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Georgia Tech life-cycle study finds TCO of medium-duty electric and diesel delivery trucks similar; electric life-cycle energy use and GHG lower than diesel

6 July 2013

Lee2
Life-cycle energy use and GHG emissions normalized with NYCC diesel case (8.06 MJ/t·km and 0.63 kgCO2e/t·km) at 100%. Numbers in red are net total including recycling effect. Credit: ACS, Lee et al. Click to enlarge.

Comparing life-cycle energy consumption, greenhouse gas (GHG) emissions, and total cost of ownership (TCO) of medium-duty electric and diesel urban delivery trucks for a range of drive cycles and electricity generation scenarios, a team from Georgia Tech found that all in all, the life-cycle energy use and GHG emissions of the electric truck are lower than that of the diesel truck, particularly for the frequent stop and low average speed (NYCC- and OCTA-type) drive cycles.

They also found that the total costs of ownership (TCO) of the electric and diesel trucks are similar. Over an array of possible conditions, the median TCO of electric trucks is 22% less than that of diesel trucks on the NYCC. However, the cost-competitiveness of the electric truck diminishes in drive cycles with higher average speed. Battery replacement along with EVSE will also greatly affect the relative TCO of the electric truck. The study is published in the ACS journal Environmental Science & Technology.

For both types of trucks, vehicle efficiency is important from the perspective of energy consumption, GHG emissions, and TCO over the vehicle lifetime. The TTW [tank-to-wheels] efficiency of the truck depends strongly on the drive cycle, and the electric truck is more likely to provide higher benefits with the NYCC-style driving conditions than with the CSHVC or similar conditions. Given the same drive cycle and thus the same vehicle efficiency, the electric truck would be more attractive to fleet operators with high truck utilization (VKT [vehicle kilometers traveled] demand), of course within the electric drive range.

Battery replacement is another key factor; to maximize the benefits from electric trucks, the durability and reliability of the automotive Li-ion battery are crucial, which might be advanced with technological development. Recycling of the EV Li-ion battery could also improve life-cycle energy consumption and GHG emissions. There is also variation by state in the electric truck’s comparative energy consumption and GHG emissions. For the baseline case, recent and projected future generation mixes result in similar or less energy consumption and GHG emissions of the electric truck compared to the diesel truck in most parts of the US.

—Lee et al.

For both types of trucks, vehicle efficiency is important from the perspective of energy consumption, GHG emissions, and TCO over the vehicle lifetime. The TTW efficiency of the truck depends strongly on the drive cycle, and the electric truck is more likely to provide higher benefits with the NYCC-style driving conditions than with the CSHVC or similar conditions. Given the same drive cycle and thus the same vehicle efficiency, the electric truck would be more attractive to fleet operators with high truck utilization (VKT demand), of course within the electric drive

For the study, the team used vehicle operation data from a FedEx Express parcel delivery diesel truck of GVW class 5 (16,001−19,500 lbs) and from 219 SEV Newton electric trucks in 63 cities across the US.

The research team calculated life-cycle energy use and GHG emissions including vehicle operation, vehicle production and end-of-life management, electric drive battery, and electric vehicle supply equipment; they also evaluated the total cost of ownership parameters with all monetary values in 2011 constant dollars.

Master.img-001
System boundary diagram. Credit: ACS, Lee et al. Click to enlarge.

The life-cycle energy use of the electric truck consists of three upstream components and two downstream components. The first upstream component accounts for indirect energy input for the production and distribution of power generation fuel and the construction, maintenance, decommissioning, and waste disposal of the power plant. The second upstream efficiency component is the electric power plant’s generation efficiency (ηpp). Electric grid transmission and distribution efficiency (from power plants to end-use customers) is the third component.

Downstream energy use of the electric truck comprises electric drivetrain (DC−DC converter, inverter, and electric motor) efficiency and the loss in charging/ discharging.

For the diesel truck, the overall energy use is composed of upstream efficiency of diesel fuel production and vehicle operation efficiency.

Lee3
Monte Carlo simulation results for different drive cycles (as a proxy for fuel economy), operational ranges (64 or 80 km; 40 or 50 miles), EVSE Level 1 or 2, and battery replacement (0 or 1) scenarios. Credit: ACS, Lee et al.Click to enlarge.

Among their other findings were:

  • Over the life-cycle the electric truck consumes 28% less energy (3.49 vs 4.86 MJ/ t·km) and emits 38% less GHGs (0.24 vs 0.38 kgCO2e/t·km) than the diesel truck in the baseline case for both the 2011−2012 and the 2025 projected US average electricity mix. (The difference in GHG emissions is larger than the difference in energy use due to diesel fuel’s larger fuel-cycle energy use and emissions per unit VKT and payload.)

