NREL report: Battery-electric buses are four times more fuel-efficient than CNG


The National Renewable Energy Laboratory (NREL) has published a new report that found that Proterra’s battery-electric buses are nearly four times more fuel-efficient than comparable compressed natural gas (CNG) buses.

The study focuses on a pilot project for California’s Foothill Transit, in which 12 Proterra e-buses logged nearly 400,000 miles of on-road testing. The NREL team found that the battery-electric buses (or BEBs, in bureaucrat-speak) demonstrated average efficiency of 2.15 kWh per mile, which translates to about 17.48 miles per diesel gallon equivalent (DGE). The NABI CNG buses used for comparison had an average fuel economy of just 4.51 DGE.

NREL Report

The Proterra e-buses were also more reliable than their CNG ancestors, logging 133,000 miles between road calls (yes, MBRC), while the baseline CNG buses had an MBRC of about 45,000, which NREL said is “expected” for a new CNG vehicle.

The BEBs were on the road an average of 13.2 hours per day, receiving a 20 kWh recharge about 13 times a day.

While the BEBs trounced the CNGs in both DGE and MBRC, they also have a substantially higher up-front cost (UFC [OK, I just MTOU {made that one up}]): $904,000 apiece, compared with $575,000 for the CNG buses.


Source: National Renewable Energy Laboratory via Next-Gen Transportation

  • EMF

    That upfront cost is critical. At 133,000 miles quoted the equivalent fuel cost difference is roughly $210,000. That’s at a little over $2.00 per gallon of diesel. I’m guessing the buss is rated at 750,000 miles+/-. Over its expected service life it should be less expensive to own and operate. I wounded if it attracts more riders because its electric?

    • GearsOfWoe

      I wonder how, or if, transit authorities consider other less tangible benefits. I’ve used public transit for most of my life. The first time that I rode a trolley bus, I was amazed by how quiet and clean they were. It was strange not to hear the ubiquitous rumble of the Diesel engine when it came to a completely silent stop. Nowadays I look buses spewing exhaust, grinding and growling up the hill to my home and wonder at how much better they would be if they were electric.

      • EMF

        I think there will be a time in the not too distant future that people will cringe at the sight of billowing clouds of diesel fumes poring out of the back end of a bus.

    • Electric Bill

      EMG (ElectroMagnetic Force?!):

      You are tragically myopic, in a tragically common way: this is NOT just about a few numbers you can calculate on the back of an envelope, based on miles and gallons and years. It is more, even, than the enormous environmental costs associated with Climate Change.

      Just yesterday, inept, cowardly terrorists killed and injured hundreds of people in three attacks in Brussels. These attacks and hundreds of others going back even before the 9/11 tragedy could never have happened if we had simply gotten serious decades ago about finding a way of weaning ourselves off of OPEC oil, which is the major source of funding for terrorists as well as despotic regimes that have been responsible for much more severe human rights abuses than Cuba was ever accused of. Saudi Arabia recently executed 48 prisoners in a single day, some by decapitation. They were condemned to death for things that are not even crimes in the US or any civilized country; crimes such as criticizing the oligarchic Saudi regime, or blasphemy of their deity, even though it may have only been a rumored offense.

      Yet, like always, the US sat on its hands, shamefully mute and impotent, because this country and so many others are grossly addicted to their oil– to the same degree that they are addicted to our money… it is such a disgusting, sad co-dependency we suffer.

      If numbers are important to you, consider the hundreds of billions of dollars we spend annually (that figure is shifting wildly due to a number of factors including OPEC’s palpable fear of the costs of driving EVs coming anywhere close to the cost of driving an ICE car, something which always results in increased EV sales. And once a driver realizes how advantageous and guilt-free driving a EV is, he never goes back).

      Consider too, that those hundreds of billions of dollars leave this country, and the fuel we buy is, not a durable asset– very quickly it is literally up in smoke, never to be used a second time, as opposed to a TRUE asset such as furniture, appliances, computers, toys, and… BATTERIES, which can continue to be used and reused for years, and then recycled when no longer of service.

      And if those hundreds of billions of dollars does not leave this country for foreign oil, it stays here and continues to circulate in our economy and to be used to rebuild our decrepit health care system, education and schools, and roads and bridges.

      Simply put: do you want to spend your money supporting terrorists, or buying electricity for less money, which then stays here in the country… or, alternatively, maybe buying solar panels and a Powerwall to store those electrons to run your EV nearly cost-free?

      So… to me, it’s a no – brainer… let’s do, all we can to push EV use forward, and cut this OPEC co-dependency.

      BTW: anyone who drives an EV is the best friend to anyone still driving an ICE car, since EVs today have dramatically reduced the cost of gasoline due to the laws of supply and demand. So if you drive an ICE car, even if it’s not a NICE car, you can thank me.

      You’re welcome.

      Back to buses: it is my bet that a lot of riders would rather pay a little more for bus (not buss) fare for a year or to offset the cost of EV buses, just for the obvious advantages– I rarely ever need to use buses (not busses), but when I do I can’t stand their horrid vibration, noise, and odors. I have only ridden the electric passenger train here once, but it is so much more pleasant I realize I would ride the buses more often if they were replaced or converted.

      BTW: Adomani is a company right here in Southern California (city of Orange) that does very competent bus and truck conversions, as you see in the attachment… so yes, conversions are an option.

      I ache for the day our monies do not aid terrorists.

      • EMF

        Myopic? Me? Well, let’s leave that aside.
        Your overall point about the state of civil society and the international disruptive murderous band of loonies being funded by petro dollars is taken. Petro Euros and Petro Yuens are probably equally to blame as funding sources, given they buy a larger % of their energy from the region. The US imports less than 10% of its oil from the Middle East, has done for a long long time. Some years as low as 5%, If I had my way it would be 0%. Pre shale bloom, Canada was by far the biggest supplier of oil to the US. But all that aside, it’s irrelevant to my point. My point about the article was straight back of the envelope number crunching. The article was directed at the financial advantages of the electric bus over the CNG bus. It pointed out the considerable reduction in running and service costs. Then it pointed out the higher purchase price of the Electric bus. Unfortunately given the miles quoted, the whole point of the article was dissolved by that truth. And when the economics of EV mass transit work, which they do in the case of some BYD buses and coaches in many markets, they are fantastic. I am a huge fan of EVs. I look forward to the day when they are widely adopted, and believe that process is closer than most people think. But I believe the climate change issues are not persuasive. Security should be a persuasive argument. Ultimately, if you want people to buy EVs of any kind and put PVs and solar hot water on their homes, it has to financially work for the buyers. Musk et al are doing the only thing that will work to move the cause along; build the best mass produced batteries at colossal production numbers to reduce the unit cost. He and others like him are are providing one part of the two part equation to this issue, financial pressure on the legacy transport industry. We must provide the other critical side; political pressure.

      • Alexis Boom

        “Just the oppression of free speech”… on Disqus… an internet forum for opinions and ideas…

  • LEAFican

    Good data. Comparing to my Nissan LEAF I get about 4.2 miles/kWh on average. The Battery Electric Bus is slightly more than eight times less efficient than my LEAF. However if it transports over eight passengers then it would be more efficient (assuming the LEAF is driven solo). I would like to know the average passenger load during the test period.

    • Alexis Boom

      Since the bus pictured would carry 50-60 passengers then overall it is somewhat more efficient than your Leaf.

      Out of interest, what speeds are you doing to attain 4.2m/kW in your Leaf?