translates to a lower lifetime energy consumption of 15%'
That 15% better efficiency than the BYD only comes out to $12,000 better than the BYD, or $1,000 a year.
And:
'BYD Coach and Bus announced a 12-year unconditional battery warranty for their Purpose Built Propulsion Battery used in their transit and over the road coaches.
“We know our Iron-Phosphate battery is the best battery on the market today.and we have no doubt they will outlast the life of the bus and now we have given our customers the peace of mind of knowing they’ve made the safe choice”'
http://www.masstransitmag.com/press_release/12058920/byd-announces-12-year-battery-warranty
I hope Proterra survive and prosper, but there is no question which is the juggernaut in the market.
Posted by: Davemart | 10 June 2015 at 03:48 PM
The Proterra e-bus has between 15% and 20% of the battery pack energy compared to BYD and is therefore much lighter but has much less range between recharges.
The BYD unit is best suited for longer routes and cold winter operation.
Many major Chinese cities have already ordered 1000+ BYD e-bus each. More Chinese manufacturers will produce equivalent e-buses shortly.
Both e-buses cost about 2X equivalent diesel units to purchase but the total cost is much the same after 8 to 10 years of operation (without counting the fair cost of pollution) and less than 4 to 5 years (counting pollution reduction at a fair price).
Our large cities should do like their Chinese counterpart and mandate accelerated replacement of all existing diesel city buses with e-buses.
Posted by: HarveyD | 10 June 2015 at 04:59 PM
@Harvey:
If the comment I quoted by Inst is correct, then the high cost of en-route chargers means that the Proterra would be way more expensive than the BYD.
Posted by: Davemart | 10 June 2015 at 11:54 PM
I think there is some confusion about the previous (and perhaps lighter) Proterra option with Lithium Titanate, at around 85 kWh if I recall, and the newer Lithium NMC option from Proterra going up to about 320 kWh. The Proterra NMC option has comparable range to the BYD but I believe they also retain the overhead fast charge option, which BYD does not. There are some routes where a third of a megawatt hour is not enough for full work day, apparently. I assume that most routes are fully served by >300 kWh and would not need an in-route fast charger, meaning either Proterra or BYB is competitive without an overhead charger.
Keep in mind that other North American transit bus OEMs such as New Flyer and Nova Bus either have or will soon have full EV buses on the market. Maybe even Gillig, though I have not seen their data.
Posted by: James McLaughlin | 11 June 2015 at 09:48 AM
I don't understand the $600,000 per charging station cost. The charging hardware can't be that expensive. It's just a surface contact system where the pickups rise to meet overhead outlet contacts.
The $600k number comes from a comment that furnishes no supporting link.
Posted by: Bob Wallace | 11 June 2015 at 02:50 PM
The choice between lighter/lower cost 100 kWh batteries and more charging stations and heavier/more costly 300+ kWh with charging facilities limited to end of routes is not an easy choice to make.
The mid-term (2020/2025) answer will probably be with 2X to 4X (400+ kWh) lighter weight battery packs with charging at end of bus routes only.
Upgrading of current e-buses with improved batteries will always be a possibility.
Posted by: HarveyD | 11 June 2015 at 05:20 PM
China is building and putting in operation more than 1000 large e-buses/month in 2015 and many more to come.
The majority have large capacity battery banks for extended range operation. It seems that 400+ kWh will soon be reached with near future 2X batteries.
The rest of the world will get on board by 2017/2018 and extended range city e-buses will be produced at 10,000+/month? Very few on-route recharge stations will be required.
Posted by: HarveyD | 14 June 2015 at 08:04 AM