  • The comparative energy consumption and GHG emissions vary depending upon the drive cycles and the electric powertrain efficiency for the baseline diesel truck efficiency case.

    For the NYCC drive cycle, for which the diesel truck achieves only 4.6 mpg (51.1 l/100 km), life-cycle energy use and GHG emissions are 39−54% and 48−61% less for the electric truck than the diesel truck, depending upon the electric powertrain efficiency.

    For the CSHVC drive cycle, for which the diesel truck achieves 8.6 mpg (27.4 l/100 km), the energy use of the electric truck is 14% and 34% less than the diesel truck for the lowest and highest electric truck efficiency, respectively.

    For the same drive cycle, the GHG emissions of the electric truck are 27% lower than the diesel truck for the lowest electric truck efficiency and 43% less for the highest. highest.

  • Results vary with the carbon-intensity of regional electricity generation. For the baseline case with the 2011−2012 US electricity mix, electric trucks have an energy efficiency advantage in most parts of the US, with the largest advantage in the Pacific Northwest. For GHG emissions, electric vehicles have the lowest relative emissions in the Pacific Northwest, the West, and in the Northeast.

  • Other than the battery replacement, TTW efficiency of both types of trucks, diesel fuel’s upstream efficiency, electric grid transmission efficiency, and coal power plant generation efficiency and GHG emissions are the top five variables with the most significant influence.

  • The relative TCO is most sensitive to the diesel truck’s fuel consumption (or fuel economy), VKT, and diesel fuel price scenario. The NPV of TCO differential is sensitive to battery replacement, battery price, and EVSE price.

Resources

  • Dong-Yeon Lee, Valerie M. Thomas, and Marilyn A. Brown (2013) Electric Urban Delivery Trucks: Energy Use, Greenhouse Gas Emissions, and Cost-Effectiveness. Environmental Science & Technology doi: 10.1021/es400179w

July 6, 2013 in Diesel, Electric (Battery), Fleets, Fuel Efficiency, Lifecycle analysis | Permalink | Comments (20) | TrackBack (0)

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“the baseline case with the 2011−2012 US electricity mix ”

More LCA double counting. BEV like to take credit for improvements to the grid. Since fossil fuel is the fuel used after nuclear and renewable energy are used up, you have to find a place where there is not some old inefficient coal plant running.

“largest advantage in the Pacific Northwest ”

That is easy to check: http://transmission.bpa.gov/Business/Operations/Wind/baltwg.aspx

Whenever the red line for thermal plants is above 2000 MWe those old coal plants are running to provide additional power.

My boat is on the Columbia River. Everyday I observe mile long trains carrying Powder River Basin coal to the two power plants.

Correctly done LCA show more emissions.

Here is Staples experience managing their electric delivery trucks:
http://www.greenfleetmagazine.com/article/3201/what-staples-expects-from-all-electric-medium-duty-work-trucks

'WT: When do medium-duty electric trucks make sense for a fleet? What's the
ideal application?

PAYETTE: What's not a good fit is if you have to take the truck out on the freeway and drive 20 miles at 55 mph. That will drain your battery too quickly.

The ideal setup is to be able to pull out of a terminal and make the first delivery within a mile of where the vehicle left. We have several of those situations at Staples.

In Los Angeles, for example, 180 of our routes operate between 35-70 miles per day. That's why electric vehicles are perfect for the L.A. market, as well as many other inner city ­metropolitan-type markets.

The shorter routes are actually more harmful for the diesels. We found that with some of our diesels in the L.A. market, we'll pull a download off the engine control module (ECM) and find the ECM called for a regeneration of the diesel particulate filter (DPF) 119 times, but was only able to complete the re-gen three times because the vehicle was not running long enough for the 20 minutes required to clean that filter out.

If we're making 50-60 deliveries per day, the truck is running about eight minutes between stops. The driver must pull the truck over to the side of the road, put it in park, hit the exhaust re-gen button, and let it go through a 20-minute re-gen.

By pulling those diesels out of the short-mileage routes and incorporating electric trucks, you're helping the diesel vehicles run cleaner and putting the electric in its optimal operating environment.

WT: What is the upgrade cost going to the all-electric versus diesel power?

PAYETTE: When you factor available federal and state funds, the cost of these electric trucks is roughly two times the cost of a conventional-powered diesel truck.

WT: How long do you anticipate it will take for you to recoup that investment?

PAYETTE: Understand that over the life of the vehicle, the equation in place today will change. Fuel prices will change; the electric rate I'm paying is likely to change. However, if you use today's numbers, here's what you're looking at:

If you're going to run a diesel truck on a 100-mile route at 10 miles per gallon, that's roughly $35 in diesel fuel to cover the route. In California, by charging electric trucks during off-peak hours, we're paying $9 in electricity to run the same 100-mile route. So that's about $8,900 per year for fuel and $2,300 in electricity.

Since we plan to keep these units in service at least 10 years, the overall differential is $66,000 per truck - if fuel remained $3.50 per gallon or $0.10-$0.12 per kilowatt hour. That alone offsets the incremental cost of the electric vehicle over 10 years without even talking maintenance.

WT: What's different with maintenance?

PAYETTE: On an equivalent 100 mile-per-day diesel vehicle, we spend roughly $900 per year in preventive maintenance - oil changes, filter changes, anti-freeze adds, and eventually transmission oil changes. With the electric vehicles, we take that down to $250 per year.

The electric trucks are only equipped with four grease fittings and no engine or transmission oil. The truck must still be taken to look at brake lines and other wear components that may be cracked. Overall, there is virtually nothing that goes wrong with these things.

You're running air disc brakes that, with regenerative braking (a system that leverages the motor to slow the truck when you take your foot off the accelerator, reducing wear on the brakes, while also restoring charge to the battery), gives us two to four times the brake life over a conventional set of hydraulic brakes.

The electric motors are expected to last about 20 years. By the fifth year, you get into what's called a "battery-­refresh" program. The truck is removed from service and the large battery pods are pulled off each side. They're opened up and disassembled. There are individual battery cells inside each pod, which are put through a complete regenerative process, one at a time. Any bad [cells] are removed, new ones are put in, and the battery pack is reassembled. They're good to go for another five years after that.

The estimated cost for this five years from now is between $4,000-$5,000. That's strictly an estimate, which assumes you need to replace at least 10 percent of the batteries on board.'

Electric delivery vehicles are viable, although of course there are currently subsidies, but at this stage that seems to me fair enough - there is no expectation that these will continue forever.

The fleets need to plan a bit more, since they are using a mix of long range capable vehicles and short range electric, but really we are way beyond the stage of wondering if it works.

It does.

The word hybrid is nowhere to be seen in this article, and that is a big omission in the study.

Create a diesel hybrid truck with a battery 1/4 the size of the EV version (or even less) and a small 4-cylinder clean diesel engine. Then run the diesel in long enough bursts that the emissions can be clean, and use thermos bottles and thermal management to keep the engine as warm as possible during off cycles.

Result: You have a vehicle that has a higher fossile efficiency and lower CO2/mile than the electrical version running on average grid mix.

Clean diesel hybrid is the best solution.

That's a great interview you linked, Dave. Reading the whole piece was certainly worth my time.

Thanks Bob.
Its nice that we have now reached the stage where electric vehicles are just part of the fleet, and can be evaluated pretty much in the same way as the rest of it.

Regarding Jus7tme's link, there are a whole host of hybrid, biomass and NG designs about, with Volvo at the forefront of development, and it is pretty difficult even to keep track of them all.

Exciting times in transport and road haulage!

What a waste of time, listening to some CEO greenwash with EEV from the state of elsewhere emissions.

Not too long ago LA threatened to boycott Arizona. A Arizona power commissioner said fine, we will start with electricity.

California has already solved its air pollution problem without BEV.

@KP, be sure and tell the CA ALA:

"Nearly ninety percent of Californians still live in counties plagued with unhealthy air, particularly in the
San Joaquin Valley, Los Angeles, Inland Empire, and Sacramento. That means people are at greater risk
for asthma attacks, heart attacks, and premature death."

http://www.lung.org/associations/states/california/assets/pdfs/sota-2013/sota-2013-press-release-english.pdf

KP, your a barometer of wrong.

“KP, your a barometer of wrong. ”

Let me check the current air quality in California @ http://www.airnow.gov/

Not wrong! There is no plague of unhealthy air. Air quality is mostly good with a little of moderate pollution.

So why would fear mongers say there is a plague?
“Ways to Donate”

So how are the scam artist over at the American Lung Association doing?

“Every year, more than 36,000 California kids will start smoking. Preventing youth smoking saves lives, since 90 percent of smokers began smoking by the age of 18.”

"So how are the scam artist over at the American Lung Association doing?"

KP, only you would know.

@Kelly

Lots of people know the difference between non-profits organizations that carefully and effectively use our contributions or tax dollars.

Maybe fear mongering is a good way to raise money.

http://abcnews.go.com/blogs/health/2013/04/24/los-angeles-tops-dirty-air-list-for-13th-time-in-14-years/

http://www.psfk.com/2013/06/los-angeles-air-pollution-map.html

http://www.cbsnews.com/8301-204_162-57581250/state-of-the-air-report-finds-improvements-in-u.s-air-quality-but-smog-problems-persist/

etc, etc as Kit P is swamped by a endless world of scam artists fear mongering his every turn.

However, the article charts reflect well on low EV pollution levels AND economics.

“the article charts reflect well on low EV pollution levels AND economics. ”

The LCA is about ghg emissions not general pollution. Economics are not discussed at all.

Let me check the current air quality in California @ http://www.airnow.gov/

When you post a link over and over to real time measurements, it is true.

Some believe if you tell a lie often enough some will believe it. Of course if you tell the truth often enough some will learn.

And...the advantages will soon be multiplied with next generation, 4,000 to 10,000 cycles, ultra quick charge batteries with 2X to 4X the energy density?

Read the LCA! The life of the batteries and the time it takes to charge them are not important factors.

It is the source of power and the energy lost heating the battery during charging and discharging the prevents BEV from reducing ghg.

BEV are a poor choice to solve any problem.

"It is the source of power and the energy lost heating the battery during charging and discharging the prevents BEV from reducing ghg."

EVs would have been a lot "dirtier" a few years back when the US got 57% of its electricity from coal and none from non-hydro renewables. Now we get 37% from coal and 5.4% from non-hydro renewables.

Coal use will continue to drop. We've got around 100 of the least efficient plants scheduled to close in the next few years. New EPA regulations could close 100 to 200 more.

Renewables totally dominated new capacity installed in the first half of 2012.

BEVs run on 100% coal-produced electricity would be slightly worse than ICEVs in terms of greenhouse gases. But since our grid is not 100% coal, or even 100% fossil fuel, BEVs run on current grid power give us a drop in GHGs now. And it will get better and better.

Of all our options for powering vehicles batteries are the least lossy. About 10% of the energy is lost in battery charging. All but 10% of the energy in the batteries make it into kinetic energy. About 80% of the power at the plug makes it to moving the vehicle.

ICEVs waste about 80% of the energy that's in the gas tank. Before the fuel gets there major energy losses occur between the oil field and gas pump.

Hydrogen FCEVs, the only other option at the moment, are big energy losers. Out of 100 kWh of renewable electricity only 30 kWh or so make it to kinetic energy.

So we've got BEVs at 80%, FCEVs at 30% and ICEVs at 20% (with 0% renewable energy input). That's not a fair race....


“So we've got BEVs at 80%, FCEVs at 30% and ICEVs at 20% (with 0% renewable energy input). ”

BS Bob is very good at making up stuff but not a clue about engineering. The amount of energy that a BEV uses is very easy to measure. How many kwh did you use? With all those BEV out there you would think that some of them would tell.

For example, just bought 13.5 gallons for my work truck with 10% coming from ethanol.

Add in the petroleum input for that ethanol and tell us the very low single digit renewable portion of your 13.5 gallons.

Last time checked, it does not take much oil to make ethanol. NG, coal, and power do provide some energy.

There are many LCA on on ethanol. Much better than hauling batteries around and a lot cheaper.

Way to go American farmers.

Electric vehicle cheer leaders who think the electric car will be the solution to our pollution problems better think again. Check out July 2013 IEEE Spectrum article "Unclean at Any Speed".

http://spectrum.ieee.org/energy/renewables/unclean-at-any-speed

A study by the National Academies concluded that the health and non climate damage from Electrics will exceed the damage from conventionally fueled cars. This is the case even considering changes to the grid and vehicle technology improvements in the future. Low sulfur diesel, gasoline from tar sands, compressed natural gas, out perform electrics. Only fuel cell cars fare worse.

A similar study done in Norway which appeared in The Journal of Industrial Ecology last October comes to the conclusion "Electric vehicles consistently perform worse or on par with modern combustion engine vehicles, despite virtually zero direct emissions during operation."

If nothing is changed, this may (will) be the first time that the next generation (our children) life expectancy will be lower than ours.

Air pollution is not the only factor but it is a contributing factor. Industrial and junk foods are certainly important factors.

This is not a dream or guess but facts based on recent data from industrial countries.

Will this trend be reversed or will it increase at a higher rate with our grandchildren?

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